TW202407733A - Case for electric power storage device, and electric power storage device - Google Patents

Abstract

This case for an electric power storage device comprises: a first valve unit that has a valve that opens when an internal pressure in a storage portion has exceeded a threshold value, the valve being provided, at a portion of a housing bottom portion that forms the storage portion, with a flat surface portion that is formed in a surface direction of the housing bottom portion and is constituted by a groove that is formed in the thickness direction of the housing bottom portion, the flat surface portion being formed having a predetermined area at the deepest position of the groove; and a second valve unit that has one end that is connected to the first valve unit and another end that is formed having a predetermined length in the outer peripheral direction of the storage portion, the second valve unit being provided with an inclined surface portion that alters the depth between the flat surface portion and the surface of the housing bottom portion. At least a plurality of the second valve unit are formed in different directions along the surface of the housing bottom portion, and an opening of the valve that faces the housing bottom portion has an opening width in a portion that is adjacent to the first valve unit that is greater than an opening width that is adjacent to the second valve unit. This makes it possible to restrict the operating range of the valve with respect to an increase in internal pressure in the case, and to control a state of discharge from the case interior when the valve is open.

Description

Case for power storage device and power storage device

Field of invention

The present disclosure relates to a technology for adjusting the pressure rise inside the casing through operation for electricity storage devices such as electrolytic capacitors.

Background of the invention

In the power storage device, the internal pressure of the case may suddenly rise due to the occurrence of abnormal conditions such as vaporization of the electrolyte due to the application of a voltage exceeding the rated voltage. To cope with such a rise in internal pressure, some power storage devices are provided with a valve that weakens a part of the case. When the allowable strength of the case is exceeded, the valve is actuated to release the internal pressure.

Regarding the valve structure of such a casing, there is one in which at least two grooves connected to the outer peripheral portion are formed on the bottom surface of the outer side of the aluminum casing, and the thickness of the grooves is varied according to the slope (for example, Patent Document 1). In addition, there is a case in which an explosion-proof groove is provided at the bottom of a capacitor case and the thickness of the explosion-proof groove is made different between the center side and the vicinity of the outer peripheral portion of the case (for example, Patent Document 2). Prior technical literature patent documents

[Patent document 1] Japanese Utility Model Publication No. Sho 60-22827 [Patent Document 2] Japanese Patent Application Publication No. 2000-021692

Summary of the invention The problem to be solved by the invention

However, a conventional valve with an explosion-proof function provided in a casing is, for example, provided with a fragile portion in order to achieve a state in which the valve opening position can be assumed in advance. However, the state in which this valve is operated can be said to be a very high-pressure state within the casing. Opening the valve and rapidly releasing the pressure in the casing to the outside may cause the valve to become almost fully open. In electronic equipment equipped with a power storage device, if the valve is opened widely in this way, in addition to accumulating gas in the case, electrolyte, etc. will also be sprayed out in a wide area, which may have a great impact on surrounding electronic parts, etc. . In a power storage device, when the valve is opened to a large extent, the internal pressure is suddenly released, which may deform the components arranged in the case.

The inventor of the disclosed technology has found that by adjusting the direction or position of the pressure inside the housing according to the shape of the groove forming the valve, the opening position of the valve or the operating range of the valve can be adjusted.

Without disclosure or suggestion of this problem, this problem cannot be solved by the structures disclosed in Patent Documents 1 and 2.

Therefore, an object of the technology disclosed in the present disclosure is to provide an explosion-proof valve that suppresses the operating range of the valve that operates in response to an increase in the internal pressure of the casing and can control the release state from the inside of the casing when the valve is opened. means to solve problems

In order to achieve the above object, an outline of a case for an electric storage device of the present disclosure is: a case for an electric storage device having a valve that opens when the internal pressure of the accommodation portion exceeds a critical value. The valve is formed by forming the accommodation portion. A part of the bottom of the frame is formed by a groove in the thickness direction of the bottom of the frame, and is provided with: a first valve part, which is provided with: a flat surface, a specific area is formed at the deepest position of the groove, and is formed on the frame the surface direction of the bottom of the body; and a second valve part having an inclined surface part, one end connected to the first valve part, the other end formed with a specific length in the outer circumferential direction of the accommodating part, and between the flat surface part and the bottom part of the frame The depth is varied between the surfaces, and at least a plurality of the second valve portions are formed in different directions along the surfaces of the bottom of the frame. The opening of the valve facing the bottom of the frame is different from the first valve portion. The opening width of the adjacent portion is wider than the opening width adjacent to the second valve portion.

