Power storage device, lower case, and method for manufacturing lower case

Abstract

To provide a power storage device capable of efficiently manufacturing a lower case and suppressing damage to a bottom wall when a load is applied to a side wall.SOLUTION: A power storage device 1 includes a plurality of power storage cells and a housing. The housing has a lower case 201 and an upper cover. The lower case 201 has a bottom wall 210, a peripheral wall 220 that slopes gradually outward as it separates away from the bottom wall, a bottom rib 240, and a side rib 250. The peripheral wall 220 has a pair of side walls 222 that faces each other. The bottom rib 240 has a shape that extends in an opposing direction in which the pair of side walls 222 faces each other. The side rib 250 extends along a portion of each side wall 222 that intersects with a plane that includes the bottom rib 240. The side rib 250 has an outer surface 250s that slopes gradually outward in the opposing direction as it approaches the bottom wall 210.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power storage device, a lower case, and a method for manufacturing the lower case.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2015-210895 discloses a battery pack module including a plurality of secondary batteries, a housing made of aluminum die-cast for housing the plurality of secondary batteries, and a lid for covering an opening of the housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the housing of the battery pack module described in Japanese Unexamined Patent Application Publication No. 2015-210895 is manufactured by the aluminum die-casting method, in view of the mold release property, the side wall of the housing is designed to have a shape that gradually inclines outward upward from the bottom wall. For this reason, when a load is input from the side to the battery pack module, the load input position becomes the upper end portion of the housing, and there is a concern that the bottom wall may be damaged due to the moment generated by the load.

[0005] An object of the present disclosure is to provide a power storage device, a lower case, and a method for manufacturing the lower case that enable both efficient manufacturing of the lower case and suppression of damage to the bottom wall when a load is input to the side wall.

Means for Solving the Problems

[0006] A power storage device according to an aspect of the present disclosure includes a plurality of power storage cells and a housing that houses the plurality of power storage cells. The housing has a lower case that opens upward and an upper cover that covers the plurality of power storage cells. The lower case has a bottom wall, a peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it separates from the bottom wall, a bottom surface rib provided on the bottom wall, and a side surface rib provided on the peripheral wall. The peripheral wall has a pair of side walls facing each other. The bottom surface rib has a shape extending in a facing direction in which the pair of side walls face each other. The side surface rib extends along a portion intersecting a plane including the bottom surface rib among each of the side walls, and the side surface rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall.

[0007] A lower case according to an aspect of the present disclosure is a lower case that houses at least a lower portion of each of a plurality of power storage cells and opens upward. The lower case has a bottom wall, a peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it separates from the bottom wall, a bottom surface rib provided on the bottom wall, and a side surface rib provided on the peripheral wall. The peripheral wall has a pair of side walls facing each other. The bottom surface rib has a shape extending in a facing direction in which the pair of side walls face each other. The side surface rib extends along a portion intersecting a plane including the bottom surface rib among each of the side walls, and the side surface rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall.

[0008] A method for manufacturing a lower case according to an aspect of the present disclosure is the method for manufacturing the lower case, including: a preparation step of preparing a first mold and a second mold that are capable of contacting and separating from each other and have a space corresponding to the lower case when they are in contact with each other; and a supply step of supplying a material for forming the lower case into the space between the first mold and the second mold. In the preparation step, as the second mold, a mold having a side wall forming portion that forms a portion other than the side surface ribs among the pair of side walls is prepared, and as the first mold, a side surface rib forming portion that forms the side surface ribs is prepared, which is configured to be an inlay with respect to the side wall forming portion, and an inner surface of the side surface rib forming portion corresponds to an outer surface of the side surface rib.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a power storage device, a lower case, and a method for manufacturing a lower case that enable both efficient manufacturing of the lower case and suppression of breakage of the bottom wall when a load is input to the side wall.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0011] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are given the same numbers.

[0012] FIG. 1 is a perspective view schematically showing a power storage device according to an embodiment of the present disclosure. FIG. 2 is a plan view of the power storage device.

[0013] As shown in FIGS. 1 to 8, the power storage device 1 includes a plurality of power storage cells 100 (see FIGS. 5 and 6) and a housing 200.

[0014] The plurality of power storage cells 100 are arranged so as to be aligned along the first direction. Examples of each power storage cell 100 include a lithium ion battery. Each power storage cell 100 may be composed of a so-called all-solid-state battery containing a solid electrolyte. Each power storage cell 100 is formed in a substantially rectangular parallelepiped shape.

