阅读说明：本技术 铅蓄电池用液口栓以及铅蓄电池 (Liquid tap for lead storage battery and lead storage battery ) 是由 武藤诚 于 2020-10-27 设计创作，主要内容包括：本发明提供一种被改进的浮子式的铅蓄电池用液口栓。铅蓄电池用液口栓具备筒状部与浮子,该浮子具有位于筒状部的筒轴方向的一方的开口侧的浮子主体、及与浮子主体的筒轴方向的移动连动,并在筒状部的筒轴方向的另一方的开口侧位移的连动部。铅蓄电池用液口栓构成为进一步具备：盖体,其能够对筒状部的另一方的开口进行开闭；盖体用密封部,其在盖体关闭的状态下配置于筒状部的另一方的开口与盖体之间；以及过滤器,其配置于在筒状部的侧壁以及盖体的至少一方形成的贯通孔,或者铅蓄电池用液口栓构成为具备从筒状部的一方的开口突出并且介于一方的开口与浮子主体之间的板状的突出体,并在突出体的一部分形成有贯通突出体的第一贯通路。(The invention provides an improved float-type liquid port bolt for a lead storage battery. The liquid tap for lead-acid battery comprises a cylindrical part and a float, wherein the float has a float body positioned at one opening side of the cylindrical part in the cylinder axis direction, and an interlocking part interlocked with the movement of the float body in the cylinder axis direction and displaced at the other opening side of the cylindrical part in the cylinder axis direction. The lead-acid battery liquid port plug is further provided with: a lid body capable of opening and closing the other opening of the cylindrical portion; a lid sealing portion disposed between the other opening of the cylindrical portion and the lid in a state where the lid is closed; and a filter disposed in a through hole formed in at least one of the side wall of the cylindrical portion and the lid, or a liquid vent plug for a lead-acid battery includes a plate-like protrusion protruding from one opening of the cylindrical portion and interposed between the one opening and the float main body, and a first through-passage penetrating the protrusion is formed in a part of the protrusion.)

1. A liquid port plug for a lead-acid battery, comprising:

a cylindrical portion;

a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion;

a lid body capable of opening and closing the other opening of the cylindrical portion;

a lid sealing portion disposed between the other opening of the cylindrical portion and the lid in a state where the lid is closed; and

and a filter disposed in a through-hole formed in at least one of the side wall of the cylindrical portion and the lid body.

2. The port plug for lead-acid battery according to claim 1,

the lid has a convex portion protruding toward the other side in the cylinder axis direction in a closed state and at least a part of which is formed of a transparent material,

the interlocking portion of the float can protrude into the convex portion of the closed cover,

the through hole in which the filter is disposed is formed in a position different from the convex portion in the side wall of the cylindrical portion and the lid body.

3. The port plug for lead-acid battery according to claim 1 or 2, characterized in that,

the through hole is formed in a side wall of the cylindrical portion.

4. The lead-acid battery port plug according to any one of claims 1 to 3,

further, the filter device is provided with an annular filter sealing portion disposed between the through hole and the filter.

5. The port plug for lead-acid battery according to claim 4,

the through hole is cut open on the other side of the cylindrical portion.

6. The port plug for lead-acid battery according to claim 4 or 5,

the lid sealing portion and the filter sealing portion are integrally formed.

7. The port plug for lead-acid battery according to claim 5 or 6,

the cover body is provided to the cylindrical portion so as to be openable and closable about a predetermined rotation axis and has an engaging portion that engages with the cylindrical portion,

the through hole is located between the rotation shaft and the engagement portion when viewed from the rotation shaft direction.

8. The liquid vent plug for lead-acid battery according to any one of claims 1 to 7,

the lid body is further provided with a communication portion that communicates the inside of the cylindrical portion with the outside on condition that the internal pressure of the cylindrical portion becomes equal to or greater than a reference value in a state where the lid body is closed.

9. The port plug for lead-acid battery according to claim 8,

the communication portion is configured to release the engagement between the cylindrical portion and the lid body on the condition that the cylindrical portion is engaged with the lid body and the internal pressure of the cylindrical portion is equal to or higher than the reference value.

10. The port plug for lead-acid battery according to claim 8,

the communication portion is disposed on at least one of the cylindrical portion and the lid body, and is configured to open when the internal pressure of the cylindrical portion is equal to or greater than the reference value.

11. A lead-acid battery is characterized by comprising:

a housing formed with a mounting hole,

The lead-acid battery liquid inlet plug according to any one of claims 1 to 10 attached to the attachment hole of the case, and

and the positive electrode and the negative electrode are accommodated in the shell.

12. A liquid port plug for a lead-acid battery, comprising:

a cylindrical portion;

a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion; and

a plate-like protrusion protruding from the one opening of the cylindrical portion and interposed between the one opening and the float main body,

a first through-hole is formed in a part of the protrusion to penetrate the protrusion.

13. The port plug for lead-acid battery according to claim 12,

the first through-passage is a slit that opens at a peripheral edge of the protrusion.

14. The port plug for lead-acid battery according to claim 13,

at least a part of the first through-passage is located in the cylindrical portion in the cylinder axis direction.

15. The lead-acid battery port plug according to any one of claims 12 to 14,

a second through passage penetrating the cylindrical portion is formed in the one side of the cylindrical portion.

16. The port bolt for lead-acid battery according to claim 15,

at least a part of the second through passage is located on the other side in the tube axis direction than an inner wall surface of a case of the lead-acid battery to which the lead-acid battery liquid tap is attached.

17. A lead-acid battery is characterized by comprising:

a housing formed with a mounting hole,

The lead-acid battery tap according to any one of claims 12 to 16 attached to the attachment hole of the case, and

and the positive electrode and the negative electrode are accommodated in the shell.

Technical Field

The technology disclosed in the specification relates to a liquid port plug for a lead storage battery.

Background

The lead storage battery is mounted on, for example, an electric vehicle such as an automobile, and is used as a power source for the electric vehicle and a power supply source for supplying electric power to electronic components mounted on the electric vehicle. In such a lead-acid battery, a float-type liquid port plug for replenishing the electrolytic solution is often provided.

The float-type liquid port plug includes a cylindrical portion and a float. The cylindrical portion is formed with an injection hole for replenishing the electrolytic solution and is attached to an attachment hole formed in the case of the lead-acid battery. The float has a float main body positioned in the housing, and an interlocking portion that can protrude from the upper end opening side of the cylindrical portion in interlocking with the movement of the float main body. When the liquid level of the electrolyte in the case changes, the float body moves up and down, and the length of the projection of the interlocking portion on the upper end opening side of the cylindrical portion changes in interlocking with the change. Therefore, the height of the liquid level of the electrolyte in the case can be grasped from the length of the protrusion of the interlocking portion (see, for example, patent document 1).

Patent document 1: japanese Kokai publication Sho-52-59224

Conventionally, a float-type spout plug has not been sufficiently studied, and there is still room for improvement.

