Water inlet valve for lead-acid batteries, lead-acid batteries, battery packs

Abstract

This lead storage battery water refilling faucet includes: a faucet body 30 having a valve chamber 54 therein; and a float valve 60. The faucet body 30 is cylindrical and extends in the shaft direction. The float valve 60 comprises: a float 63; a float shaft 61 that is provided in the faucet body 30, that is fixed to the float 63, and that extends in the shaft direction of the faucet body 30; a water shut-off valve 62 that is provided in the valve chamber 54 and that is for opening and closing a valve hole 55; and a support part 64 that is provided to the float shaft 61 and that supports the water shut-off valve 62. The faucet body 30 comprises a pair of guide parts 57, 58. The pair of guide parts 57, 58 have insertion portions 57a, 58b that are for inserting the float shaft 61 so as to be movable in the shaft direction, and that are positioned at both ends of the support part 64 in the shaft direction.

Description

Technical Field

[0001] The present invention relates to a technique for replenishing water to the battery case of a lead-acid battery.

Background Art

[0002] During the use of a lead-acid battery, due to electrolytic reactions, evaporation, etc., the moisture in the electrolyte decreases, and the liquid level of the electrolyte gradually drops. It is necessary to replenish water into the battery case so that the liquid level height of the electrolyte does not fall below a certain limit.

[0003] Patent Document 1 describes a water replenishing plug for a storage battery having an automatic water stop function. The water replenishing plug for a storage battery of Patent Document 1 has a buoyancy body (float) that moves up and down following the liquid level of the electrolyte, a connecting rod (float shaft) connected to the float, and a dish-shaped valve (water stop valve). The float shaft can be displaced while sliding with the plug body. When the liquid level rises to a specified height, the water stop valve that is displaced integrally with the float closes the water inlet to stop the water supply, and the water replenishment is stopped.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In such a water replenishing plug, when the float shaft is inclined with respect to the displacement direction, the sliding property deteriorates due to frictional resistance. As a result, the followability of the float shaft with respect to the rise of the liquid level deteriorates, and the closing of the valve hole (inlet) by the valve body may be delayed.

[0006] The present invention has been completed based on the above problems, and discloses a technique for suppressing the inclination of the float shaft accompanying the opening and closing of the valve hole and enhancing the sliding property.

Means for Solving the Problems

[0007] A water supply valve for a lead-acid battery includes a valve body having a valve chamber inside, and a float valve, wherein the valve body is cylindrical and extends in the axial direction, and the float valve includes a float, a float shaft located inside the valve body and fixed to the float and extending in the axial direction of the valve body, a shut-off valve located inside the valve chamber, and a support portion provided on the float shaft and supporting the shut-off valve, wherein the valve body includes a pair of guide portions, the pair of guide portions having insertion portions through which the float shaft is inserted so as to be movable in the axial direction, and are located on both sides of the support portion in the axial direction. [Effects of the Invention]

[0008] According to the present invention, the tilting of the float shaft associated with the opening and closing of the valve hole can be suppressed, thereby improving the sliding properties of the float shaft relative to the stopper body. [Brief explanation of the drawing]

[0009] [Figure 1] Plan view of a battery pack [Figure 2] Perspective view of a water supply valve for lead-acid batteries [Figure 3] Front view of a water supply valve for lead-acid batteries [Figure 4] Cross-sectional view of a water supply valve for lead-acid batteries. [Figure 5] Cross-sectional view of a water supply valve for a lead-acid battery. [Figure 6] Diagram showing the water pathway and the position of each partition when viewed from above. [Figure 7] CC cross-sectional view (diagram showing water path) of a water supply valve for lead-acid batteries. [Figure 8] DD cross-section when the float valve is in its lower limit position. [Figure 9] DD cross-sectional view when the float valve is in the upper limit position. [Figure 10] Overall diagram of the float valve [Modes for carrying out the invention]

[0010] <Overview of water supply valve for lead-acid batteries> (1) A water supply valve for a lead-acid battery according to one embodiment of the present invention includes a valve body having a valve chamber inside, and a float valve, wherein the cylindrical body is cylindrical and extends in the axial direction, and the float valve comprises a float, a float shaft located inside the valve body and fixed to the float and extending in the axial direction of the valve body, a shut-off valve located inside the valve chamber that opens and closes a valve hole, and a support portion provided on the float shaft and supporting the shut-off valve, wherein the valve body comprises a pair of guide portions, the pair of guide portions having insertion portions that allow the float shaft to be inserted so as to be movable in the axial direction, and are located on both sides of the support portion in the axial direction.