In this power storage device case, the valve is provided with an inclined wall whose opening width is reduced from the bottom of the housing toward the side of the flat surface or the inclined surface. In this case for a power storage device, the second valve part is formed with a constant opening width of the inclined surface part, and the first valve part is a part of the flat surface part connected to the second valve part so as to be connected with the inclined surface part. The width is the same as or close to its width. In this power storage device case, among the openings of the valve facing the bottom of the housing, a portion adjacent to the second valve portion has an opening width that changes along the longitudinal direction of the inclined surface portion. In this power storage device case, the opening of the second valve portion is formed such that its opening width gradually becomes wider toward the first valve portion side along the longitudinal direction of the inclined surface portion. In this case for a power storage device, the valve moves from a reference position set in a part of the first valve part to a connection position with the second valve part, based on a direction parallel to the bottom surface of the frame bottom. The ratio between the length of the first valve part and the length of the second valve part from the connection position to the front end position is set in the range of 0.12 or more and 0.9 or less.

In order to achieve the above object, an outline of the power storage device of the present disclosure includes a storage portion for accommodating the power storage element, and a casing. The casing has a structure on the bottom side of the frame that opens when the internal pressure of the storage portion exceeds a critical value. state of the valve, the valve is composed of a groove formed in the thickness direction of the bottom of the aforementioned frame, and is provided with: a first valve portion having a flat surface, a specific area is formed at the deepest position of the groove, and is formed on the aforementioned The surface direction of the bottom of the frame; and the second valve part is provided with an inclined surface part, one end is connected to the first valve part, the other end is formed with a specific length in the outer circumferential direction of the accommodating part, and the flat surface part is connected to the frame body The depth is varied between the surfaces of the bottom, and at least a plurality of the second valve portions are formed in different directions along the surfaces of the bottom of the frame, and the opening of the valve facing the bottom of the frame is different from the opening of the first valve. The opening width of the portion adjacent to the second valve portion is wider than the opening width adjacent to the second valve portion. Invention effect

According to the structure of this disclosure, any of the following effects can be obtained. (1) By having the first valve part with the deepest flat surface and a specific area, an open area of a specific area is ensured when the pressure inside the housing reaches the operating pressure and the valve is operated, and the sudden release of accumulated gas, etc. can be prevented. condition. (2) After the first valve part opens and reaches the initial pressure release, the valve opening range on the second opening side can be suppressed by the gradually thickening inclined surface according to the residual pressure inside the casing. (3) By providing an inclined surface from the second valve part toward the first valve part, and by making the opening width of the valve to the bottom surface of the frame wider from the second valve part toward the first valve part, the gas inside the storage part is Or the pressure generated by the electrolyte is concentrated on the first valve side, and the valve opening position can be set. (4) In response to an increase in pressure within the storage portion, by opening the first valve portion with a specific area into an open state, damage or deformation of the storage element due to sudden external release can be prevented, and the storage element can be prevented from being deformed. A part of the valve extends to the valve opening part and is exposed outside the shell.

Next, other purposes, features, and advantages of the technology of the present disclosure can be made clearer by referring to the attached drawings and each embodiment.

Form used to implement the invention

[One embodiment] FIG. 1 shows a structural example of a power storage device. The structure shown in FIG. 1 is an example, and the technology of this disclosure is not limited to this structure. The power storage device 2 is, for example, an electric double layer capacitor, an electrolytic capacitor, or an example of other power storage devices. As shown in FIG. liquid. The exterior case 4 is made of a metal material such as aluminum (Al). The electricity storage element 8 is formed by, for example, laminating a strip-shaped anode foil and a cathode foil through a separator, and winding the laminate in a specific direction. In this electric storage element 8, for example, at least one external terminal 10A, 10B is provided protruding from the anode foil and the cathode foil on one side of the winding end surface.

The power storage device 2 places the surface with the external terminals 10A and 10B protruding toward the opening 12 of the outer case 4 and accommodates the power storage element 8 in the accommodating portion 6 so that the external terminals 10A and 10B protrude outward from the opening 12 . condition. The outer case 4 is provided with a sealing member 14 for sealing the accommodating portion 6 on the opening 12 side. Next, the exterior case 4 is provided with the fastening portion 16 which is aligned with the opening 12 side and the placement position of the sealing member 14 and is pressed from the outer peripheral side to be in close contact with the sealing member 14 .

