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

Abstract

This water-refilling faucet 20 for a lead storage battery is provided with: a faucet body 30; a valve chamber 54 that is positioned inside the faucet body 30 and that has an introduction port 53 and a discharge hole 55 for a refill liquid; and a valve body 66 accommodated in the valve chamber 54, the valve body 66 opening and closing the discharge hole 55. An inner circumferential portion 55A of the discharge hole 55 has a tapered shape in which the opening area decreases from the inside of the valve chamber 54 toward the outside thereof in a cross-section taken along a central axis L of the valve chamber 54 that passes through the discharge hole 55, and the introduction port 53 is positioned, relative to the discharge hole 55, on an extension line of the tapered shape of the inner circumferential portion of the discharge hole.

Description

TECHNICAL FIELD

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

BACKGROUND ART

[0002] In lead-acid storage batteries, the water content in the electrolyte decreases due to electrolytic reactions, evaporation and the like during use, so that 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 includes a float that moves up and down following the liquid level of the electrolyte, a dish-shaped valve body (valve element) connected to the float, and a valve chamber that accommodates the valve element. The valve chamber has an inflow port (introduction port) as an upstream opening and a water replenishing port (discharge port) as a downstream opening.

[0004] Water that has flowed into the valve chamber from the introduction port flows out from the discharge port to replenish the battery case with water. When the liquid level in the battery case rises to a predetermined height, the valve body connected to the float closes the discharge port to stop water flow, and water replenishment is stopped.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0005]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] In such a water replenishing plug, turbulent flow may occur inside the valve chamber. The turbulent flow affects the opening and closing operation of the valve body, and causes "early closing" in which the discharge port is closed even though water replenishment is insufficient, and "late closing" in which the discharge port is not closed even though water replenishment has been sufficiently completed. In addition, when turbulent flow occurs, the water pressure decreases due to pressure loss, so the flow rate decreases and it takes time to replenish water to the battery case.

[0007] This invention was completed based on the above-mentioned problems and discloses a technique for suppressing the generation of turbulence in the valve chamber. [Means for solving the problem]

[0008] The lead-acid battery water supply valve comprises a valve body, a valve chamber located inside the valve body and having an inlet and a outlet for the replenishment fluid, and a valve body housed in the valve chamber and for opening and closing the outlet. The inner circumference of the outlet has a tapered shape in a cross-section cut along the central axis of the valve chamber passing through the outlet, where the opening area decreases from the inside to the outside of the valve chamber. The inlet is located on the extension of the tapered shape of the inner circumference of the outlet in relation to the outlet.

[0009] Here, "the inlet is located on the extension of the tapered shape of the inner circumference of the discharge hole" means that at least a part of the inlet is located on the extension of the tapered shape. [Effects of the Invention]

[0010] According to the present invention, the flow of water within the valve chamber is made smoother, the generation of turbulence is suppressed, the opening and closing operation of the valve body is made smoother, and the decrease in flow rate is suppressed. [Brief explanation of the drawing]

[0011] [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 [Figure 11] Cross-sectional view of the valve chamber 54 passing through the discharge hole 55 along the central axis L. [Modes for carrying out the invention]

[0012] <Overview of water supply valve for lead-acid batteries> (1) A water supply tap for a lead-acid battery according to one embodiment of the present invention comprises a tap body, a valve chamber located inside the tap body and having an inlet and a outlet for the replenishment fluid, and a valve body housed in the valve chamber and for opening and closing the outlet, wherein the inner circumference of the outlet has a tapered shape in a cross section cut through the central axis of the valve chamber passing through the outlet, with the opening area decreasing from the inside to the outside of the valve chamber, and the inlet is located on the extension of the tapered shape of the inner circumference of the outlet in relation to the outlet.

[0013] Because the inner circumference of the discharge port is tapered, a water flow is created near the discharge port that follows the tapered shape. In this configuration, the inlet is located on the extension of the tapered shape of the discharge port, so the replenishment fluid supplied from the inlet flows out into the valve chamber and then merges with the water flow that flows into the discharge port along the tapered shape. Therefore, a smooth water flow towards the discharge port is created within the valve chamber, and the generation of turbulence can be suppressed.

