Battery pack

Abstract

To provide a case having excellent strength even not comprising a conventional intervening member.SOLUTION: A case according to the present disclosure comprises a lower case for housing at least one battery cell group, and at least one reinforcing plate for reinforcing the lower case. The lower case is a die-cast molded body. The lower case includes a bottom wall portion and at least one surrounding wall portion standing upward from the bottom wall portion and surrounding each of the at least one battery cell group. The at least one reinforcing plate is arranged in such a manner that it partitions a housing area surrounded by the surrounding wall portion in a lamination direction of a plurality of battery cells included in the battery cell group.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a case and a battery pack.

Background Art

[0002] Patent Document 1 discloses an in-vehicle battery pack (hereinafter also referred to as a "battery pack") mounted in a vehicle luggage compartment. The battery pack disclosed in Patent Document 1 includes a battery stack, an intake member, a casing, and an intervening member. The battery stack includes a battery group (hereinafter also referred to as a "battery cell group") in which a plurality of battery cells are stacked in the vehicle width direction with a spacer member sandwiched between each battery cell, and a restraint band that holds the lower surface of the spacer member and restrains the plurality of battery cells in the vehicle width direction. The intake member supplies cooling air to a cooling passage formed between each battery cell by the spacer member. The intake member is disposed below the battery stack. The casing houses the battery stack and the intake member. The casing includes at least a pair of side walls disposed on both sides of the battery stack along the vehicle width direction of the battery cell, a bottom portion fixed to each lower portion of the pair of side walls, and a ceiling portion fixed to an upper portion of the pair of side walls. In the casing, both ends of the battery stack in the vehicle width direction are fixed to the bottom portion. The intervening member is disposed between the battery stack and the intake member and between the restraint band and the side wall, and is integrally formed with the intake member. The intervening member includes a front intervening member and a rear intervening member. The front intervening member is provided in a central region in the vehicle front direction and the vehicle width direction of the intake member. The front intervening member extends so as to be closer to the side wall of the casing than the side surface of the battery stack in the vehicle front direction. The rear intervening member is provided in a central region in at least the vehicle rear direction and the vehicle width direction of the intake member. The rear intervening member extends so as to be closer to the side wall of the casing than the side surface of the battery stack in the vehicle rear direction. The length of the rear intervening member in the vehicle width direction is longer than the length of the front intervening member in the vehicle width direction.

[0003] In the battery pack disclosed in Patent Document 1, when an inertial force acts on the front side wall of the casing, the rear intervening member is sandwiched between the restraint band on the rear side of the vehicle and the rear side wall of the casing. As a result, the battery stack collides with the rear side wall 52 of the casing. Consequently, the occurrence of damage to the battery cells 18 is suppressed. When an inertial force acts on the rear side wall of the casing, the front intervening member is sandwiched between the restraint band on the front side of the vehicle and the front side wall of the casing. As a result, the battery stack collides with the front side wall of the casing. Consequently, the occurrence of damage to the battery cells is suppressed. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-83524 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the battery pack disclosed in Patent Document 1, space must be secured in the casing for intervening members (i.e., a front intervening member and a rear intervening member) in the front-to-rear direction perpendicular to the vehicle width direction (i.e., the stacking direction of the multiple battery cells). Therefore, there is a need for a case that is superior in strength even without conventional intervening members.

[0006] This disclosure is made in light of the circumstances described above. One embodiment of this disclosure aims to solve the problem of providing a case and battery pack that are superior in strength even without conventional intervening members. [Means for solving the problem]

[0007] The following embodiments are included as means for solving the above problems.

[0008] <1> A case according to a first aspect of the present disclosure comprises a lower case for housing at least one group of battery cells, and at least one reinforcing plate for reinforcing the lower case, wherein the lower case is a die-cast molded body, and the lower case has a bottom wall portion and at least one enclosure wall portion erected above the bottom wall portion and surrounding each of the at least one group of battery cells, and the at least one reinforcing plate is arranged to partition the housing area enclosed by the enclosure wall portion in the stacking direction of the plurality of battery cells included in the group of battery cells.

[0009] In this disclosure, "die-cast molded body" refers to a molded body formed by injecting molten metal into a mold. "Housing area" refers to an area for housing a group of battery cells.

