Lead-acid battery plug and lead-acid battery

Abstract

A vent plug (18) is provided with a head section (35), a cylindrical section (36), and a filter (34). The cylindrical section (36) is provided with a cylinder portion (40), a threaded portion (42), a slit (45), and a through-hole (43), the filter (43) is disposed at the position where the through-hole (43) is disposed in a central axis (L) direction, and the threaded portion (42) intersects with the slit (45) only at the first thread part thereof.

Description

[Technical field]

[0001] The present invention relates to a lead-acid battery vent plug and a lead-acid battery. [Background technology]

[0002] Lead-acid batteries are used in various applications, including automotive and industrial use. Lead-acid batteries include a plate group in which positive and negative plates are alternately stacked with separators between them. In addition, in lead-acid batteries, the plate group is immersed in an electrolyte held in a battery case, and the opening of the battery case is sealed with a lid. Some of these lead-acid batteries have a liquid port plug on the lid for refilling the electrolyte. The liquid port plug includes a cylindrical body with an open lower end and a head that seals the upper end of the cylindrical body. In addition, some of the liquid port plugs have a through hole formed therein for connecting to an exhaust passage that communicates with an exhaust hole provided in the lid. The through hole, the exhaust passage, and the exhaust hole have the function of discharging oxygen gas and hydrogen gas generated on the plates in the battery case when the lead-acid battery is charged to the outside of the lead-acid battery.

[0003] In a lead-acid battery, gas generated on the plate during charging of the lead-acid battery may exist as bubbles in the electrolyte, causing the electrolyte level to rise. When the electrolyte level reaches the bottom of the cylindrical body due to this rise in the electrolyte level, the opening at the bottom is blocked by the electrolyte. Then, the inside of the cylindrical body of the vent plug is not in communication with the outside of the cylindrical body, and the exhaust path of the gas generated in the battery case is blocked. When the gas exhaust path is blocked, the electrolyte around the vent plug is pushed down by the pressure of the gas remaining in the battery case, and the pushed-down electrolyte enters the inside of the cylindrical body of the vent plug and enters the exhaust path through the through hole, which may result in the electrolyte overflowing outside the lead-acid battery. In order to suppress overflow due to the rise in the electrolyte level caused by such gas generation, a pair of slits extending from the bottom of the cylindrical body to the same position toward the upper side have been formed in the cylindrical body.

[0004] For example, Patent Document 1 discloses a liquid plug for a lead-acid battery in which the upper end of the slit is set at a position as high as possible, thereby making it difficult for the electrolyte to overflow when gas is generated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-71601 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, lead-acid batteries have been developed with a higher electrolyte level than before, with the aim of increasing the capacity of the lead-acid battery. When the electrolyte level is increased, the distance between the electrolyte level and the bottom of the tubular body of the electrolyte plug becomes shorter. As a result, there is a problem that the electrolyte is more likely to overflow (spill).

[0007] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a lead-acid battery vent plug and a lead-acid battery that are less likely to cause spillage. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a vent plug for a lead-acid battery comprising a head, a tubular portion extending from the head, and a filter provided inside the tubular portion, wherein when an end of the tubular portion on the head side is defined as a first end and an end opposite to the first end is defined as a second end, the tubular portion comprises a tubular portion, a helical thread portion provided on an outer peripheral surface of the tubular portion, a slit, and a through hole connecting the inside and outside of the tubular portion, and the filter is disposed at a position in the axial direction of the tubular portion where the through hole is provided. The thread portion is arranged discontinuously in the circumferential direction (by the slits), and if a circumferential position at which a starting end, which is the end of the thread portion on the second end side, is located is defined as a first circumferential position, and a first-turn thread portion is defined as a portion from the starting end to a thread that is located closer to the first end side than the starting end at the first circumferential position and is located closest to the second end, when the slits are viewed in a plane from the radial outside of the tubular portion, the thread portion intersects the slits only at the first-turn thread portion. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a lead-acid battery 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a vent plug 18 according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a front view of the vent plug 18 shown in FIG. 2. [Figure 4] FIG. 3 is a rear view of the vent plug 18 shown in FIG. 2. [Diagram 5] 3 is a cross-sectional view taken along the line A-A2 in FIG. 2, showing the internal structure of the vent plug 18. FIG. [Figure 6] FIG. 6 is a diagram showing the relationship between the slit 45 and the thread portion 42, where (a) is a rear view of the main body portion 31 of the vent plug 18 and (b) is a front view of the main body portion 31 of the vent plug 18. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] [General configuration of lead-acid battery 100] Fig. 1 is a perspective view showing a lead-acid battery 100 according to an embodiment of the present invention. As shown in Fig. 1, the lead-acid battery 100 includes a plurality of plate groups (not shown), an electrolyte (not shown), a battery case 12 that contains the plate groups and the electrolyte and is open at the top, and a lid 15 that seals the opening of the battery case 12.

