Explosion-proof valve for sealed energy storage devices
The groove pattern for the explosion-proof valve in sealed energy storage devices addresses complexity by concentrating stress at a central opening point, allowing rupture at lower pressures with stable opening areas and reduced design complexity.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- AISAN IND CO LTD
- Filing Date
- 2025-12-09
- Publication Date
- 2026-07-01
AI Technical Summary
Existing groove patterns for explosion-proof valves in sealed energy storage devices require complex design considerations due to residual stress at intersections, and fail to rupture at lower pressures effectively.
A groove pattern for the explosion-proof valve that includes a first groove passing through the center of a thin film, with second and third grooves extending from both ends, featuring arc and straight sections, and specific radius and distance configurations to concentrate stress for easier rupture at lower pressures without intersecting straight lines.
The valve can rupture at lower pressures with a stable opening area and reduced design complexity by concentrating stress at a central opening point, ensuring robustness and consistent performance.
Smart Images
Figure 2026109577000001_ABST
Abstract
Description
Technical Field
[0001] The technology disclosed in this specification relates to an explosion-proof valve of a sealed energy storage device.
Background Art
[0002] In a part of a sealed container of a sealed battery or capacitor (sealed energy storage device), an explosion-proof valve composed of a thin film portion with grooves formed thereon is provided. When the pressure inside the sealed container abnormally rises, the thin film portion of the explosion-proof valve cracks at the groove portion to discharge the internal gas, thereby preventing the explosion of the battery or capacitor. Various groove patterns (groove patterns) have been disclosed for forming on the thin film portion which is the explosion-proof valve.
[0003] For example, Patent Document 1 discloses a battery pack including a thin film portion having a groove pattern of two intersecting straight lines.
[0004] Also, Patent Document 2 discloses an explosion-proof valve of a sealed energy storage device having a groove pattern shown in FIG. 10 as one of the groove patterns.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0006] Analysis by the inventors revealed that in the groove pattern of the battery pack described in Patent Document 1, the residual stress generated at the intersection of two straight lines is higher than the residual stress generated in the groove portions other than the intersection. Therefore, if the magnitude of the residual stress generated at the intersection is not taken into consideration, the pressure at which fracture begins may be lower than expected. For this reason, groove patterns with two intersecting straight lines are undesirable because they require consideration of the magnitude of the residual pressure generated at the intersection, which can lead to increased complexity in design and manufacturing.
[0007] Furthermore, various groove patterns are disclosed for explosion-proof valves of sealed energy storage devices described in Patent Document 2. For example, in the conventional groove pattern 120 shown in Figure 10, in each conventional second groove 132 extending from the end of the conventional first groove 131, the radius RY of the arc of the conventional second arc portion 143 is greater than or equal to the radius RX of the arc of the conventional first arc portion 141. As a result, the area of the region enclosed by the conventional first groove 131, conventional first arc portion 141, conventional first straight portion 142, conventional second arc portion 143, and conventional second straight portion 144 (the area that receives internal pressure) is slightly smaller, and it cannot rupture at lower pressures. In recent years, it has been desirable to be able to rupture at lower pressures.
[0008] The objective of the technology disclosed herein to solve the above problems is to provide an explosion-proof valve for a sealed energy storage device that can be opened at lower pressure without complicating the design or manufacturing process. [Means for solving the problem]
[0009] To solve the above problems, the explosion-proof valve for a sealed energy storage device disclosed herein takes the following measures.
