JP6447861B2 - Electricity storage element - Google Patents

Description

  The technology described in this specification relates to a power storage element in which a power storage element is accommodated in a case.

  Conventionally, as an electrical storage element, the thing of Unexamined-Japanese-Patent No. 2011-154813 is known, for example. The power storage element includes a bottomed cylindrical case and a power storage element housed in the case.

JP 2011-154813 A

  When charging or discharging of the power storage element is repeated, for example, gas may be generated in the case. Then, there is a concern that the internal pressure in the case increases and the case is deformed. Such a problem may also occur in power storage elements other than alkaline storage batteries.

  In this specification, it aims at providing the technique which concerns on the electrical storage element by which the deformation | transformation of the case was suppressed.

  The power storage element described in the present specification is a power storage element including a power storage element and a case having a bottomed cylindrical shape and containing the power storage element therein, and the case has a disk shape. A bottom wall formed, and a side wall rising from a side edge of the bottom wall, the bottom wall having a concentric shape with the bottom wall and a convex portion protruding outward of the case, The ratio of the diameter of the convex portion to the diameter of the bottom wall is 0.20 to 0.95.

  According to said structure, a bottom wall is reinforced with the convex part formed in the bottom wall. Thereby, even if it is a case where the internal pressure in a case rises, it can suppress that the bottom wall of a case deform | transforms.

  Furthermore, by setting the ratio of the diameter of the convex portion to the diameter of the bottom wall to be 0.20 to 0.95, deformation of the bottom wall of the case can be further suppressed. When the ratio of the diameter of the convex portion to the diameter of the bottom wall is smaller than 0.20, it is not preferable because deformation of the bottom wall cannot be sufficiently suppressed. Further, when the ratio of the diameter of the convex part to the diameter of the bottom wall is larger than 0.95, the diameter of the bottom wall and the diameter of the convex part are almost equal, and the convex part can be formed. Since it becomes difficult, it is not preferable.

  According to the invention described in this specification, it is possible to suppress the deformation of the case of the power storage element.

Sectional drawing which shows the battery which concerns on Embodiment 1. Partially enlarged sectional view showing batteries according to samples 1 to 23 Partially enlarged sectional view showing batteries according to samples 1 to 23 In the batteries according to Samples 1 to 23, a graph showing the relationship between the ratio of the diameter of the convex portion to the diameter of the bottom wall and the amount of displacement of the central portion of the bottom wall. Partially expanded sectional view which shows the battery which concerns on samples 24-29 Partially expanded sectional view which shows the battery which concerns on samples 24-29 In the batteries according to samples 24-29, the ratio of the radius of curvature of the outer corner curved surface to the thickness of the bottom wall, the ratio of the radius of curvature of the inner corner curved surface to the thickness of the bottom wall, and the bottom wall Graph showing the relationship with the displacement of the central part of The partially expanded sectional view which shows the battery which concerns on Embodiment 2. FIG. The partially expanded sectional view which shows the battery which concerns on Embodiment 2. FIG. In the batteries according to samples 30 to 49, the ratio of the radius of curvature of the inner first curved surface to the thickness of the bottom wall, the ratio of the radius of curvature of the inner second curved surface to the thickness of the bottom wall, the radius of curvature of the outer first curved surface Of the ratio of the thickness of the bottom wall to the thickness of the bottom wall, the ratio of the radius of curvature of the outer second curved surface to the thickness of the bottom wall, and the displacement of the center portion of the bottom wall

<Outline of Embodiment>
The power storage element described in the present specification is a power storage element including a power storage element and a case having a bottomed cylindrical shape and containing the power storage element therein, and the case has a disk shape. A bottom wall formed, and a side wall rising from a side edge of the bottom wall, the bottom wall having a concentric shape with the bottom wall and a convex portion protruding outward of the case, The ratio of the diameter of the convex portion to the diameter of the bottom wall is 0.20 to 0.95.

  According to said structure, a bottom wall is reinforced with the convex part formed in the bottom wall. Thereby, even if it is a case where the internal pressure in a case rises, it can suppress that the bottom wall of a case deform | transforms.

  Furthermore, by setting the ratio of the diameter of the convex portion to the diameter of the bottom wall to be 0.20 to 0.95, deformation of the bottom wall of the case can be further suppressed. When the ratio of the diameter of the convex portion to the diameter of the bottom wall is smaller than 0.20, it is not preferable because deformation of the bottom wall cannot be sufficiently suppressed. Further, when the ratio of the diameter of the convex part to the diameter of the bottom wall is larger than 0.95, the diameter of the bottom wall and the diameter of the convex part are almost equal, and the convex part can be formed. Since it becomes difficult, it is not preferable.

  In the electric storage element, a ratio of the diameter of the convex portion to the diameter of the bottom wall is 0.38 to 0.85.

  According to said structure, since the displacement amount of a bottom wall becomes small, it is more preferable.