[0011] In this configuration, the guiding action of the insertion parts provided on the pair of guide parts allows for the movement of the float shaft along its axial direction while restricting its movement perpendicular to the axial direction. Moreover, since the pair of guide parts are provided on "both sides of the support part," the distance between the pair of guide parts can be increased compared to the case where the pair of guide parts are provided on "one side of the support part." Increasing the distance between the pair of guide parts widens the distance between the insertion parts, allowing for the restriction of vertical movement at two points with a large gap between them, thereby suppressing the tilt (tilting) of the float shaft relative to its axial direction.

[0012] By suppressing the tilt (tilting) of the float shaft associated with the opening and closing of the valve hole, the sliding properties of the float shaft relative to the pair of guide parts can be improved. Therefore, the delay in the rise of the shut-off valve in response to the rise in liquid level can be reduced, improving the water-stopping performance.

[0013] (2) In the lead-acid battery water tap described in (1) above, the tap body includes a first partition wall that divides the inside of the tap body into a first space in which the valve chamber is provided and a second space in which the valve chamber is not provided, at least one of the pair of guides is provided on the first partition wall, and the float shaft supported by the pair of guides may be positioned facing the valve chamber with the first partition wall in between.

[0014] In this configuration, the float shaft is positioned facing the valve chamber with the first partition wall in between, and the distance from the float shaft to the water stop valve housed in the valve chamber can be shortened. Therefore, when water is stopped, the moment acting on the float shaft through the water stop valve can be reduced. By reducing the moment, the float shaft becomes less likely to tilt, and the slidability of the float shaft can be improved.

[0015] (3) In the water replenishing plug for a lead-acid battery according to (2) above, the plug body has a second partition wall that partitions the second space, and the second partition wall connects one end to the first partition wall and the other end to the peripheral wall of the plug body. At least one of the pair of guide portions is provided at the intersection of the first partition wall and the second partition wall, and may be fixed to both the first partition wall and the second partition wall.

[0016] At the intersection of the plurality of partition walls, since the intersecting partition walls support each other, the rigidity is high. By providing at least one guide portion at the intersection of the partition walls with high rigidity, displacement and collapse of the guide portion accompanying the vertical movement of the float shaft can be further suppressed.

[0017] (4) In the water replenishing plug for a lead-acid battery according to any one of (1) to (3) above, a surface roughened region in which a fine protrusion group is formed may be provided on the surface of the float shaft.

[0018] The droplets of electrolyte solution or water adhering to the float shaft contact the float shaft at the tips of the respective protrusions due to the action of surface tension. Since the direct contact area between the float shaft and the droplets is reduced, the electrolyte solution adhering to the float shaft is likely to separate from the float shaft due to vibration or gravity. Since components and dirt contained in the electrolyte solution or the like are unlikely to remain on the surface of the float shaft, the surface of the float shaft can be kept clean, and a decrease in slidability can be suppressed.

[0019] (5) The object of the present technology may be a lead-acid battery equipped with the water replenishing plug for a lead-acid battery according to any one of (1) to (4) above.

[0020] (6) A battery pack comprising a plurality of lead-acid batteries as described in (5) above, wherein a lead-acid battery water tap provided by one of the lead-acid batteries may be connected to a lead-acid battery water tap provided by another lead-acid battery via a water supply tube.

[0021] By replenishing the electrolyte from one end of the water supply tube, each lead-acid battery can be supplied with electrolyte up to a predetermined level. Multiple lead-acid batteries can be replenished with electrolyte at once.