Disclosure of Invention

In the present specification, a technology capable of providing an improved float-type liquid inlet plug for a lead acid battery is disclosed.

The lead-acid battery liquid port plug disclosed in the present specification includes: a cylindrical portion; a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion; a lid body capable of opening and closing the other opening of the cylindrical portion; a lid sealing portion disposed between the other opening of the cylindrical portion and the lid in a state where the lid is closed; and a filter disposed in a through-hole formed in at least one of the side wall of the cylindrical portion and the lid body.

Further, the lead-acid battery liquid inlet plug disclosed in the present specification includes: a cylindrical portion; a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion; and a plate-shaped protrusion protruding from the one opening of the cylindrical portion and interposed between the one opening and the float main body, wherein a first through-passage penetrating the protrusion is formed in a part of the protrusion.

Drawings

Fig. 1 is a perspective view showing an external configuration of a lead storage battery 100 according to the present embodiment.

Fig. 2 is an explanatory diagram showing the XZ cross-sectional structure of the lead-acid battery 100 at the position II-II in fig. 1.

Fig. 3 is a perspective view (closed posture) showing an external configuration of the liquid inlet plug 200.

Fig. 4 is a perspective view (open position) showing an external configuration of the spout plug 200.

Fig. 5 is an explanatory diagram showing the XY cross-sectional structure of the lead acid battery 100 at the V-V position in fig. 4.

Fig. 6 is an explanatory view showing a YZ plane structure of the spout plug 200.

Fig. 7 is a perspective view showing an external appearance structure of the integrated packing 250.

Fig. 8 is an explanatory diagram schematically illustrating the operation of the embodiment and the comparative example.

Fig. 9 is an explanatory diagram illustrating a method of measuring the internal pressure of the spout plug 200.

Description of the reference numerals

100 … lead-acid battery; 101 … casing; 102 … electrolytic cell; 104 … plate groups; 106 … cover; 106A, 530 … mounting holes; 107 … lower surface; 110N … negative plate; 110P … positive plate; 112P … current collecting means; 120 … spacers; 150N, 150P … terminal portions; 200. 200a … liquid port plug; 210 … cylindrical portion; 211 … injection holes; 212 … outer cylindrical wall portion; 214 … an inner cartridge wall portion; 216 … second engaging projection; 220 … support portion; 222 … through hole; 224 … catch projection; 226 … through holes; 228 … side slits; 230 … a cover; 230A … handle portion; 230B … cover projection; 232 … peripheral wall portion; 234 … upper wall portion; 236 … first snap fit projection; 240 … a float; 242 … float body; 244 … a rod-shaped portion; 244A … marker; 246 … projection; 250 … integral packing; 252 … packing for the cap; 252A … groove; 254 … packing for filter; 255 … opening; 256 … Filter tank; 257. 258 … contact tabs; 259 … fastening the convex strip; 260 … sealing member; 270. 270a … protrusions; 272 … slits; a 280 … filter; 282 … filter ribs; 290 … valve mechanism; 500 … casing for measurement; 502. s … inner space; 510 … introduction holes; 520, 520 … outlet orifice; 600 … pressure gauge; g … gas; h … hollow; upper ends of P1 and P2 …; a U … electrolyte; y1 … rotation axis; z1 … center axis.

Detailed Description

(1) Conventionally, a case where a filter is provided to a float-type spout plug has not been sufficiently studied, and in the present specification, a technology capable of providing a float-type spout plug for a lead acid battery having a filter is disclosed. This technique can be realized as the following mode.

(1-1) A lead-acid battery port plug disclosed in the present specification comprises: a cylindrical portion; a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion; a lid body capable of opening and closing the other opening of the cylindrical portion; a lid sealing portion disposed between the other opening of the cylindrical portion and the lid in a state where the lid is closed; and a filter disposed in a through-hole formed in at least one of the side wall of the cylindrical portion and the lid body. In the liquid port plug for a lead-acid storage battery, when the lid body is closed, the sealing property between the opening of the cylindrical portion and the lid body is ensured by the lid body sealing portion. The filter is disposed in a through hole formed in the side wall of the cylindrical portion or the lid body. Therefore, when the present liquid vent plug for a lead-acid battery is attached to the case of a lead-acid battery, gas generated by gassing or the like in the case of the lead-acid battery can be discharged to the outside through the filter.

(1-2) in the port plug for a lead-acid battery, the lid may have a protrusion protruding toward the other side in the cylinder axis direction in a closed state and formed at least partially of a transparent material, the interlocking portion of the float may protrude into the protrusion of the closed lid, and the through hole in which the filter is disposed may be formed in a position different from the protrusion in the side wall of the cylinder portion and the lid. In the liquid vent plug for a lead acid battery, a filter is disposed at a position other than a projection of a lid body from which a float projects. According to the liquid port plug for a lead-acid battery, the visibility of the float can be ensured and the effect of the filter can be obtained in the state where the lid is closed.

(1-3) in the lead-acid battery liquid port plug, the through hole may be formed in a side wall of the cylindrical portion. According to the lead-acid battery liquid port plug, the filter is disposed in the through hole formed in the side wall of the cylindrical portion. This can prevent the electrolyte solution that has entered the cylindrical portion due to gassing or the like from directly acting on the filter, thereby preventing the filter function from being degraded.

(1-4) the lead-acid battery spout plug may further include an annular filter sealing portion disposed between the through hole and the filter. According to the liquid port plug for a lead-acid battery, the sealing property between the through hole and the filter can be improved.

(1-5) in the lead-acid battery spout plug, the through-hole may be formed in a cutout shape that opens to the other side of the cylindrical portion. According to the liquid port plug for a lead-acid battery of the present invention, the pressing force from the closed lid body is applied to the sealing portion for a filter via the sealing portion for a lid body, whereby the sealing property between the through hole and the filter can be improved.

(1-6) in the lead-acid battery spout plug, the lid sealing portion and the filter sealing portion may be integrally formed. According to the liquid inlet plug for a lead-acid battery of the present invention, the number of components of the liquid inlet plug for a lead-acid battery can be reduced, and a decrease in sealing performance due to a positional displacement between the sealing portion for a lid and the sealing portion for a filter can be suppressed as compared with a structure in which the sealing portion for a lid and the sealing portion for a filter are separate.

(1-7) in the lead-acid battery spout plug, the cover may be provided openably and closably around a predetermined rotation axis in the cylindrical portion, and may have an engagement portion that engages with the cylindrical portion, and the through hole may be located between the rotation axis and the engagement portion when viewed from the rotation axis direction. According to the liquid port plug for a lead-acid battery of the present invention, the through-holes (the sealing portion for a filter and the filter) are disposed between the position where the lid body is pivotally supported and the position where the lid body is engaged, and thus a strong pressing force from the lid body is applied to the sealing portion for a filter, so that the sealing property between the through-holes and the filter can be more effectively improved.