  The power storage element has a base portion in which the bottom wall is positioned outward in the radial direction of the bottom wall from the convex portion, and the base portion and the convex portion are connected by a bottom wall connecting portion, A curved surface is formed on both or one of the inner surface and the outer surface of the bottom wall connecting portion.

  According to said structure, when the internal pressure in a case rises, it becomes easy to concentrate stress on the bottom wall connection part with which the convex part and the base were connected. Therefore, in the above configuration, a curved surface is formed on both or one of the inner surface and the outer surface of the bottom wall connecting portion. Thereby, since it is suppressed that stress concentrates on a bottom wall connection part, it can control that a bottom wall of a case changes.

  In the electric storage element, the bottom wall has a base portion that is located outward in the radial direction of the bottom wall with respect to the convex portion, and the base portion and the convex portion are connected by a bottom wall connecting portion, An inner first curved surface is formed between the inner surface of the base and the inner surface of the bottom wall connecting portion, and an inner second curved surface is formed between the inner surface of the bottom wall connecting portion and the inner surface of the convex portion. An outer first curved surface is formed between the outer surface of the base and the outer surface of the bottom wall connecting portion, and an outer side is formed between the outer surface of the bottom wall connecting portion and the outer surface of the convex portion. A second curved surface is formed, and at least one of a ratio of a curvature radius of the inner first curved surface, the inner second curved surface, the outer first curved surface, or the outer second curved surface to a thickness dimension of the bottom wall. One is 0.50 to 11.90.

  When the internal pressure in the case rises, stress tends to concentrate on the bottom wall connecting portion where the convex portion and the base portion are connected. Therefore, in the above configuration, an inner first curved surface is formed between the inner surface of the base portion and the inner surface of the bottom wall connecting portion, and an inner second surface is formed between the inner surface of the bottom wall connecting portion and the inner surface of the convex portion. A curved surface is formed, an outer first curved surface is formed between the outer surface of the base and the outer surface of the bottom wall connecting portion, and an outer second curved surface is formed between the outer surface of the bottom wall connecting portion and the outer surface of the convex portion. doing. Thereby, between the base and the bottom wall connection part and between the convex part and the bottom wall connection part are connected by the smooth curved surface. As a result, even when the internal pressure in the case rises, stress is prevented from concentrating on the bottom wall connecting portion, so that deformation of the bottom wall of the case can be suppressed.

  Further, at least one of the curvature radii of the inner first curved surface, the inner second curved surface, the outer first curved surface, and the outer second curved surface is set to 0.50 to 11.90 with respect to the thickness dimension of the bottom wall. ing. As a result, it is possible to further suppress the stress from concentrating on the bottom wall connecting portion, thereby further suppressing the deformation of the bottom wall of the case.

  In the electric storage element, a thick portion protruding outward is formed on the outer surface of the side wall at a position near the bottom wall, and the thickness dimension of the thick portion is the thickness of the side wall. It is set larger than the thickness dimension of the part different from the part.

  In the region near the bottom wall of the side wall, stress is easily concentrated when the internal pressure in the case increases. Therefore, in the above configuration, the thick portion is formed at a position near the bottom wall in the side wall. Thereby, even when the internal pressure in a case rises, it can suppress that the side wall of a case deform | transforms.

  In the electric storage element, a corner connecting portion for connecting the bottom wall and the side wall is formed at a peripheral portion of the bottom wall, and a corner is formed on both or one of the inner surface and the outer surface of the corner connecting portion. A curved surface is formed, and at least one of the ratio of the radius of curvature of the curved corner surface to the thickness dimension of the bottom wall is 1.33 to 4.67.

  The corner connecting portion is a peripheral portion of the bottom wall and is formed at the boundary between the bottom wall and the side wall. For this reason, stress tends to concentrate on the corner connecting portion when the internal pressure in the case increases. Therefore, in the above-described configuration, a corner curved surface is formed on both or one of the inner surface and the outer surface of the corner connecting portion, so that even when the internal pressure in the case rises, Since stress concentration is suppressed, the case is prevented from being deformed.

  Furthermore, at least one of the ratio of the radius of curvature of the corner curved surface to the thickness dimension of the bottom wall is set to 1.33 to 4.67. As a result, it is possible to further suppress the stress from concentrating on the corner connecting portion, thereby further suppressing the case from being deformed.

<Embodiment 1>
Embodiment 1 of the present invention will be described with reference to FIGS. The battery 10 (an example of a power storage element) according to the present embodiment is an alkaline storage battery such as a nickel hydride storage battery or a nickel cadmium storage battery. In the following description, the front side of the paper in FIG. 1 is the front side of the battery 10, the right side of the paper is the right side of the battery 10, and the upper side of the paper is the upper side of the battery 10.

(Battery 10)
As shown in FIG. 1, the battery 10 includes a power storage element 11 and a metal case 12 in which the power storage element 11 is accommodated. The case 12 has an opening 13 that opens upward, and an accommodation space 14 in which the electricity storage element 11 is accommodated. The opening 13 of the case 12 is closed from above by a lid 15 having a shape corresponding to the opening 13 of the case 12.