[0010] The first means is an explosion-proof valve for a sealed energy storage device, which is provided in the sealed container of the sealed energy storage device and comprises a thin film portion that is thinner than the surrounding sealed container and ruptures when the internal pressure rises, and the thin film portion has a groove pattern that breaks when it ruptures. The groove pattern comprises a first groove that is a straight line passing through approximately the center of the thin film portion and has one end and the other end both extending to just before the edge of the thin film portion and sandwiched between one region and the other region of the thin film portion; a second groove that extends from one end of the first groove to the other region of the thin film portion and a third groove that extends from one end of the first groove to the one region of the thin film portion and a third groove that extends from the other end of the first groove to the other region of the thin film portion. Each of the second grooves has a first arc-shaped section that is convex toward the edge of the thin film portion, starting from one end and the other end of the first groove, and a first straight section that extends linearly from the end of each first arc-shaped section so as to be substantially parallel to the first groove, and a second arc-shaped section that extends toward the first groove from the end of each first straight section, and a second straight section that extends linearly from the end of each second arc-shaped section to just before the first groove, with the end of each second straight section being the end of each second groove. Each of the third grooves has a third arc-shaped section that is convex toward the edge of the thin film portion, starting from one end and the other end of the first groove, and a third straight section that extends linearly from the end of each third arc-shaped section so as to be substantially parallel to the first groove and just before the second arc-shaped section, with the end of each third straight section being the end of each third groove. Furthermore, the end of each of the third grooves extends to the end of the first straight section of the adjacent second groove, which is straddling the first groove, in the direction along the first groove, and the radius of each of the second arc sections is smaller than the radius of each of the first arc sections, thus forming an explosion-proof valve for a sealed energy storage device.
[0011] According to the first method described above, the end of each third groove extends to the end of the first straight section of the second groove adjacent to the first groove in the direction along the first groove. This increases the area of the second pressure-receiving section enclosed by the third groove and the first groove, allowing the thin film to be ruptured at a lower pressure. Furthermore, the radius of the second arc section is set smaller than the radius of the first arc section. This increases the area of the first pressure-receiving section enclosed by the second groove and the first groove, allowing the thin film to be ruptured at a lower pressure. In addition, since the groove pattern does not involve the intersection of two straight lines, there is no need to consider the magnitude of residual pressure generated at the intersections, thus avoiding complexity in design and manufacturing.
[0012] The second means is an explosion-proof valve for a sealed energy storage device relating to the first means, wherein the distance from the end of each of the second grooves to the first groove is shorter than the distance from the end of each of the third grooves to the adjacent second groove in the direction along the first groove.
[0013] According to the second method described above, the opening on the central side of the explosion-proof valve (thin film portion) (distance from the end of the second groove to the first groove) is shorter than the opening on the outer circumference side (distance from the end of the third groove to the second groove), making it easier for the groove to rupture due to pressure.
[0014] The third means is an explosion-proof valve for a sealed energy storage device relating to the first or second means, wherein the end of the second groove is located between the first groove and a virtual parallel line passing through the center of the first arc portion or the center of the third arc portion and parallel to the first groove.
[0015] According to the third method described above, when the internal pressure of the sealed energy storage device increases, stress concentrates in such a way that the center of the explosion-proof valve becomes the opening starting point (the position from which the valve opens). As a result, when the valve opens, it opens from the center of the explosion-proof valve, making it easier to ensure robustness when opening the valve (it becomes easy to open the valve from the same opening starting point regardless of the pressure at which it is opened).
[0016] The fourth means is an explosion-proof valve of the sealed storage battery according to the first or second means, and the distance from the center line of the first groove, which is parallel to the first groove and passes through the center of the first groove, to the end of the second groove is 2.15 mm to 2.80 mm. It is an explosion-proof valve of a sealed storage battery.
[0017] According to the above fourth means, when the internal pressure of the sealed storage battery rises, stress can be appropriately concentrated at the valve opening starting point (the position that becomes the starting point when the valve opens), and it is possible to avoid the stress becoming too large. It is possible to open the valve at a desired opening pressure (for example, 0.4 to 0.6 [Mpa]), and it is possible to stably obtain a desired opening area (for example, 75 [mm 2 ) so that the valve opening shape of "Pattern A" shown in FIG. 11 can be obtained.
Advantages of the Invention
[0018] The explosion-proof valve of the sealed storage battery disclosed in this specification can be cracked at a lower pressure without causing complication in design and manufacture by taking the above means.