[0022] <Embodiment> 1. Overall Structure Figure 1 is a plan view of a battery pack 10 used in electric vehicles such as electric forklifts. The battery pack 10 consists of 12 lead-acid batteries 11, which are arranged in 6 rows horizontally and 2 rows vertically inside the battery case 13.

[0023] A lead-acid battery water valve (hereinafter also simply referred to as "water valve") 20, shown in Figure 2, is attached to the liquid port that penetrates the top surface of the battery cover of the lead-acid battery 11. The water valves 20 of adjacent lead-acid batteries 11 are connected to each other via a water supply tube 12. By connecting a water tank (not shown) to one end 12a of the water supply tube 12 and pumping water (an example of "replenishment fluid"), water can be supplied to all 12 lead-acid batteries 11 at once.

[0024] The water supply valve 20 will be described below using Figures 2 to 10. The water supply valve 20 comprises a valve body 30 and a float valve 60.

[0025] 2. Stopper body Figure 2 is a perspective view of the water supply valve 20, and Figure 3 is a front view. The valve body 30 is made of synthetic resin such as ABS and is roughly cylindrical in shape, extending in the axial direction. Figures 2 and 3 show the valve body 30 with its axial direction oriented vertically. As shown in Figure 8, the axial direction is the direction of the axis L of the valve body 30. The widest part of the valve body 30 in the horizontal direction is the flange portion 31. Below the flange portion 31, a ring-shaped rubber packing 32 is arranged along the outer circumference of the valve body 30. When the water supply valve 20 is attached to the lead-acid battery 11, the rubber packing 32 is in close contact with both the lower surface of the flange portion 31 and the upper surface of the battery cover, sealing the area around the liquid inlet. In this state, the part of the water supply valve 20 on the valve cover portion 37 side of the rubber packing 32 is exposed above the upper surface of the battery cover, while the other part is inserted into the liquid inlet of the battery cover and located inside the battery case.

[0026] A water inlet 33 (see Figure 8) is provided on the upper surface of the flange portion 31, and a three-pronged water supply pipe fitting 34 is connected to the water inlet 33. The water supply tube 12 connected to the water supply pipe fitting 34 connects the water supply pipe fittings 34 of adjacent lead-acid batteries 11.

[0027] A semi-cylindrical portion 35 is erected on the upper surface of the flange portion 31, at a position on the left front side of Figure 2, where it does not overlap with the water inlet 33 in a plan view. The upper end of the semi-cylindrical portion 35 is an opening 35a with a semicircular opening edge. A stopper cover portion 37 is connected to the chord portion of the opening edge via a hinge 36. The opening 35a can be opened or closed by rotating the stopper cover portion 37 around the hinge 36 as an axis.

[0028] Figures 4 and 5 are cross-sectional views AA and BB of the plug body 30 shown in Figure 3, respectively. The plug body 30 has three partitions (first partition 41 to third partition 43). The three partitions 41 to 43 are integral with the plug body 30. The first partition 41 extends approximately parallel to the axial direction inside the plug body 30. As shown in Figure 5, both ends of the first partition 41 are connected to the circumferential wall 38, and the first partition 41 divides the internal space of the plug body 30 into two spaces.

[0029] The second partition wall 42 and the third partition wall 43 are partition walls that extend approximately parallel to the axial direction within the plug body 30. One second partition wall 42 and one third partition wall 43 are located in each of the internal spaces of the plug body 30 that have been divided into two by the first partition wall 41. The second partition wall 42 and the third partition wall 43 each extend from the circumferential wall 38 toward the first partition wall 41 and are connected to the first partition wall 41. The second partition wall 42 and the third partition wall 43 further divide each of the internal spaces of the plug body 30 that have been divided into two by the first partition wall.