[0015] The housing 200 houses a plurality of power storage cells 100. The housing 200 has a lower case 201 and an upper cover 202 (see FIGS. 5 and 6). The lower case 201 houses at least the lower portions of the respective power storage cells 100. The lower case 201 supports the plurality of power storage cells 100. The lower case 201 is open upward. The lower case 201 is made of metal. In the present embodiment, the lower case 201 is made of aluminum. The upper cover 202 covers the plurality of power storage cells 100.

[0016] Hereinafter, the lower case 201 will be described in detail. The lower case 201 has a bottom wall 210, a peripheral wall 220, a partition wall 230, a bottom surface rib 240, a side surface rib 250, a flange 260, and a thick portion 262.

[0017] The bottom wall 210 supports the plurality of power storage cells 100. The bottom wall 210 has a support surface 212 and a recess 214.

[0018] The support surface 212 supports the plurality of power storage cells 100. In the present embodiment, the bottom wall 210 has a pair of support surfaces 212 that support each power storage cell 100. The pair of support surfaces 212 are spaced apart from each other in a second direction orthogonal to both the first direction and the vertical direction. The support surface 212 is formed flat. The support surface 212 extends along the first direction.

[0019] The recess 214 is recessed downward from the support surface 212. The recess 214 is formed between a pair of support surfaces 212 facing each other in the second direction. As shown in FIGS. 5 and 6, a space S is formed below each power storage cell 100. The recess 214 is formed flat. The recess 214 may be used as a cooling air duct for air-cooling each power storage cell 100 or as a smoke exhaust duct that constitutes a discharge path for gas discharged from a safety valve disposed on the lower surface of the power storage cell 100. Further, the recess 214 may be used as a space for disposing battery management devices such as a BMS and an ECU, and electronic devices such as an SMR and a fuse.

[0020] The peripheral wall 220 stands up from the bottom wall 210. The peripheral wall 220 is inclined so as to gradually face outward as it separates from the bottom wall 210. An opening 220h that opens the space S to the outside is formed in one of a pair of wall portions of the peripheral wall 220 that face each other in the first direction.

[0021] The peripheral wall 220 has a pair of side walls 222 that face each other. The pair of side walls 222 face each other in the second direction. Each side wall 222 extends along the first direction, that is, the arrangement direction of the plurality of power storage cells 100.

[0022] The partition wall 230 partitions the space surrounded by the peripheral wall 220. In the present embodiment, the partition wall 230 divides the space surrounded by the peripheral wall 220 into two parts. The partition wall 230 extends along the first direction. The end portion of the partition wall 230 in the first direction is connected to the peripheral wall 220. The partition wall 230 stands up from the bottom wall 210. The lower end portion of the partition wall 230 is connected to the support surface 212.

[0023] The bottom surface rib 240 is provided on the bottom wall 210. The bottom surface rib 240 has a shape that extends in the facing direction (second direction) in which the pair of side walls 222 face each other. In the present embodiment, the lower case 201 has two bottom surface ribs 240 provided at positions spaced apart from each other in the first direction. Each bottom surface rib 240 has a support surface overlapping portion 242 and a recess overlapping portion 244.

[0024] The support surface overlapping portion 242 overlaps with the support surface 212 in the vertical direction. The recess overlapping portion 244 overlaps with the recess 214 in the vertical direction. The lower surface of the support surface overlapping portion 242 is formed flush with the lower surface of the recess overlapping portion 244. As shown in FIGS. 7 and 8, the length H4 of the recess overlapping portion 244 in the vertical direction is smaller than the length H2 of the support surface overlapping portion 242 in the vertical direction. The length L4 of the recess overlapping portion 244 in the orthogonal direction (first direction) orthogonal to both the vertical direction and the opposing direction is larger than the length L2 of the support surface overlapping portion 242 in the orthogonal direction. The volume of the support surface overlapping portion 242 and the volume of the recess overlapping portion 244 may be set to be equal to each other. In FIG. 8, the recess 214 and the recess overlapping portion 244 are shown by a two-dot chain line.

[0025] The side rib 250 is provided on the peripheral wall 220. Specifically, the side rib 250 extends along a portion where it intersects with the plane including the bottom rib 240 among the side walls 222. The side rib 250 is connected to the bottom rib 240. As shown in FIG. 1, the portion of the side wall 222 that overlaps with the side rib 250 protrudes outward in the second direction.

