JP4256979B2 - Rectangular electrochemical device storage container - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exterior container for storing a power generation element of an electrochemical element such as a battery or an electric double layer capacitor, and more particularly to a rectangular electrochemical element storage container having a bottomed rectangular tube shape.
[0002]
[Prior art]
The shape of an electrochemical element (hereinafter referred to as a battery) such as a battery is determined by the standard, but there is also a non-standard shape according to the shape of an electronic device incorporating the battery. In particular, in response to the thinning of electronic devices, in recent years, there is a great demand for a rectangular battery having a flat rectangular tube shape. This prismatic battery accommodates an electrode (winding group) or electrolyte solution wound in the flat bottomed rectangular tube-shaped outer casing 4 shown in FIG. It is produced by sealing with. A rectangular battery outer container (hereinafter referred to as a container) is based on this flat bottomed rectangular tube shape, and is changed into various shapes in consideration of productivity and the like. For example, in the container 5 shown in FIGS. 7A and 7B, in order to prevent the lid 33 inserted into the opening end 10 from falling into the container 5, embossing is performed in the vicinity of the opening end 10. A protrusion 32 is provided on the inner side (A). The protrusion 32 supports the lid 33 and prevents it from falling into the container 5 and is also used for positioning for inserting the lid 33 to a predetermined depth (B). Further, the container 6 shown in the external view of FIG. 8 has a two-stage rectangular tube shape in which an upper tube portion 34 and a lower tube portion 35 having different cross-sectional areas are joined for the purpose of preventing deformation of the container when the lid is inserted. The container 6 is used. The technology of this two-stage cylindrical container is disclosed in Japanese Patent Laid-Open No. 9-92235.
[0003]
[Problems to be solved by the invention]
The battery generates electricity by a chemical reaction in a power generation element housed in the exterior container. This chemical reaction is an exothermic reaction and raises the internal pressure of the sealed container. Therefore, the container is deformed so as to bulge outward by this pressure. Since the above-described conventional containers 4 to 6 are based on a simple square cylindrical shape, the side wall surfaces are flat. Therefore, the pressure is concentrated on the wall surface, resulting in a biased stress distribution. Therefore, it is easy to deform. The deformation of the container may make it difficult to attach the battery to the device, or the attached battery may fall off. In many cases, the container is integrally mounted as a part of the apparatus housing, and it is conceivable that the appearance of the apparatus is impaired by deformation of the container.
[0004]
The container 5 has a problem when inserting a winding group. FIG. 9 shows a state where the winding group is inserted into the container 5 as a plan view from the opening end 10 side. The winding group 30 applied to the prismatic battery has a substantially oval cross-sectional shape in contact with the inner wall 36 of the container, and the protrusion 32 interferes when trying to insert the winding group 30 into the container 2. Therefore, the productivity of the battery is reduced.
[0005]
The above-mentioned two-stage cylindrical container 6 can prevent the lid from dropping at the stepped portion, but has no effect of suppressing deformation due to the increase in the internal pressure described above. In addition, this shape increases the total thickness (vertical and horizontal dimensions at the opening end face), making it difficult to reduce the size and thickness of the battery.
[0006]
Therefore, the present invention is a rectangular electrochemical element that can suppress shape deformation due to a pressure increase due to a chemical reaction of a power generation element, and further improves workability when inserting a winding group, and the lid is difficult to fall into the container. It aims at providing the exterior container.
[0007]
[Means for Solving the Problems]
The rectangular electrochemical device storage container of the present invention is a bottomed rectangular tube-shaped container, and has an upper cylindrical portion that extends downward while maintaining the shape of the open end surface formed in a substantially rectangular shape as a cross section, and the short shape of the substantially rectangular shape. The lower cylinder part extending toward the bottom surface is integrally connected while maintaining the shape in which the side is substantially semicircular, and the long side wall surface of the upper cylinder part and the length of the lower cylinder part are integrally connected. A flat surface that is substantially flush with the side wall surface is formed, and a side line that connects a short-side midpoint of the substantially rectangular shape at the opening end and a midpoint of the semicircular shape at the bottom surface is a substantially straight line.
[0008]
More preferably, protrusions protruding in the in-cylinder direction are formed in at least two opposing corners of the substantially rectangular four corners in the vicinity of the opening end, and the protrusions correspond to the inner wall of the lower cylinder part. It is to make it a rectangular electrochemical element storage container outside. Moreover, it is good also as a square electrochemical element storage container which formed the convex part in the inner wall surface of the said substantially rectangular long side of the said lower cylinder part.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
=== Shape of Square Electrochemical Element Storage Container ===
FIG. 1 shows a rectangular electrochemical element storage container (hereinafter referred to as a container) 1 according to an embodiment of the present invention as a three-dimensional view obliquely from above. 2 (A) to 2 (D) show plan views from four directions in the container 1, and in the order of (A) to (D), the opening end side, the long side, the bottom side, and the short side, respectively. A plan view is shown. The container 1 is integrally formed in a generally flat bottomed rectangular tube shape. The container 4 in this embodiment is made of stainless steel (SUS304L) having a plate thickness t = 0.35 mm, and the outer dimensions thereof are a width W = 10 mm, a length L = 34 mm, and a height H = 50 mm. .