(Case 12)
The case 12 is made of a metal plate having a nickel plating layer formed on the surface. As a metal constituting the case 12, any metal such as iron, steel, aluminum, aluminum alloy, or the like can be appropriately selected as necessary. Moreover, as a metal which comprises the plating layer formed in the surface of a metal plate, arbitrary metals, such as nickel and zinc, can be selected suitably as needed.

  The case 12 functions as a negative electrode terminal of the battery 10 by electrically connecting a negative electrode plate 16 described later. The case 12 has an elongated shape in the vertical direction, and one end (upper end in the present embodiment) in the longitudinal direction (vertical direction) is opened, and the other end (lower end in the present embodiment) is closed. The case 12 has a bottomed cylindrical shape.

  The case 12 is formed, for example, by pressing one nickel-plated steel plate. The case 12 according to the present embodiment is formed by performing a process of further reducing the diameter after this press working. The diameter reduction process may be omitted.

  The case 12 includes a disk-shaped bottom wall 17 and side walls 18 that rise upward from the side edges of the bottom wall 17. The bottom wall 17 has a circular shape when viewed from above.

(Bottom wall 17)
As shown in FIG. 2, the bottom wall 17 has a convex portion 19 that is concentric with the bottom wall 17 and protrudes outward (downward in FIG. 1) of the case 12. The convex portion 19 has a circular shape when viewed from above. The diameter D1 of the convex part 19 is set smaller than the diameter D2 of the bottom wall 17, and the bottom wall 17 and the convex part 19 are formed concentrically as viewed from above.

The ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is expressed by the following equation.
(Diameter of convex part) / (Diameter of bottom wall)

  The ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is preferably 0.20 to 0.95. Thereby, it can suppress that the bottom wall 17 of case 12 deform | transforms. When the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is smaller than 0.20, it is not preferable because deformation of the bottom wall 17 cannot be sufficiently suppressed. Further, when the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is larger than 0.95, the diameter D2 of the bottom wall 17 and the diameter D1 of the convex portion 19 are almost equal. Since it becomes difficult to form the convex part 19, it is not preferable.

  When the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is 0.38 to 0.85, the displacement amount of the bottom wall 17 is small, which is more preferable. In addition, when the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is 0.52 to 0.80, the amount of displacement of the bottom wall 17 is small, which is particularly preferable.

  As shown in FIG. 3, the bottom wall 17 has a base portion 20 that surrounds the convex portion 19 in an annular shape at a position radially outward of the bottom wall 17 relative to the convex portion 19. The base portion 20 and the convex portion 19 are connected by a bottom wall connecting portion 21. The bottom wall connecting portion 21 is formed between the base portion 20 and the convex portion 19 and bent in a crank shape when viewed from the side.

  An outer curved surface 22 (an example of a curved surface) is formed on the outer surface of the bottom wall connecting portion 21. An inner curved surface 23 (an example of a curved surface) is formed on the inner surface of the bottom wall connecting portion 21.

  In the present embodiment, the radius of curvature P1 of the outer curved surface 22 is 0.35 mm. The curvature radius P2 of the inner curved surface 23 is also 0.35 mm.

(Sidewall 18)
The side wall 18 has a cylindrical shape, and the cross-sectional shape of the side wall 18 is circular. The thickness dimension of the side wall 18 is set smaller than the thickness dimension of the bottom wall 17.

  A thick portion 24 that protrudes outward in the thickness direction of the side wall 18 is formed at a position near the convex portion 19 in the side wall 18 (a position near the lower end portion in the present embodiment). In other words, the thick portion 24 protrudes from the side wall 18 radially outward of the side wall 18 having a circular cross section. The thickness dimension of the thick portion 24 is set to be larger than the thickness dimension of the portion of the side wall 18 different from the thick portion 24. The thick part 24 is formed over the entire circumference of the side wall 18.

  Of the inner surface of the side wall 18, a region corresponding to the thick portion 24 and a region corresponding to a portion different from the thick portion 24 are formed flush with each other. Further, in the region corresponding to the thick portion 24 on the outer surface of the side wall 18, the slope of the upper portion of the thick portion 24 is formed more gently than the slope of the lower portion of the thick portion 24. Has been.

(Corner connecting part 25)
At the peripheral edge of the bottom wall 17, a corner connecting portion 25 is formed at the boundary between the bottom wall 17 and the side wall 18. In the present embodiment, the corner connecting portion 25 is connected to the base portion 20 formed on the bottom wall 17. An outer corner curved surface 26 (an example of a corner curved surface) is formed on the outer surface of the corner connecting portion 25, and an inner corner curved surface 27 (an example of a corner curved surface) is formed on the inner surface of the corner connecting portion 25. Has been. Due to the outer corner curved surface 26, the outer surface of the side wall 18 and the outer surface of the bottom wall 17 are smoothly continuous. Further, due to the inner corner curved surface 27, the inner surface of the side wall 18 and the inner surface of the bottom wall 17 are smoothly continuous.