[0012] The battery case 12 is a container having a substantially rectangular parallelepiped shape with an opening on the top surface, and is made of, for example, synthetic resin. The battery case 12 has a partition wall. The interior of the battery case is divided by the partition wall into a plurality of cell chambers arranged in a predetermined direction. A group of electrodes is arranged in each of the plurality of cell chambers.

[0013] The opening of the battery case 12 is sealed with a lid 15 having a shape corresponding to the opening. More specifically, the peripheral portion of the lower surface of the lid 15 and the peripheral portion of the opening of the battery case 12 are joined by, for example, thermal welding. The lid 15 includes a base 19 and a platform portion 20 protruding from the base 19. A negative electrode terminal 16 and a positive electrode terminal 17 are provided on the base of the lid 15.

[0014] The pedestal portion 20 of the lid 15 includes a first protruding portion 21 protruding between the positive electrode terminal 17 and the negative electrode terminal 16, and a second protruding portion 22 extending parallel to the arrangement direction of the positive electrode terminal 17 and the negative electrode terminal 16. The pedestal portion 20 includes a handle 23 for allowing a user of the lead-acid battery 100 to hold the lead-acid battery 100.

[0015] Further, the second protruding portion 22 is provided with a water refill port at a position corresponding to each cell chamber, and the lid 15 is provided with a liquid vent plug 18 for sealing the water refill port. In the example shown in Fig. 1, the lid 15 is provided with six liquid vent plugs. When refilling the lead-acid battery 100 with water, the liquid vent plug 18 is removed and refilling liquid is supplied.

[0016] Additionally, exhaust holes 24 are provided on the side surface of second protruding portion 22 of lid 15. Exhaust holes 24 are connected to an exhaust path (not shown) provided in lid 15, and exhaust gas generated in each cell chamber to the outside. Additionally, exhaust holes 24 are provided at the end in the arrangement direction in which vent plugs 18 are arranged when lid 15 is viewed from above. In other words, exhaust holes 24 are provided so that vent plugs 18 and exhaust holes 24 are in a straight line.

[0017] [General configuration of the liquid outlet plug 18] Fig. 2 is a perspective view of the vent plug 18 according to the embodiment of the present invention. Fig. 3 is a front view of the vent plug 18, and Fig. 4 is a rear view of the vent plug 18. Fig. 5 is a cross-sectional view taken along line AA in Fig. 2, showing the internal structure of the vent plug 18.

[0018] As shown in FIGS. 2 to 5, the liquid vent plug 18 includes a main body 31, a packing 32, a splash guard 33, and a filter .

[0019] The main body 31 of the vent plug 18 includes a circular, plate-like head 35 and a tubular portion 36 that extends from the head 35 and has a generally cylindrical shape. A tool hole 41 is formed in the head 35 of the vent plug 18. A screw thread portion 42 having a helical screw thread is formed on the outer periphery of the tubular portion 36. The vent plug 18 is fixed to a water refill port provided in the lid 15 by screwing the screw thread portion 42 into the tool hole 41. The lead-acid battery 100 allows the vent plug 18 to be attached and detached by inserting a coin, a screwdriver, or the like having a shape corresponding to the tool hole 41 into the tool hole 41 and rotating the vent plug 18.

