Electricity storage unit

Abstract

In a power storage unit, a case has a bottom portion, a first side surface portion, a second side surface portion, a first end surface portion, a second end surface portion, a welded portion, and a rib. The first side surface portion rises from the bottom portion. The second side surface portion faces the first side surface portion and rises from the bottom portion. The first end surface portion extends from the first side surface portion in a direction from the first side surface portion toward the second side surface portion. The second end surface portion extends from the second side surface portion in a direction toward the first side surface portion along the second side surface portion. The welding portion connects the first end face portion and the second end face portion. The rib is provided at a corner portion formed by the first side surface portion and the first end surface portion.

Description

Technical Field

[0001] The present disclosure relates to a power storage unit. Background Art

[0002] A secondary battery is disclosed in Japanese Patent Gazette No. 2013-125737. The secondary battery includes an electrode body and a shell for accommodating the electrode body. The shell is in the shape of a horizontally long rectangular plate and includes a main body and a cover. The main body is formed by bending a metal plate and welding the edges of the bent metal plate to each other. The metal plate includes a bottom face portion, a pair of side faces, and four half end faces. Each half end face portion is connected to the short side of a pair of side faces. The edges of the mutually opposite half end faces are butted against each other and joined by welding.

[0003] As disclosed in Japanese Patent Application Laid-Open No. 2013-125737, when the edges of the half end surface portions are welded to each other, there is a possibility that the housing may be deformed due to the welding. Summary of the invention

[0004] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide an electric storage unit in which deformation of a case due to welding of end faces is suppressed.

[0005] Technical solutions to solve problems

[0006] The storage unit based on the present disclosure comprises an electrode body and a shell, wherein the shell accommodates the electrode body. The shell has a bottom, a first side surface, a second side surface, a first end surface, a second end surface, a welding portion and a rib. The first side surface rises from the bottom. The second side surface is opposite to the first side surface and rises from the bottom. The first end surface extends from the first side surface along the direction from the first side surface toward the second side surface. The second end surface extends from the second side surface along the direction from the second side surface toward the first side surface. The welding portion connects the first end surface and the second end surface. The rib is arranged at a corner formed by the first side surface and the first end surface.

[0007] According to the above structure, the rigidity of the corner portion is improved by the rib. Thus, when the first end face portion and the second end face portion are welded to form the welded portion, the first side face portion can be prevented from being deformed due to the deformation of the welded first end face portion. Therefore, a storage cell can be provided in which deformation of the housing caused by welding of the end faces is prevented.

[0008] In the power storage unit of the present disclosure, preferably, the welded portion extends in a height direction. The height direction is a direction in which the first side surface portion stands. The rib extends in the height direction.

[0009] According to the above structure, the rigidity of the corner portion can be further improved by the rib. When the first end face portion and the second end face portion are welded in the height direction, the deformation of the first side face portion due to the deformation of the welded first end face portion can also be effectively suppressed. Therefore, it is possible to provide a storage cell in which the deformation of the housing caused by the welding of the end face is further suppressed.

[0010] In the power storage unit of the present disclosure, preferably, the rib protrudes from the corner portion toward the inside of the case.

[0011] According to the above configuration, it is possible to improve the rigidity of the corner portion while suppressing an increase in size of the housing.

[0012] In the power storage unit of the present disclosure, preferably, the rib protrudes from the corner portion toward the outside of the case.

[0013] According to the above configuration, it is possible to improve the rigidity of the corner portion while suppressing a reduction in the storage space of the housing.

[0014] In the power storage unit disclosed in the present invention, preferably, the weld portion extends in a height direction. The height direction is a direction in which the first side portion stands. The rib extends in the height direction. The rib protrudes from the corner portion toward both the inside and the outside of the housing.

[0015] According to the above structure, the rigidity of the corner can be further improved by the rib, and even when the first end face and the second end face are welded in the height direction, the first side face can be effectively prevented from being deformed due to the deformation of the welded first end face. Therefore, a storage unit can be provided that further prevents the deformation of the shell caused by the welding of the end face. In addition, the housing space of the shell can be prevented from becoming too small. In addition, the shell can be prevented from becoming too large. In addition, the rigidity of the corner can be improved.