[0014] Based on the above, the effect of turbulence on the opening and closing operation of the valve body can be suppressed, allowing for smooth valve operation. Furthermore, suppressing the generation of turbulence reduces the pressure loss of the replenishment fluid passing through the valve chamber. This allows the pressure of the replenishment fluid to be maintained, and the decrease in the flow rate of the replenishment fluid passing through the valve chamber can be suppressed.

[0015] (2) In the water refilling faucet for a lead-acid battery according to the above (1), the valve element may move between a first position where the valve element is separated from the discharge hole to be open and a second position where the valve element abuts on the discharge hole to be closed, and the introduction port may be located at a position closer to the discharge hole than the valve element in the first position in relation to the valve element.

[0016] In such a configuration, the water flow of the replenishing liquid flowing in from the introduction port does not interfere with the valve element in the first position, so the water flow does not collide with the valve element, and turbulence is less likely to occur. Thereby, a smooth water flow toward the discharge hole can be created. In addition, the water flow can be suppressed from pushing the valve element from the first position to the second position, so premature closing is less likely to occur.

[0017] (3) In the water refilling faucet for a lead-acid battery according to the above (1) or (2), the discharge hole penetrates one wall surface of the valve chamber, and the valve element is located facing the discharge hole in the valve chamber, and may have a hemispherical shape convex toward the discharge hole.

[0018] With this configuration, even if solid foreign matter contained in the replenishing liquid rides onto the upper surface of the valve element, it easily slides down along the spherical surface. Since foreign matter hardly remains on the upper surface of the valve element, it is possible to suppress the situation where foreign matter is caught between the valve element and the discharge hole and the replenishing liquid leaks out from the discharge hole during closing.

[0019] Further, if the replenishing liquid heading toward the discharge hole cannot pass through the discharge hole and flows toward the lower valve element, the water flow may push the valve element and hinder the opening and closing operation. When the valve element has an upwardly convex hemispherical shape, even if the water flow of the replenishing liquid hits from above, the momentum can be diverted along the spherical surface, which hardly hinders the opening and closing operation.

[0020] (4) The water refilling faucet for a lead-acid battery according to any one of the above (1) to (3) may have an introduction part that guides the replenishing liquid to the introduction port. The introduction part may be parallel to the moving direction of the valve element. Compared with the case where the introduction part is orthogonal to the moving direction of the valve element, the water flow of the replenishing liquid flowing into the valve chamber from the introduction port is less likely to hinder the movement of the valve element. Therefore, the movement of the valve element becomes smooth, and good water shutoff performance can be secured.

[0021] (5) The subject of this technology may also be a lead-acid battery equipped with a water supply valve for lead-acid batteries as described in any one of the above items (1) to (4).

[0022] (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.

[0023] 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.

[0024] <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.

[0025] 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.

[0026] The water supply valve 20 will be described below using Figures 2 to 11. The water supply valve 20 comprises a valve body 30 and a float valve 60.

[0027] 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. 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 positioned 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 tightly fitted to both the lower surface of the flange portion 31 and the upper surface of the battery cover, sealing the area around the electrolyte opening. In this state, the portion of the water supply valve 20 closer to the valve cover portion 37 than the rubber packing 32 is exposed above the upper surface of the battery cover, while the other portion is inserted into the electrolyte opening of the battery cover and positioned inside the battery case.

[0028] 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.

[0029] 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.

[0030] 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 vertical direction inside the plug body 30. As shown in Figure 5, both ends of the first partition 41 are connected to the peripheral wall 38, and the first partition 41 divides the internal space of the plug body 30 into two spaces.

[0031] The second partition wall 42 and the third partition wall 43 are partition walls that extend substantially parallel to the vertical direction within the interior of the plug body 30. One second partition wall 42 and one third partition wall 43 are located in each of the two internal spaces of the plug body 30 that are divided by the first partition wall 41. The second partition wall 42 and the third partition wall 43 each extend from the peripheral 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 two internal spaces of the plug body 30 that are divided by the first partition wall.