The outer case 4 is provided with a bottom portion 18 that forms a part of the housing portion 6 and faces the non-protruding winding end surfaces of the external terminals 10A and 10B of the power storage element 8 arranged in the housing portion 6 . Furthermore, a valve 20 is formed in a part of the bottom portion 18 inside the exterior case 4 . This valve 20 is a functional component that is opened by an increase in the pressure of the storage portion 6 of the present disclosure to reduce the pressure in the storage portion 6 and prevent damage caused by the explosion of the power storage device 2 . The valve 20 is provided on the bottom surface 18 in the accommodating portion 6 on the inside of the connection portion between the frame, that is, the side surface of the exterior case 4 and the bottom surface 18 . The valve 20 is a groove that reduces the thickness of a part of the bottom surface 18 and is formed in a range including the center of the bottom surface 18 or a position close to this position. In other words, by thinning a portion of the bottom portion 18 of the valve 20, the pressure resistance is lower than that of the non-thin portion. Thereby, when the internal pressure of the storage portion 6 rises, the power storage device 2 can adjust the internal pressure by rupturing the valve 20 with low pressure resistance to release the gas accumulated in the storage portion 6 .

FIG. 2A is a structural example of the bottom side of the housing, and FIG. 2B shows a part of the valve. For example, as shown in FIG. 2A , the valve 20 includes a first valve portion 22 (hereinafter referred to as “valve portion 22”) formed on the center side of the bottom surface 18; and second valve portions 24-1, 24-2, and 24-3. (hereinafter referred to as "valve parts 24-1, 24-2, 24-3"), a plurality of valve parts are formed in the radial direction from the valve part 22, one end is connected to the valve part 22, and the other end is formed in the storage part with a specific length. 6 in the peripheral direction. For example, as shown in FIG. 2B , the valve portion 22 is composed of a flat surface portion 26 that is the deepest position among the grooves forming the valve 20 and is formed into a planar shape, and a wall portion 28 between the flat surface portion 26 and the bottom surface portion 18 .

The flat surface portion 26 is the portion that first breaks open to open the valve when the pressure P in the accommodation portion 6 exceeds a specific value. This flat surface part 26 is formed in the surface direction of the bottom surface part 18 of the exterior case 4, for example. The surface direction refers to a direction that is parallel to or close to the angle of the bottom surface 18 . Thereby, the flat surface portion 26 can withstand, for example, the pressure P acting in the direction of the bottom surface portion 18 among the pressure components in the accommodation portion 6 at a perpendicular or close angle. The flat surface portion 26 can be formed based on the amount of gas generated and the size of the internal pressure P that can be assumed from the volume of the housing portion 6, the capacity of the power storage device 2, the voltage value during operation, etc., and the size of the gas released by opening the valve. For flow rate or flow rate, just set the length L1 (Figure 3), area or width, etc. The wall portion 28 is an inclined wall having an angle determined by the difference between the opening width W4 ( FIG. 4C ) of the valve 20 facing the bottom surface portion 18 and the width W1 ( FIG. 4C ) of the flat surface portion 26 .

The valve portions 24-1, 24-2, and 24-3 are formed in plural lines in the radial direction from the flat surface portion 26 of the valve portion 22, and are formed with inclined portions 30 whose grooves become shallower as they are further apart from the flat surface portion 26, and The wall portion 32 is between the inclined surface portion 30 and the bottom surface portion 18 . The inclined surface portion 30 is a valve body in which the operating pressure of the valve is set higher than that of the flat surface portion 26 . For example, the inclined surface portion 30 has the groove width W1 ( FIGS. 4A and B ) constant, and the length L2 ( FIG. 3 ) in the inclined direction is set to be much longer than the groove width W1 . One end of each inclined surface portion 30 of the valve portions 24-1, 24-2, and 24-3 is connected to the flat surface portion 26, and the other end is formed to have the same height as the bottom surface portion 18. In this way, the valve portions 24-1, 24-2, and 24-3 use the inclined surface portion 30 to change the thickness of the valve body and the bottom of the housing, so that the operating pressure for the internal pressure of the accommodation portion 6 is adjusted according to the inclined surface portion. The location on the 30's is different. Specifically, the valve portions 24-1, 24-2, and 24-3 have a low operating pressure at the portion connected to the flat portion 26 along the longitudinal direction of the inclined portion 30, and because the valve portions 24-1, 24-2, and 24-3 are further apart from the flat portion 26, The valve body becomes thicker and the operating pressure becomes higher. The degree of change in the operating pressure of the valve portions 24-1, 24-2, and 24-3 is determined by the inclination angle of the inclined surface portion 30. The inclination angle of the inclined surface part 30 is determined based on, for example, the length of the long side in the direction away from the flat surface part 26 and the depth of the inclined surface part 30 . Furthermore, the valve portions 24-1, 24-2, and 24-3 may have the same length L2 and width W1 in the tilt direction of the inclined surface portion 30, or may be formed with different lengths or widths. When the length L2 of the inclined surface part 30 is made different, the inclination angle of the inclined surface part 30 is different between the valve parts 24-1, 24-2, and 24-3, and the thickness of the valve changes, that is, the valve operation The pressure becomes different. Thereby, for example, after the valve portion 22 opens, the valve portions 24-1, 24-2, 24-3, etc. of the valve 20 will open at different timings, and the opening area can be adjusted according to the pressure remaining in the accommodating portion 6. The wall 32 is an inclined wall having an angle determined by the difference between the opening width W2 ( FIG. 4A ) or W3 ( FIG. 4B ) of the valve 20 facing the bottom surface 18 and the width W1 ( FIGS. 4A, B ) of the inclined surface 30 .