[0016] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view showing a power storage unit according to one embodiment of the present disclosure. Figure 2 Observe along the arrow direction of line II-II Figure 1 A cross-sectional view of a power storage unit. Figure 3 Observe from the direction of the arrow on line III-III Figure 2 A cross-sectional view of an electrode body. Figure 4 This is a perspective view showing a housing in one embodiment of the present disclosure from one side. Figure 5This is a perspective view showing a housing in one embodiment of the present disclosure from another side. Figure 6 It is a schematic perspective view showing the state of each member constituting the housing before being welded. DETAILED DESCRIPTION

[0018] The embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings referred to below, the same or corresponding components are denoted by the same reference numerals.

[0019] Figure 1 It is a perspective view showing a power storage unit according to one embodiment of the present disclosure. Figure 2 Observe along the arrow direction of line II-II Figure 1 A cross-sectional view of a power storage unit.

[0020] like Figure 1 and Figure 2 As shown, the power storage cell 1 includes an electrode body 100 , a case 200 , a pair of external terminals 300 , a pair of connecting members 400 , and an insulating member 500 .

[0021] Figure 3 Observe from the direction of the arrow on line III-III Figure 2 The cross-sectional view of the electrode body is obtained. Figure 3 As shown, the electrode body 100 includes a plurality of electrodes 110 and 120 and a separator 130 .

[0022] like Figure 3 As shown, the plurality of electrodes 110 and 120 are arranged in a row along a thickness direction T. In the present embodiment, the thickness direction T is orthogonal to the height direction H. The plurality of electrodes 110 and 120 include a plurality of positive electrodes 110 and a plurality of negative electrodes 120 .

[0023] Each positive electrode 110 is formed into a rectangular shape that is long in the width direction W. The width direction W is a direction orthogonal to both the thickness direction T and the height direction H. Each positive electrode 110 includes a positive electrode collector foil 112 and a positive electrode active material layer 114 provided on both sides of the positive electrode collector foil 112. The positive electrode active material layer 114 is provided on both sides of the positive electrode collector foil 112. The positive electrode collector foil 112 includes a positive electrode tab 112p (see Figure 2 ). The positive electrode tab 112p is not provided with the positive electrode active material layer 114. The positive electrode tab 112p protrudes toward one side in the width direction W.

[0024] Each negative electrode 120 is formed in a rectangular shape that is long in the width direction. Each negative electrode 120 includes a negative electrode current collector foil 122 and a negative electrode active material layer 124. The negative electrode active material layer 124 is provided on both sides of the negative electrode current collector foil 122. Figure 2As shown, the negative electrode current collector foil 122 has a negative electrode tab 122n (see Figure 2 ). The negative electrode tab 122n is not provided with the negative electrode active material layer 124. The negative electrode tab 122n protrudes toward the other side in the width direction.

[0025] The separator 130 insulates the positive electrode 110 from the negative electrode 120. The separator 130 is made of an insulating material. The separator 130 has a tiny gap that allows ions to pass through. Figure 3 As shown, the partition 130 is formed in a zigzag shape.

[0026] The separator 130 has a rectangular shape before being formed into a zigzag shape. The separator 130 is arranged while being formed into a zigzag shape between the electrodes 110 and 120. The separator 130 has a plurality of intervening portions 132a, a plurality of upper folded portions 132b, a plurality of lower folded portions 132c, and an outermost covering portion 132d.

[0027] Each intervening portion 132a is interposed between a pair of electrodes 110 and 120 adjacent to each other in one direction. That is, each intervening portion 132a has a function of insulating the positive electrode 110 from the negative electrode 120. Each intervening portion 132a is composed of a rectangular region.

[0028] Each upper folded portion 132b connects the upper end of one of the plurality of clamping portions 132a to the upper end of a clamping portion 132a adjacent to the one clamping portion 132a on one side in one direction. In the present embodiment, the upper folded portion 132b is disposed above the positive electrode 110.

[0029] Each lower folded portion 132c connects the lower end of one of the plurality of clamping portions 132a to the lower end of a clamping portion 132a adjacent to the one of the plurality of clamping portions 132a on the other side in one direction. In the present embodiment, the lower folded portion 132c is disposed below the negative electrode 120. In other words, the negative electrode 120 is disposed on the lower folded portion 132c.