[0020] The cylindrical portion 36 includes a cylindrical portion 40, a thread portion 42, and a restricting portion 44. Here, the end of the cylindrical portion 36 on the head 35 side is referred to as a first end portion 50, and the end opposite to the first end portion 50 is referred to as a second end portion 51. That is, the cylindrical portion 36 is connected to the head 35 at the first end portion 50 and is integrated with the head 35. The head 35 seals the first end portion 50 of the cylindrical portion 36. The cylindrical portion 40 of the cylindrical portion 36 is a hollow cylindrical member whose end opposite to the head 35 is open. The cylindrical portion 36 holds the filter 34 and the splash guard 33 inside the cylindrical portion 40. The cylindrical portion 40 also includes a through hole 43 and a slit 45. Hereinafter, the central axis of the cylindrical portion 36 is referred to as the central axis L, and the direction parallel to the central axis L is referred to as the "axial direction of the cylindrical portion 36". In addition, in the axial direction of the tubular portion 36, the direction from the second end portion 51 to the first end portion 50 is defined as the upward direction, and the direction from the first end portion 50 to the second end portion 51 is defined as the downward direction.

[0021] The restricting portion 44 is a ring-shaped member with a portion cut out, and protrudes outward from the tubular portion 40. The packing 32 is a ring-shaped member made of, for example, synthetic rubber. The packing 32 ensures a tight seal between the lid 15 and the liquid outlet plug 18 when the liquid outlet plug 18 is attached to the water refill port. The packing 32 is fitted between the head 35 and the restricting portion 44. The packing 32 is arranged so that its outer diameter is smaller than the head 35 and larger than the restricting portion 44, and is held in a predetermined position by the restricting portion 44 and the head 35.

[0022] The through hole 43 communicates the inside and outside of the tubular portion 40 (tubular portion 36). Therefore, openings are formed on the inner and outer circumferential surfaces of the tubular portion 36. The through hole 43 is connected to an exhaust path (not shown) provided in the lid 15. Gas generated in each cell chamber of the lead-acid battery 100 escapes from the inside of the tubular portion 40 to the exhaust path through the through hole 43 and is released to the outside through the exhaust hole 24. The through holes are provided at two opposing positions across the central axis L of the tubular portion 36.

[0023] The slit 45 is provided so as to extend from the second end 51 of the cylindrical portion 36 toward the first end 50. In the example shown in Figs. 2 to 5, the slit 45 is provided at two positions facing each other across the central axis L of the cylindrical portion 36. The width of the slit 45 is approximately uniform over the entire length in the vertical direction. Since the slit 45 is provided in the liquid outlet plug 18, even if the liquid level of the electrolyte rises above the second end 51, which is the lowest part of the cylindrical portion 36, the gas escapes through the slit 45 to the through hole 43 and the exhaust path, so that overflow can be suppressed.

[0024] As shown in Figs. 2 to 5, the through hole 43 and the slit 45 are formed at the same position in the circumferential direction of the outer circumferential surface of the cylindrical portion 36. In addition, the end of the slit 45 on the first end 50 side is referred to as an end 45a. In this embodiment, the vent plug 18 is shown in which the through hole 43 and the slit 45 are formed at the same position in the circumferential direction of the outer circumferential surface of the cylindrical portion 36. However, the positional relationship between the through hole 43 and the vent plug 18 is not limited to this. That is, the through hole 43 and the slit 45 may be formed at different positions in the circumferential direction of the outer circumferential surface of the cylindrical portion 36.

[0025] The thread portion 42 is a helical thread provided on the outer circumferential surface of the tubular portion 40 and protruding outward from the tubular portion 40. The end of the thread portion 42 on the second end 51 side is referred to as a starting end 42a. The end of the thread portion 42 on the first end 50 side is referred to as a terminal end 42b. In other words, the starting end 42a and the terminal end 42b are the starting end and the terminal end of the thread portion 42 provided on the outer circumferential surface of the tubular portion 40 so as to draw a spiral from the second end 51 side to the first end 50 side.

[0026] 2 to 5, in the liquid outlet plug 18, the slit 45 and the thread portion 42 are provided in an overlapping region on the outer circumferential surface of the cylindrical portion 40. That is, the thread portion 42 is provided with a discontinuous thread. This point will be described with reference to FIG.