[0010] In the first embodiment, at least one reinforcing plate is positioned to partition the housing area enclosed by the enclosure wall in the stacking direction of the multiple battery cells included in the battery cell group. In other words, at least one reinforcing plate reinforces a pair of wall portions (hereinafter also referred to as the "pair of side wall portions") of the enclosure wall portion that face each other in the lateral direction perpendicular to the stacking direction. As a result, when an external impact force (for example, the impact force during a vehicle collision) acts on the enclosure wall portion of the lower case in the lateral direction, the displacement (i.e., deflection) of the pair of side wall portions is suppressed by at least one reinforcing plate. Therefore, the lower case, which is a die-cast molded body, is less prone to cracking. Consequently, the case of the first embodiment has superior strength even without conventional intervening members.

[0011] <2> In the case of a second aspect of this disclosure, the at least one reinforcing plate is located in the center of the accommodation area in the stacking direction, <1> This is the case described in [the relevant section].

[0012] In the second embodiment, when an external force acts on the enclosure wall of the lower case in the lateral direction, the displacement of the pair of side walls is efficiently suppressed by at least one reinforcing plate. As a result, the case in the second embodiment has superior strength.

[0013] <3> In the case of a third aspect of this disclosure, the reinforcing plate includes a metal plate, <1> or <2> This is the case described in [the relevant section].

[0014] In the third embodiment, the reinforcing plate provides superior mechanical strength compared to the case without a metal plate. Therefore, when an external force acts on the enclosure wall of the lower case, at least one reinforcing plate further suppresses the displacement of the pair of side walls. As a result, the case in the third embodiment has superior strength.

[0015] <4> The battery pack according to the fourth aspect of this disclosure is the same as <1> ~ <3> A battery pack comprising a case as described in any one of the above, and the at least one group of battery cells housed in the case, wherein the group of battery cells includes a plurality of battery cells stacked along the stacking direction, and the at least one reinforcing plate is interposed between adjacent battery cells among the plurality of battery cells.

[0016] In the fourth embodiment, the case is highly durable. That is, the case is less likely to break when external force is applied. Therefore, the multiple battery cells housed in the battery pack are less likely to be damaged. As a result, the battery pack of the fourth embodiment can protect at least one group of battery cells housed within it.

[0017] <5> A fifth aspect of the present disclosure further comprises a pair of end plates facing each other in the stacking direction, and fastening members for fastening the pair of end plates together, wherein the group of battery cells and the at least one reinforcing plate are sandwiched between the pair of end plates, <4> This is the battery pack described in [the document / page].

[0018] The battery pack of the fifth embodiment can more reliably protect at least one group of battery cells that it houses. [Effects of the Invention]

[0019] According to this disclosure, a case and battery pack with superior strength are provided, even without conventional intervening members.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a schematic exploded perspective view of a battery pack according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a top view of the battery pack according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic view of an electric four-wheel vehicle equipped with the battery pack according to the first embodiment of the present disclosure. [Figure 4] FIG. 4 is a top view of a case of a comparative example of the present disclosure. [Figure 5] FIG. 5 is a top view of the battery pack according to the second embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0021] In the present disclosure, a numerical range indicated using “~” means a range including the numerical values described before and after “~” as the minimum value and the maximum value, respectively. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0022] Hereinafter, embodiments of the power storage device of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and the description thereof will not be repeated.

[0023] (1) First Embodiment (1.1) Battery Pack As shown in FIG. 1, the battery pack 1A according to the first embodiment includes a case 10A and two battery stacks 20. The two battery stacks 20 are housed in the case 10A. The case 10A has a lower case 11. The lower case 11 is a rectangular parallelepiped that opens upward.

[0024] In the first embodiment, one side of the lower case 11 in the short direction is defined as the positive X-axis direction (hereinafter also referred to as "front"), and the opposite side is defined as the negative X-axis direction (hereinafter also referred to as "rear"). One side of the lower case 11 in the long direction is defined as the positive Y-axis direction (hereinafter also referred to as "right"), and the opposite side is defined as the negative Y-axis direction (hereinafter also referred to as "left"). One side in the direction of gravity is defined as the negative Z-axis direction (hereinafter also referred to as "down"), and the opposite side is defined as the positive Z-axis direction (hereinafter also referred to as "up"). The X-axis, Y-axis, and Z-axis are all orthogonal to each other. The Y-axis direction is an example of the stacking direction. Note that these directions do not limit the orientation of the battery pack when it is used.