[0030] The outermost covering portion 132d covers all the upper folded portions 132b and all the lower folded portions 132c. In more detail, the outermost covering portion 132d covers all the electrodes 110, 120, all the sandwiching portions 132a, all the upper folded portions 132b and all the lower folded portions 132c while winding them around a central axis parallel to the width direction. The end 132e of the outermost covering portion 132d is set in a range that does not overlap with the positive electrode active material layer 114 and the negative electrode active material layer 124 in one direction. In the present embodiment, the end 132e of the outermost covering portion 132d is arranged below each electrode 110, 120. In addition, an insulating film (not shown) is coated on the peripheral surface and bottom surface of the plurality of electrodes 110, 120 and the separator 130.

[0031] like Figure 1 and Figure 2 As shown, the case 200 accommodates the electrode body 100. An electrolyte (not shown) is accommodated in the case 200. The case 200 is sealed. The case 200 is made of metal such as aluminum or aluminum alloy.

[0032] Figure 4 This is a perspective view showing a housing in one embodiment of the present disclosure from one side. Figure 5 This is a perspective view showing a housing in one embodiment of the present disclosure from another side. Figure 6 : is a schematic three-dimensional diagram showing the state of each component constituting the housing before being welded. Figure 1 , Figure 2 , Figure 4~Figure 6 As shown, the housing 200 has a bottom 210, a first side surface 221, a second side surface 222, a first end surface 231, a second end surface 232, a third end surface 233, a fourth end surface 234, a first welding portion 251, a second welding portion 252, a plurality of ribs 260 and a cover 270. Figure 4~Figure 6 The cover portion 270 is not shown in the figure.

[0033] The bottom 210 has a flat plate-like shape. The bottom 210 extends in a plane direction perpendicular to the height direction H. When viewed from the height direction H, the bottom 210 has a substantially rectangular shape. The bottom 210 has a pair of long sides 211 and a pair of short sides 212. The length of each of the pair of long sides 211 is longer than the length of each of the pair of short sides 212.

[0034] In the present embodiment, the bottom portion 210 includes a first bottom portion 213, a second bottom portion 214, and a bottom welding portion 215. Alternatively, the bottom portion 210 may be integrally formed without a welding portion.

[0035] The first bottom portion 213 and the second bottom portion 214 are arranged in the thickness direction T of the power storage cell 1. The first bottom portion 213 includes one of the pair of long sides 211 and a portion of each of the pair of short sides 212. The second bottom portion 214 includes the other of the pair of long sides 211 and the other portion of each of the pair of short sides.

[0036] The bottom welding part 215 connects the first bottom part 213 and the second bottom part 214. The bottom welding part 215 is formed by welding the edge of the first bottom part 213 and the edge of the second bottom part 214 to each other (refer to Figure 6 The bottom welding portion 215 extends along the width direction W of the power storage cell 1 .

[0037] The first side surface portion 221 stands up from the bottom portion 210. The direction in which the first side surface portion 221 stands up is the height direction H. Specifically, the first side surface portion 221 stands up from one of the pair of long sides 211. In this embodiment, the first side surface portion 221 and the bottom portion 210 are not welded but formed integrally. The first side surface portion 221 and the bottom portion 210 may also be connected to each other by welding.

[0038] The second side surface portion 222 is opposite to the first side surface portion 221 and rises from the bottom 210. Therefore, the direction in which the second side surface portion 222 rises is also the height direction H. Specifically, the second side surface portion 222 rises from the other of the pair of long sides 211. In this embodiment, the second side surface portion 222 and the bottom 210 are integrally formed without being welded. The second side surface portion 222 and the bottom 210 may also be connected to each other by welding.

[0039] The first end surface portion 231 extends from the first side surface portion 221 in a direction from the first side surface portion 221 toward the second side surface portion 222. This direction is one direction in the thickness direction T.

[0040] In this embodiment, the first end surface portion 231 rises from the bottom portion 210. Specifically, the first end surface portion 231 rises from one of the pair of short sides 212. The first end surface portion 231 rises from the first bottom portion 213. The first end surface portion 231 and the first bottom portion 213 are integrally formed without welding. The first end surface portion 231 and the first bottom portion 213 may also be connected to each other by welding.