[0030] Figure 6 is a schematic diagram showing the positions of the first partition wall 41 to the third partition wall 43 superimposed on a plan view of the valve body 30. In the following explanation, the internal space of the water supply valve 20, which is divided into four sections by the first partition wall 41 to the third partition wall 43, will be referred to as (1) the measurement chamber 44, (2) the anteroom 45, (3) the water shut-off chamber 46, and (4) the water supply chamber 47, starting from the lower right of Figures 4 to 6 and moving counterclockwise.

[0031] Of the internal space of the valve body 30, which is divided into two by the first partition wall 41, the space on the side where the front chamber 45 and the water-stopping chamber 46 are located (the side where the valve chamber 54 is located) is called the "first space," and the space on the side where the water-supplying chamber 47 and the measurement chamber 44 are located (the space on the side where the valve chamber 54 is not located) is called the "second space."

[0032] Parts of each bulkhead 41-43 have gaps or slits, allowing water to pass through the four divided spaces 44-47. For example, as will be described later, as shown in Figure 7, water in the anteroom 45 can flow into the water-stopping chamber 46 through a gap 52 opened below the end 49a of the first bulkhead 41 (partition wall 49). Also, as shown in Figure 4, a slit 39 is provided through the first bulkhead 41, spanning the water-stopping chamber 46 and the water-supplying chamber 47.

[0033] Figure 7 is a cross-sectional view along line CC in Figure 6. Points b to f in Figure 7 correspond to the positions of points b to f in the plan view of Figure 6, respectively. The arrows in Figures 6 and 7 connecting each point indicate the water path inside the water valve. The following describes each space 44 to 47 and the water path. Water supplied from the water supply tube 12 to the water inlet 33 travels through the water path inside the water valve to the water supply chamber 47, and is finally supplied to the electric reservoir. In the following description, any point in the water path will be used as a reference, with the water inlet 33 side being the upstream side and the water supply chamber 47 side being the downstream side.

[0034] (1) The measurement chamber 44 is a space enclosed by the peripheral wall 38, the first partition wall 41, and the second partition wall 42, and is located in the lower right in Figures 4 to 6. The measurement chamber 44 has no ceiling or bottom surface and the water supply valve 20 passes through it axially. The portion of the measurement chamber 44 on the side of the valve cover 37 from the flange portion 31 is part of the internal space of the semi-cylindrical portion 35. The measurement chamber 44 functions as an insertion port for inserting a hydrometer when measuring the specific gravity of the electrolyte. When a rod-shaped hydrometer is inserted into the specific gravity measurement port from the opening 35a of the semi-cylindrical portion 35, the tip of the hydrometer reaches the electrolyte, and the specific gravity can be measured.

[0035] (2) The anteroom 45 is a space enclosed by the surrounding wall 38, the first partition wall 41, and the third partition wall 43, and is located in the upper right in Figures 4 to 6. The anteroom 45 is in communication with the water inlet 33, and water supplied to the water inlet 33 flows into and temporarily remains there. Specifically, as shown in Figures 6 and 7, the water supplied from the water supply tube 12 (point a), passes through the water supply pipe joint 34 (point b), and flows into the anteroom 45 from the water inlet 33 (point c).

[0036] A guide passage 48 is provided at the boundary between the anteroom 45 and the water-stopping chamber 46. The guide passage 48 is formed by a partition wall 49 (part of the first partition wall 41) and the side wall 50 of the valve chamber 54. There is a gap 52 between the end 49a of the partition wall 49 and the bottom surface 51 of the valve body 30, and this gap 52 is the entrance to the guide passage 48. Water that enters the guide passage 48 from the entrance (point d) flows downstream through the guide passage 48 and then flows into the valve chamber 54 through an inlet 53 that penetrates the upper part of the side wall 50 of the valve chamber 54 (point e).

[0037] (3) The water-stopping chamber 46 is a space enclosed by the peripheral wall 38, the first partition wall 41 and the third partition wall 43, and is located in the upper left in Figures 4 to 6. The water-stopping chamber 46 has the guide passage 48 described above and a valve chamber 54. The valve chamber 54 is cylindrical with its axis in the vertical direction. The valve chamber 54 houses the water-stopping valve 62, which will be described later. A valve hole 55 is provided in the ceiling wall of the valve chamber 54, penetrating in the axial direction. The ceiling wall of the valve chamber 54 is tapered, narrowing towards the downstream side, with the center of the ceiling wall being the valve hole 55. Water flowing into the valve chamber 54 flows out of the valve chamber 54 into the space above it through the valve hole 55.