(Cover 15)
As shown in FIG. 1, the lid portion 15 is electrically connected to a positive electrode plate 28 described later via an elastic connection terminal 29 and functions as a positive electrode terminal of the battery 10. The lid portion 15 has a disk shape as a whole and closes the opening 13 of the case 12. Specifically, the peripheral edge portion of the lid portion 15 is fitted to the distal end portion of the opening portion 13 of the case 12 via the gasket 30 formed of an insulating synthetic resin or the like, and is caulked to the distal end portion. . As a result, the case 12 is hermetically sealed while maintaining the insulation between the lid 15 and the case 12. The lid 15 is provided with a safety valve 31, and when the internal pressure of the case 12 exceeds a predetermined value, the safety valve 31 can discharge the gas in the case 12 to the outside.

(Electric storage element 11)
As shown in FIG. 1, the power storage element 11 is housed in the housing space 14 of the case 12. The power storage element 11 includes a positive electrode plate 28, a negative electrode plate 16, and a separator 32 disposed between them, for example, spirally around a winding axis along the longitudinal direction of the case 12 (vertical direction in the present embodiment). It is the structure wound around.

  The positive electrode plate 28 is obtained by, for example, applying a mixture of a positive electrode active material such as nickel hydroxide and a conductive agent such as a cobalt compound to a positive electrode metal plate such as foamed nickel. The negative electrode plate 16 is obtained by applying a negative electrode active material such as cadmium powder or hydrogen storage alloy powder to a negative electrode metal plate such as a flat perforated steel plate plated with nickel. The separator 32 is made of, for example, a nonwoven fabric made of polyolefin. The separator 32 is impregnated with an electrolytic solution mainly composed of potassium hydroxide or sodium hydroxide.

(Manufacturing process)
Then, an example of the manufacturing process of the battery 10 according to the present embodiment will be described. In addition, the manufacturing process of this embodiment is not limited to the following description.

  The case 12 is created by pressing a nickel-plated steel sheet into a predetermined shape. The power storage element 11 is accommodated in the case 12. Next, an electrolytic solution is injected into the case 12 and impregnated in the electricity storage element 11.

  The lid 15 is overlapped on the opening 13 of the case 12 via the gasket 30, and the tip of the side wall 18 of the case 12 is caulked to the lid 15. As a result, the case 12 is sealed by the lid 15.

  Subsequently, a diameter reduction process is performed on the case 12. Thereby, the diameter of the case 12 is reduced to the standard width dimension of the battery 10.

(Samples 1 to 23)
In the battery 10 according to the present embodiment, a general CAE (Computer Aided Engineering) analysis method is performed on samples 1 to 23 in which the diameter D1 of the convex portion 19 is different, and the bottom wall 17 having the diameter D1 of the convex portion 19 is obtained. The ratio of the diameter to the diameter D2 and the amount of displacement of the center portion of the bottom wall 17 and the convex portion 19 outward of the case 12 were calculated. The results are shown in FIG. Further, the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 and the center portion of the bottom wall 17 and the convex portion 19 outward from the central portion C of the bottom wall 17 (downward in FIG. 1). The displacement amount is summarized in Table 1.

  The dimensions of each part of the battery 10 according to Samples 1 to 23 are shown below. The diameter D2 of the bottom wall 17 was 7.05 mm. The thickness dimension of the bottom wall 17 was 0.30 mm. The thickness dimension of the side wall 18 was 0.13 mm.

  The projecting dimension of the convex portion 19 outward (downward) from the outer surface (lower surface) of the base portion 20 was set to 0.30 mm, which is the same as the thickness dimension of the bottom wall 17.

  In Samples 1 to 23, the radius of curvature Q2 of the inner corner curved surface 27 was 0.65 mm. On the other hand, the outer corner curved surface 26 is formed by smoothly and continuously forming curved surfaces having a plurality of (two in this analysis example) curvature radii. The curvature radius Q11 of the outer corner curved surface 26 in the region near the bottom wall 17 was 0.60 mm. The curvature radius Q12 of the outer corner curved surface 26 in the region near the side wall 18 was set to 0.80 mm.

The nickel-plated steel sheet constituting the case 12 had a Young's modulus of 1.72 × 10 ¹¹ Pa, a Poisson's ratio of 0.23, a yield stress of 1.95 × 10 ⁸ Pa, and a tangential coefficient of 5.99 × 10 ⁹ Pa. .

  The analysis was performed as follows. First, as an initial state, the temperature of the battery 10 was set to 25 ° C., and the internal pressure and the external pressure of the battery 10 were set to 0 Pa. The position of the center portion C of the bottom wall 17 at this time point was used as the reference position of the center portion C of the bottom wall 17 in this analysis. Thereafter, the internal pressure of the battery 10 was set to 2 MPa, and this pressure was held for 1 second. Thereafter, the internal pressure of the battery 10 was reduced to 0 Pa and unloaded. After the unloading, the position of the central portion C of the bottom wall 17 in a state where the bottom wall 17 is restored and deformed was calculated. The difference between the reference position of the center portion C of the bottom wall 17 and the position of the center portion C of the bottom wall 17 after unloading was defined as the amount of outward displacement of the center portion C of the bottom wall 17.