[0010]
The open end 10 has a substantially rectangular shape with R portions 11 formed at the corners, and the bottom surface 12 has a shape in which the short side of the rectangle is formed in a semicircular shape. The container 1 is directed toward the bottom while maintaining the shape of the upper cylindrical portion 13 extending downward while maintaining the substantially rectangular shape of the open end 10 surface as a cross-section, and the shape in which the rectangular short side is formed in a semicircular shape as the cross-section. The cylindrical portions 13 and 14 are integrally connected via the boundary portion 15 while continuously changing their shapes. In addition, the boundary part 15 is based on the press work precision at the time of manufacture of this container 1, and the shape where the upper cylinder part 13 and the lower cylinder part 14 were connected intermittently may be sufficient.
[0011]
In the present embodiment, the height h1 of the upper tube portion 13 is about 10 mm. This height h1 is a value when the manufacturing apparatus performs positioning with reference to the short side wall surface 16 of the upper cylindrical portion 13 when a battery is manufactured by inserting a power generation element into the container 1 or sealing the open end. It is determined appropriately in consideration of the accuracy and handling property at the time of clamping (ease when the “hand” of the manufacturing apparatus grasps the container).
[0012]
Further, the surface from the long side wall surface 18 of the upper tube portion 13 to the long side wall surface 19 of the lower tube portion 14 is flat and flush. Further, a side line 22 connecting the short-side midpoint 20 of the open end 10 to the semicircular midpoint 21 of the low surface 12 is a straight line orthogonal to the bottom surface 12 and is on the same plane. That is, the maximum length and the maximum width of the cross section parallel to the bottom surface 12 are almost equal at any height, and all the vertical cross sections centering on the central axes 23 and 24 of the opening end surface are substantially rectangular.
[0013]
=== Characteristics of Rectangular Electrochemical Element Storage Container ===
Next, when the container according to the present invention is actually applied to a battery, it is necessary to verify how the shape of the container works against an increase in internal pressure. Therefore, the change in shape of the container according to the present invention (new model) and the conventional container (old model) on the simple rectangular tube shown in FIG. FIG. 3 is a characteristic comparison graph obtained by the simulation. The change amount of the long side wall surface with respect to the increase in internal pressure is shown. In this simulation, the materials and dimensions of the two types of new and old containers were unified to the same numerical values as those of the container of the above embodiment. It can be seen that the amount of change in the old container with the increase in pressure is larger than that in the new container. This is because the side wall surface of the short side of the old container is a flat surface, and pressure is not dispersed but is applied as it is. On the other hand, the new container has a semicircular wall on the short side of the portion (lower tube portion) that houses the power generation element of the battery. This wall shape is thought to be because the pressure is dispersed and the stress applied to the long side wall surface is reduced.
[0014]
=== Second Embodiment ===
4A and 4B show the container 2 in the second embodiment of the present invention. As shown in the external view shown in (A), the container 2 is provided with protrusions 25 protruding inward at the four corners (R portion) 11 of the upper tube portion 13. Since the container of the present invention has a structure in which the cross-sectional area of the lower cylinder part is smaller than the cross-sectional area of the upper cylinder part, the lid is basically not easily dropped into the lower cylinder part when the lid is inserted. Since the protrusion 25 supports the lid, it is more difficult to drop. In addition, alignment when inserting the lid to a predetermined depth is facilitated. In this embodiment, the protrusion 25 is protruded inward by pressing from the outside of the R portion 11. (B) has shown the enlarged view of the R part 11 as a top view from the opening end 10 side. The projecting portion 25 is located outside the region corresponding to the semicircular inner wall 26 of the lower cylindrical portion 14, and is considered so as not to interfere when the winding group is inserted. Note that the protrusions 25 do not have to be provided at all four corners of the upper tube portion 13, and may be provided at least at two opposing locations.
[0015]
=== Third embodiment ===
5A and 5B show the container 3 in the third embodiment of the present invention. A concave portion 26 is formed on the long side wall surface 19 of the lower cylinder portion 14 by pressing or the like (A). (B) shows a cross-sectional view of the lower tube portion 14 with the winding group 30 inserted into the container 3, and a convex surface portion 28 is formed inside the container 3 corresponding to the concave surface portion 27. This convex surface portion 28 functions as an “offset” in consideration of outward deformation accompanying an increase in internal pressure. That is, the time until the short side width W of the container 3 becomes larger than the dimension at the time of manufacture can be delayed. Further, when the winding group 30 is inserted into the container 3, the cross-sectional shape of the winding group 30 is a substantially oval shape (saddle shape) with a concave short axis direction. This does not hinder the insertion of the winding group 30 corresponding to 28.