(1-8) the lead-acid battery spout plug may further include a communication portion for communicating the inside of the cylindrical portion with the outside, on condition that the internal pressure of the cylindrical portion is equal to or greater than a reference value in a state where the lid body is closed. According to the liquid vent plug for a lead-acid battery of the present invention, when the internal pressure of the cylindrical portion becomes equal to or greater than the reference value in the state where the lid body is closed, the inside of the cylindrical portion communicates with the outside, and therefore, an excessive increase in the internal pressure of the cylindrical portion can be suppressed.

(1-9) in the lead-acid battery liquid vent plug, the communicating portion may be configured to release the engagement between the cylindrical portion and the lid body on condition that the cylindrical portion engages with the lid body and that the internal pressure of the cylindrical portion is equal to or greater than the reference value. According to the liquid tap for a lead-acid battery of the present invention, the communicating portion can be easily formed by adjusting the degree of engagement between the cylindrical portion and the lid body.

(1-10) in the lead-acid battery spout plug, the communicating portion may be disposed on at least one of the cylindrical portion and the lid body, and may be configured to be opened on the condition that the internal pressure of the cylindrical portion is equal to or greater than the reference value. According to the liquid vent plug for a lead-acid battery of the present invention, the mechanism for opening the cylindrical portion to the outside is provided on at least one of the cylindrical portion and the lid body, whereby an excessive increase in the internal pressure of the cylindrical portion can be suppressed.

(1-11) the lead-acid battery may include: a case having a mounting hole formed therein, a liquid inlet plug for a lead-acid battery, which is mounted in any one of the above-mentioned (1-1) to (1-10) of the mounting hole of the case, and a positive electrode and a negative electrode accommodated in the case.

(2) In order to prevent the refill liquid from directly acting on the float main body, a conventional float-type liquid port plug includes a protrusion interposed between a lower opening of the cylindrical portion and the float main body. In a conventional vent plug for a lead-acid battery having a float and a protrusion, the electrolyte easily overflows due to gassing (a state in which water in the electrolyte is electrolyzed by overcharging and bubbles (gas: oxygen, hydrogen) are generated). The present specification discloses a technology capable of providing a float-type liquid tap for a lead acid battery, which can suppress overflow of an electrolyte due to gassing. This technique can be realized as the following mode.

(2-1) A lead-acid battery port plug disclosed in the present specification comprises: a cylindrical portion; a float having a float main body positioned on one opening side in a cylinder axis direction of the cylindrical portion, and an interlocking portion that interlocks with movement of the float main body in the cylinder axis direction and displaces on the other opening side in the cylinder axis direction of the cylindrical portion; and a plate-shaped protrusion protruding from the one opening of the cylindrical portion and interposed between the one opening and the float main body, wherein a first through-passage penetrating the protrusion is formed in a part of the protrusion. In the liquid vent plug for a lead-acid battery, since the first through-passage penetrating the protrusion is formed in a part of the protrusion, a gas passage opening to the cylindrical portion is also secured on the back surface side of the protrusion. This can suppress the water replenishing liquid from directly acting on the float body, and can suppress the overflow of the electrolyte due to the gassing.

(2-2) in the lead-acid battery spout plug, the first through-hole may be a slit that opens to a peripheral edge of the protrusion. According to the vent plug for a lead-acid battery of the present invention, since the slit that opens at the peripheral edge of the protrusion is formed, it is possible to suppress formation of a liquid film at the opening of the cylindrical portion (precisely, the opening formed by a part of the peripheral edge of the opening of the cylindrical portion and the peripheral edge of the protrusion), and as a result, it is possible to more effectively suppress overflow of the electrolyte solution due to gassing.

(2-3) in the lead-acid battery spout plug, at least a part of the first through-passage may be located in the cylindrical portion in the cylindrical axial direction. According to the liquid vent plug for a lead-acid battery of the present invention, gas generated on the back surface side of the protrusion can be easily discharged to the opening side of the cylindrical portion, and accordingly, gas generation on the front surface side of the protrusion can be suppressed, as compared with a structure in which the first through-passage is not located in the cylindrical portion in the cylindrical axial direction.

(2-4) in the lead-acid battery spout plug, a second through passage may be formed through the cylindrical portion on the one side of the cylindrical portion. According to the liquid vent plug for a lead-acid battery of the present invention, as compared with a structure in which the second through passage is not formed in the cylindrical portion, a gas path from the periphery of the cylindrical portion to the opening of the cylindrical portion can be secured, and accordingly, generation of gas on the surface side of the protrusion can be suppressed, and as a result, overflow of the electrolytic solution due to gassing can be more effectively suppressed.

(2-5) in the lead-acid battery spout plug, at least a part of the second through passage may be located on the other side in the tube axis direction than an inner wall surface of a case of the lead-acid battery to which the lead-acid battery spout plug is attached. According to the liquid vent plug for a lead-acid battery of the present invention, as compared with a structure in which the second through passage is not located on the other side in the cylindrical axis direction than the inner wall surface of the case of the lead-acid battery, gas generated around the cylindrical portion is easily discharged to the opening side of the cylindrical portion, and accordingly, gas generation on the surface side of the protrusion can be suppressed, and as a result, overflow of the electrolytic solution due to gassing can be more effectively suppressed.

(2-6) the lead-acid battery may further include: a case having a mounting hole formed therein, a liquid inlet plug for a lead-acid battery, which is mounted in any one of the above-mentioned (2-1) to (2-5) of the mounting hole of the case, and a positive electrode and a negative electrode accommodated in the case.

A. The implementation mode is as follows:

a-1. overall structure:

(Structure of lead storage battery 100)

Fig. 1 is a perspective view showing an external configuration of a lead storage battery 100 according to the present embodiment. In fig. 1, a part of a case 101, which will be described later, provided in a lead storage battery 100 is cut away for convenience, and an internal structure thereof is shown. Fig. 1 shows mutually orthogonal XYZ axes for a specific direction. In the present description, 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" for convenience, but the lead-acid battery 100 may actually be provided in a direction different from this direction. The same applies to fig. 2 and subsequent figures. Hereinafter, "P" is assigned to the end of the reference numeral of the positive-side component, and "N" is assigned to the end of the reference numeral of the negative-side component. The vertical direction (Z-axis direction) is an example of the tube axis direction in the claims.

As shown in fig. 1, a lead-acid battery 100 includes a case 101 and an electrode group 104. The housing 101 includes an electrolyzer 102 and a lid 106. The electrolytic bath 102 is a substantially rectangular parallelepiped container having an open upper surface, and is formed of, for example, a synthetic resin. An electrolyte U (not shown in fig. 1) and the electrode group 104 are accommodated in the internal space S of the case 101. The electrolyte U is, for example, dilute sulfuric acid.