Brief Description of the Drawings
[0019] [Figure 1] It is a figure explaining an example of the external appearance of a sealed storage battery. [Figure 2] It is a sectional view taken along the line II-II of the sealed storage battery shown in the example of FIG. 1. [Figure 3] It is a perspective view of the sealing plate of the sealed container. [Figure 4] It is an enlarged view of the thin film part formed on the sealing plate shown in the example of FIG. 3. [Figure 5] It is a plan view of the sealing plate of the sealed container. [Figure 6] It is a sectional view taken along the line VI-VI of FIG. 5. [Figure 7] It is an enlarged view of part VII shown in FIG. 6. [Figure 8] It is an enlarged view of part VIII shown in FIG. 7. [Figure 9]Figure 5 is an enlarged view of the thin film portion, illustrating the shape of the groove pattern provided in the thin film portion. [Figure 10] This diagram illustrates an example of a conventional groove pattern shape. [Figure 11] This diagram illustrates an example of the valve opening shape when an explosion-proof valve opens. [Figure 12] This diagram illustrates the relationship between the length of distance D4, the valve opening shape (pattern A, pattern B, pattern C), and the evaluation results. [Figure 13] This shows the simulation results for distance D4 and the displacement of the central part of the explosion-proof valve when the internal pressure of the container is 0.4 [MPa] (and the explosion-proof valve does not open). [Modes for carrying out the invention]
[0020] <External appearance (Figure 1) and structure (Figure 2) of sealed energy storage device 1> The embodiments will be described below with reference to the drawings. Figure 1 shows a schematic overview of the external appearance of a sealed energy storage device 1 as one embodiment. The sealed energy storage device 1 is a battery or capacitor, and its components 6, such as electrodes, active material, electrolyte, and dielectric, are housed inside a sealed container 4.
[0021] The sealed container 4 is made of, for example, an aluminum alloy and is, for example, shaped like a rectangular parallelepiped. However, the material and shape of the sealed container 4 are not limited to these. The sealed container 4 has a roughly cylindrical container body 8 with one end closed at the bottom and the other end open, and a sealing plate 10 that closes the opening of the container body 8. The sealing plate 10 is joined to the opening of the container body 8 around its entire circumference by, for example, laser welding, so as to create an airtight seal.
[0022] The sealing plate 10 is made of a metal such as an aluminum alloy. The container body 8 and the sealing plate 10 may be made of the same metal material or different metal materials. The sealing plate 10 is shaped to correspond to the opening of the container body 8, and is, for example, rectangular. The sealing plate 10 may also be provided with necessary holes, such as holes 14 for inserting terminals 12 that are electrically connected to the electrodes of the components 6 housed in the sealed container 4, and holes (not shown) for injecting electrolyte. However, these holes are sealed by appropriate means during manufacturing.
[0023] The thin film portion 16 is formed at a predetermined position on the sealing plate 10 and functions as an explosion-proof valve 15. The thin film portion 16 is the explosion-proof valve 15. As shown in the examples in Figures 1 and 2, when there are terminals 12 near both ends of the sealing plate 10, the thin film portion 16 is positioned, for example, between the two terminals 12. When one of the terminals 12 is near the center of the sealing plate 10, the thin film portion 16 is positioned, for example, near one of the terminals 12.
[0024] <Sealing plate 10 and thin film portion 16 (Figures 3-7)> The shape of the thin film portion 16 is as shown in Figures 3 to 5, with the ends of two parallel straight lines connected by an arc, which is the shape of a running track (also called an oval shape, rounded rectangle, or ellipse). However, it is not limited to this shape and may be circular or elliptical. As shown in Figures 3 and 4, the thin film portion 16 is formed as a recess 18 where a predetermined position of the sealing plate 10 is crushed, and is integrally formed with the other parts of the sealing plate 10. For example, by compressing and crushing a predetermined position of the sealing plate 10 with a punch or the like using a press device to form a recess 18, the predetermined position of the sealing plate 10 can be made thinner than the surrounding sealing plate 10 (thin-walled). The method of forming the thin film portion 16 is not particularly limited.