[0032] 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.

[0033] 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."

[0034] 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.

[0035] 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.

[0036] (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 penetrates it vertically. 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.

[0037] (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).

[0038] As shown in Figure 7, 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 third partition wall 43) 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 wall 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). As shown in Figure 11, the guide passage 48 is parallel to the direction of movement (up and down direction) of the valve body 66, and the water moves from bottom to top through the guide passage 48 to the inlet 53. The guide passage 48 is an inlet that introduces water into the inlet 53.

[0039] (3) The water-stopping chamber 46 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 left in Figures 4 to 6. The water-stopping chamber 46 has the guide passage 48 described above and the valve chamber 54.

[0040] As shown in Figure 7, the valve chamber 54 is surrounded by a cylindrical side wall 50 with an axis in the vertical direction, a top wall 57, and a bottom wall 51. The valve chamber 54 houses the valve body 66, which will be described later.

[0041] The valve chamber 54 has an inlet 53 and a discharge hole 55 on one wall surface. In this example, the inlet 53 is installed through the side wall 50, and the discharge hole 55 is installed through the ceiling wall 57. Water flowing into the valve chamber 54 from the inlet 53 is discharged into the space above the valve chamber 54 through the discharge hole 55.

[0042] (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. As shown in Figure 7, 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 discharge hole 55 into the space above the valve chamber 54 flows horizontally over the valve chamber 54 and enters the water supply chamber 47, where it falls downward and is replenished in the battery cell (point f).

[0043] 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 parts 56 that are spaced apart in the vertical direction. Each of the pair of guide parts 56 is provided with an insertion hole that penetrates in the vertical direction, and a float shaft 61, which will be described later, is inserted through the insertion hole. The float shaft 61 is displaced in the vertical direction while being kept approximately vertical by the pair of guide parts 56.

[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 that are integrally connected. The part of the float valve 60 excluding the float 63 is housed inside the valve body 30 (see Figure 2). The float valve 60 is not fixed to the valve body 30 and 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 a pair of guides 56 with its axis oriented vertically. The float shaft 61 also extends downward through the second guide 56b and protrudes downward from the bottom wall 51 of the stopper body 30.

[0046] 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 56a and the second guide portion 56b. 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.

[0047] The shut-off valve 62 consists of a valve stem 65 and a valve body 66. The valve stem 65 extends vertically and passes through the discharge hole 55 vertically. The upper end of the valve stem 65 is fixed to a support portion 64, and the valve body 66 is fixed to the lower end.

[0048] The valve body 66 is housed within the valve chamber 54 in a manner that allows it to move vertically. The valve body 66 is positioned facing the discharge hole 55, both vertically and horizontally. The valve body 66 is a convex hemispherical shape toward the discharge hole 55, and its upper surface 66a, which contacts the discharge hole 55, is spherical.

[0049] 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.

[0050] As the electrolyte level rises or falls, the float valve 60 moves up and down as a whole, following the change in the liquid level due to the buoyancy of the float 63.

[0051] The range of vertical movement of the float valve 60 is between the lower limit position (Figure 8) and the upper limit position (Figure 9). The lower limit position is an example of the "first position," and the upper limit position is an example of the "second position."

[0052] When the shut-off valve 62 is in its lower limit position, it is spaced away from the discharge hole 55 and in contact with the bottom wall 51, and at this time the discharge hole 55 is open (Figure 8).

[0053] When the float valve 60 moves from the lower limit position to the upper limit position, the valve body 66 contacts the discharge hole 55 from below, closing the discharge hole 55 (Figure 9).

[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 supplied to 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, discharge hole 55, and replenishment chamber 47 in that order. When water is supplied to 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 discharge hole 55 from below by the buoyancy of the float 63, closing the discharge hole 55 (Figure 9).