[0026] The side rib 250 has an outer surface 250s having a shape that gradually faces outward in the opposing direction (second direction) as it approaches the bottom wall 210. In the present embodiment, the outer surface 250s is formed flat. However, as long as the outer surface 250s has a shape that gradually faces outward in the opposing direction as it approaches the bottom wall 210, for example, it may be curved so as to protrude outward or inward in the opposing direction, or may be composed of a plurality of flat surfaces intersecting each other.

[0027] The side wall 222 is inclined so as to gradually face outward in the second direction as it goes upward, and since the outer surface 250s of the side rib 250 is inclined so as to gradually face outward in the second direction as it goes downward, the side rib 250 has a shape in which the thickness (length in the second direction) gradually increases as it approaches the bottom wall 210.

[0028] The flange 260 projects outward from the upper end of each side wall 222. In the present embodiment, the flange 260 projects outward from the upper end of the peripheral wall 220. That is, the flange 260 is formed in an annular shape.

[0029] The thick portion 262 is provided on the flange 260. The thick portion 262 has a thickness larger than the thickness of the flange 260. The thick portion 262 receives a fastening member (not shown) for fastening the upper cover 202 to the lower case 201. The thick portion 262 is formed at a position spaced apart from the side rib 250 in the first direction. The outer end portion of the thick portion 262 in the second direction may be located outside the outer end portion of the side rib 250 in the second direction in the second direction.

[0030] The bottom wall 210, the peripheral wall 220, the bottom rib 240, and the side rib 250 are made of the same material (aluminum in the present embodiment) and are continuously connected to each other. More specifically, the bottom wall 210, the peripheral wall 220, the partition wall 230, the bottom rib 240, the side rib 250, the flange 260, and the thick portion 262 are made of the same material and are continuously connected to each other.

[0031] Next, a method for manufacturing the lower case 201 will be described. The lower case 201 is manufactured, for example, by die casting. That is, the lower case 201 is a die-cast case. The manufacturing method of the lower case 201 includes a preparation step and a supply step.

[0032] In the preparation process, the first mold 10 and the second mold 20 used for manufacturing the lower case 201 are prepared. FIGS. 9 and 10 show the first mold 10 and the second mold 20. The first mold 10 and the second mold 20 can contact and separate from each other, and have a space corresponding to the lower case 201 in the state of contacting each other. FIG. 9 shows a cross section of the first mold 10 and the second mold 20 in a plane orthogonal to the first direction and passing through a part forming the thick part 262. FIG. 10 shows a cross section of the first mold 10 and the second mold 20 in a plane orthogonal to the first direction and passing through a part forming the side rib 250.

[0033] As shown in FIG. 9, the second mold 20 has a side wall forming portion 22 that forms a part other than the side rib 250 among the pair of side walls 222.

[0034] As shown in FIG. 10, the first mold 10 has a side rib forming portion 12 that forms the side rib 250. The inner surface 12a of the side rib forming portion 12 corresponds to the outer surface 250s of the side rib 250. The inner surface 12a is inclined so as to gradually separate from each other downward. The side rib forming portion 12 is configured to be an inlay with respect to the side wall forming portion 22.

[0035] In the supply process, a material (aluminum in this embodiment) for forming the lower case 201 is supplied into the space between the first mold 10 and the second mold 20. After the supply process, the lower case 201 is formed by separating the first mold 10 and the second mold 20.

[0036] As described above, in the power storage device 1 according to the present embodiment, the peripheral wall 220 is inclined so as to gradually face outward as it separates from the bottom wall 210, and the side rib 250 has an outer surface 250s having a shape that gradually faces outward in the facing direction (second direction) as it faces the bottom wall 210. Therefore, the lower case 201 can be efficiently manufactured by die casting.

[0037] Also, for example, as shown in FIG. 11, when a load F is applied to the side wall 222 of the lower case 201 that does not have the side rib 250, a bending moment M is generated by the load F, so there is a concern that the recess 214 in the bottom wall 210 may be damaged.

[0038] However, in the present embodiment, the side rib 250 extends along a portion intersecting the plane including the bottom rib 240 among the side walls 222, and the outer surface 250s of the side rib 250 has a shape that gradually faces outward in the opposing direction as it approaches the bottom wall 210. Therefore, as shown in FIG. 12, the load F applied to the side wall 222 is effectively received by the lower end portion of the side rib 250 and the bottom rib 240. That is, in the present embodiment, within the plane including the bottom rib 240 and the side rib 250, a moment caused by the load F applied to the side wall 222 does not substantially occur.

[0039] Also, when the second direction is perpendicular to the first direction (the direction in which the plurality of power storage cells 100 are arranged), since the bottom rib 240 extends in the second direction, it is possible to reduce the input of the load to the power storage cell 100 in the second direction where the allowable range of the input load is relatively small.