Furthermore, in this embodiment, the number of the valve portions 24 (24-1, 24-2, 24-3) is shown to be three, but the invention is not limited to this. As long as the inclined surface portion 30 of the valve portion 24 communicates with the flat surface portion 26, it is sufficient to form a plurality of them in different directions. Moreover, although the valve 20 is specifically constituted by one flat surface part 26 and the inclined surface parts 30 of the plurality of valve parts 24-1, 24-2, and 24-3, it is not limited to this. The valve 20 is specifically provided with, for example, a valve portion formed with the same width W1 and connecting one inclined surface portion 30 to a part of the flat surface portion 26 of the deepest groove, and similarly connecting the other inclined portions 30 to other portions of the flat surface portion 26 . A plurality of valve parts may be formed by connecting the flat surfaces 26 of these valve parts.

For example, the valve 20 may be formed by pressing the bottom surface 18 of the outer case 4 using a single mold having a shape corresponding to the valve parts 22 and 24, or by using a plurality of molds for each of the valve parts 22 and 24. A plurality of independent models or a common model may be formed. Otherwise, the valve 20 may be formed by, for example, cutting with a cutting tool or a cutting machine such as laser cutting or other processing on the bottom portion 18 of the outer case 4 .

FIG. 3 shows an example of the section along line III-III of FIG. 2A. Gas is generated in the storage portion 6 of the power storage device 2 due to evaporation and chemical reaction of the electrolyte solution, etc., and the internal pressure increases due to the influence of volume expansion accompanying such gasification. The gas in the power storage device 2 may be caused by, for example, deterioration due to the operation time or a temperature rise due to the application of an overcurrent. In the accommodating part 6 , for example, due to the expansion of the volume generated by gas, the pressure P acts radially in all directions of the outer casing 4 . The exterior case 4 uses its frame rigidity to maintain the accommodating portion 6 against the stress generated by the pressure PA it receives. In the valve 20 , for example, as shown in FIG. 3 , a specific pressure PA acts in a direction perpendicular to or close to the intersection of the bottom portion 18 and the space passing through the accommodating portion 6 between the bottom portion 18 and the power storage element 8 .

In the valve part 24 (24-1, 24-2, 24-3), for example, the pressure PA acts in the vertical direction with respect to the inclined surface part 30, and the gas in the storage part 6 is concentrated. Pressure PB acts in the direction of the inclined surface. This allows vertical stress to act on the inclined surface of the inclined surface portion 30 . In addition, the pressure PB acts on the thin valve portion 22 side. Thereby, in the valve 20, the stress based on the pressure PA and the pressure PB is concentrated on the flat surface part 26.

FIG. 4 shows an IVA-IVA line cross-section, a IVB-IVB line cross-section, and an IVC-IVC line cross-section in FIG. 2B as an example of the cross-section of the valve. For example, as shown in FIG. 4A , in the valve portion 24 , the depth H2 of the groove is reduced in the portion close to the outer peripheral side of the outer casing 4 and the thickness H1 of the valve body is made thicker, so that the pressure P in the accommodating portion 6 can be increased. The rigidity is set to high. As shown in FIG. 4B , for example, the groove depth H4 of the valve portion 24 increases toward the valve portion 22 side, whereby the thickness H3 of the valve body becomes thinner. Thereby, the rigidity of the valve portion 24 with respect to the pressure P is further reduced than when the valve has a thickness H1, that is, the operating pressure of the valve is set to be low.

Furthermore, in the valve part 22, for example, as shown in FIG. 4C, the depth H6 of the groove on the center side of the bottom surface 18 is made deeper than the depths H2 and H4 of the grooves of the valve part 24, so that the thickness H5 of the valve body becomes smaller than the thickness H5 of the valve body. The thinnest state among 20.