(Structure of electrode group 104)

The electrode group 104 includes a plurality of plate-shaped positive electrode plates 110P, a plurality of plate-shaped negative electrode plates 110N, and a plurality of separators 120 disposed between the positive electrode plates 110P and the negative electrode plates 110N. Specifically, the plurality of positive electrode plates 110P and the plurality of negative electrode plates 110N are alternately arranged one by one with the separators 120 interposed therebetween. Thus, a plurality of battery cells each having one positive electrode plate 110P and one negative electrode plate 110N facing each other with the separator 120 interposed therebetween are arranged in a predetermined direction (X-axis direction). Hereinafter, the arrangement direction of the battery cells (X-axis direction) is referred to as "battery cell arrangement direction". Each of the electrode plates 110P and 110N is a conductive member in which an active material is filled in a grid body. The plurality of positive electrode plates 110P are connected by a positive-side current collecting member 112P, and the plurality of negative electrode plates 110N are connected by a negative-side current collecting member (not shown).

(Structure of the cover 106)

The lid 106 is a substantially rectangular member having an open lower surface, has a size corresponding to the upper end opening of the electrolytic bath 102, and is formed of, for example, a synthetic resin. The lid 106 is fitted into the upper end opening of the electrolytic bath 102, and the lid 106 and the electrolytic bath 102 are, for example, thermally welded to each other, whereby the internal space S of the case 101 is sealed.

Cover 106 is provided with a positive terminal portion 150P and a negative terminal portion 150N. Positive terminal portion 150P and negative terminal portion 150N are disposed near both ends in the cell arrangement direction (X-axis direction). The lower end of the positive-side terminal portion 150P is electrically connected to the plurality of positive electrodes 110P via the positive-side current collecting member 112P. The negative terminal portion 150N is electrically connected to the negative electrode plates 110N via the negative current collecting member.

The cover 106 is formed with a mounting hole 106A (see fig. 2 described later) that vertically penetrates the cover 106. Specifically, mounting hole 106A is formed between positive terminal portion 150P and negative terminal portion 150N of lid 106. The liquid port plug 200 is attached to the attachment hole 106A.

(Structure of liquid port plug 200)

The spout plug 200 includes a cylindrical portion 210, a lid 230, and a float 240. Fig. 2 is an explanatory diagram showing the XZ cross-sectional structure of the lead-acid battery 100 at the position II-II in fig. 1. Fig. 2 shows the structure of the peripheral portion of the liquid inlet plug 200 of the lead-acid battery 100. Fig. 3 and 4 are perspective views showing an external configuration of the spout plug 200. Fig. 3 shows the spout plug 200 when the lid 230 is in the closed position, which will be described later, and fig. 4 shows the spout plug 200 when the lid 230 is in the open position. In fig. 3 and 4, the float 240 is omitted.

As shown in fig. 2, the cylindrical portion 210 is a cylindrical member having an injection hole 211 penetrating in the vertical direction as a whole, and is attached to the attachment hole 106A of the cover 106 (housing 101). Specifically, as shown in fig. 2 to 4, the cylindrical portion 210 includes an outer cylindrical wall portion 212 and an inner cylindrical wall portion 214.

The outer cylindrical wall portion 212 is a portion of the cylindrical portion 210 disposed outside the housing 101, and the inner cylindrical wall portion 214 is a portion of the cylindrical portion 210 disposed inside the housing 101. The outer cylindrical wall portion 212 has an outer diameter greater than the diameter of the mounting bore 106A of the cap 106, and the inner cylindrical wall portion 214 has an outer diameter less than the diameter of the mounting bore 106A. An annular seal member 260 (e.g., an O-ring) is fitted to the stepped portion between the outer cylindrical wall portion 212 and the inner cylindrical wall portion 214 (see fig. 2). A plurality of locking projections 224 (see fig. 3 and 4) are formed on the outer peripheral surface of the inner cylindrical wall portion 214. Each locking protrusion 224 is locked to the lower surface 107 of the cover 106. Thereby, the liquid port plug 200 is attached to the housing 101, and the space between the outer periphery of the cylindrical portion 210 and the inner peripheral wall of the cover 106 in which the attachment hole 106A is formed is sealed by the sealing member 260.

The cylindrical portion 210 has a support portion 220 that supports the float 240 so as to be movable up and down. The support portion 220 is disposed on the inner circumferential side of the cylindrical portion 210. Specifically, the support portion 220 is disposed at a position displaced from the central axis Z1 of the injection hole 211 of the cylindrical portion 210 when viewed in the vertical direction (see fig. 2 and fig. 5 described later). The support portion 220 is a tubular body having an insertion hole 222 penetrating in the vertical direction and is formed integrally with the inner peripheral wall of the cylindrical portion 210. In the present embodiment, the support portion 220 extends over substantially the entire length of the cylindrical portion 210 (the outer cylindrical wall portion 212 and the inner cylindrical wall portion 214) in the vertical direction.

The lid 230 is provided to be able to open and close the upper end opening of the cylindrical portion 210. Specifically, the cover 230 is disk-shaped as a whole. The lid 230 is supported by the cylindrical portion 210 so as to be displaceable between a closed posture (see fig. 3) in which the upper end opening side of the cylindrical portion 210 is closed and an open posture (see fig. 4) in which the upper end opening side of the cylindrical portion 210 is opened, about a predetermined rotation axis Y1 (see fig. 2). The cover 230 is entirely formed of a transparent material (e.g., transparent plastic). Therefore, the inside of the cylindrical portion 210 can be visually recognized through the lid body 230 in the closed position. Further, a handle portion 230A is formed to protrude from the cover 230 on the side opposite to the rotation axis Y1. The user can easily open and close the lid 230 by holding the handle 230A.

The cover 230 has an annular peripheral wall portion 232 and an upper wall portion 234 closing an upper end of the peripheral wall portion 232. The inner diameter of the peripheral wall portion 232 is larger than the outer diameter of the outer cylindrical wall portion 212 of the cylindrical portion 210. Therefore, as shown in fig. 2 and 3, when the lid body 230 is in the closed position, the peripheral wall portion 232 is disposed so as to surround the outer periphery of the upper end portion (and an integral packing 250 described later) of the outer tubular wall portion 212. As shown in fig. 4, a plurality of first engaging protrusions 236 are formed on the inner peripheral side of the peripheral wall portion 232. A second engaging projection 216 that can engage with each of the plurality of first engaging projections 236 is formed on the outer peripheral side of the outer cylindrical wall portion 212. When the lid 230 is in the closed position, the plurality of first engaging projections 236 engage with the second engaging projections 216, respectively, thereby firmly maintaining the closed position of the lid 230. The first engaging projection 236 is an example of an engaging portion in the claims.

As shown in fig. 2, the upper wall portion 234 of the lid 230 in the closed position has a lid projection 230B that partially projects upward. The inside of the lid body protrusion 230B is a cavity H opened downward. The lid body protrusion 230B (cavity H) overlaps with a rod-shaped portion 244, described later, of the float 240 when viewed in the vertical direction. Therefore, the upper end of the rod-like portion 244 can enter the cavity H of the lid convex portion 230B. The cover convex portion 230B is an example of a convex portion in the claims.