[0041] The second end surface portion 232 extends from the second side surface portion 222 in a direction from the second side surface portion 222 toward the first side surface portion 221 . This direction is the other direction of the thickness direction T.

[0042] In this embodiment, the second end surface portion 232 rises from the bottom portion 210. Specifically, the second end surface portion 232 rises from one of the pair of short sides 212. The second end surface portion 232 rises from the second bottom portion 214. The second end surface portion 232 and the second bottom portion 214 are integrally formed without welding. The second end surface portion 232 and the second bottom portion 214 may also be connected to each other by welding.

[0043] The third end surface portion 233 extends from the first side surface portion 221 in a direction from the first side surface portion 221 toward the second side surface portion 222 . This direction is one direction in the thickness direction T. The third end surface portion 233 is opposite to the first end surface portion 231 in the width direction W.

[0044] In this embodiment, the third end surface portion 233 rises from the bottom portion 210. Specifically, the third end surface portion 233 rises from the other of the pair of short sides 212. The third end surface portion 233 rises from the first bottom portion 213. The third end surface portion 233 and the first bottom portion 213 are integrally formed without welding. The third end surface portion 233 and the first bottom portion 213 may also be connected to each other by welding.

[0045] The fourth end surface portion 234 extends from the second side surface portion 222 in a direction from the second side surface portion 222 toward the first side surface portion 221 . This direction is the other direction in the thickness direction T. The fourth end surface portion 234 is opposite to the second end surface portion 232 in the width direction W.

[0046] In this embodiment, the fourth end surface portion 234 rises from the bottom portion 210. Specifically, the fourth end surface portion 234 rises from the other of the pair of short sides 212. The fourth end surface portion 234 rises from the second bottom portion 214. The fourth end surface portion 234 and the second bottom portion 214 are integrally formed without being welded. The fourth end surface portion 234 and the second bottom portion 214 may also be connected to each other by welding.

[0047] In the housing 200, the first side surface 221 and the first end surface 231 form a first corner 241. The second side surface 222 and the second end surface 232 form a second corner 242. The first side surface 221 and the third end surface 233 form a third corner 243. The second side surface 222 and the fourth end surface 234 form a fourth corner 244. These corners are rounded.

[0048] The first welding portion 251 connects the first end surface portion 231 and the second end surface portion 232. The first welding portion 251 is formed by welding the edge of the first end surface portion 231 and the edge of the second end surface portion 232 to each other (see Figure 6 ). The first welding portion 251 extends along the height direction H. The first welding portion 251 is connected to the bottom welding portion 215 .

[0049] The second welding portion 252 connects the third end surface portion 233 and the fourth end surface portion 234. The second welding portion 252 is formed by welding the edge of the third end surface portion 233 and the edge of the fourth end surface portion 234 to each other (see Figure 6 ). The second welding portion 252 extends along the height direction H. The second welding portion 252 is connected to the bottom welding portion 215 .

[0050] The plurality of ribs 260 are respectively provided at the first corner 241, the second corner 242, the third corner 243 and the fourth corner 244. The plurality of ribs 260 extend respectively in the height direction H. The plurality of ribs 260 respectively include inner ribs 261. The plurality of inner ribs 261 protrude from the first corner 241, the second corner 242, the third corner 243 and the fourth corner 244 to the inner side of the housing 200. The plurality of ribs 260 respectively include outer ribs 262. The plurality of outer ribs 262 protrude from the first corner 241, the second corner 242, the third corner 243 and the fourth corner 244 to the outer side of the housing 200.

[0051] The rib 260 may have other shapes. For example, the rib 260 may be configured such that the thickness (the length of the rib 260 in the protruding direction) gradually decreases as it approaches the bottom 210. The rib 260 may also have a cylindrical shape having an axial direction along the height direction H.

[0052] The housing 200 further includes a plurality of bottom ribs 265. The plurality of bottom ribs 265 are provided on the pair of long sides 211. The plurality of bottom ribs 265 may be connected to the rib 260 at both ends in the width direction W, respectively.