In the grooves of the valve parts 22 and 24, for example, the flat surface part 26 or the inclined surface part 30 not only acts on the pressure PA in the direction perpendicular to the bottom surface part 18, but also acts along the respective wall parts 28, The inclined surface of 32 makes the gas concentrate in the groove, exerting a specific pressure PC.

In the valve portion 24, along the longitudinal direction of the inclined surface portion 30, the groove becomes deeper toward the valve portion 22 side, and the widths W2 and W3 of the opening portion facing the bottom portion 18 of the housing are formed to be wider. That is, the relationship between the opening widths of each portion of the valve portion 24 is W2<W3, and the opening width gradually becomes wider toward the valve portion 22. Furthermore, the relationship between the opening widths of the valve portion 24 and the valve portion 22 is W3<W4. Next, the opening width of the valve portion 24 is set to be the same as the opening width W4 of the valve portion 22 in the portion connected to the valve portion 22 . Furthermore, in the valve portion 24, the opening width changes along the longitudinal direction of the inclined surface portion 30, and the groove becomes deeper, so that the wall surface is exposed from the opening. This wall surface is formed at a specific inclination angle in the valve portion 24 . The inclination angle of the wall surface is determined based on, for example, the relationship between the width W1 of the inclined surface portion 30 and the opening widths W2 and W3 of the valve portion 24 and the inclination state set in the inclined portion 30 . It may also be determined within the valve portion 24 It is a fixed angle, or it may be set so that the angle changes along the longitudinal direction of the inclined surface part 30. Furthermore, the exposed amount of the wall surface increases toward the valve portion 22 , making it easier for the gas of the vaporized electrolyte solution to flow toward the valve portion 22 side, thereby increasing the stress load on the valve portion 22 .

FIG. 5 is a view showing the exterior case 4 from the outside, showing an example of a state in which the valve is opened. For example, as shown in FIG. 5A , when the internal pressure of the housing portion 6 rises and exceeds the operating pressure value of the valve portion 22 , part or all of the flat surface portion 26 of the exterior case 4 is crushed, and the valve is opened. This state is, for example, the first release state of the valve 20 . By opening the valve, part of the gas or electrolyte accumulated inside the accommodating part 6 can be released to the outside at a specific flow rate, thereby reducing the pressure in the accommodating part 6 .

Furthermore, as shown in FIG. 5B , for example, in the outer case 4 , after the first release state, if the pressure inside the case is further increased, or if the internal pressure is not sufficiently released and the internal pressure is not reduced, the valve portion The portion of 24 close to the flat surface 26 continuously crushes part or all of the inclined surface 30 along the inclined direction of thickening, thereby entering the valve open state. At this time, since a certain release process is performed in the first release state and a certain pressure in the accommodation portion 6 is reduced, the valve 20 will not explode into the expanded state. Furthermore, depending on the magnitude of the internal pressure, the valve will be in an open state up to the rigid portion corresponding to the inclined surface portion 30 .

<Effects of one embodiment> According to this configuration, any effect up to the time limit can be achieved. (1) By opening the valve first from the valve portion 22 side with a specific area and a thin thickness, the opening position of the valve 20 can be set and the operating range of the valve 20 can be suppressed. (2) By configuring the valve portion 22 with a low operating pressure with a specific area, a release area within a specific range is ensured when the internal pressure exceeds a critical value, and a sudden release state of accumulated gas can be prevented. (3) After the valve portion 22 opens and reaches the initial pressure release, depending on the residual pressure inside the outer case 4, the gradually thickening inclined surface portion 30 can suppress the valve opening range on the valve portion 24 side.

(4) By providing an inclined surface from the valve portion 24 toward the valve portion 22 and widening the opening width of the valve 20 to the bottom portion 18 from the valve portion 24 toward the valve portion 22 , the gas in the accommodation portion 6 can be Or the pressure generated by the electrolyte is concentrated on the valve part 22 side, and the valve opening position can be set. (5) In response to an increase in pressure in the housing portion 6, by opening the valve portion 22 with a specific area to an open state, damage or deformation of the storage element 8 due to sudden external release can be prevented, and the This prevents a part of the electricity storage element 8 from extending to the valve opening portion and being exposed outside the housing. (6) By setting the width of the inclined surface portion 30 to be constant to equalize the pressure acting on the valve body, the valve operating pressure can be set according to the thickness of the valve body.