As shown in fig. 2, the float 240 has a float body 242 and a rod 244. The float main body 242 is a hollow body having a sealed hollow inside, and is positioned on the lower end opening side of the cylindrical portion 210. The outer shape of the float main body 242 when viewed in the vertical direction is a shape that cannot be inserted into the insertion hole 222 of the support portion 220. Specifically, the width of the float main body 242 in at least one direction perpendicular to the vertical direction is larger than the inner diameter of the insertion hole 222 of the support portion 220. The rod-shaped portion 244 is a rod-shaped body extending in the vertical direction, and is inserted into the insertion hole 222 of the support portion 220 so as to be movable up and down. Specifically, the outer diameter of the rod 244 is smaller than the inner diameter of the injection hole 211 of the support 220, and the entire length of the rod 244 is longer than the entire length of the insertion hole 222. The float main body 242 is provided at the lower end of the rod 244. A protrusion 246 that engages with the upper end opening of the support portion 220 is formed at the upper end of the rod 244. The protrusion 246 prevents the float 240 (rod 244) from falling downward from the insertion hole 222. Further, the rod 244 is provided with a mark 244A. The upper end portion of the rod-like portion 244 is an example of the interlocking portion in the claims.

With the above configuration, the upper end portion of the rod-shaped portion 244 can protrude from the upper end opening side of the cylindrical portion 210 in conjunction with the vertical movement of the float main body 242. In the state where the lid 230 is in the closed posture, the upper end portion of the rod-like portion 244 can protrude into the lid protrusion 230B of the lid 230. Thus, the upper end of the rod-like portion 244 functions to indicate the height of the liquid surface of the electrolyte solution U in the case 101 (referred to as "liquid surface indicating function"). The following description will be specifically made. First, as shown in fig. 2, when the float main body 242 of the float 240 is submerged in the electrolyte U in the case 101, the float 240 is pushed up in the upward direction by the buoyancy acting on the float main body 242. Therefore, the float 240 moves up and down according to the liquid level of the electrolyte U in the case 101. For example, when a sufficient amount of the electrolyte U is put into the case 101 and the liquid surface height of the electrolyte U is set to an appropriate position, the upper end portion of the rod-like portion 244 of the float 240 protrudes from the upper end opening of the cylindrical portion 210 to such an extent that the mark 244A is positioned near the upper end opening of the cylindrical portion 210 in the state where the lid 230 is in the open position. In this state, when the lid 230 is in the closed position, the upper end of the rod-shaped portion 244 abuts against the inner circumferential surface of the lid projection 230B of the lid 230, and the float 240 is pressed downward against the buoyancy of the electrolyte U (see fig. 2). At this time, the upper end portion of the rod-like portion 244 is positioned in the cavity H of the lid convex portion 230B, and is visible from the side surface of the lid convex portion 230B.

For example, when the lead-acid battery 100 is used for a long time and the level of the electrolyte U in the case 101 is lowered due to the decrease in the electrolyte U, the float 240 is also lowered in accordance with the decrease. The float 240 descends to such an extent that the upper end of the rod-shaped portion 244 cannot be seen from the side of the lid projection 230B, meaning that the replenishment liquid (electrolyte U, water) needs to be replenished. In this case, the lid 230 is opened from the closed position, and the water replenishing liquid is replenished from the filling hole 211 of the cylindrical portion 210. When the water replenishing liquid is replenished, the mark 244A being located at a position higher than the upper end opening of the cylindrical portion 210 by a predetermined distance or more means that an excessive amount of the water replenishing liquid is replenished into the cylindrical portion 210.

A-2. countermeasure against overflow of the electrolyte U due to gassing:

(concrete Structure)

The liquid port plug 200 has a structure for suppressing the overflow of the electrolyte U due to gassing (a state in which bubbles (gas: oxygen, hydrogen) are generated by electrolysis of the electrolyte due to overcharge). Fig. 5 is an explanatory diagram showing the XY cross-sectional structure of the lead acid battery 100 at the V-V position in fig. 4. In fig. 5, the cap 230 and the float 240 are omitted from the spout plug 200. Fig. 6 is an explanatory view showing a YZ plane structure of the spout plug 200. In fig. 6, the liquid port plug 200 mainly shows the inner cylindrical wall portion 214 of the cylindrical portion 210, and the float 240 is omitted.

As shown in fig. 2 to 6, the cylindrical portion 210 includes a plate-shaped protrusion 270. The protrusion 270 is a substantially semicircular plate-like body, protrudes from the lower end opening of the cylindrical portion 210, and is interposed between the lower end opening and the float main body 242. The base end of the protrusion 270 is engaged with the lower end side of the support portion 220, and the protrusion 270 is inclined such that the distance from the float 240 becomes longer as it approaches the front end. In the present embodiment, as shown in fig. 2 and 5, the protrusion 270 extends to a position where the tip exceeds the center axis Z1 when viewed in the vertical direction.

Here, the protrusion 270 is formed with a slit 272. The slit 272 penetrates the protrusion 270 and opens at the peripheral edge of the protrusion 270. That is, the slit 272 extends to the periphery of the protrusion 270. Specifically, as shown in fig. 5 and 6, the slit 272 extends to the foremost end of the protrusion 270 (the lowermost end closest to the liquid surface of the electrolyte U in fig. 2). The slit 272 extends linearly in substantially parallel to the projecting direction of the projection 270. The slit 272 is formed in the protrusion 270 substantially at the center in the left-right direction (Y-axis direction, direction perpendicular to the cylinder axis direction). Further, an upper end P1 (closed end) of the slit 272 is located in the cylindrical portion 210 in the vertical direction. In other words, the upper end P1 of the slit 272 is located above the lower end opening of the cylindrical portion 210. The width of the slit 272 is preferably 1.5mm or more, and preferably less than 2 mm. The slit 272 is an example of the first through-passage in the claims.

A side slit 228 is formed in a portion (inner cylindrical wall portion 214) of the cylindrical portion 210 located inside the housing 101. The side slit 228 penetrates the inner cylindrical wall portion 214 and opens at the lower end of the inner cylindrical wall portion 214. The side slit 228 extends linearly in the vertical direction. The side slit 228 is located on the surface (surface on the opposite side from the float 240) side of the protrusion 270. In the present embodiment, as shown in fig. 2 to 4 and 6, the side slits 228 are formed in the inner cylindrical wall portion 214 at positions facing the surfaces of the protrusions 270. As shown in fig. 2 to 4, the side slits 228 are formed in the inner cylindrical wall portion 214 at positions on both sides of the protrusion 270. The upper end P2 of each side slit 228 extends upward in the vertical direction with respect to the lower surface 107 of the cover 106. The side slit 228 is an example of the second through passage in the claims.