(Function, effect)
Next, functions and effects of Samples 1 to 23 will be described. Samples 3 to 23 are examples, and samples 1 to 2 are comparative examples. The power storage elements according to Samples 3 to 23 include a power storage element 11 and a case 12 having a bottomed cylindrical shape and containing the power storage element 11 therein, and the case 12 includes a bottom wall 17 having a disk shape, , And a side wall 18 rising from the side edge of the bottom wall 17. The bottom wall 17 has a concentric shape with the bottom wall 17 and a convex portion 19 projecting outward from the case 12. Thereby, the bottom wall 17 is reinforced by the convex part 19 formed in the bottom wall 17. Thereby, even if it is a case where the internal pressure in case 12 rises, it can suppress that the bottom wall 17 of case 12 deform | transforms.

  Further, from Table 1, the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is preferably 0.20 to 0.95. Thereby, it can suppress that the bottom wall 17 of case 12 deform | transforms. When the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is smaller than 0.20, it is not preferable because deformation of the bottom wall 17 cannot be sufficiently suppressed. Further, when the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is larger than 0.95, the diameter D2 of the bottom wall 17 and the diameter D1 of the convex portion 19 are almost equal. Since it becomes difficult to form the convex part 19, it is not preferable.

  When the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is 0.38 to 0.85, the displacement amount of the bottom wall 17 is small, which is more preferable. In addition, when the ratio of the diameter D1 of the convex portion 19 to the diameter D2 of the bottom wall 17 is 0.52 to 0.80, the amount of displacement of the bottom wall 17 is small, which is particularly preferable.

  Further, according to the samples 3 to 23, the thickness dimension T1 of the side wall 18 is set smaller than the thickness dimension T2 of the bottom wall 17. Thereby, compared with the case where the thickness dimension T1 of the side wall 18 and the thickness dimension T2 of the bottom wall 17 are set to be the same, the volume of the case 12 can be increased, so that the capacity of the battery 10 is increased. be able to.

  Further, according to Samples 3 to 23, a thick portion 24 protruding outward is formed on the outer surface of the side wall 18 at a position near the bottom wall 17, and the thickness dimension of the thick portion 24 is The side wall 18 is set larger than the thickness dimension of the portion different from the thick portion 24. In the region near the bottom wall 17 in the side wall 18, stress tends to concentrate when the internal pressure in the case 12 increases. Therefore, in the samples 1 to 23, the thick portion 24 is formed at a position near the bottom wall 17 in the side wall 18. Thereby, even when the internal pressure in case 12 rises, it can control that side wall 18 of case 12 changes.

  Further, according to Samples 3 to 23, the bottom wall 17 has a base portion 20 positioned radially outward of the bottom wall 17 with respect to the convex portion 19, and the base portion 20 and the convex portion 19 are the bottom wall connecting portion. 21, and a curved surface is formed on both or one of the inner surface and the outer surface of the bottom wall connecting portion 21. When the internal pressure in the case 12 rises, the stress tends to concentrate on the bottom wall connecting portion 21 to which the convex portion 19 and the base portion 20 are connected. Therefore, in Samples 13 to 23, a curved surface is formed on both or one of the inner surface and the outer surface of the bottom wall connecting portion 21. Thereby, since it is suppressed that stress concentrates on the bottom wall connection part 21, it can suppress that the bottom wall 17 of case 12 deform | transforms.

<Samples 24-29>
Next, samples 24 to 29 will be described. In samples 24 to 29, as shown in FIGS. 5 and 6, the curvature radius Q1 and the curvature radius Q2 of the outer corner curved surface 26 and the curvature radius Q2 of the inner corner curved surface 27 are set to the same value. The amount of displacement of the central portion C of the bottom wall 17 when the value of was changed in various ways was analyzed by the CAE analysis technique.

  Samples 24 to 29 have substantially the same configuration as that of sample 9 except for the configuration described above. Further, CAE analysis was performed on samples 24-29 in the same manner as samples 1-23. The analysis results of Sample 24 to Sample 29 are summarized in Table 2 and FIG.

(Function, effect)
Samples 24-29 are examples. In the samples 24 to 29, a corner connecting portion 25 to which the bottom wall 17 and the side wall 18 are connected is formed on the peripheral portion of the bottom wall 17. An inner corner curved surface 27 is formed on the inner surface of the corner connecting portion 25, and an outer corner curved surface 26 is formed on the outer surface of the corner connecting portion 25. Both the radius of curvature Q2 of the inner corner curved surface 27 and the radius of curvature Q1 of the outer corner curved surface 26 are set to the same value, and are set to 0.40 mm to 1.40 mm. In samples 24-29, the thickness dimension of the bottom wall 17 is 0.30 mm, so the ratio of the radius of curvature Q2 of the inner corner curved surface 27 to the thickness dimension of the bottom wall 17 is 1.33-4. 67. The ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 is also 1.33 to 4.67.