[0053] The cover 270 closes the open end 280 (see Figure 1 and Figure 2 ). In the housing 200, the opening end 280 is located on the side opposite to the bottom 210. The opening end 280 is formed by the end edges of the first side surface portion 221, the second side surface portion 222, the first end surface portion 231, the second end surface portion 232, the third end surface portion 233, and the fourth end surface portion 234. The cover portion 270 is connected to the opening portion by welding or the like. The cover portion 270 is formed in a flat plate shape.

[0054] The cover 270 is supported by the plurality of ribs 260 (inner ribs 261 ). Specifically, the cover 270 is supported by the plurality of ribs 260 (inner ribs 261 ) via the lower insulating portion 520 described later. The cover 270 may be directly supported by the plurality of ribs 260 (inner ribs 261 ).

[0055] The cover 270 includes a pressure relief valve 272 and a sealing member 274. The pressure relief valve 272 is formed in the center of the cover 270. The pressure relief valve 272 is formed to break when the internal pressure of the housing 200 becomes equal to or higher than a predetermined pressure. The internal pressure of the housing 200 is reduced by the rupture of the pressure relief valve 272. Since the gas in the housing 200 is released to the outside of the housing 200 through the pressure relief valve 272, the internal pressure of the housing 200 is reduced.

[0056] The sealing member 274 seals the liquid injection port h formed in the cover 270. The liquid injection port h is a through hole in the manufacturing process of the power storage unit 1. The through hole is provided for injecting the electrolyte into the housing 200. The liquid injection port h is sealed by the sealing member 274. The liquid injection port h is sealed after the electrolyte is injected into the housing 200. The electrolyte is injected through the liquid injection port h.

[0057] A pair of external terminals 300 are fixed to the housing 200. One of the pair of external terminals 300 is a positive external terminal. The other of the pair of external terminals 300 is a negative external terminal. Each external terminal 300 is fixed to the upper surface of the cover 270 via an upper insulating portion 510 described later. Each external terminal 300 is made of metal such as aluminum.

[0058] A pair of connecting members 400 connects a plurality of electrode tabs 112p, 122n and an external terminal 300. One connecting member 400 connects a plurality of positive electrode tabs 112p and a positive external terminal 300. Another connecting member 400 connects a plurality of negative electrode tabs 122n and a negative external terminal 300. The pair of connecting members 400 each have substantially the same structure as each other. Therefore, one connecting member 400 will be described below.

[0059] The connecting member 400 includes a current collector tab 410 , a secondary tab 420 , and a connecting pin 430 .

[0060] The current collector tab 410 has a side portion 412 and an upper portion 414. The side portion 412 is located on the side of the electrode body 100 in the width direction. The upper portion 414 is located above the electrode body 100. The upper portion 414 extends from the upper end of the side portion 412 toward the inner side in the width direction.

[0061] The auxiliary tab 420 connects the plurality of positive tabs 112p to the collector tab 410. One end 422 of the auxiliary tab 420 is connected to the plurality of positive tabs 112p by welding or the like. The other end 424 of the auxiliary tab 420 is connected to the side portion 412 of the collector tab 410 by welding or the like.

[0062] The connecting pin 430 connects the collector tab 410 and the external terminal 300. The connecting pin 430 connects the upper portion 414 and the external terminal 300. Specifically, the lower end of the connecting pin 430 is connected to the upper portion 414 by welding or the like. The lower end of the connecting pin 430 is connected to the upper portion 414 in a state of being inserted into a through hole provided in the upper portion 414. The upper end of the connecting pin 430 is connected to the external terminal 300 by welding, riveting or the like. The upper end of the connecting pin 430 is connected to the external terminal 300 in a state of being inserted into a through hole provided in the external terminal 300.

[0063] The insulating member 500 insulates the housing 200 from the connecting member 400. The insulating member 500 includes an upper insulating portion 510, a lower insulating portion 520, an insulating tube 530, and an insulating plate 540.

[0064] The upper insulating portion 510 is fixed to the upper surface of the cover portion 270. The upper insulating portion 510 is disposed between the cover portion 270 and the external terminal 300. The upper insulating portion 510 is provided with an insertion hole through which the coupling pin 430 is inserted.

[0065] The lower insulating portion 520 is fixed to the lower surface of the cover portion 270. The lower insulating portion 520 is disposed between the cover portion 270 and the upper portion 414 and the lower portion of the connecting pin 430. The lower insulating portion 520 is provided with an insertion hole through which the connecting pin 430 is inserted.