[0027] FIG. 6 shows the relationship between the slit 45 and the thread portion 42, where FIG. 6(a) is a rear view of the main body 31 of the vent plug 18, and FIG. 6(b) is a front view of the main body 31 of the vent plug 18. Here, the circumferential position of the tubular portion 36 where the start end 42a of the thread portion 42 is provided is defined as the first circumferential position P. Furthermore, of the thread portion 42 at the first circumferential position P, the thread located closer to the first end 50 than the start end 42a and closest to the second end 51 is referred to as the first intermediate thread portion 42c. Furthermore, of the thread portion 42 at the first circumferential position P, the thread located closer to the first end 50 than the first intermediate thread portion 42c and closest to the second end 51 is referred to as the second intermediate thread portion 42d. In other words, the first intermediate thread portion 42c is located at a position where the thread portion 42 is advanced one helical cycle (360 degrees) from the starting end portion 42a toward the first end portion 50. Also, the second intermediate thread portion 42d is located at a position where the thread portion 42 is advanced one helical cycle (360 degrees) from the first intermediate thread portion 42c toward the first end portion 50.

[0028] Here, the thread portion 42 from the starting end 42a to the first intermediate thread portion 42c is referred to as the first turn thread portion. Furthermore, the thread portion 42 from the first intermediate thread portion 42c to the second intermediate thread portion 42d is referred to as the second turn thread portion. As shown in FIG. 6 and other figures, the thread portion 42 is provided discontinuously because the cylindrical portion 36 is provided with a slit 45. That is, the thread portion 42 has an area between the starting end 42a and the terminal end 42b where the thread portion 42 does not exist. In such an area, the thread is assumed to be provided continuously in the same shape as the area where the thread portion 42 exists, and is referred to as the imaginary thread portion I (see FIG. 6). Note that the "first turn thread portion" includes not only the thread portion 42 but also the imaginary thread portion I existing from the starting end 42a to the first intermediate thread portion 42c.

[0029] In the liquid outlet plug 18 according to this embodiment, when the slit 45 is viewed in plan from the radial outside of the cylindrical portion 40, the thread portion 42 intersects with the slit 45 only at the first turn thread portion. The imaginary thread portion I is provided in the first turn thread portion, and the end portion 45a of the slit 45 is located closer to the first end portion 50 than the end portion of the imaginary thread portion on the second end portion 51 side, when compared with the imaginary thread portion I provided at the same circumferential position. Also, the end portion 45a of the imaginary thread portion is located closer to the second end portion 51 than the end portion of the imaginary thread portion on the first end portion 50 side. In other words, the slit 45 is provided so as to overlap the first turn thread portion, but not to overlap the second turn thread portion.

[0030] The filter 34 is a porous body made of a sintered body of ceramics such as alumina or a sintered body of resin particles such as polypropylene. The filter 34 is an explosion-proof filter that prevents sparks and the like generated outside from penetrating into the battery case 12. As shown in Figs. 3 to 5, the filter 34 is held inside the cylindrical portion 40 of the cylindrical portion 36. The filter 34 is further disposed in the axial direction of the cylindrical portion 36 at a position where the through hole 43 is provided.

[0031] The splash guard 33 is held inside the cylindrical part of the cylindrical part 36. The splash guard 33 is integrally formed of, for example, resin. As shown in FIG. 5, the splash guard 33 includes a bottom part 60, a support part 61, a first splash guard plate 62, a second splash guard plate 63, a third splash guard plate 64, a fourth splash guard plate 65, and a fifth splash guard 66. The splash guard 33 includes the first splash guard plate 62 to the fifth splash guard plate 66, so that the gas exhaust path inside the cylindrical part 36 is labyrinth-shaped. As a result, the gas generated inside the battery case 12 is exhausted to the outside through the inside of the cylindrical part 36, while the electrolyte is not easily leaked out. In the following, the first splash guard plate 62 to the fifth splash guard plate 66 may be collectively referred to as a plurality of splash guard plates.

[0032] The bottom 60 is a circular plate-like member and is provided to seal the second end 51 of the cylindrical part 36. The diameter of the bottom 60 is slightly larger than the inner diameter of the cylindrical part 36 at the second end 51, and the bottom 60 of the splash protector 33 is press-fitted into the second end 51 of the cylindrical part 36. As a result, the splash protector 33 is locked inside the cylindrical part 36. In addition, a convex part 60a that protrudes outward in the circumferential direction is formed on the outer circumferential surface of the bottom 60 at a position corresponding to the slit 45. The convex part 60a is formed in two places at a position corresponding to the slit 45. In the liquid outlet plug 18, the splash protector 33 is press-fitted into the cylindrical part 36 so that the convex part 60a is inserted into the slit 45, thereby defining the direction (orientation) in which the splash protector 33 is held by the cylindrical part 36. The support portion 61 is a rod-shaped body that extends from the center of the bottom portion 60 in parallel with the axial direction of the cylindrical portion 36 toward the first end side.