Note that the ratio of the radius of curvature to the thickness dimension of the bottom wall is expressed by the following equation.
(Curvature radius) / (bottom wall thickness dimension)

  The corner connecting portion 25 is a peripheral portion of the bottom wall 17 and is formed at the boundary between the bottom wall 17 and the side wall 18. For this reason, stress is easily concentrated on the corner connecting portion 25 when the internal pressure in the case 12 increases. Therefore, in the samples 24 to 29, the inner corner curved surface 27 is formed on the inner surface of the corner connecting portion 25, and the outer corner curved surface 26 is formed on the outer surface of the corner connecting portion 25. Even when the internal pressure in 12 rises, stress is prevented from concentrating on the corner connecting portion 25, so that the case 12 is prevented from being deformed.

  Further, at least one of the ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 and the ratio of the radius of curvature Q2 of the inner corner curved surface 27 to the thickness dimension of the bottom wall 17 is at least one. In this embodiment, the ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 and the radius of curvature Q2 of the inner corner curved surface 27 are set. Both ratios to the thickness dimension of the bottom wall 17 are 1.33 to 4.67. As a result, it is possible to further suppress the stress from concentrating on the corner connecting portion 25, and thus it is possible to further suppress the case 12 from being deformed.

  As shown in FIG. 7, the ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 and the ratio of the radius of curvature Q2 of the inner corner curved surface 27 to the thickness dimension of the bottom wall 17 are as follows. As the size increases, the amount of outward displacement of the central portion C of the bottom wall 17 decreases. This is because the ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness of the bottom wall 17 and the ratio of the radius of curvature Q2 of the inner corner curved surface 27 to the thickness of the bottom wall 17 are increased. This is considered to be because the stress concentration in the corner connecting portion 25 is alleviated.

  The ratio of the curvature radius Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 or the ratio of the curvature radius Q2 of the inner corner curved surface 27 to the thickness dimension of the bottom wall 17 is 1.33-4. In the case of 67, the amount of displacement of the bottom wall 17 can be reduced, and the power storage element 11 can be accommodated with less gap space, which is more preferable. More specifically, if it is less than 1.33, the amount of displacement of the bottom wall 17 becomes too large, which is not preferable. If it is larger than 4.67, when the electricity storage element 11 is accommodated in the case 12, the electricity storage element 11 cannot be accommodated in the rounded portion, and the curved portion becomes an empty space. It is not preferable. In addition, if the space is vacant, the power storage element 11 may be deformed by vibration, which is not preferable.

  Further, the ratio of the radius of curvature Q1 of the outer corner curved surface 26 to the thickness dimension of the bottom wall 17 or the ratio of the radius of curvature Q2 of the inner corner curved surface 27 and the thickness dimension of the bottom wall 17 is 1.33-2. 67 is particularly preferred because it is the same as above.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIGS. In the present embodiment, an inner first curved surface 33 is formed between the inner surface of the base portion 20 and the inner surface of the bottom wall connecting portion 21. Thereby, the inner surface of the base part 20 and the inner surface of the bottom wall connection part 21 are smoothly connected. An inner second curved surface 34 is formed between the inner surface of the bottom wall connecting portion 21 and the inner surface of the convex portion 19. Thereby, the inner surface of the bottom wall connection part 21 and the inner surface of the convex part 19 are connected smoothly.

  On the other hand, an outer first curved surface 35 is formed between the outer surface of the base portion 20 and the outer surface of the bottom wall connecting portion 21. Thereby, the outer surface of the base 20 and the outer surface of the bottom wall connection part 21 are smoothly connected. An outer second curved surface 36 is formed between the outer surface of the bottom wall connecting portion 21 and the outer surface of the convex portion 19. Thereby, the outer surface of the bottom wall connection part 21 and the outer surface of the convex part 19 are connected smoothly.

  In the present embodiment, the curvature radius R2 of the inner first curved surface 33, the curvature radius S2 of the inner second curved surface 34, the curvature radius R1 of the outer first curved surface 35, and the curvature radius S1 of the outer second curved surface 36 are all the same. Is set to a value. In the present embodiment, the ratio of the radius of curvature R2 of the inner first curved surface 33 to the thickness dimension T2 of the bottom wall 17, the ratio of the radius of curvature S2 of the inner second curved surface 34 to the thickness dimension T2 of the bottom wall 17, The ratio of the curvature radius R1 of the first curved surface 35 to the thickness dimension T2 of the bottom wall 17 and the ratio of the curvature radius S1 of the outer second curved surface 36 to the thickness dimension T2 of the bottom wall 17 are set to 0.50 to 11.90. The

  Since the configuration other than the above is substantially the same as that of the sample 9 of the first embodiment, the same members are denoted by the same reference numerals, and redundant description is omitted.