[0056] When the discharge hole 55 is closed, the water in the valve chamber 54 can no longer pass through the discharge hole 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 water flow in the valve chamber Figure 11 is a cross-sectional view of the valve chamber 54 along its central axis L, passing through the discharge hole 55 (an enlarged view of the area around the valve chamber 54 in Figure 7). The discharge hole 55 penetrates the ceiling wall 57 in the vertical direction. The inner circumference 55A of the discharge hole 55 is conical, and in the above cross-section, it has a tapered shape in which the opening area decreases from the inside to the outside of the valve chamber 54 (from bottom to top in Figure 11).

[0059] The inlet 53 penetrates the side wall 50 horizontally and connects the guide passage 48 and the valve chamber 54. In Figure 11, the extent of the inlet 53 is shown by dimension A. In relation to the discharge hole 55, the inlet 53 is located on the extension of the tapered shape of the discharge hole 55. The dashed line 58 in Figure 11 is the extension of the tapered shape.

[0060] When water is supplied to the valve chamber 54, as shown in Figure 11, a water flow Q is generated that flows into the valve chamber 54 from the inlet 53 via the guide passage 48, and a water flow R is generated that flows from the valve chamber 54 through the discharge hole 55 towards the upper space.

[0061] Since the inner circumference 55A of the discharge hole 55 is tapered, the water flow R from the valve chamber 54 toward the discharge hole 55 flows into the discharge hole 55 along the tapered shape of the discharge hole 55. Since the inlet 53 is located on the extension line 58 of the tapered shape, it can smoothly merge with the water flow R1 that flows into the discharge hole 55 along the tapered shape. As a result, turbulence is suppressed at the point where the water flow R and the water flow Q merge, and the influence of turbulence on the opening and closing operation of the valve body 66 can be reduced.

[0062] Furthermore, suppressing turbulence reduces pressure loss within the valve chamber 54. Since a smaller pressure loss prevents a decrease in the flow rate of water passing through the valve chamber 54, it is possible to replenish the water to the specified amount in a shorter time.

[0063] As shown in Figure 11, the valve chamber 54 is composed of two members: an upper member 71 including a ceiling wall 57 and a lower member 72 including a bottom wall 51. The upper member 71 has a third partition wall 43 hanging down from above, a ceiling wall 57 extending horizontally from the third partition wall 43, and a partition wall 49 and a first side wall 50a hanging down from the ceiling wall 57.

[0064] The lower member 72 has a bottom wall 51 that extends horizontally and a second side wall 50b that rises vertically from the bottom wall 51. Both the first side wall 50a and the second side wall 50b are curved in an arc shape when viewed from above, forming a cylindrical side wall 50 that surrounds the valve body 66.

[0065] The upper end of the second side wall 50b is cut out in a horizontally elongated rectangular shape. When the upper and lower members are combined, the upper end of the second side wall and the ceiling wall are in contact without any gaps except for the cut-out portion, but the cut-out portion becomes a rectangular opening. This opening is the inlet 53, which connects the valve chamber 54 and the guide passage 48.

[0066] As shown in Figure 11, at the lower limit position (first position), the valve body 66 is positioned down to the bottom wall 51 of the valve chamber 54. On the other hand, the inlet 53 is located above the valve body 66 at the lower limit position. Specifically, the lower end 53a of the inlet 53 is above the upper surface 66a of the valve body 66, so the inlet 53 does not overlap with the valve body 66 at the lower limit position in the vertical direction. Also, as shown in Figure 11, the inlet 53 is located closer to the discharge hole 55 in the vertical direction than the valve body 66 at the lower limit position.

[0067] By positioning the inlet 55 closer to the discharge hole 55 than the valve body 66 at its lower limit, the water flow (water flow Q) from the inlet 53 towards the discharge hole 55 of the valve chamber 54 can merge with the water flow R near the discharge hole 55 without colliding with (non-interfering with) the valve body 66 at its lower limit. Therefore, turbulence can be suppressed near the discharge hole inlet. This makes it possible to create a smooth water flow from the inlet 53 towards the discharge hole 55.