[0025] As shown in Figures 4 and 9, a groove pattern 20 is formed on the surface of the thin film portion 16, having a first groove 31, a second groove 32, and a third groove 33 that rupture when the internal pressure of the sealed energy storage device 1 rises. The first groove 31, the second groove 32, and the third groove 33 constituting the groove pattern 20 prevent the sealed container 4 (see Figures 1 and 2) of the sealed energy storage device 1 from rupturing due to internal pressure when the internal pressure of the sealed energy storage device 1 rises to a predetermined pressure or higher. The grooves forming the groove pattern 20 can be formed, for example, by compression processing with a punch having a convex portion for forming grooves and a press device.
[0026] Figure 6 is a cross-section of VI-VI in Figure 5, Figure 7 is an enlarged view of section VII in Figure 6, and Figure 8 is an enlarged view of section VIII in Figure 7. When grooves are formed by the compression process described above, as shown in the example in Figure 7, the thin film portion 16 around the grooves (first groove 31, third groove 33) becomes a roughly dome shape, raised in the direction in which the punch or the like is pressed. The method for forming each groove in the groove pattern 20 is not particularly limited.
[0027] <Details of the groove pattern 20 formed on the thin film portion 16 (Figure 9)> Next, using Figure 9, we will explain in detail the individual grooves (first groove 31, second groove 32, and third groove 33) that form the groove pattern 20.
[0028] The first groove 31 is a straight groove that passes through approximately the center P of the thin film portion 16, with both one end 31A and the other end 31B of the first groove extending to just before the edge of the thin film portion 16. The first groove 31 is sandwiched between one region 16A (the upper half of the thin film portion 16 shown in Figure 9) and the other region 16B (the lower half of the thin film portion 16 shown in Figure 9), and is a groove that divides the thin film portion 16 into one region 16A and the other region 16B, and is a single groove.
[0029] The second groove 32 consists of two grooves: one extending from one end 31A of the first groove 31 to the other region 16B of the thin film portion 16, and another extending from the other end 31B of the first groove 31 to the other region 16A of the thin film portion 16.
[0030] The third groove 33 consists of two grooves: one extending from one end 31A of the first groove 31 to one region 16A of the thin film portion 16, and another extending from the other end 31B of the first groove 31 to the other region 16B of the thin film portion 16.
[0031] Each of the second grooves 32 has a first arc portion 32S that is convex toward the edge of the thin film portion 16, with the first end 31A and the other end 31B of the first groove 31 serving as the starting point (second groove starting point 32A). Each of the second grooves 32 has a first straight portion 32T that extends linearly from the end 32B (end of the first arc portion) of the first arc portion 32S so as to be approximately parallel to the first groove 31. Each of the second grooves 32 has a second arc portion 32U that is arc-shaped and extends toward the first groove 31 from the end 32C (end of the first straight portion) of the first straight portion 32T. Furthermore, each of the second grooves 32 has a second straight section 32V that extends linearly from the end 32D (end of the second arc) of the second arc section 32U to just before the first groove 31, along a direction perpendicular to the first groove 31. The end of each second straight section 32V (end of the second straight section) is the end of the second groove 32, which is the second groove end 32Z. The positions of the second groove ends 32Z of the two second grooves 32 are opposite each other, with the approximate center P of the thin film section 16 in between.
[0032] Each of the third grooves 33 has a third arc portion 33S that is convex toward the edge of the thin film portion 16, with the first end 31A and the other end 31B of the first groove 31 serving as the starting point (third groove starting point 33A). Each of the third grooves 33 has a third straight portion 33T that extends linearly from the end 33B (third arc portion end) of the third arc portion 33S, substantially parallel to the first groove 31, to just before the second groove 32 (second arc portion 32U). The end of each third straight portion 33T (third straight portion end) is the third groove end 33Z, which is the end of the third groove 33.