[0033] The first splash protection plate 62 is the splash protection plate located closest to the second end 51 among the multiple splash protection plates included in the splash protection body 33. The first splash protection plate 62 is formed as a pair facing each other across the central axis L of the cylindrical portion 36. The first splash protection plate 62 has a substantially semicircular plate shape, with a straight portion of the semicircular shape connected to the support portion 61 and an arc facing outward. The first splash protection plate 62 is also arranged to extend obliquely upward from the support portion 61.

[0034] In the first splash plate 62, the lowermost part connected to the support portion 61 is the base portion 62a. In addition, in the first splash plate 62, the uppermost end portion 62b (closer to the first end portion 50) is located above (closer to the first end portion 50) the end portion 45a of the slit 45. Here, if the axial distance of the cylindrical portion 36 from the second end portion 51 to the upper end portion 62b of the first splash plate 62 is defined as a distance h2, the distance h2 satisfies the following relational expression between the distance h1 representing the depth of the slit 45 and the pitch α of the thread portion 42. h1 < h2 < h1 + α (1)

[0035] Consider the case where the distance h2 is equal to or less than the distance h1, that is, the depth of the slit 45 is equal to or shorter than the distance to the upper end 62b of the first splash plate 62. In such a case, the end 45a of the slit 45 is located closer to the first end 50 than the upper end of the first splash plate 62, so that the electrolyte easily infiltrates into the inside of the cylindrical body 36 from above the first splash plate 62 due to vibration or the like. The electrolyte that has infiltrated into the inside of the cylindrical body 36 may creep up inside the cylindrical body 36 and overflow due to further vibration or the like being applied to the lead-acid battery 100.

[0036] When the distance h2 is h1+α or more, the distance in the axial L direction from the upper end 62b of the first splash plate 62 to the end 45a of the slit 45 becomes large. Therefore, compared with the case where the distance h2 is less than h1+α, the electrolyte that has infiltrated into the inside of the cylindrical body 36 due to vibration or the like is more likely to hit the inner wall of the cylindrical body 36, and the electrolyte that has infiltrated into the inside of the cylindrical body 36 is less likely to be discharged to the outside of the cylindrical body 36. In this case, as in the above case, when vibration or the like is further applied to the electrolyte that has infiltrated into the cylindrical body 36, the electrolyte may creep up inside the cylindrical body 36 and overflow.

[0037] In this way, since the vent plug 18 satisfies the above relational expression (1), the vent plug 18 is less susceptible to overflowing due to vibrations or the like (it has excellent dynamic overflowing performance).

[0038] In addition, in the vent plug 18, the upper end 62b of the first splash plate 62 is located closer to the first end 50 (higher) than the starting end 42a of the thread portion 42.

[0039] The second splash protection plate 63 is provided above (toward the first end portion 50) the first splash protection plate 62 and has a generally rectangular flat plate shape. The second splash protection plates 63 are formed as a pair facing each other across the central axis L of the cylindrical portion 36, and are disposed to extend obliquely downward from the support portion 61.

[0040] The third splash protection plate 64 is provided above the second splash protection plate 63 and has approximately the same shape as the first splash protection plate 62. That is, the third splash protection plate 64 is formed as a pair so as to face each other across the central axis L of the cylindrical portion 36. The third splash protection plate 64 has an approximately semicircular plate shape, with a chord connected to the support portion 61 and an arc facing outward. The third splash protection plate 64 is also disposed so as to extend obliquely upward from the support portion 61. Similarly to the first splash protection plate 62, the lowest portion of the third splash protection plate 64 connected to the support portion 61 is called the base, and the uppermost portion (on the first end portion 50 side) is called the upper end portion.

[0041] The fourth splash protection plate 65 is provided so as to extend downward from between the base and the upper end of the third splash protection plate 64. The fourth splash protection plate is a substantially rectangular flat plate. The fourth splash protection plate 65 is formed as a pair so as to face each other across the central axis L of the cylindrical portion 36.