[0038] (4) The water supply chamber 47 is a space enclosed by the peripheral wall 38, the first partition wall 41, and the second partition wall 42, and is located in the lower left in Figures 4 to 6. The water supply chamber 47 has an opening at the bottom. The side of the water supply chamber 47 with the plug cover 37 is also the internal space of the semi-cylindrical section 35. Water that flows out from the valve hole 55 into the space above the valve chamber 54 flows horizontally over the water stop chamber 46 and enters the water supply chamber 47, where it falls downward and is replenished in the battery cell (point f).

[0039] Figures 8 and 9 are DD cross-sectional views of the water supply valve 20. The water supply chamber 47 is provided with a pair of guide sections 56 spaced apart in the axial direction (vertical direction). The upper one is the first guide section 57, and the lower one is the second guide section 58. The distance between the first guide section 57 and the second guide section 58 is denoted as "L1".

[0040] As shown in Figure 4, the first guide section 57 is located inside the water supply chamber 47. The first guide section 57 is provided at the intersection where the first partition wall 41 and the second partition wall 42 intersect in a plan view. In this example, as shown in Figure 4, the first partition wall 41 and the second partition wall 42 intersect approximately in the center of the stopper body 30, and the first guide section 57 is provided at the left intersection position J1 of the left and right intersection positions J1 and J2 on either side of the second partition wall 42. In this embodiment, as shown in Figure 4, the first guide section 57 is rectangular in a plan view. The upper end surface of the first guide section 57 is fixed (connected) to the first partition wall 41, and the right end surface is fixed (connected) to the second end surface 42. By fixing the first guide section 57 to both of the two partition walls 41 and 42, positional displacement due to elastic deformation is less likely to occur compared to fixing it to only one side.

[0041] As shown in Figure 5, the second guide section 58 is attached to the wall surface of the first bulkhead 41 on the side of the water supply chamber 47. The second guide section 58 is a roughly fan-shaped plate. The second guide section 58 extends horizontally from the lower end of the first bulkhead 41.

[0042] The first guide section 57 and the second guide section 58 are each provided with a circular first through-hole 57a and a second through-hole 58a that penetrate vertically. The float shaft 61 is inserted through the two through-holes 57a and 58a. The float shaft 61 moves back and forth in the vertical direction while being kept approximately vertical by the guiding action of the two through-holes 57a and 58a. Furthermore, the guiding action of the two through-holes 57a and 58a restricts movement in the direction perpendicular to the axial direction (horizontal direction).

[0043] The first guide section 57 and the second guide section 58 are both located on the first partition wall 41 within the water supply chamber 47. On the opposite side of the first partition wall 41 is a water-stopping chamber 46 having a valve chamber 54. Therefore, the float shaft 61 held by the pair of guide sections 56 is positioned facing the valve chamber 54 with the first partition wall 41 in between. The distance between the float shaft 61 and the water-stopping valve 62 housed in the valve chamber 54 is defined as "L2" (see Figures 4 and 8).

[0044] 3. Float valve Figure 10 shows an overall view of the float valve 60. The float valve 60 consists of a float shaft 61, a shut-off valve 62, and a float 63, all connected integrally. The part of the float valve 60 excluding the float 63 is housed inside the valve body 30 (see Figures 2 and 3). The float valve 60 is not fixed to the valve body 30, but can move up and down relative to the valve body 30.

[0045] As shown in Figure 8, the float shaft 61 is supported within the water supply chamber 47 by two guide parts 57 and 58 with its axis oriented vertically. The float shaft 61 also extends downward through the second guide part 58 and protrudes downward from the bottom surface 51 of the stopper body 30.