[0016]
【The invention's effect】
According to the rectangular electrochemical element storage container of the present invention, the upper cylindrical portion having a substantially rectangular cross-sectional shape and the lower cylindrical portion having a cross-sectional shape in which the short side of the substantially rectangular shape is semicircular are integrally connected. It has become. In the lower cylinder portion in which the power generation element is accommodated, the stress caused by the heat generated by the chemical reaction is dispersed by the semicircular side wall on the short side. Therefore, a uniform stress distribution characteristic with little deviation is obtained in the cylinder, and the maximum displacement amount of the shape of the storage container can be reduced, and the change with time of the shape can be moderated.
[0017]
Moreover, since the side surface of the upper cylinder part which makes a substantially rectangular cross section is a flat surface, the manufacturing apparatus can use the flat surface as a positioning reference when manufacturing the battery. Contributes to improved handling when clamping the short side of the upper tube. Further, the lid for sealing inserted on the opening end side is also substantially rectangular, so that it is easier to fit than the semicircular side surface. Accordingly, the dimensional accuracy is reduced without requiring strict dimensional accuracy.
[0018]
Further, the long side wall surfaces of the upper cylinder portion and the lower cylinder portion are flush with each other, and the line connecting the short side midpoint of the opening end and the short side midpoint of the bottom surface is a straight line. Therefore, since the width and length of the container can be aligned with the lower cylinder portion that houses the power generation element, it is effective for reducing the size and thickness of the battery.
[0019]
The difference in cross-sectional area between the upper tube portion and the lower tube portion is a structure in which the lid inserted into the open end is unlikely to drop to the lower tube portion. Furthermore, by providing protrusions that project inward at at least two opposing corners of the four corners near the open end of the upper tube, the insertion depth of the lid can be easily adjusted, and the lid can be prevented from falling into the interior. It can be surely prevented. Therefore, the accuracy and workability when welding the lid are improved. Moreover, since this protrusion part is located outside the semicircle of the short side surface of the lower cylinder part, it does not interfere when the winding group is inserted. This structure also contributes to the improvement of productivity.
[0020]
If a concave surface is formed on the long side surface of the lower cylindrical portion, the change with time in the shape of this portion can be further delayed. The convex portion protruding into the cylinder by the concave surface corresponds to the saddle-shaped cross-sectional shape of the winding group, and therefore does not interfere with the insertion of the winding group.
[Brief description of the drawings]
FIG. 1 is an external view of a rectangular electrochemical element storage container according to an embodiment of the present invention.
FIG. 2 is a four-side view of the container. Plan views of the opening end side, the long side, the bottom side, and the short side are shown in the order of (A) to (D).
FIG. 3 is a performance comparison diagram between the container and a conventional container.
FIG. 4 shows a rectangular electrochemical element storage container according to a second embodiment of the present invention. (A) is an external view, (B) is an enlarged plan view from the opening end side.
FIG. 5 shows a rectangular electrochemical element storage container according to a third embodiment of the present invention. (A) is an external view, (B) has shown sectional drawing in the state which inserted the winding group in the said container.
FIG. 6 is an external view showing a basic shape of a conventional rectangular electrochemical element storage container.
FIG. 7 shows a modified example of the conventional container as an external view.
FIG. 8 is an external view of another modified example of the conventional container.
FIG. 9 shows a state in which a winding group is inserted into the conventional container as a plan view from the open end side.
[Explanation of symbols]
1-3 Square electrochemical element storage container 4-6 according to the present invention Conventional square electrochemical element storage container 10 Open end 12 Bottom surface 13 Upper cylinder part 14 Lower cylinder part

Claims (3)

A bottomed rectangular tube-shaped container for storing a power generation element of an electrochemical element, and an upper tube portion extending downward to an appropriate height while maintaining an opening end surface shape formed in a substantially rectangular shape as a cross section; A lower cylindrical portion that extends toward the bottom surface while maintaining a shape in which the short side of the substantially rectangular shape is formed in a substantially semicircular shape is integrally connected, and the long side wall surface of the upper cylindrical portion and the lower side A flat surface that is substantially flush with the long side wall surface of the cylindrical portion is formed, and a side line that connects the short-side midpoint of the substantially rectangular shape at the opening end and the midpoint of the semicircular shape at the bottom surface is substantially a straight line. A rectangular electrochemical element storage container. In Claim 1, the projection part which protrudes in a cylinder inward direction is formed in at least two places which oppose among the four corners of the said substantially rectangular shape in the vicinity of the said opening end, The said projection part respond | corresponds to the inner wall of the said lower cylinder part. A rectangular electrochemical element storage container characterized by being outward from the region. 3. The rectangular electrochemical element storage container according to claim 1, wherein the lower cylinder part is formed with a convex part on the inner wall surface of the substantially rectangular long side.

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