[0025] (1.1.1) Case Case 10A comprises a lower case 11 for housing two battery stacks 20 and two metal plates 12. Each of the two metal plates 12 is sandwiched between each of the two battery stacks 20. The metal plates 12 are examples of reinforcing plates.

[0026] (1.1.1.2) Lower case The lower case 11 is a die-cast molded body. The lower case 11 has a bottom wall 111 and two enclosing wall sections 112. The two enclosing wall sections 112 are erected upward (in the negative X-axis direction) from the bottom wall section 111. One enclosing wall section 112 surrounds one battery stack 20. The enclosing wall section 112 consists of a front wall section 1121, a rear wall section 1122, a right wall section 1123, and a left wall section 1124. Each of the front wall section 1121, rear wall section 1122, right wall section 1123, and left wall section 1124 is a flat plate-like object and extends upward (in the negative X-axis direction) from the bottom wall section 111. The length of the enclosing wall section 112 in the vertical direction (in the Z-axis direction) is the same as or longer than the length of the battery stack 20 in the vertical direction (in the Z-axis direction). The bottom wall 111 and the two surrounding wall sections 112 are integrated into a single unit.

[0027] The material of the lower case 11 is metal. Examples of metals include iron, copper, nickel, gold, silver, platinum, cobalt, zinc, lead, tin, titanium, chromium, aluminum, magnesium, manganese, and their alloys (stainless steel, brass, phosphor bronze, etc.). In particular, from the viewpoint of reducing the weight of the lower case 11, the material of the metal is preferably aluminum or an aluminum alloy.

[0028] (1.1.1.3) Metal plate The metal plate 12 reinforces the lower case 11. When the battery stack 20 is housed in the lower case 11, the metal plate 12 partitions the housing area R112 in the left-right direction (Y-axis direction). The housing area R112 is the area enclosed by the enclosure wall 112. More specifically, the metal plate 12 partitions the housing area R112 into two parts: a right area and a left area.

[0029] The metal plate 12 is a flat plate. The battery stack 20 includes a rectangular battery cell 210, which is an example of a battery cell. The length of the metal plate 12 in the front-to-back direction (X-axis direction) may be the same as or longer than the length of the rectangular battery cell 210 in the front-to-back direction (X-axis direction). The length of the metal plate 12 in the up-and-down direction (Z-axis direction) and the left-to-right direction (Y-axis direction) may be appropriately selected according to the size of the case 10A, etc.

[0030] The metal plate 12 is not particularly limited and may be a die-cast body, a roll-formed body, a machined body, a rolled body, a press-formed body, or an extruded body. The material of the metal plate 12 is metal. The metal of the metal plate 12 is not particularly limited and may be the same as that exemplified as the metal of the lower case 11. The material of the metal plate 12 may be the same as or different from the metal of the lower case 11.

[0031] (1.1.2) Battery stack As shown in Figure 1, the battery stack 20 includes a group of battery cells 21, a pair of end plates 22, two fastening members 23, and one metal plate 12. The pair of end plates 22 face each other in the left-right direction (Y-axis direction). The group of battery cells 21 and the metal plate 12 are sandwiched between the pair of end plates 22. The two fastening members 23 fasten the pair of end plates 22 together. As shown in Figure 2, the metal plate 12 is positioned in the center of the housing area R112 in the left-right direction (Y-axis direction). The end plates 22 and fastening members 23 can be any known type.

[0032] (1.1.2.1) Battery cell group The battery cell group 21 includes a plurality of prismatic battery cells 210 and a plurality of resin spacers 211. The plurality of prismatic battery cells 210 are stacked along the left-right direction (Y-axis direction). Each of the plurality of resin spacers 211 is interposed between two adjacent prismatic battery cells 210 among the plurality of prismatic battery cells 210. The metal plate 12 is interposed between adjacent prismatic battery cells 210 among the plurality of prismatic battery cells 210 via the resin spacers 211 so as to be located in the center of the housing area R112 in the left-right direction (Y-axis direction).