[0040] Therefore, in the present embodiment, both efficient manufacturing of the lower case 201 and suppression of damage to the bottom wall 210 when a load is applied to the side wall 222 are achieved.

[0041] Note that, as shown in FIGS. 13 and 14, the pair of side walls 222 face each other in the first direction (the direction in which the plurality of power storage cells 100 are arranged), and the bottom rib 240 may extend along the first direction, that is, the longitudinal direction of the peripheral wall 220.

[0042] Those skilled in the art will understand that the above-described exemplary embodiments and examples are specific examples of the following aspects.

[0043] [Aspect 1] A plurality of power storage cells, A housing that houses the plurality of power storage cells, and the housing is a lower case that opens upward, and an upper cover that covers the plurality of power storage cells, and has the lower case is a bottom wall, and a peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it moves away from the bottom wall, and a bottom surface rib provided on the bottom wall, and a side surface rib provided on the peripheral wall, and has the peripheral wall has a pair of side walls facing each other, and the bottom surface rib has a shape extending in the facing direction in which the pair of side walls face each other, and the side surface rib extends along a portion intersecting a plane including the bottom surface rib among each of the side walls, and the side surface rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall, a power storage device.

[0044] In this power storage device, since the peripheral wall is inclined so as to gradually face outward as it moves away from the bottom wall, and the side surface rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall, it is possible to efficiently manufacture the lower case by die-casting. Furthermore, since the side surface rib extends along a portion intersecting a plane including the bottom surface rib among each of the side walls, the load input to the side wall is effectively supported by the lower end portion of the side surface rib and the bottom surface rib. Therefore, both efficient manufacturing of the lower case and suppression of breakage of the bottom wall when a load is input to the side wall are achieved.

[0045] [Aspect 2] the lower case is a flange that projects outward from the upper end portion of each of the side walls, and a thick portion provided on the flange and having a thickness larger than the thickness of the flange, the power storage device according to Aspect 1.

[0046] In this aspect, since the load input to the side wall due to vibration or the like is received by the thick-walled portion, deformation of the side wall is suppressed.

[0047] [Aspect 3] The power storage device according to aspect 2, wherein the thick-walled portion is formed at a position spaced apart from the side rib.

[0048] In this aspect, compared with the case where the thick-walled portion is provided in the plane including the side rib, the load input to the side wall is more reliably received by the lower end portion of the side rib and the bottom rib, so that the load resistance of the lower case is improved.

[0049] [Aspect 4] The bottom wall has a support surface for supporting the plurality of power storage cells, and a recess recessed downward from the support surface, and the bottom rib has a support surface overlapping portion overlapping the support surface in the vertical direction, and a recess overlapping portion overlapping the recess in the vertical direction, and the length of the recess overlapping portion in the vertical direction is smaller than the length of the support surface overlapping portion in the vertical direction, and the length of the recess overlapping portion in the orthogonal direction orthogonal to both the vertical direction and the facing direction is larger than the length of the support surface overlapping portion in the orthogonal direction. The power storage device according to any one of aspects 1 to 3.

[0050] In this aspect, while an increase in the overall length of the lower case in the vertical direction is suppressed, the load resistance of the lower case is improved.

[0051] [Aspect 5] The power storage device according to aspect 4, wherein the lower surface of the support surface overlapping portion is formed flush with the lower surface of the recess overlapping portion.

[0052] In this aspect, suppression of an increase in the overall length of the lower case in the vertical direction and improvement of the load resistance of the lower case are more reliably achieved.

[0053] [Aspect 6] The power storage device according to any one of Aspects 1 to 5, wherein the side rib is connected to the bottom rib.

[0054] [Aspect 7] The power storage device according to any one of Aspects 1 to 6, wherein the bottom wall, the peripheral wall, the bottom rib, and the side rib are made of the same material and are continuously connected to each other.

[0055] [Aspect 8] The power storage device according to any one of Aspects 1 to 7, wherein the housing is a die-cast case.

[0056] [Aspect 9] A lower case that houses at least the lower portions of a plurality of power storage cells and is open upward, a bottom wall, a peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it moves away from the bottom wall, a bottom rib provided on the bottom wall, a side rib provided on the peripheral wall, and the peripheral wall has a pair of side walls facing each other, the bottom rib has a shape extending in a facing direction in which the pair of side walls face each other, the side rib extends along a portion intersecting a plane including the bottom rib among each of the side walls, the side rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall. A lower case.