(Effect)

In the above embodiment, in the configuration in which the cylindrical portion 210 does not include the protrusion 270, the replenishment liquid replenished from the filling hole 211 of the cylindrical portion 210 acts directly on the float main body 242 when the electrolytic solution U is replenished. Accordingly, the float 240 (the upper end portion of the rod 244) does not move up and down normally according to the liquid level of the electrolyte U in the case 101, and thus the liquid level indication function cannot be achieved. In contrast, in the liquid port plug 200 according to the present embodiment, the protrusion 270 is interposed between the lower end opening of the cylindrical portion 210 and the float main body 242. Therefore, the replenished refill liquid can be prevented from directly acting on the float main body 242, and as a result, the float 240 can normally exhibit the liquid level indicating function.

Here, in the above-described embodiment, in the structure in which the slit 272 is not formed in the protrusion 270 (hereinafter, referred to as "the liquid inlet plug 200a of the comparative example"), it is assumed that the overflow of the electrolyte solution U due to the gassing is likely to occur. Fig. 8 is an explanatory diagram schematically illustrating the operation of the present embodiment and a comparative example. Fig. 8 (a) schematically shows the operation of the liquid inlet plug 200a of the comparative example, and fig. 8 (B) schematically shows the operation of the liquid inlet plug 200 of the present embodiment. In fig. 8, only a part of each of the liquid port plugs 200 and 200a is shown, and the float 240 and the casing 101 are omitted. The "gas G" in fig. 8 refers to gas (bubbles) generated in the electrolyte U due to gassing.

Here, it is considered that when gassing occurs, the electrolyte U that has been foamed adheres to the lower end opening side of the cylindrical portion 210 of the port plugs 200, 200a to form a liquid film, and this liquid film is pushed out of the case 101 by the gas G via the cylindrical portion 210, thereby causing the electrolyte U to overflow due to gassing. As shown in fig. 8 (a), the liquid inlet plug 200a of the comparative example includes a protrusion 270a protruding toward the electrolyte U in the case 101. Therefore, when the distance between the tip of the protrusion 270a and the liquid surface of the electrolyte solution U is short, a liquid film is easily formed in the lower end opening of the cylindrical portion 210 (precisely, the opening formed by a part of the peripheral edge of the lower end opening of the cylindrical portion 210 and the peripheral edge of the protrusion 270 a). In the comparative example, no slit or hole was formed in the protrusion 270 a. Therefore, on the back side of the protrusion 270a (the float main body 242 side), the path of the gas G that opens toward the lower end of the cylindrical portion 210 is restricted by the protrusion 270a, and therefore the generated gas G is difficult to be discharged to the outside of the housing 101. On the other hand, on the front side (the side opposite to the float main body 242) of the protrusion 270a, the path (hollow arrow in fig. 8 a) of the gas G toward the lower end opening of the cylindrical portion 210 is not restricted, and therefore the gas G is actively and intensively generated compared to the rear side of the protrusion 270 a. This is considered to be because the overflow of the electrolyte U due to gassing is likely to occur in the comparative example.

On the other hand, as shown in fig. 8 (B), since the liquid port plug 200 of the present embodiment also includes the protrusion 270, when the distance between the tip of the protrusion 270 and the liquid surface of the electrolyte solution U is short, a liquid film is easily formed in the lower end opening of the cylindrical portion 210. However, in the present embodiment, since the slit 272 penetrating the protrusion 270 is formed in a part of the protrusion 270, a path (hollow arrow in fig. 8 (B)) for opening the gas G toward the lower end of the cylindrical portion 210 is also secured on the back surface side of the protrusion 270. This can suppress the water-replenishing liquid from directly acting on the float main body 242, and can suppress the overflow of the electrolyte U due to gassing.

In the present embodiment, the slit 272 is open at the peripheral edge of the protrusion 270 (see fig. 2 to 6). The presence of the opening of the slit 272 can suppress the formation of a liquid film on the lower end opening side of the cylindrical portion 210, and as a result, the overflow of the electrolyte solution U due to gassing can be more effectively suppressed.

In the present embodiment, the upper end P1 (closed end) of the slit 272 is located in the cylindrical portion 210 in the vertical direction (see fig. 2). According to the present embodiment, the gas G generated on the back surface side of the protrusion 270 is easily discharged to the lower end opening side of the cylindrical portion 210, compared to the configuration in which the slit 272 is not located in the cylindrical portion 210, and accordingly, the generation of the gas G on the front surface side of the protrusion 270 can be suppressed. As a result, the overflow of the electrolyte U due to gassing can be more effectively suppressed.

In the present embodiment, a side slit 228 (see fig. 2 to 4 and 6) is formed in the inner cylindrical wall portion 214 of the cylindrical portion 210. According to the present embodiment, as compared with a configuration in which the side slits 228 are not formed in the cylindrical portion 210, a path for the gas G to open from the periphery of the cylindrical portion 210 to the lower end of the cylindrical portion 210 can be ensured, and accordingly, generation of the gas G on the surface side of the protrusion 270 can be suppressed. As a result, the overflow of the electrolyte U due to gassing can be more effectively suppressed. The side slit 228 opens at the lower end of the cylindrical portion 210 (inner cylindrical wall portion 214). Therefore, the formation of a liquid film in the lower end opening of the cylindrical portion 210 can be more effectively suppressed.

In the present embodiment, the upper end P2 of the side slit 228 extends upward in the vertical direction to a position above the lower surface 107 of the cover 106. According to the present embodiment, compared to the configuration in which the side slits 228 are located below the lower surface 107 of the cover 106, the gas G generated around the cylindrical portion 210 is easily discharged to the lower end opening side of the cylindrical portion 210, and accordingly, the generation of the gas G on the surface side of the protrusion 270 can be suppressed. As a result, the overflow of the electrolyte U due to gassing can be more effectively suppressed.

A-3. sealing and gas venting strategy:

(concrete Structure)

The liquid port plug 200 has a structure capable of discharging gas G generated by gassing or the like to the outside while securing sealability between the cylindrical portion 210 and the lid body 230. Specifically, the port plug 200 further includes an integrated packing 250 and a filter 280. Fig. 7 is a perspective view showing an external appearance structure of the integrated packing 250. As shown in fig. 7, the integrated packing 250 is formed by integrating a lid packing 252 and a filter packing 254. That is, the integrated packing 250 is formed by integrally forming (molding) the lid packing 252 and the filter packing 254 from the same material. The integrated packing 250 is formed of a sealing material such as rubber.

As shown in fig. 4 and 5, the lid packing 252 has an annular shape corresponding to the upper end opening of the cylindrical portion 210 when viewed in the vertical direction. The lid packing 252 is disposed between the upper end opening of the cylindrical portion 210 and the lid 230 in the closed posture. A groove 252A is formed in the lower surface of the lid packing 252, and the upper end of the cylindrical portion 210 is inserted into the groove 252A (see fig. 5). This improves the sealing property between the lid packing 252 and the cylindrical portion 210. Two contact convex portions 257 (see fig. 4 and 7) are formed over the entire length of the upper surface of the lid packing 252 that faces the lid 230 in the closed position. The two contact protrusions 257 contact the lower surface of the lid body 230 in the closed posture. This improves the sealing property between the lid packing 252 and the lid 230. The lid packing 252 is an example of a lid seal in the claims.