[0033] Furthermore, the virtual lines V1 passing through the position of the end of each third groove 33, which is the end of the third groove 33, and the end of the first straight section 32T of the second groove 32 adjacent to the first groove 31, which is the end of the first straight section, which is the end of the first straight section, which is the end of the second groove 32 adjacent to the first groove 31, are each approximately perpendicular to the first groove 31. In other words, the position of the end of the third straight section 33T of the third groove 33 (third groove end 33Z) extends from the end 33B of the third arc section 33S to the position of the end of the first straight section 32T of the second groove 32 adjacent to the first groove 31, in the direction along the first groove 31 (in a direction approximately parallel to the first groove 31).
[0034] Furthermore, in Figure 9, the radius R2 of each second arc section 32U is set to be smaller than the radius R1 of each first arc section 32S (radius R2 < radius R1).
[0035] Furthermore, in Figure 9, the distance D2 from the end of each second groove 32, which is the end of the second groove 32, to the first groove 31 is set to be shorter than the distance D3 from the end of each third groove, which is the end of the third groove, which is the end of the third groove, to the adjacent second groove 32 (to the second arc portion 32U) in the direction along the first groove 31.
[0036] <Position of the end of the second groove 32Z and the distance D4 from the end of the second groove 32Z to the center line H1 of the first groove (Figures 9, 11-13)> In Figure 9, if we virtually set a line parallel to the first groove 31 passing through the center C1 of the first arc portion 32S or the center C3 of the third arc portion 33S as a virtual parallel line V2, then, as shown in Figure 9, the position of the end of the second groove 32Z is located between the virtual parallel line V2 and the first groove 31.
[0037] Here, as shown in Figure 9, if the distance from the first groove center line H1, which is parallel to the first groove 31 and passes through the center of the first groove 31, to the end of the second groove 32Z is defined as distance D4, the inventors experimentally confirmed that the valve opening shape when the explosion-proof valve 15 opens changes depending on the length of distance D4. The inventors confirmed that the valve opening shape when the explosion-proof valve 15 opens will be one of the shapes (or a shape close to one of them) shown in Figure 11: "Pattern A", "Pattern B", or "Pattern C".
[0038] As an example of evaluating the opening of the explosion-proof valve 15, consider a case where the evaluation result is considered OK if both (1) and (2) below are satisfied. Note that "Pattern A," "Pattern B," and "Pattern C" shown in Figure 11 all satisfied (1) below. Furthermore, "Pattern A" also satisfied (2) below, but "Pattern B" sometimes did not satisfy (2), and "Pattern C" did not satisfy (2) below. Therefore, the evaluation result for "Pattern A" is OK, while the evaluation results for "Pattern B" and "Pattern C" are NG. Note that the length L1 in the X-axis direction of the groove pattern 20 shown in Figure 9 is approximately 21.8 [mm], and the length L2 in the Y-axis direction of the groove pattern 20 is approximately 14 [mm]. In this case, the area enclosed by the groove pattern 20 is approximately 284 [mm]. 2 ] (1) If the internal pressure of the sealed energy storage device 1 rises, the explosion-proof valve 15 will open when the internal pressure reaches 0.4 [Mpa] to 0.6 [Mpa]. (2) The opening area of the explosion-proof valve 15 after opening is 75 [mm²] 2 That's all.
[0039] "Pattern A" shown in Figure 11 is a valve opening shape in which the first groove 31, the first arc portion 32S, and the third arc portion 33S split (break), while the first straight portion 32T, the third straight portion 33T, the second arc portion 32U, and the second straight portion 32V do not split (break).
[0040] In the case of "Pattern A," the length of distance D4 is an appropriate value (2.15 [mm] to 2.80 [mm] as described later), so that the valve opening starting point KA (see "Pattern A" in Figure 11), which is the starting point when the valve opens, is near the center P shown in Figure 9. Also, in the case of "Pattern A," stress is concentrated near the center P shown in Figure 9, and the magnitude of the concentrated stress is neither excessive nor insufficient, but of an appropriate size. As shown in Figure 11, the opening area MA of the hatched "Pattern A" is larger than the opening area MB of "Pattern B" and larger than the opening area MC of "Pattern C."