[0057] [Aspect 10] A method for manufacturing the lower case according to Aspect 9, a preparation step of preparing a first mold and a second mold that can contact and separate from each other and have a space corresponding to the lower case in a state of contacting each other, a supply step of supplying a material for forming the lower case into the space between the first mold and the second mold. In the preparation step, as the second mold, a mold having a side wall forming portion that forms a portion other than the side ribs among the pair of side walls is prepared, and as the first mold, a side rib forming portion that forms the side ribs is prepared. The side rib forming portion is configured to be an inlay with respect to the side wall forming portion, and the inner surface of the side rib forming portion corresponds to the outer surface of the side rib. A method for manufacturing a lower case.

[0058] It should be noted that the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the above embodiments, and further includes all changes within the meaning and scope equivalent to the claims.

Explanation of Reference Numerals

[0059] 1 Power storage device, 10 First mold, 12 Side rib forming portion, 20 Second mold, 22 Side wall forming portion, 100 Power storage cell, 200 Housing, 201 Lower case, 202 Upper cover, 210 Bottom wall, 212 Support surface, 214 Recess, 220 Peripheral wall, 222 Side wall, 230 Partition wall, 240 Bottom surface rib, 242 Support surface overlapping portion, 244 Recess overlapping portion, 250 Side rib, 250s Outer surface, 260 Flange, 262 Thick portion.

Claims

1. A plurality of power storage cells, and a housing that houses the plurality of power storage cells, wherein the housing has a lower case that opens upward, and an upper cover that covers the plurality of power storage cells, the lower case has a bottom wall, and a peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it moves away from the bottom wall, has a bottom surface rib provided on the bottom wall, and a side surface rib provided on the peripheral wall, the peripheral wall has a pair of side walls facing each other, the bottom surface rib has a shape extending in the facing direction in which the pair of side walls face each other, the side surface rib extends along a portion intersecting a plane including the bottom surface rib among each of the side walls, the side surface rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall, a power storage device.

2. The lower case further has a flange that projects outward from the upper end of each of the side walls, and a thick portion provided on the flange and having a thickness greater than the thickness of the flange, the power storage device according to claim 1.

3. The thick portion is formed at a position separated from the side surface rib, the power storage device according to claim 2.

4. The bottom wall has a support surface that supports the plurality of power storage cells, and a recess that depresses downward from the support surface, the bottom surface rib has a support surface overlapping portion that overlaps the support surface in the vertical direction, and a recess overlapping portion that overlaps the recess in the vertical direction, the length of the recess overlapping portion in the vertical direction is smaller than the length of the support surface overlapping portion in the vertical direction, and the length of the recess overlapping portion in a direction orthogonal to both the vertical direction and the facing direction is greater than the length of the support surface overlapping portion in the orthogonal direction, the power storage device according to claim 1.

5. The lower surface of the support surface overlapping portion is formed flush with the lower surface of the recess overlapping portion, the power storage device according to claim 4.

6. The side surface rib is connected to the bottom surface rib, the power storage device according to claim 1.

7. The bottom wall, the peripheral wall, the bottom surface rib, and the side surface rib are made of the same material as each other and are continuously connected, the power storage device according to claim 1.

8. The housing is a die-cast case, the power storage device according to claim 1.

9. A lower case that houses at least the lower portions of each of the plurality of power storage cells and opens upward, has a bottom wall, A peripheral wall that stands up from the bottom wall and is inclined so as to gradually face outward as it moves away from the bottom wall, A bottom rib provided on the bottom wall, And side ribs provided on the peripheral wall, The peripheral wall has a pair of side walls facing each other, The bottom rib has a shape extending in the facing direction in which the pair of side walls face each other, The side rib extends along a portion intersecting a plane including the bottom rib among each of the side walls, The side rib has an outer surface having a shape that gradually faces outward in the facing direction as it approaches the bottom wall, a lower case.

10. A method for manufacturing the lower case according to claim 9, A preparation step of preparing a first mold and a second mold that can contact and separate from each other and have a space corresponding to the lower case in a state where they are in contact with each other, A supply step of supplying a material for forming the lower case into the space between the first mold and the second mold, In the preparation step, as the second mold, one having a side wall forming portion that forms a portion other than the side rib among the pair of side walls is prepared, and as the first mold, a side rib forming portion that forms the side rib, which is configured to be an inlay with respect to the side wall forming portion, and a method for manufacturing a lower case, wherein an inner surface of the side rib forming portion corresponds to the outer surface of the side rib.

Images