(Samples 30-49)
Subsequently, samples 30 to 49 will be described. In samples 30 to 49, as shown in FIG. 9, the curvature radius R2 of the inner first curved surface 33, the curvature radius S2 of the inner second curved surface 34, the curvature radius R1 of the outer first curved surface 35, and the outer second curved surface 36. The amount of displacement of the central portion C of the bottom wall 17 when the curvature radius S1 was changed to various values while keeping the same value was analyzed by the CAE analysis technique.

  About structures other than the above, CAE analysis was performed like the samples 1-23. The analysis results of samples 30 to 49 are summarized in Table 3 and FIG. Samples 30-49 are examples.

(Function, effect)
When the internal pressure in the case 12 rises, the stress tends to concentrate on the bottom wall connecting portion 21 to which the convex portion 19 and the base portion 20 are connected. Therefore, in the samples 30 to 49, an inner first curved surface 33 is formed between the inner surface of the base portion 20 and the inner surface of the bottom wall connecting portion 21, and the inner surface of the bottom wall connecting portion 21 and the inner surface of the convex portion 19 are formed. An inner second curved surface 34 is formed therebetween, an outer first curved surface 35 is formed between the outer surface of the base portion 20 and the outer surface of the bottom wall connecting portion 21, and the outer surface of the bottom wall connecting portion 21 and the convex portion 19. An outer second curved surface 36 is formed between the outer surface and the outer surface. Thereby, between the base 20 and the bottom wall connection part 21, and between the convex part 19 and the bottom wall connection part 21 are connected by the smooth curved surface. As a result, even when the internal pressure in the case 12 increases, the stress is suppressed from concentrating on the bottom wall connecting portion 21, so that the deformation of the bottom wall 17 of the case 12 can be suppressed.

  Furthermore, at least one of the curvature radius R2 of the inner first curved surface 33, the curvature radius S2 of the inner second curved surface 34, the curvature radius R1 of the outer first curved surface 35, and the curvature radius S1 of the outer second curved surface 36 is a bottom wall. It is set to 0.50 to 11.90 with respect to the thickness dimension T2 of 17. In the present embodiment, the ratio of the radius of curvature R2 of the inner first curved surface 33 to the thickness dimension T2 of the bottom wall 17, the ratio of the radius of curvature S2 of the inner second curved surface 34 to the thickness dimension T2 of the bottom wall 17, The ratio of the curvature radius R1 of the first curved surface 35 to the thickness dimension T2 of the bottom wall 17 and the ratio of the curvature radius S1 of the outer second curved surface 36 to the thickness dimension T2 of the bottom wall 17 are all 0.50 to 11. 90. As a result, it is possible to further suppress the stress from concentrating on the bottom wall connecting portion 21, thereby further suppressing the deformation of the bottom wall 17 of the case 12.

  At least one of the curvature radius R2 of the inner first curved surface 33, the curvature radius S2 of the inner second curved surface 34, the curvature radius R1 of the outer first curved surface 35, and the curvature radius S1 of the outer second curved surface 36 is the thickness of the bottom wall 17. When it is 0.50 to 9.17 with respect to the dimension T2, the amount of displacement of the bottom wall 17 becomes smaller, which is more preferable. Further, at least one of the curvature radius R2 of the inner first curved surface 33, the curvature radius S2 of the inner second curved surface 34, the curvature radius R1 of the outer first curved surface 35, and the curvature radius S1 of the outer second curved surface 36 is the bottom wall 17. When the thickness T2 is 1.00 to 7.17, the amount of displacement of the bottom wall 17 is small, which is particularly preferable.

<Other embodiments>
The technique described in the present specification is not limited to the embodiment described with reference to the above description and drawings, and includes, for example, the following aspects.

  In the present embodiment, the storage element is an alkaline storage battery, but is not limited thereto, and the storage element may be a capacitor or a capacitor. Moreover, the secondary battery different from alkaline storage batteries, such as a lead storage battery and a lithium ion battery, may be sufficient as an electrical storage element, for example.

  In the present embodiment, the thickness dimension T1 of the side wall 18 is set to be smaller than the thickness dimension T2 of the bottom wall 17. However, the thickness dimension T1 of the side wall 18 is not limited to this. It may be set to be equal to or larger than the thickness dimension T2.

  In the present embodiment, the thick portion 24 is formed on the outer surface of the side wall 18, but the thick portion 24 may not be provided.

  In the first embodiment, the curved surface is formed on both the inner surface and the outer surface of the bottom wall connecting portion 21. However, the present invention is not limited to this, and the curved surface is formed only on the inner surface of the bottom wall connecting portion 21. Alternatively, a curved surface may be formed only on the outer surface of the bottom wall connecting portion 21.

  In the first embodiment, the radius of curvature P2 of the inner curved surface 23 and the radius of curvature P1 of the outer curved surface 22 are set to be the same. However, the present invention is not limited to this. The curvature radius P1 of the curved surface 22 may be different.