[0046] The outer surface of the float shaft 61 is textured, creating a surface roughening area with numerous minute protrusions. When droplets of electrolyte or water adhere to this surface roughening area, the contact area with the droplets is reduced. As a result, the attached droplets are more likely to fall off due to vibration or gravity.

[0047] The float shaft 61 has a support portion 64 on its outer circumferential surface. The support portion 64 protrudes horizontally from the float shaft 61 between the first guide portion 57 and the second guide portion 58. The support portion 64 passes through a slit 39 that penetrates the first partition wall 41 forming the boundary between the water supply chamber 47 and the water shut-off chamber 46. The slit 39 is elongated in the vertical direction and functions as a guide groove that guides the vertical movement of the support portion 64. The tip of the support portion 64 extends to the upper space of the valve chamber 54 and supports the water shut-off valve 62 housed in the valve chamber 54 by suspending it.

[0048] The shut-off valve 62 consists of a valve stem 65 and a valve body 66. The valve stem 65 extends vertically, in the same direction as the axial direction of the plug body 30, and passes vertically through the valve hole 55 located on the ceiling surface of the valve chamber 54. The upper end of the valve stem 65 is fixed to the support part 64, and the valve body 66 is fixed to the lower end.

[0049] The valve body 66 is sized to be able to close the valve without any gaps by contacting the tapered surface of the valve hole 55. The valve hole 55 has a tapered shape that narrows towards the downstream side, and the valve body 66 has a roughly hemispherical shape that narrows on the side that contacts the valve hole 55.

[0050] The float 63 is a roughly cylindrical floating body made of hollow or foamed synthetic resin. The lower end of the float shaft 61 is inserted into and fixed to the float 63. The float 63 floats on the surface of the electrolyte in the electrolytic case and moves up and down in accordance with the liquid surface.

[0051] As the electrolyte level rises or falls, the entire float valve 60 moves up and down as a single unit with respect to the stopper body 30.

[0052] The range in which the float valve 60 moves up and down relative to the plug body 30 is between the lower limit position (Figure 8) and the upper limit position (Figure 9). At the lower limit position, the support portion 64 abuts against the lower end of the slit 39, and the shut-off valve 62 abuts against the bottom surface of the valve chamber 54.

[0053] When the float valve 60 is displaced from its lower limit position to its upper limit position, the valve body 66 comes into contact with the valve hole 55 from below, thereby blocking the valve hole 55.

[0054] 4. Automatic water shut-off function Next, the automatic shut-off function of the water supply valve 20 will be explained. When the electrolyte in the battery cell decreases due to electrolysis or evaporation and the liquid level drops, the float 63 floating on the surface of the electrolyte also drops in conjunction, and eventually the float valve 60 reaches its lower limit position (Figure 8).

[0055] When water is supplied to the water inlet 33, the water is replenished into the battery cell in the path shown by the arrow in Figure 7, passing through the front chamber 45, guide passage 48, inlet 53, valve chamber 54, valve hole 55, and replenishment chamber 47 in that order. When water is replenished into the battery cell, the electrolyte level rises, and the float valve 60 rises in conjunction with this. When the liquid level reaches a predetermined height, the float valve 60 reaches its upper limit position, and the valve body 66 in the valve chamber 54 is pressed against the valve hole 55 from below by the buoyancy of the float 63, closing the valve hole 55 (Figure 9).

[0056] When the valve opening 55 is closed, the water in the valve chamber 54 can no longer pass through the valve opening 55, and the supply of water to the battery cell stops. In this way, the water supply valve 20 automatically stops supplying water when the liquid level reaches a predetermined height.

[0057] This automatic water replenishment function allows all lead-acid batteries 11 constituting the battery pack 10 to be replenished at once from a single water tank, without having to perform water replenishment work on each battery individually.

[0058] 5. Explanation of Effects In this configuration, since the pair of guides 56 are located on both sides of the support 64, the distance L1 between the first guide 57 and the second guide 58 can be increased compared to the case where the pair of guides 56 are located on one side of the support 64. In other words, since the distance between the two support points of the float shaft 61 is increased, tilting (tilting) of the float shaft 61 in the vertical direction can be suppressed during water shutoff operation.