[0033] The prismatic battery cell 210 is a battery cell with a prismatic shape. The type of battery cell is not particularly limited and includes primary batteries (e.g., manganese batteries, alkaline manganese batteries, lithium graphite fluoride batteries, lithium manganese dioxide batteries, solid electrolyte batteries, water-filled batteries, thermal batteries, etc.) and secondary batteries (e.g., lithium-ion batteries, lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-iron batteries, silver-zinc oxide batteries, lithium manganese dioxide secondary batteries, lithium cobalt oxide carbonate secondary batteries, lithium vanadium secondary batteries, etc.). The lithium-ion battery may be a lithium-ion battery using a non-aqueous electrolyte or a lithium-ion battery using a solid electrolyte. The number of prismatic battery cells 210 is appropriately selected according to the application of the battery pack 1A.

[0034] The resin spacer 211 electrically insulates adjacent prismatic battery cells 210. The resin spacer 211 may be formed between adjacent prismatic battery cells 210. The resin spacer 211 is a molded resin product. The resin spacer 211 may be an injection-molded product or a press-molded product. The resin of the resin spacer 211 is not particularly limited and may be any known resin.

[0035] (1.2) Purpose The battery pack 1A can be mounted and used in an electric four-wheeled vehicle 100, as shown in Figure 3. The electric four-wheeled vehicle 100 comprises the battery pack 1A, a front seat 110, a rear seat 120, a floor panel 130, and a motor (not shown) for driving force. The battery pack 1A is positioned between the rear seat 120 and the front panel 130. The stacking direction (Y-axis direction) of the multiple prismatic battery cells 210 of the battery pack 1A is parallel to the vehicle width direction (Y-axis direction) of the electric four-wheeled vehicle 100. The battery pack 1A supplies power to the motor. Examples of electric four-wheeled vehicles 100 include electric vehicles (EVs), plug-in hybrid electric vehicles (PHEVs), and hybrid vehicles (HVs).

[0036] (1.3) Effects As explained with reference to Figures 1 to 3, case 10A comprises a lower case 11 and two metal plates 12. The lower case 11 is a die-cast molded body. The lower case 11 has a bottom wall portion 111 and two enclosure wall portions 112. The metal plates 12 are arranged to partition the housing area R112 in the left-right direction (Y-axis direction). Figure 4 shows the behavior of the front wall portion 1121 and the rear wall portion 1122 of a case without a metal plate 12 when an external impact force (for example, the impact force during a collision with an electric four-wheeled vehicle 100) acts on the enclosure wall portion 112 of the lower case 11 in the front-rear direction (X-axis direction). In Figure 4, the dashed lines indicate the deflection of the front wall portion 1121 and the rear wall portion 1122 caused by the external impact force. In case 10A, the metal plate 12 reinforces the front wall 1121 and rear wall 1122 of the enclosure wall 112. As a result, when an external impact force acts on the enclosure wall 112 of the lower case 11 in the front-rear direction (X-axis direction), the displacement L (see Figure 4) of the front wall 1121 and rear wall 1122 is suppressed by the metal plate 12. Therefore, the lower case 11, which is a die-cast molded body, is less prone to cracking. Consequently, case 10A has superior strength even without conventional intervening members.

[0037] As explained with reference to Figures 1 to 3, in case 10A, the metal plate 12 is positioned in the center of the housing area R112 in the left-right direction (Y-axis direction). As a result, when an external force acts on the enclosure wall 112 of the lower case 11 in the front-to-back direction (X-axis direction), the displacement L (see Figure 4) of the front wall 1121 and rear wall 1122 is efficiently suppressed by the metal plate 12. Consequently, case 10A has superior strength.

[0038] As explained with reference to Figures 1 to 3, case 10A includes a metal plate 12. The metal plate 12 has excellent mechanical strength. Therefore, when an external force acts on the enclosure wall 112 of the lower case 11, the displacement L (see Figure 4) of the front wall 1121 and rear wall 1122 is further suppressed by the metal plate 12. As a result, case 10A has superior strength.