[Example] FIG. 6 shows a structural example of the valve part according to the embodiment. In the structural example shown in FIG. 6 , the same parts as those in FIG. 2 and others are given the same reference numerals. For example, as shown in FIG. 6A , the valve 20 has three valve parts 24 - 1 , 24 - 2 , and 24 radially formed in a straight line or close to the valve part 22 formed on the center side of the bottom surface 18 of the outer case 4 . -3. That is, when the valve 20 is distinguished based on, for example, the reference position O ( FIG. 6B ) set so as to intersect with the center of the bottom portion 18 or a position close to the bottom portion 18 and the central portion of the valve portion 22 , the combination valve portion It is composed of a part of 22 and valve parts 24-1, 24-2, and 24-3.

The length L of the valve portion is, for example, as shown in FIG. 6B , which is the total value of the length L1 from the reference position O to the connection position with the valve portion 24 and the length L2 of the valve portion 24 in the direction S parallel to the bottom surface. In addition, the inclination angle θ between the inclined surface portion 30 ( FIG. 2B ) of the valve portion 24 and the flat surface portion 26 ( FIG. 2B ) of the valve portion 22 is also determined by, for example, in addition to the length L of the valve portion and the length L2 of the valve portion 24 . The thickness of the bottom portion 18, the depth of the valve portion 22, etc. are determined.

FIG. 7 shows an example of the experimental results of the state of the valve operation with respect to the dimensional conditions of the valve portion. In this experimental example, the purpose is to confirm the valve operating state and the state of the valve opening area according to the lengths of the valve portion 22 and the valve portion 24 . The valve used for the experiment is shown in Figure 7, and Comparative Example 1 and Examples 1 to 5 were set. For example, the overall length L of the valve is 4.1 [mm], and the length L2 of the valve 24 having the inclined surface 30 is set based on the length L1 of the valve 22 having the flat surface 26 . In Comparative Example 1, the length L1 of the valve portion 24 is set to the shortest 1.16 [mm]. An example is to set L1 at a specific interval of 2.16 [mm] to 3.96 [mm], for example. Furthermore, the length L2 of the valve portion 24 is determined from the overall length L=4.1 [mm] corresponding to the set length L1. The ratio of the length L2 based on the length L1 at this time was 2.53 in Comparative Example 1, and 0.90, 0.34, 0.12, 0.076, and 0.035 in Examples 1 to 5, respectively.

An example of the electricity storage device 2 used in the experiment is a capacitor having a diameter of ψ10 [mm] and having a non-combustible gas sealed inside. In this experiment, for example, five or more capacitors formed under the size conditions shown in Comparative Example 1 and Examples 1 to 5 were used, the valve portion 22 was opened under the same measurement conditions, and the internal pressure value at that time was measured. In this experiment, a reverse voltage is applied to each capacitor, and the measurement condition is controlled to, for example, 170 [°C].

The measured value of the valve operating pressure is shown in Fig. 7, and the highest value of 2.04 [MPa] was measured in Comparative Example 1. In Examples 1 to 5, the values from the top are 1.68 [MPa], 1.64 [MPa], 1.57 [MPa], 1.57 [MPa], and 1.56 [MPa].

In addition, in the capacitor experiment, the valve opening area of each valve was measured as an evaluation of the valve opening state. In this measurement, the average value of the valve opening area is calculated for each size condition. For example, the average value of the valve opening area for each size is used as the reference area, and the number of open valves having an opening area that differs from the reference area by 0.5 [mm ² ] or more is measured to perform the evaluation. In this evaluation, for example, when the difference from the reference area is 0.5 [mm ² ] or more and the number of openings is 2 or less out of 10 measured, "small" is set to indicate that the error is small. When the number is 2-4, set it to "medium", and when the number of openings is 5 or more, set it to "large". The evaluation of the valve opening state affects, for example, the amount of gas or other substances released in the storage portion when the valve is operated, or the stabilization of the release position.

As a result of this experiment, as shown in FIG. 8 , the valve operating pressure with respect to the length L1 of the valve portion 22 reaches the maximum value under the conditions of Comparative Example 1 in which the length L1 is a small value. Then, the valve operating pressure increases sequentially with the value of L1 in Examples 1 to 5, causing the valve operating pressure to slightly decrease.

In addition, in the evaluation of the valve opening area of the length L1 of the valve portion 22, for example, as shown in FIG. 9, in the range of Comparative Example 1 and Examples 1 to 3 in which the length L1 is set to a small value, the valve opening area is The mean range is about 0.2 to 3.0, and the error range of the distribution is small. On the other hand, in Examples 4 and 5 in which the length L1 is set to be large, the valve opening area is enlarged and the error range of the area is enlarged.