[0042] The fifth splash protection plate 66 is provided above the third splash protection plate 64 and is connected to the top of the support column 61. The upper end 66a, which is the end of the fifth splash protection plate 66 on the first end 50 side, is the end of the splash protection body 33 on the first end 50 side. The upper end 66a is located closer to the first end 50 than the upper end 42b of the threaded portion 42.

[0043] Furthermore, in the liquid outlet plug 18 of this embodiment, the filter 34 is arranged in the axial direction of the tubular portion 36 at a position where the through hole 43 is provided, and the axial distance from the end of the through hole 43 on the second end 51 side to the upper end 66a, which is the end on the first end 50 side of the splash guard 33, is 4.0 mm or less.

[0044] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0045] 〔summary〕 (1) A lead-acid battery vent plug according to one embodiment of the present invention is a lead-acid battery vent plug 18 including a head 35, a tubular portion 36 extending from the head 35, and a filter 34 provided inside the tubular portion 36. When an end of the tubular portion 36 on the head side 35 is defined as a first end 50 and an end opposite to the first end 50 is defined as a second end 51, the tubular portion 36 includes a tubular portion 40, a helical thread portion 42 provided on the outer peripheral surface of the tubular portion 40, a slit 45, and a through hole 43 communicating between the inside and the outside of the tubular portion 40. The filter 34 is disposed on the axis (center) of the tubular portion 36. In the direction of axis L), the thread portion 42 is positioned at a position where the through hole 43 is provided, and the circumferential position at which the starting end 42a, which is the end of the thread portion 42 on the second end 51 side, is located is defined as a first circumferential position P, and the first circumferential position P is the portion from the starting end 42a to the thread that is located closer to the first end 50 than the starting end 42a at first circumferential position P and is located closest to the second end 51, when the tubular portion 36 is viewed in a plane from the radial outside of the tubular portion 40, the thread portion 42 may intersect with the slit 45 only at the first circumferential position P.

[0046] In the vent plug 18 according to the present embodiment, when the cylindrical portion 36 is viewed in plan from the radial outside of the cylindrical portion 40, the thread portion 42 intersects with the slit 45 only at the first turn of the thread portion. That is, the slit 45 is provided so as to cut out the first turn of the thread portion 42. In this way, by overlapping the region where the slit 45 and the thread portion 42 are formed, the axial length of the cylindrical portion 36 can be shortened. Therefore, it is possible to shorten the axial length of the vent plug 18, and in the lead-acid battery 100, the distance from the electrolyte level to the lower end of the vent plug 18 can be made longer than in the past. In the lead-acid battery 100, by making the distance from the electrolyte level to the lower end of the vent plug 18 longer than in the past, the electrolyte is less likely to infiltrate into the inside of the vent plug 18 even if the electrolyte level rises during charging. Therefore, it is possible to provide a vent plug 18 that is less likely to overflow than in the past.

[0047] Furthermore, when the axial length of the vent plug 18 is shortened and the distance from the electrolyte level to the vent plug 18 is set to the same as in the conventional case, the electrolyte level can be raised higher than in the conventional case, thereby making it possible to increase the capacity of the lead-acid battery 100.

[0048] Furthermore, since the slit 45 is provided so as to cut out only the first turn of the thread portion 42, there is little effect on the tightness of the vent plug 18 when the vent plug 18 is fixed to the water refill port. In other words, if the slit 45 is provided so as to cut out the second and subsequent turns of the thread portion 42, the vent plug 18 may be installed at an angle when attached to the water refill port, and the sealing between the lid 15 and the vent plug 18 may not be ensured. In addition, if the depth of the slit 45 is set so as to intersect with the second turn of the thread portion, the second end 51 of the cylindrical portion 36 is easily deformed radially outward of the cylindrical portion 36, and the fitting force between the cylindrical portion 36 and the bottom portion 60 of the splash guard 33 is weakened. Therefore, there is a risk that the splash guard 33 may fall off the cylindrical portion 36 due to vibration or the like when the lead-acid battery 100 is used.