The filter 280 is, for example, an explosion-proof filter that prevents hydrogen gas discharged from the injection hole 211 of the cylindrical portion 210 from igniting and prevents hydrogen gas in the case 101 from igniting and exploding. As shown in fig. 3 and 4, the filter 280 has, for example, a rectangular shape, and filter ridges 282 are formed over the entire length of the outer peripheral surface.

As shown in fig. 3, 4, and 7, the filter packing 254 has a rectangular ring shape, and a filter 280 is disposed in the opening 255 formed in the filter packing 254. Further, the filter groove 256 is formed over the entire circumference on the inner circumferential surface of the filter packing 254 where the opening 255 is formed, and the filter ridge 282 formed in the filter 280 is inserted into the filter groove 256. This improves the sealing property between the integrated packing 250 and the filter packing 254. The upper end of the packing 254 for a filter is integrally coupled to the lower surface of the packing 252 for a cover. Two contact ridges 258 are formed on the outer peripheral surface of the packing 254 for a filter over the entire length (only one contact ridge 258 is shown in fig. 7). Further, an engagement convex strip 259 having a longer protruding length than the contact convex strip 258 is formed between the two contact convex strips 258 over the entire length. The packing 254 for a filter is an example of a seal portion for a filter in the claims.

A through hole 226 in which the filter 280 is disposed is formed in the outer cylindrical wall portion 212 of the cylindrical portion 210. Specifically, the through hole 226 has a rectangular shape and opens at the upper end of the cylindrical portion 210. When viewed in a direction parallel to the rotation axis Y1 (Y-axis direction), the through-hole 226 is located between the rotation axis Y1 and the second engaging projection 216 (the engaging position between the lid 230 and the cylindrical portion 210) (see fig. 5). A packing 254 for a filter is disposed in the through hole 226. Further, an engagement groove (not shown) is formed over the entire length of the inner peripheral surface of the outer cylindrical wall portion 212 that constitutes the through hole 226, and an engagement protrusion 259 formed in the filter packing 254 is inserted into the engagement groove. Further, the engagement protrusion 259 is sandwiched by two contact protrusions 258 formed in the filter packing 254, and the two contact protrusions are in contact with the inner circumferential surface constituting the through hole 226. This improves the sealing property between the filter packing 254 and the cylindrical portion 210. The outer cylindrical wall portion 212 of the cylindrical portion 210 is an example of a side wall of the cylindrical portion in the claims.

As shown in fig. 3 and 4, a valve mechanism 290 is disposed on the outer cylindrical wall portion 212 of the cylindrical portion 210. Specifically, the valve mechanism 290 is disposed in a through hole formed in the outer cylindrical wall portion 212. The valve mechanism 290 is provided with a cylindrical partThe valve that is displaced between an open state and a closed state, in which the inside and the outside of the cylindrical portion 210 communicate with each other, communicates the inside and the outside of the cylindrical portion 210 on the condition that the internal pressure of the cylindrical portion 210 becomes equal to or greater than a reference value when the lid 230 is in the closed state. Further, for example, the ventilation area of the filter 280 is 314mm²In the above case, the reference value is preferably 206Pa, and the ventilation area of the filter 280 is less than 314mm²In the case of (3), the reference value is preferably 441 Pa. In the structure in which the liquid port plug 200 does not include the filter 280 and the through-hole 226 is closed, the reference value is preferably 441 Pa. In the present embodiment, the lid 230 maintains the closed position even when the internal pressure of the cylindrical portion 210 is equal to or greater than the reference value. The valve mechanism 290 is an example of a communicating portion in the claims.

The internal pressure of the cylindrical portion 210 (hereinafter referred to as "opening pressure") when the valve mechanism 290 is opened from the closed state can be measured as follows. Fig. 9 is an explanatory diagram illustrating a method of measuring the internal pressure (open pressure) of the spout plug 200. As shown in fig. 9, the measurement case 500 includes an introduction hole 510 into which air enters, a discharge hole 520 through which air is discharged to the outside, and a mounting hole 530 to which the liquid supply port plug 200 is attached in a sealed state. The pressure gauge 600 is attached to the discharge hole 520. In a state where the lid 230 is in the closed position, air is introduced into the internal space 502 of the measurement case 500 through the introduction hole 510. As the air is introduced, the internal pressure of the liquid outlet plug 200 rises, and the pressure measured by the pressure gauge 600 when the lid 230 is in the open position is the open pressure.

(Effect)

If the filter 280 is disposed on the inner peripheral side of the cylindrical portion 210, the visibility of the displacement of the float 240 (the upper end portion of the rod-shaped portion 244) as viewed from the cover 230 side is lowered due to the presence of the filter 280, and the liquid level height cannot be checked by the float 240. In order to solve this problem, a configuration is considered in which the filter 280 is disposed on the inner circumferential side of the cylindrical portion 210 so as to secure a space in which the float 240 can be visually recognized and avoid the space. However, in this configuration, a part of the generated gas G is discharged from the cylindrical portion 210 to the outside of the housing 101 without passing through the filter, and therefore the effect of the filter 280 cannot be obtained.

In contrast, in the present embodiment, the lid packing 252 ensures the sealing between the opening of the cylindrical portion 210 and the lid 230. The filter 280 is disposed in the through hole 226 formed in the side wall of the cylindrical portion 210 or the lid 230. Therefore, when the liquid outlet plug 200 is attached to the case 101 of the lead-acid battery 100, the gas G generated by gassing or the like in the case 101 of the lead-acid battery 100 can be discharged to the outside through the filter 280.

In the present embodiment, the filter 280 is disposed at a position other than the cover convex portion 230B of the cover 230 from which the float 240 protrudes. According to the present embodiment, the visibility of the float 240 can be ensured, and the effect of the filter 280 can be obtained. Specifically, the through-hole 226 in which the filter 280 is disposed is formed in the outer cylindrical wall portion 212 of the cylindrical portion 210. According to the present embodiment, it is possible to suppress a decrease in the filter function due to the electrolyte U entering the cylindrical portion 210 due to gassing or the like directly acting on the filter 280.

In the present embodiment, since the packing 254 for a filter is disposed between the through-hole 226 formed in the cylindrical portion 210 and the filter 280, the sealing property between the through-hole 226 and the filter 280 can be improved. The through hole 226 formed in the cylindrical portion 210 opens at the upper end of the cylindrical portion 210. Therefore, the pressing force of the lid 230 in the closed position is applied to the filter packing 254 via the lid packing 252, whereby the sealing property between the through-hole 226 and the filter 280 can be improved.

In the present embodiment, the packing 252 for the lid body is formed integrally with the packing 254 for the filter. According to the present embodiment, the number of components of the liquid port plug 200 can be reduced. In addition, compared to a structure in which the lid packing 252 and the filter packing 254 are separate bodies, for example, a decrease in sealing performance due to a positional displacement or the like of the lid packing 252 and the filter packing 254 accompanying opening and closing of the lid 230 can be suppressed.