Based on the experimental results, for example, from the allowable range of the measurement results of the valve operating pressure (Fig. 8) and the allowable range of the measurement results of the valve opening area (Fig. 9), the setting range of the length L1 of the valve portion 22 only needs to be 2.16 [mm] is the lower limit value La, and 3.66 [mm] is the range of the upper limit value Lb. At this time, the ratio of the length L1 of the valve part 22 to the length L2 of the valve part 24 has a minimum value of 0.12 or more and a maximum value of 0.9 for the valve part 22, for example.

<Effects of the Example> According to this configuration, any of the following effects can be expected. (1) The same effect as in the first embodiment is obtained. (2) It can be assumed that the ratio of the length L1 of the thin valve portion 22 to the length L2 of the valve portion 24 having an inclined surface is set based on the experimental results of changes in the valve operating pressure or the valve opening area. The valve opening position or range and the state when internal gas is released can be adjusted. (3) By setting the lengths of the valve portion 22 and the valve portion 24, the pressure adjustment accuracy during valve operation can be improved. (4) Considering the pressure or opening area during valve operation, increasing the length L1 of the valve portion 22 can prevent a sudden release of internal pressure during valve operation and slowly reduce the internal pressure of the power storage device.

＜Modification＞ Regarding the above-described embodiment, features and modifications thereof are listed below.

(1) In the above embodiment, the inclined surface portion 30 is formed at a single inclination angle along the longitudinal direction, but the invention is not limited to this. The inclined surface portion 30 may have different inclination angles along the longitudinal direction. At this time, the tilt angle of the inclined surface portion 30 may be continuously increased or decreased, for example, between the bottom surface portion 18 and the flat surface portion 26 of the valve portion 22, or the inclination angle may be changed stepwise for each specific length. Thereby, the valve 20 can be more finely adjusted for the concentration of the inducibility of the gas or the electrolyte or the internal pressure in the valve portion 24 .

(2) In the above embodiment, the setting of the length L2 of the valve portion 24 from the length L1 of the valve 22 is shown as setting the ratio of the length L2 based on the length L1, but the invention is not limited to this. In forming the valve, for example, the ratio of the length L1 of the valve part 22 or the length L2 of the valve part 24 may be set to the length L of the valve, that is, (L1 + L2).

(3) In the above embodiment, a capacitor of ψ10 [mm] is used as an example and the ratio of the lengths L1 and L2 of the valve parts 22 and 24 is set. However, the technology of the present disclosure is not limited to the value of this ratio. . For example, the length ratio of the valve portions 22 and 24 may be different depending on the outer diameter of the capacitor or the outer casing, the set value of the valve length L, etc. For example, a capacitor having an outer diameter of ψ8 [mm] to ψ18 [mm] can be used. Next, in order to utilize this capacitor, it is only necessary to set the ratio of the lengths L1 and L2 of the valve portions 22 and 24 according to the outer diameter dimension ψ8 [mm]. In addition, in the case of a capacitor whose outer dimension is ψ18 [mm], the ratio of the lengths L1 and L2 of the valve portions 22 and 24 may be set according to the outer dimension.

(4) In the above embodiment, the lengths L1 and L2 of the valve portion or their proportions are selected based on the experimental measurement results based on the valve operating pressure or the valve opening area or the error of the values. However, Not limited to this. In the technology of the present disclosure, for example, the valve opening area or the valve operating pressure is measured immediately after the valve is opened, and the state inside the outer casing when a specific time has elapsed after the valve is opened, and the valve portions 22 and 24 are selected including the measurement results. The value or ratio of the lengths L1 and L2 can also be used. In other words, in the power storage device 2 , for example, the values of the valve portions 22 and 24 or the ratio thereof may be set large so that the internal pressure or temperature can be further prevented from rising and the internal state is stabilized after the valve is opened.

(5) In the above-mentioned embodiment, for example, the ratio of the lengths L1 and L2 of the valve portions 22 and 24 is set to be common for the valves formed in three directions, but the present invention is not limited to this. For example, the valve 20 may have a different ratio to the lengths L1 and L2 of the valve portion 22 for each of the valve portions 24-1, 24-2, and 24-3. In this case, for example, when the valve 20 is not formed in the center of the bottom portion 18 , the length L2 or the length L2 of each valve portion 24 - 1 , 24 - 2 , 24 - 3 is adjusted according to the operating state of the internal pressure. The ratio of the length L1 can also be different.

As described above, the best embodiments and examples of the technology of the present disclosure will be described. The technology of the present disclosure is not limited to those described above. Various modifications or changes may be made among those skilled in the art based on the purpose described in the scope of the patent application or the form disclosed for carrying out the invention. This deformation or change is naturally included in the technical scope of this disclosure. Industrial availability

In the case and the electricity storage device of the present disclosure, the thinnest valve portion with a specific area is formed at the bottom of the case, and a plurality of valve portions whose thickness is gradually changed in the circumferential direction, the pressure in the accommodation portion reaches a specific value. When the value is set, in addition to setting the valve opening position, the release state of the internal pressure can also be adjusted, so it is effective.