[0049] Furthermore, according to the above configuration, even if the axial length of the vent plug 18 is shortened, the axial length of the region where the thread portion 42 is formed does not need to be changed. Considering the case where the vent plug 18 is removed from the lead-acid battery 100, the screw of the vent plug 18 is loosened and the head of the vent plug 18 is pinched and removed. At this time, the amount by which the vent plug 18 protrudes from the pedestal portion 20 of the lid 15 depends on the axial length of the region where the thread portion 42 is formed. Therefore, in the vent plug 18 according to this embodiment, since it is not necessary to change the axial length of the region where the thread portion 42 is formed, the height by which the vent plug 18 protrudes from the pedestal portion 20 is the same as the conventional one, and it is not difficult for an operator to remove (pinch) the vent plug 18.

[0050] Furthermore, in the vent plug 18 according to this embodiment, the filter 34 is disposed at a position where the through hole 43 is provided in the axial direction of the tubular portion 36. That is, the filter 34 is disposed so as to cover the through hole 43. Here, a case where the filter 34 is disposed at a different axial position from the through hole 43 is considered. The filter 34 needs to be disposed between the exhaust hole 24 of the lead-acid battery 100 and the inside of the battery case 12, and therefore is disposed closer to the battery case 12 side (the second end 51 side) than the through hole 43. That is, in the vent plug 18 according to this embodiment, the filter 34 is disposed at a position where the through hole 43 is provided in the axial direction of the tubular portion 36, and therefore the splash guard 33 can be disposed at a position farther from the liquid surface (upper) than the case where the filter 34 is disposed at a different height from the through hole 43.

[0051] Here, the gas generated in the battery case 12 passes through a labyrinth-shaped exhaust path formed by the splash guard 33 and the inner circumferential surface of the tube portion 40 of the tube-shaped portion 36, and is discharged to the outside of the lead-acid battery 100. Therefore, when the liquid level rises to a height at which the base 62a of the first splash guard plate 62, which is the entrance of the exhaust path, of the splash guard 33, is immersed in the electrolyte, the gas generated in the battery case 12 is no longer discharged to the outside. According to the liquid vent plug 18 of this embodiment, the splash guard 33 can be disposed at a position far from the liquid level (above). Therefore, in the liquid vent plug 18 of this embodiment, overflow can be prevented even at a liquid level height at which overflow would occur in the past. As a result, it is possible to provide a liquid vent plug 18 that is less likely to cause overflow than in the past.

[0052] Note that "filter 34 is disposed at a position where through hole 43 is provided in the axial (central axis L) direction of cylindrical portion 36" includes both a case where filter 34 is provided so as to cover all of through hole 43 and a case where filter 43 is provided so as to cover at least a part of through hole 43. Also, "intersecting with slit 45" means that filter 34 is provided in a region overlapping with a region where slit 45 is provided in plan view.

[0053] In addition, the "slit" is not limited to one extending from the second end 51 of the cylindrical portion 36 to the first end 50 side. In other words, the shape of the "slit" is not particularly limited, and the shape is not particularly limited as long as the slit has a function of introducing the gas generated in the battery case 12 from the outside of the cylindrical portion 36 to the inside and communicates the inside and outside of the cylindrical portion 36. For example, the "slit" also includes a hole provided in the cylindrical portion 36 whose end on the second end 51 side does not reach the second end 51. In addition, in the above-mentioned embodiment, only a slit extending parallel to the central axis L is shown, but the slit may be formed on the outer circumferential surface of the cylindrical portion 40 of the cylindrical portion 36 so as to intersect with the central axis L.

[0054] (2) The liquid outlet plug 18 in one embodiment of the present invention comprises a splash guard body 33 having a plurality of splash guard plates, and the end portion (upper end portion 62b) of the first splash guard plate 62, which is the first splash guard plate closest to the second end portion 51 among the plurality of splash guard plates, on the first end portion 50 side may be located closer to the first end portion 50 in the axial (central axis L) direction than the starting end portion 42a.

[0055] (3) The liquid outlet plug 18 in one embodiment of the present invention includes a splash guard body 33 having a plurality of splash guard plates, and among the plurality of splash guard plates, the end portion (upper end portion 66a) located closest to the first end portion may be located closer to the first end portion 50 in the axial (central axis L) direction than the end portion (terminal portion 42b) of the thread portion 42 located on the first end portion 50 side.