[0068] Furthermore, since the valve body 66 at the lower limit position and the water flow Q do not interfere with each other, the water flow Q can suppress pushing the valve body 66 from the lower limit position to the upper limit position. This makes it less likely for the valve body 66 to close prematurely.

[0069] In the water supply tap 20 of this embodiment, the valve body 66 is circular in plan view, and the side wall 50 is cylindrical and surrounds the valve body 66. This reduces the gap between the valve body 66 and the side wall 50. As a result, it becomes difficult for the water flow to wrap around to the opposite side of the valve body 66, and the water flow is prevented from interfering with the opening and closing operation of the valve body 66.

[0070] The valve body 66 faces the discharge hole 55 vertically within the valve chamber 54. The valve body 66 is a convex hemispherical shape toward the discharge hole 55, and in this embodiment, the discharge hole 55 is located above and the valve body 66 is located below. In this configuration, even if solid foreign matter contained in the replenishment fluid rides up onto the upper surface 66a of the valve body 66, it is easy for it to slide off along the upper surface 66a. As a result, foreign matter is less likely to get stuck between the valve body 66 and the discharge hole 55, suppressing water leakage from the discharge hole 55 when closed and improving water-stopping performance.

[0071] Furthermore, there are cases where the water flow R directed towards the discharge hole 55 cannot pass through the discharge hole 55 and reverses direction towards the valve body 66 (downward in Figure 11). If the valve body 66 is an upwardly convex hemispherical shape, even if a downward water flow hits the upper surface 66a, the force of the water flow can be deflected along the spherical surface, so the water flow is less likely to interfere with the opening and closing operation, and smooth opening and closing operation can be performed.

[0072] <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.

[0073] (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.

[0074] (2) In the above embodiment, an example was shown in which the inlet 53 is provided at a position closer to the upper end of the side wall 50 (50b). The inlet 53 only needs to be a part of the extension of the tapered shape of the discharge hole 55, and may be located lower than the position in the above embodiment. [Explanation of symbols]

[0075] 20 Water supply tap 30 Stopper body 53 Inlet 54 valve chambers 55 Discharge hole 55A inner circumference 57 Ceiling and wall (one wall surface) 58. Extension of tapered shape 66 Valve body P, Q, R, S water flow

Claims

1. A water supply valve for lead-acid batteries, The stopper body and A valve chamber located inside the stopper body has an inlet and an outlet for the replenishment liquid, The valve chamber comprises a valve body that is housed therein and opens and closes the discharge hole, The valve chamber is constructed by being surrounded by a bottom wall, a cylindrical side wall rising upward from the bottom wall, and a ceiling wall connected to the upper end of the side wall. The inlet is provided penetrating the upper part of the side wall, and the discharge hole is provided penetrating the ceiling wall. The inner circumference of the discharge hole has a tapered shape in a cross-section cut along the central axis of the valve chamber passing through the discharge hole, where the opening area decreases from the inside to the outside of the valve chamber. The inlet is located on the extension of the tapered shape of the inner circumference of the discharge hole in relation to the discharge hole, and is a water supply valve for a lead-acid battery.

2. A water tap for a lead-acid battery according to claim 1, The valve body moves between a first position in which it is open and away from the discharge hole, and a second position in which it is closed and in contact with the discharge hole. The inlet is located closer to the discharge hole than the valve body in the first position, in relation to the valve body, in a water supply valve for a lead-acid battery.

3. A water tap for a lead-acid battery according to claim 1 or claim 2, The aforementioned discharge hole penetrates the ceiling wall of the valve chamber, The valve body is located in the valve chamber, facing the discharge hole, and is hemispherical in shape, convex toward the discharge hole, in a water supply valve for a lead-acid battery.

4. A water tap for a lead-acid battery according to claim 1 or claim 2, It has an inlet that guides the replenishment liquid to the inlet, The aforementioned introduction section is a water supply valve for a lead-acid battery, parallel to the direction of movement of the valve body.

5. A lead-acid battery equipped with a water supply valve for a lead-acid battery as described in claim 1 or claim 2.

6. A battery pack comprising a plurality of lead-acid batteries as described in claim 5, 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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