[0059] By suppressing the tilt of the float shaft 61, frictional resistance against each guide portion 57, 58 can be reduced when the float shaft 61 moves axially (up and down) in the plug body 30. This improves the sliding performance of the float shaft 61.

[0060] As a result, the float valve 60's ability to follow vertical fluctuations in the liquid level is improved, making it possible to close the valve hole 55 with the valve body 66 in time with the moment the electrolyte level in the battery cell reaches the target height, thereby preventing the electrolyte level from exceeding the target height.

[0061] In this configuration, as shown in Figures 4, 5 and 8, 9, the pair of guides 56 (first guide 57 and second guide 58) are positioned opposite the valve chamber 54 with the first partition wall 41 in between. Therefore, the distance L2 from the float shaft 61 held by the pair of guides 56 to the shut-off valve 62 housed in the valve chamber 54 can be reduced. As a result, when the valve body 66 closes the valve hole 55 to stop the flow of water, the moment acting on the float shaft 61 through the shut-off valve 62 is reduced. By reducing the moment, the tilt of the float shaft 61 can be further suppressed.

[0062] In this configuration, as shown in Figure 4, the second partition wall 42 is connected at one end to the first partition wall 41 and at the other end to the peripheral wall 38 of the plug body 30. The first guide portion 57 is fixed to both the first partition wall 41 and the second partition wall 42 at the point where they intersect.

[0063] Because the intersection of the two bulkheads 41 and 42 is highly rigid, the first guide section 57 is less prone to deformation. By suppressing the deformation of the first guide section 57, the tilt of the float shaft 61 can be further suppressed.

[0064] In this configuration, the surface of the float shaft 61 is a surface roughening region in which a group of fine protrusions is formed. In this way, droplets of electrolyte or water adhering to the surface of the float shaft 61 come into contact with the float shaft 61 at the tips of each protrusion due to the action of surface tension. Since the direct contact area between the float shaft 61 and the droplets is reduced, the droplets are more likely to detach from the float shaft 61, and components and dirt contained in the droplets are less likely to remain. This keeps the surface of the float shaft 61 clean and suppresses a decrease in sliding performance.

[0065] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings. For example, the following embodiments are also included within the technical scope of the present invention, and furthermore, various modifications can be made without departing from the spirit of the invention.

[0066] (1) In the above embodiment, a battery pack 10 used in an electric forklift is shown as an example. In addition, the battery pack 10 can also be used in electric trolleys, aerial work platforms, etc. The use of the battery pack 10 is not limited to mobile devices such as electric vehicles. It can also be used for stationary purposes such as uninterruptible power supplies and energy storage devices for power generation systems.

[0067] (2) In the above embodiment, the shape of the valve body 66 is a hemispherical shape that widens downwards. The shape of the valve hole 55 is a tapered shape that narrows upwards. The shapes of the valve body 66 and the valve hole 55 are not limited to these, and other shapes are acceptable as long as the valve body 66 can close the valve hole 55 and stop the flow of water. For example, the valve body 66 may be a hemispherical shape that widens upwards, and the valve hole 55 may be a tapered shape that narrows downwards.

[0068] (3) In the above embodiment, the insertion holes 57a and 58a of each guide portion 57 and 58 are circular, but they may be elliptical, polygonal, or have other shapes.

[0069] (4) In the above embodiment, an example was shown in which the support portion 64 extends horizontally from the float shaft 61, but the extension direction does not have to be horizontal. For example, it may extend diagonally upward or diagonally downward. Also, the shape of the support portion 64 does not have to be a straight rod. For example, it may be curved or crank-shaped.

[0070] (5) In the above embodiment, the first guide portion 57, which is positioned above the pair of guide portions 56, is provided at the point where the two partition walls (first partition wall 41, second partition wall 42) intersect. However, the embodiment is not limited to this, and the second guide portion 58, which is positioned below, may be provided at the point where the two partition walls intersect, or both of the pair of guide portions 56 may be provided at the point where the two partition walls intersect.