[0056] (4) In the vent plug 18 according to one aspect of the present invention, the slits 45 and the through holes 43 may be formed at the same circumferential position on the outer circumferential surface. Here, "formed at the same circumferential position" means that the circumferential center of the slit 45 and the circumferential center of the through hole 43 are at the same circumferential position. When a plurality of slits 45 and a plurality of through holes 43 are provided, the through holes 43 are formed at positions corresponding to the respective slits 45, and it is sufficient that the respective slits 45 and the corresponding through holes 43 are at the same circumferential position.

[0057] (5) A lead-acid battery 100 according to one embodiment of the present invention is a vent plug 18 for a lead-acid battery comprising a head 35, a tubular portion 36 extending from the head 35, a filter 34 provided inside the tubular portion 36, and a splash guard 33 provided inside the tubular portion 36, wherein the tubular portion 36 has a through hole 43 connecting the inside and outside of the tubular portion, and the filter 34 is disposed at a position in the axial direction (central axis L) of the tubular portion 36 where the through hole 43 is provided, and when the end of the tubular portion 36 on the head side 35 is defined as a first end 50 and the end opposite the first end 50 is defined as a second end 51, the axial distance from the end of the through hole 43 on the second end 51 side to an upper end 66a, which is the end of the splash guard 33 on the first end 50 side, may be 4.0 mm or less.

[0058] According to the above configuration, the splash guard 33 can be disposed at a position farther from the liquid surface (upper) than when the filter 34 is not disposed at the position where the through hole 43 is provided, or when the axial distance from the end of the through hole 43 on the second end 51 side to the upper end 66a, which is the end of the splash guard 33 on the first end 50 side, exceeds 4.0 mm. Therefore, as described above, it is possible to shorten the axial length of the vent plug 18. This makes it possible to prevent overflow even at a liquid level that would cause overflow in the past, and to provide a vent plug 18 that is less likely to cause overflow than the past.

[0059] (6) The lead-acid battery 100 according to an aspect of the present invention may include the vent plug 18 described above. [Explanation of symbols]

[0060] 18: liquid port plug (liquid port plug for lead-acid battery), 33: splash guard, 34: filter, 35: head, 36: tubular portion, 40: tubular portion, 42: thread portion, 42a: starting end, 42b: ending end, 43: through hole, 45: slit, 45a: end, 50: first end, 51: second end, 62: first splash guard plate, 62b: upper end (end), 66: fifth splash guard plate, 66a: upper end (end), 100: lead-acid battery, L: central axis (axis), P: first circumferential position

Claims

1. A vent plug for a lead-acid battery comprising: a head portion; a cylindrical portion extending from the head portion; a filter provided inside the cylindrical portion; and a splash guard, In the case where the end of the tubular portion on the head side is a first end and the end opposite to the first end is a second end, The cylindrical portion is A cylindrical portion and A helical thread portion provided on an outer peripheral surface of the cylindrical portion; Slits and A through hole communicating the inside and the outside of the cylindrical portion; Equipped with the filter is disposed at a position where the through hole is provided in an axial direction of the cylindrical portion, a circumferential position at which a start end of the thread portion, which is an end portion on the second end side, is located is defined as a first circumferential position; When the first turn thread portion is defined as a thread located on the first end side from the starting end at the first circumferential position and closest to the second end side, When the cylindrical portion is viewed in a plan view from the radial outside of the cylindrical portion, the thread portion intersects with the slit only at the first turn thread portion, The splash guard has a plurality of splash guard plates housed inside the cylindrical portion, and among the plurality of splash guard plates, the splash guard plate located closest to the second end side is defined as a first splash guard plate. The axial distance from the second end to the end of the first splash guard plate on the first end side is defined as a distance h2. The depth of the slit is defined as a distance h1. The pitch of the thread portion is defined as a distance α. The relational expression h 1 < h 2 < h 1 + α is satisfied, A lead-acid battery vent plug, characterized in that the end portion of the first splash guard on the first end side is located closer to the first end side than the starting end in the axial direction.

2. A splash guard having a plurality of splash guard plates, 2. The lead-acid battery outlet plug according to claim 1, wherein the end closest to the first end among the ends of the plurality of splash guards is located closer to the first end in the axial direction than the end of the thread portion on the first end side.

3. A lead-acid battery having a liquid port plug as described in claim 1 or 2.

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