2: Electric storage device 4:Outer shell 6: Storage Department 8: Electric storage components 10A, 10B: External terminals 12:Opening part 14:Sealing component 16: Fastening part 18: Bottom face 20: valve 22: 1st valve part 24, 24-1, 24-2, 24-3: 2nd valve section 26:Flat face 28, 32: Wall 30: Tilt the face

FIG. 1 is a diagram showing a structural example of a power storage device according to one embodiment. A of FIG. 2 is a diagram showing the structure of the bottom side of the housing in which the valve is formed, and B is a diagram showing a part of the valve. Figure 3 is a cross-sectional view along line III-III. Figure 4 is a diagram showing a cross section of the valve. Figure 5 is a diagram showing the state after the valve is operated. 6 is a diagram showing the valve part of the embodiment, A is a diagram showing the structure of the bottom side of the housing, and B is a cross-sectional view showing a part of the valve. FIG. 7 is a graph showing experimental results of the state of the valve when operating according to the dimensional conditions of the valve portion. FIG. 8 is a graph showing measurement results of the valve operating pressure for the length L1 of the valve portion 22 . FIG. 9 is a diagram showing measurement results of the valve opening area with respect to the length L1 of the valve portion 22 .

2: Electric storage device

4:Outer shell

6: Storage Department

8: Electric storage components

10A, 10B: External terminals

12:Opening part

14:Sealing component

16: Fastening part

18: Bottom face

20: valve

Claims (7)

A case for an electric storage device, characterized by having a valve that opens when the internal pressure of a housing portion exceeds a critical value, The valve is composed of a groove formed in the thickness direction of the bottom of the frame in a portion of the bottom of the frame that forms the accommodating portion, and is provided with: The first valve part has: a flat surface formed with a specific area at the deepest position of the groove and formed in the surface direction of the bottom of the frame; and The second valve part is provided with an inclined surface part, one end of which is connected to the first valve part, and the other end is formed with a specific length in the outer circumferential direction of the accommodating part, and has a certain depth between the flat surface part and the surface of the bottom of the frame. changed, At least a plurality of the second valve portions are formed in different directions along the surface of the bottom of the frame, The opening width of the opening portion of the valve facing the bottom of the housing adjacent to the first valve portion is wider than the opening width adjacent to the second valve portion. The case for a storage device according to claim 1, wherein the valve is provided with an inclined wall whose opening width is reduced from the bottom of the housing toward the side of the flat surface or the inclined surface. The case for a power storage device according to claim 1, wherein the second valve portion is formed such that the opening width of the inclined surface portion is constant, The first valve portion is a portion of the flat surface portion connected to the second valve portion and is formed to have a width that is the same as or close to the width of the inclined surface portion. The case for a storage device according to claim 1, wherein a portion of the opening portion of the valve facing the bottom of the housing adjacent to the second valve portion has an opening width that changes along the longitudinal direction of the inclined surface portion. The case for a power storage device according to Claim 4, wherein the opening of the second valve portion is formed to have an opening width gradually widening along the longitudinal direction of the inclined surface portion toward the first valve portion. The case for an electric storage device according to claim 1, wherein the valve moves from a reference position set at a part of the first valve part to a position parallel to the second valve part with a direction parallel to the bottom surface of the bottom of the frame. The ratio between the length of the first valve part before the connection position and the length of the second valve part from the connection position to the front end position is set in a range of 0.12 or more and 0.9 or less. An electric storage device, characterized in that it has an accommodating portion for accommodating electric storage elements, and further includes a casing, and the casing has a valve on the bottom side of the frame that is opened when the internal pressure of the accommodating portion exceeds a critical value, The aforementioned valve is composed of a groove formed in the thickness direction at the bottom of the aforementioned frame, and has: The first valve part has: a flat surface formed with a specific area at the deepest position of the groove and formed in the surface direction of the bottom of the frame; and The second valve part is provided with an inclined surface part, one end of which is connected to the first valve part, and the other end is formed with a specific length in the outer circumferential direction of the accommodating part, and has a certain depth between the flat surface part and the surface of the bottom of the frame. changed, At least a plurality of the second valve portions are formed in different directions along the surface of the bottom of the frame, The opening width of the opening portion of the valve facing the bottom of the housing adjacent to the first valve portion is wider than the opening width adjacent to the second valve portion.

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