  In the second embodiment, the curvature radius R2 of the inner first curved surface 33, the curvature radius R1 of the outer first curved surface 35, the curvature radius S2 of the inner second curved surface 34, and the curvature radius S1 of the outer second curved surface 36 are all. Although it was set to be the same, the present invention is not limited to this. The curvature radius R2 of the inner first curved surface 33, the curvature radius R1 of the outer first curved surface 35, the curvature radius S2 of the inner second curved surface 34, and the outer second curved surface 36 The curvature radius S1 can be set to an arbitrary value as necessary.

  The inner first curved surface 33, the outer first curved surface 35, the inner second curved surface 34, and the outer second curved surface 36 according to the second embodiment can be omitted as necessary.

  In the present embodiment, the inner corner curved surface 27 is formed on the inner surface of the corner connecting portion 25, and the outer corner curved surface 26 is formed on the outer surface of the corner connecting portion 25. Without being limited thereto, the inner corner curved surface 27 may be formed only on the inner surface of the corner connecting portion 25, and the outer corner curved surface 26 may be formed only on the outer surface of the corner connecting portion 25. .

  DESCRIPTION OF SYMBOLS 10: Battery 11: Power storage element 12: Case 17: Bottom wall 18: Side wall 19: Convex part 20: Base part 21: Bottom wall connection part 22: Outer curved surface 23: Inner curved surface 24: Thick part 25: Corner part 26 : Outer corner curved surface 27: inner corner curved surface 33: inner first curved surface 34: inner second curved surface 35: outer first curved surface 36: outer second curved surface

Claims (6)

A storage element;
A storage element having a bottomed cylindrical shape and a case in which the storage element is housed;
The case has a disk-shaped bottom wall, and a side wall rising from a side edge of the bottom wall,
The bottom wall is concentric with the bottom wall, and has a protrusion protruding outward from the case.
The diameter of the convex portion, the ratio to the diameter of the bottom wall Ri der 0.20 to 0.95,
The bottom wall has a base portion located radially outward of the bottom wall from the convex portion,
The base part and the convex part are connected by a bottom wall connecting part,
An inner first curved surface is formed between the inner surface of the base portion and the inner surface of the bottom wall connecting portion,
An inner second curved surface is formed between the inner surface of the bottom wall connecting portion and the inner surface of the convex portion,
An outer first curved surface is formed between the outer surface of the base portion and the outer surface of the bottom wall connecting portion,
An outer second curved surface is formed between the outer surface of the bottom wall connecting portion and the outer surface of the convex portion,
At least one of the ratio of the radius of curvature of the inner first curved surface, the inner second curved surface, the outer first curved surface, or the outer second curved surface to the thickness dimension of the bottom wall is 0.50 to 11.90. A power storage element. The power storage device according to claim 1,
  On the outer surface of the side wall, a thick portion protruding outward is formed at a position near the bottom wall,
  The electrical storage element with which the thickness dimension of the said thick part is set larger than the thickness dimension of the part different from the said thick part among the said side walls. The electric storage element according to claim 1 or 2,
  A corner connecting portion to which the bottom wall and the side wall are connected is formed at the peripheral portion of the bottom wall,
  A corner curved surface is formed on both or one of the inner surface and the outer surface of the corner connecting portion,
  At least one of the ratio of the radius of curvature of the corner curved surface to the thickness of the bottom wall is 1.33 to 4.67. A storage element;
  A storage element having a bottomed cylindrical shape and a case in which the storage element is housed;
  The case has a disk-shaped bottom wall, and a side wall rising from a side edge of the bottom wall,
  The bottom wall is concentric with the bottom wall, and has a protrusion protruding outward from the case.
  The ratio of the diameter of the convex portion to the diameter of the bottom wall is 0.20 to 0.95,
  On the outer surface of the side wall, a thick portion protruding outward is formed at a position near the bottom wall,
  The electrical storage element with which the thickness dimension of the said thick part is set larger than the thickness dimension of the part different from the said thick part among the said side walls. The power storage device according to claim 4,
  A corner connecting portion to which the bottom wall and the side wall are connected is formed at the peripheral portion of the bottom wall,
  A corner curved surface is formed on both or one of the inner surface and the outer surface of the corner connecting portion,
  At least one of the ratio of the radius of curvature of the corner curved surface to the thickness of the bottom wall is 1.33 to 4.67. A storage element;
A storage element having a bottomed cylindrical shape and a case in which the storage element is housed;
The case has a disk-shaped bottom wall, and a side wall rising from a side edge of the bottom wall,
The bottom wall is concentric with the bottom wall, and has a protrusion protruding outward from the case.
The ratio of the diameter of the convex portion to the diameter of the bottom wall is 0.20 to 0.95,
A corner connecting portion to which the bottom wall and the side wall are connected is formed at the peripheral portion of the bottom wall,
A corner curved surface is formed on both or one of the inner surface and the outer surface of the corner connecting portion,
At least one of the ratio of the radius of curvature of the corner curved surface to the thickness of the bottom wall is 1.33 to 4.67.

Images