[0041] "Pattern B" shown in Figure 11 is a valve opening shape in which, of the adjacent first and third arc sections 32S and third arc sections 33S, the adjacent first and third arc sections 32S and third arc sections 33S on one side are split (broken), the adjacent first and third arc sections 32S and third arc sections 33S on the other side are not split (broken), the first groove 31 is not split (broken), and the first straight section 32T and third straight section 33T on the split (broken) side are split (broken) partway.
[0042] In the case of "Pattern B," the length of distance D4 is excessive (longer than 2.80 mm, as described later), causing the valve opening starting point KB (see "Pattern B" in Figure 11), which is the starting point when the valve opens, to be near one end 31A (or the other end 31B) of the first groove shown in Figure 9. Also, in the case of "Pattern B," the magnitude of the stress on the center P shown in Figure 9 is relaxed and becomes insufficient, and the stress concentrated on one end 31A of the first groove becomes larger, causing the valve opening starting point KB to be near one end 31A (or the other end 31B) of the first groove. As shown in Figure 11, the opening area MB of the hatched "Pattern B" is smaller than the opening area MA of "Pattern A" and larger than the opening area MC of "Pattern C."
[0043] "Pattern C" shown in Figure 11 is a valve opening shape in which the vicinity of the center of the first groove 31 bulges and cracks or fissures occur near the center of the first groove 31. In "Pattern C", the vicinity of the center of the first groove 31 is cracked (broken), while the positions of the first groove 31 away from the vicinity of the center, as well as the first arc section 32S, the first straight section 32T, the second arc section 32U, the second straight section 32V, the third arc section 33S, and the third straight section 33T are not cracked (broken).
[0044] In the case of "Pattern C," the length of distance D4 is too short (shorter than 2.15 mm, as described later), causing the valve opening starting point KC (see "Pattern C" in Figure 11), which is the starting point when the valve opens, to be near the center P shown in Figure 9. Also, in the case of "Pattern C," stress concentrates near the center P shown in Figure 9, but because the length of distance D4 is too short, the magnitude of the stress concentrated at the valve opening starting point KC is excessive compared to the magnitude of the stress in the case of "Pattern A." As shown in Figure 11, the opening area MC of the hatched "Pattern C" is smaller than the opening area MA of "Pattern A" and smaller than the opening area MB of "Pattern B."
[0045] The inventor conducted numerous experiments using the actual device, changing the distance D4 to various values, and obtained the following experimental results, as shown in Figure 12. (A) When the distance D4 is between 2.15 [mm] and 2.80 [mm], the explosion-proof valve 15 opens at 0.4 [Mpa] to 0.6 [Mpa], and only the opening shape of "Pattern A" occurs stably. Therefore, the evaluation result is OK (in "Pattern A", the opening area MA is 75 [mm] 2 (There are more than ) (B) When the distance D4 is longer than 2.80 [mm], the explosion-proof valve 15 opens at 0.4 [Mpa] to 0.6 [Mpa], but the opening shape is "Pattern B" and the opening area is 75 [mm] 2 In some cases, the result was less than ]. Therefore, the evaluation result is NG. (C) When the distance D4 is shorter than 2.15 [mm], the explosion-proof valve 15 opens at 0.4 [Mpa] to 0.6 [Mpa], but the opening shape is "Pattern C" and the opening area is 75 [mm] 2In some cases, the result was less than ]. Therefore, the evaluation result is NG.
[0046] As described above, with the technology disclosed herein (where the radius R2 of the second arc portion 32U shown in Figure 9 is smaller than the radius R1 of the first arc portion 32S), the evaluation result was OK when the distance D4 was between 2.15 [mm] and 2.80 [mm], as shown in Figure 12. However, with the conventional technology (where the radius R2 of the second arc portion 32U is greater than or equal to the radius R1 of the first arc portion 32S), as shown in Figure 12, the lower limit of the distance D4 at which the valve opening shape of "Pattern A" is stably achieved and the evaluation result is OK is the same 2.15 [mm], but it is estimated that the upper limit will be a value shorter than 2.80 [mm].