In the present embodiment, the through-hole 226 (the packing 254 for a filter and the filter 280) is disposed between a position where the lid body 230 is pivotally supported and a position where the lid body is engaged. According to the present embodiment, since a strong pressing force is applied to the packing 254 for a filter from the lid 230, the sealing property between the through-hole 226 and the filter 280 can be more effectively improved.

According to the present embodiment, when the lid 230 is in the closed state and the internal pressure of the cylindrical portion 210 is equal to or greater than the reference value, the interior of the cylindrical portion 210 communicates with the outside, and therefore an excessive increase in the internal pressure of the cylindrical portion 210 can be suppressed.

B. Modification example:

the technique disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the scope of the invention, and for example, the following modifications can be made.

The structure of the lead-acid battery 100 and the spout plug 200 in the above embodiment is merely an example, and various modifications are possible. For example, the case 101 may be configured such that the internal space S is partitioned into a plurality of cell chambers, and the electrolyte U and the electrode group 104 are accommodated in each cell chamber. In the above embodiment, the flat plate-shaped positive electrode plate 110P and the flat plate-shaped negative electrode plate 110N are exemplified as the positive electrode and the negative electrode, but may have a shape other than a flat plate. For example, the positive electrode may be formed by arranging a plurality of woven tubes.

The lid 230 may be completely detached from the cylindrical portion 210 without being supported by the cylindrical portion 210. In the above embodiment, the lid 230 in the closed position is held by the cylindrical portion 210 by the engagement mechanism such as the first engagement projection 236, but the lid 230 may be held by the cylindrical portion 210 by a screw mechanism or the like, for example. In the above embodiment, the first engaging convex portion 236 may be a concave portion that engages with a convex portion provided on the cylindrical portion 210 side. In the above embodiment, only a part of the cover 230 (for example, the cover projection 230B) may be formed of a transparent material. The cover 230 may not have the cover protrusion 230B. In order to prevent the electrolyte U from overflowing due to gassing, the liquid inlet plug 200 may be configured without the lid 230 or the lid packing 252.

In the above embodiment, the float 240 (the rod-shaped portion 244, the support portion 220) is disposed on the inner circumferential side of the cylindrical portion 210, but may be disposed on the outer circumferential side of the cylindrical portion 210 in order to prevent the overflow of the electrolyte solution U due to gassing. In the above embodiment, the upper end portion of the rod-shaped portion 244 is exemplified as the interlocking portion, but may have a shape other than a rod shape, and in short, may be configured to be displaced on the opening side of the cylindrical portion in interlocking with the movement of the float main body.

In the above embodiment, the slit 272 is exemplified as the first through-passage (through-passage) formed in the protrusion 270, but may be one or a plurality of slits or holes that do not reach the peripheral edge of the protrusion 270. In the above embodiment, the slit 272 is open on the tip side (lower end side) of the protrusion 270, but may be open on the side of the side surface of the protrusion 270, for example. In the above embodiment, the opening shape of the slit 272 is not limited to the linear shape, and may be a curved shape, for example. The slit 272 may be formed at a position other than the center in the left-right direction in the protrusion 270. The upper end P1 of the slit 272 may be located below the cylindrical portion 210 in the vertical direction. In short, the through-passage may be formed in a part of the protrusion 270. The opening area of the through passage (total opening area in the case of a plurality of through passages) is preferably 1/2 or less of the area of the protrusion, and more preferably 1/4 or less of the area of the protrusion. In the above embodiment, the sealing and gas discharge measures may be taken such that the slit 272 is not formed in the protrusion 270, or the protrusion 270 itself is not provided.

In the above embodiment, the side slits 228 are exemplified as the second through passage (through passage) formed in the cylindrical portion 210, but may be one or a plurality of slits or holes that do not reach the lower end of the cylindrical portion 210, for example. In the above embodiment, the opening shape of the side slit 228 is not limited to a straight line, and may be a curved line, for example, and in short, the through passage may be formed in the cylindrical portion 210. In the above embodiment, the cylindrical portion 210 may not have the side slits 228.

In the above embodiment, the lid packing 252 and the filter packing 254 may be separate bodies. In the above embodiment, the lid packing 252 has an annular shape, but may have a ring shape other than an annular shape (for example, a rectangular ring shape). The shape of the lid packing 252 may be other than a ring shape. In the above embodiment, the filter packing 254 may not be provided, and the filter 280 may be press-fitted into the through hole 226 formed in the cylindrical portion 210, for example. In the above embodiment, the through hole 226 formed in the cylindrical portion 210 may not be open at the upper end side of the cylindrical portion 210.

In the above embodiment, the filter 280 is not limited to the explosion-proof filter, and may be a filter having another function (for example, a filter that absorbs a predetermined component of the gas G). The shape of the filter 280 is not limited to a rectangular shape, and may be, for example, a circular shape. In the above embodiment, the filter 280 may be disposed on the cover 230, for example. In this case, the filter 280 is disposed at a position where the displacement of the float 240 can be visually recognized in a state where the cover 230 is closed.

In the above-described embodiment, the valve mechanism 290 is exemplified as the communication portion, but for example, an opening and closing mechanism having a door provided to be openable and closable may be used to bring the door from a closed posture to an open posture when the lid 230 is in a closed state and the internal pressure of the cylindrical portion 210 is equal to or greater than a reference value. The communicating portion may be configured to release the engagement between the first engaging convex portion 236 of the cover 230 and the second engaging convex portion 216 of the cylindrical portion 210 when the cover 230 is in the closed state and the internal pressure of the cylindrical portion 210 is equal to or greater than a reference value. In the above embodiment, the communication portion (valve mechanism 290) may not be provided.

In the present embodiment, the electrolytic cell 102 and the lid 106 may be formed integrally with the case 101. In the above embodiment, the cylindrical portion 210 is not limited to a cylindrical shape, and may be, for example, a prismatic cylindrical shape.

In the above embodiment, the lid packing 252 is a member separate from the lid 230 and the cylindrical portion 210, but may be formed integrally with the lid 230 or the cylindrical portion 210. Specifically, a known sealing structure (for example, a sealing material joined to the lid body 230, or a sealing portion formed integrally with the lid body 230 from the same material as the lid body 230) may be formed at a portion of the lid body 230 that contacts the cylindrical portion 210. Further, a known sealing structure (a sealing material joined to the cylindrical portion 210, or a sealing portion formed integrally with the cylindrical portion 210 from the same material as the cylindrical portion 210) may be formed at a portion of the cylindrical portion 210 that contacts the lid body 230. In this case, a known seal structure is an example of the seal portion for the lid body in the claims.

In the present embodiment, the transparent portion for visually recognizing the float 240 is formed in the cover 230, but may be formed in the cylindrical portion 210.

The material for forming each component of the lead-acid battery 100 and the liquid inlet plug 200 in the above embodiment is merely an example, and various modifications are possible.