[0066] The insulation tube 530 is disposed between the connection pin 430 and the cover portion 270. The insulation tube 530 is formed in a cylindrical shape and surrounds the connection pin 430.

[0067] The insulating plate 540 is fixed to the lower surface of the upper portion 414. The insulating plate 540 is disposed above the electrode body 100. Through holes are provided in the insulating plate 540 at a portion located below the pressure release valve 272 and at a portion located below the liquid injection port h.

[0068] In addition, the insulating member 500 that insulates one of the pair of connecting members 400 from the housing 200 may not have the upper insulating portion 510. The above-mentioned connecting member 400 may also be, for example, a connecting member 400 that is electrically connected to the positive electrode tab 112p. In this case, the external terminal 300 may also be in direct contact with the housing 200. Other conductive members may also be arranged between the external terminal 300 and the housing 200 instead of the upper insulating portion 510.

[0069] As described above, in the power storage cell 1 according to one embodiment of the present disclosure, the rib 260 is provided at the first corner portion 241 formed by the first side surface portion 221 and the first end surface portion 231 .

[0070] According to the above structure, the rigidity of the first corner portion 241 is increased by the rib 260. As a result, when the first end surface portion 231 and the second end surface portion 232 are welded to form a welded portion, the first side surface portion 221 can be suppressed from being deformed due to the deformation of the welded first end surface portion 231. Therefore, it is possible to provide a storage battery cell 1 in which the deformation of the housing 200 caused by the welding of the end surface is suppressed. In addition, the housing 200 is enlarged. Alternatively, if the housing 200 is further lengthened in the width direction W, the welding deformation when forming the first welded portion 251 becomes larger. However, the above-mentioned rib 260 can effectively suppress the welding deformation.

[0071] In the power storage unit 1 according to the embodiment of the present disclosure, the first welded portion 251 extends in the height direction H, which is the direction in which the first side surface portion 221 stands. The rib 260 extends in the height direction H.

[0072] According to the above structure, the rigidity of the first corner portion 241 can be further improved by the rib 260. When the first end surface portion 231 and the second end surface portion 232 are welded along the height direction H, the first side surface portion 221 can be effectively suppressed from being deformed due to the deformation of the welded first end surface portion 231. Therefore, the storage cell 1 can be provided in which the deformation of the housing 200 caused by the welding of the end surface is further suppressed.

[0073] In the power storage unit 1 according to the embodiment of the present disclosure, the rib 260 protrudes from the first corner portion 241 toward the inside of the case 200 .

[0074] According to the above structure, it is possible to improve the rigidity of the first corner portion 241 while suppressing the enlargement of the housing 200 .

[0075] In the power storage unit 1 according to the embodiment of the present disclosure, the rib 260 protrudes from the first corner portion 241 to the outside of the case 200 .

[0076] According to the above structure, it is possible to improve the rigidity of the first corner portion 241 while suppressing the accommodating space of the housing 200 from being reduced.

[0077] Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims, and it is intended to include all changes within the meaning and scope equivalent to the claims.

Claims

1. A power storage unit comprising: an electrode body; and a shell, accommodating the electrode body, The housing has: bottom; A first side portion, standing from the bottom portion; a second side surface portion, opposite to the first side surface portion and standing from the bottom portion; a first end surface portion extending from the first side surface portion along a direction from the first side surface portion toward the second side surface portion; a second end surface portion extending from the second side surface portion along a direction from the second side surface portion toward the first side surface portion; a welding portion connecting the first end surface portion and the second end surface portion; and The rib is provided at a corner portion formed by the first side surface portion and the first end surface portion.

2. The power storage unit according to claim 1, in, The welding portion extends along a height direction which is a direction in which the first side surface portion stands. The ribs extend along the height direction.

3. The power storage unit according to claim 1 or claim 2, in, The rib protrudes from the corner toward the inner side of the housing.

4. The power storage unit according to claim 1 or claim 2, in, The rib protrudes from the corner toward the outside of the housing.

5. The power storage unit according to claim 1, in, The welding portion extends along a height direction which is a direction in which the first side surface portion stands. The ribs extend along the height direction, The rib protrudes from the corner portion toward both the inside and the outside of the housing.

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