[0047] Therefore, as shown in Figure 12, the technology disclosed herein (where the radius R2 of the second arc section 32U shown in Figure 9 is smaller than the radius R1 of the first arc section 32S) is more effective than the conventional technology (where the radius R2 of the second arc section 32U is greater than or equal to the radius R1 of the first arc section 32S) because it provides a wider range of acceptable evaluation results. It is presumed that this is due to the fact that in the conventional technology, the length of the first straight section 32T is shortened because the radius of the second arc section 32U is larger.
[0048] Based on the above experimental results, the inventor determined that it is preferable to set the distance D4 to 2.15 [mm] to 2.80 [mm].
[0049] Figure 13 also shows a graph of the simulation (CAE analysis (Computer Aided Engineering)) results for the length of "distance D4" and the "central displacement" of the explosion-proof valve 15 (the displacement of the position of the center P when the internal pressure of the container is atmospheric pressure and when the internal pressure is 0.4 [MPa]) when the internal pressure of the sealed container 4 of the sealed energy storage device 1 is gradually increased to 0.4 [MPa] without opening the valve.
[0050] As shown in Figure 13, for distances D4 shorter than 2.15 [mm] or longer than 2.80 [mm], where the evaluation result was NG, the central displacement was 0.500 [mm] or less. For distances D4 between 2.15 [mm] and 2.80 [mm], where the evaluation result was OK, the central displacement was 0.503 [mm] or more. Taking into account the results in Figure 13 and the margin, it is estimated that if the internal pressure of the container is 0.4 [Mpa] and the explosion-proof valve 15 is not open, the evaluation result will be OK for distance D4 where the central displacement is greater than 0.500 [mm]. As shown in Figure 13, it is estimated that there is a correlation between the central displacement, the length of distance D4, and the evaluation result when the internal pressure of the container is 0.4 [Mpa] (and the explosion-proof valve 15 is not open).
[0051] <Effects, etc.> As explained above, in the technology disclosed herein, the radius R2 of each second arc portion 32U shown in Figure 9 is set to be smaller than the radius R1 of each first arc portion 32S (radius R2 < radius R1). In contrast, in the conventional groove pattern 120 shown in Figure 10, the radius RY of each conventional second arc portion 143 is set to be greater than or equal to the radius RX of each conventional first arc portion 141 (radius RY ≥ radius RX). Therefore, the area of the first pressure-receiving portion 32P surrounded by the first groove 31 and the second groove 32 in Figure 9 is larger than the area of the area surrounded by the conventional first groove 131 and the conventional second groove 132 in Figure 10, which is the conventional groove pattern 120, and cracking can be achieved at a lower pressure. Furthermore, since the groove pattern 20 shown in Figure 9 does not have two intersecting straight lines, it is not necessary to consider the magnitude of residual stress generated at the intersection, and this does not lead to increased complexity in design and manufacturing.
[0052] Furthermore, the position of the end of each third groove 33 (third groove end 33Z) shown in Figure 9 extends to the position of the end 32C of the first straight section 32T of the second groove 32 adjacent to the first groove 31 in the direction along the first groove 31 (parallel to the first groove 31), and the third straight section 33T of the third groove 33 is set to be longer. This increases the area of the second pressure-receiving section 33P surrounded by the third groove 33 and the first groove 31, so that it can be ruptured at a lower pressure. Also, because the third straight section 33T is made longer, the height of the dome shape of the second pressure-receiving section 33P becomes higher, and the area of the second pressure-receiving section 33P can be increased, so that it can be ruptured at a lower pressure.
[0053] Furthermore, in the technology disclosed herein, the distance D2 is set to be shorter than the distance D3 in Figure 9 (distance D2 < distance D3), which makes it easier for the groove to break due to pressure.
[0054] <Other> The explosion-proof valve (thin film portion 16) of the sealed energy storage device 1 of the technology disclosed herein is not limited to the configuration, structure, appearance, shape, etc. described in this embodiment, and various modifications, additions, and deletions are possible as long as they do not alter the gist of the technology disclosed herein.