[0071] (6) In the above embodiment, an example was given in which a rod-shaped float shaft 61 is inserted through holes provided in a pair of guide portions 56, thereby being guided in the vertical direction while its horizontal displacement is restricted. The shape of the float shaft 61 and the pair of guide portions 56 is not limited to this, and other shapes are also possible. For example, the pair of guide portions 56 may have grooves recessed along the vertical direction, and a protrusion formed on the float shaft 61 may fit into these grooves, thereby providing vertical guidance and restricting horizontal movement.

[0072] (7) In the above embodiment, a circular first insertion hole 57a and a second insertion hole 58a are shown as examples of insertion portions through which the float shaft is inserted so as to be movable in the axial direction. The insertion portion is not limited to the shape of a hole. For example, it may be groove-shaped. [Explanation of Symbols]

[0073] 11 Lead acid battery 20 Water supply tap 30 Stopper body 54 valve chambers 55 valve holes 57, 58 Pair of guide sections 57a, 58a Through hole (insertion part) 60 Float valve 61 Float shaft 62 Water shut-off valve 63 Floats 64 Support part

Claims

1. A water supply valve for lead-acid batteries, A plug body having a valve chamber inside, A float valve, and, The plug body is cylindrical and extends in the axial direction. The aforementioned float valve is Floats and, A float shaft located within the plug body, fixed to the float, and extending in the axial direction of the plug body, Within the valve chamber, there is a shut-off valve that opens and closes the valve hole, The float shaft is provided with a support portion that supports the shut-off valve, The plug body is equipped with a pair of guide parts, The pair of guide portions have insertion portions through which the float shaft is inserted so as to be movable in the axial direction, and are located on both sides of the support portion in the axial direction. The plug body includes a first partition wall that divides the inside of the plug body into a first space in which the valve chamber is provided and a second space in which the valve chamber is not provided. At least one of the pair of guides is provided on the first partition wall, The float shaft, supported by the pair of guides, is positioned opposite the valve chamber with the first partition wall in between. The plug body has a second partition wall that divides the second space, The second partition wall has one end connected to the first partition wall and the other end connected to the peripheral wall of the plug body. A water supply valve for a lead-acid battery, wherein at least one of the pair of guide sections is provided at the intersection of the first partition wall and the second partition wall and is fixed to both the first partition wall and the second partition wall.

2. A water tap for a lead-acid battery, A plug body having a valve chamber inside, A float valve, and, The plug body is cylindrical and extends in the axial direction. The aforementioned float valve is Floats and, A float shaft located within the plug body, fixed to the float, and extending in the axial direction of the plug body, Within the valve chamber, there is a shut-off valve that opens and closes the valve hole, The float shaft is provided with a support portion that supports the shut-off valve, The plug body is equipped with a pair of guide parts, The pair of guide portions have insertion portions through which the float shaft is inserted so as to be movable in the axial direction, and are located on both sides of the support portion in the axial direction. A water supply valve for a lead-acid battery, wherein a surface roughening region with a group of fine protrusions is provided on the surface of the float shaft.

3. A water tap for a lead-acid battery according to Claim 2, The plug body includes a first partition wall that divides the inside of the plug body into a first space in which the valve chamber is provided and a second space in which the valve chamber is not provided. At least one of the pair of guides is provided on the first partition wall, A water supply valve for a lead-acid battery, wherein the float shaft, supported by the pair of guides, is positioned opposite the valve chamber with the first partition wall in between.

4. A lead-acid battery having a water supply valve for a lead-acid battery as described in claim 1 or claim 2.

5. A battery pack comprising a plurality of lead-acid batteries as described in Claim 4, A battery pack in which a lead-acid battery water tap of one of the aforementioned lead-acid batteries is connected to a lead-acid battery water tap of any of the other aforementioned lead-acid batteries via a water supply tube.

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