[0055] The explosion-proof valve (thin film portion 16) described in this embodiment is not limited to application to the sealed energy storage device 1, but can be applied to various sealed devices. [Explanation of Symbols]
[0056] 1. Sealed energy storage device 4. Airtight container 6 Components 8. Container body 10 Sealing plate 12 terminals 14 holes 15 Explosion-proof valve 16 Thin film section 16A One area 16B Other area 18 recesses 20 groove pattern 31 First groove 31A 1st groove one end 31B 1st groove other end 32 2nd groove 32A 2nd groove starting end 32B Termination (Termination of the first arc section) 32C Termination (first straight section termination) 32D Termination (Termination of the second arc section) 32P First pressure receiving section 32S First arc section 32T 1st straight section 32U Second arc section 32V 2nd straight section 32Z 2nd groove end (2nd straight section end) 33 Third groove 33A 3rd groove starting end 33B Termination (Third arc section termination) 33P Second pressure receiving section 33S Third arc section 33T 3rd straight section 33Z 3rd groove end (3rd straight section end) C1 (center of the first arc section 32S) C3 (center of the third circular arc 33S) D2 distance D3 Distance D4 Distance H1 1st groove center line KA, KB, KC valve opening starting point MA, MB, MC opening area P center R1 radius R2 radius R3 radius V1 Virtual Line V2 Virtual parallel lines
Claims
1. An explosion-proof valve for a sealed energy storage device, The sealed energy storage device includes a thin film portion provided in the sealed container, which is thinner than the surrounding sealed container and ruptures when the internal pressure rises. The thin film portion has a groove pattern that breaks when it ruptures. The groove pattern is A first groove is formed by a straight line passing through approximately the center of the thin film portion, with both ends extending to just before the edge of the thin film portion, and sandwiched between one region and the other region of the thin film portion. A groove extending from one end of the first groove to the other region of the thin film, and a second groove extending from the other end of the first groove to the one region of the thin film, respectively. A third groove is a groove extending from one end of the first groove to the one region of the thin film, and a third groove extending from the other end of the first groove to the other region of the thin film, It has, Each of the second grooves has a first arc-shaped section that is convex toward the edge of the thin film portion, starting from one end and the other end of the first groove, and a first straight section that extends linearly from the end of each first arc-shaped section so as to be substantially parallel to the first groove, and a second arc-shaped section that extends linearly from the end of each first straight section toward the first groove, and a second straight section that extends linearly from the end of each second arc-shaped section to just before the first groove, with the end of each second straight section being the end of each of the second grooves. Each of the third grooves has a third arc-shaped section that is convex toward the edge of the thin film portion, starting from one end and the other end of the first groove, and a third straight section that extends linearly from the end of each third arc-shaped section, substantially parallel to the first groove, to just before the second arc-shaped section, and the end of each third straight section is the end of each of the third grooves. The end of each of the third grooves extends in the direction along the first groove to the end of the first straight section of the adjacent second groove, which straddles the first groove. The radius of each of the second arcs is smaller than the radius of each of the first arcs. Explosion-proof valve for sealed energy storage devices.
2. An explosion-proof valve for a sealed energy storage device according to claim 1, The distance from the end of each of the second grooves to the first groove is shorter than the distance from the end of each of the third grooves to the adjacent second groove in the direction along the first groove. Explosion-proof valve for sealed energy storage devices.
3. An explosion-proof valve for a sealed energy storage device according to claim 1 or 2, The end of the second groove is located between the first groove and a virtual parallel line passing through the center of the first arc portion or the center of the third arc portion, which is parallel to the first groove. Explosion-proof valve for sealed energy storage devices.
4. An explosion-proof valve for a sealed energy storage device according to claim 1 or 2, The distance from the center line of the first groove, which is parallel to the first groove and passes through the center of the first groove, to the end of the second groove is set to 2.15 mm to 2.80 mm. Explosion-proof valve for sealed energy storage devices.