[0039] As explained with reference to Figures 1 to 3, the battery pack 1A comprises a case 10A and two battery cell groups 21 housed in the case 10A. Each battery cell group includes a plurality of prismatic battery cells 210. The metal plate 12 is interposed between adjacent prismatic battery cells 210. Case 10A is highly durable. In other words, Case 10A is less likely to break when external force is applied. Therefore, the multiple rectangular battery cells 210 housed in battery pack 1A are less likely to be damaged. As a result, battery pack 1A can protect the two battery cell groups 21 it houses.

[0040] As explained with reference to Figures 1 to 3, the battery pack 1A further comprises a pair of end plates 22 and two fastening members 23. The battery cell group 21 and the metal plate 12 are sandwiched between the pair of end plates 22. Battery pack 1A can more reliably protect the two battery cell groups 21 it houses.

[0041] (2) Second Embodiment The battery pack 1B of the second embodiment of this disclosure is similar to the battery pack 1A of the first embodiment, except that the number of metal plates 12 used is different.

[0042] The battery pack 1B comprises a case 10B and two battery stacks 20. The case 10B comprises a lower case 11 and six metal plates 12. As shown in Figure 3, three of the metal plates 12 are positioned in the center, left, and right portions of the front (positive X-axis) housing area R112 in the left-right direction (Y-axis direction). Three of the metal plates 12 are positioned in the center, left, and right portions of the rear (negative X-axis) housing area R112 in the left-right direction (Y-axis direction).

[0043] As explained with reference to Figure 4, case 10B comprises a lower case 11 and six metal plates 12. The lower case 11 is a die-cast molded body. The lower case 11 has a bottom wall portion 111 and two enclosure wall portions 112. The metal plates 12 are arranged to partition the housing area R112 in the left-right direction (Y-axis direction). As a result, Case 10B has superior strength even without the conventional intervening members.

[0044] (3) Variant In the first and second embodiments, the metal plate 12 is positioned in the center of the housing area R112 in the left-right direction (Y-axis direction), but it does not have to be positioned in the center of the housing area R112 in the left-right direction (Y-axis direction).

[0045] In the first and second embodiments, a metal plate 12 is used as the reinforcing plate, but the reinforcing plate does not have to be a metal plate 12, as long as it is a plate that reinforces the lower case 11. For example, the reinforcing plate may be a laminate of a metal layer and a resin layer, or a plate made of a superhard material (e.g., diamond, cubic boron nitride, etc.).

[0046] In the first and second embodiments, a pair of end plates 22 and fastening members 23 are provided, but a pair of end plates 22 and fastening members 23 are not required. In this case, the battery stack 20 (particularly the metal plate 12) may be attached to cases 10A and 10B. Examples of attachment methods include using fastening components (hereinafter referred to as "mechanical fastening"), welding, hooking, etc. Fastening components include bolts, nuts, screws, rivets, or pins. Welding includes metal welding or brazing.

[0047] In the first and second embodiments, cases 10A and 10B do not have an upper case, but may have an upper case that covers two storage areas R112.

[0048] The number of metal plates 12 and the number of housing areas R112 are selected as appropriate depending on the application of the battery pack. [Explanation of Symbols]

[0049] 1A, 1B: Battery pack, 10A, 10B: Case, 11: Lower case, 12: Metal plate, 18: Battery cell, 20: Battery stack, 21: Battery cell group, 22: End plate, 23: Fastening member, 100: Electric four-wheeled vehicle, 110: Front seat, 111: Bottom wall, 112: Enclosure wall, 120: Rear seat, 130: Front panel, 130: Floor panel, 210: Rectangular battery cell, 211: Resin spacer

Claims

1. A case and The case comprises at least one group of battery cells, A pair of end plates, A fastening member for fastening the pair of end plates together, Equipped with, The aforementioned case is, A lower case for housing the aforementioned group of at least one battery cell, The lower case is reinforced by at least one reinforcing plate, Equipped with, The lower case is a die-cast molded body, The aforementioned lower case, The bottom wall and, At least one enclosure wall portion is erected upward from the bottom wall portion, enclosing each of the at least one battery cell group, It has, The at least one reinforcing plate is positioned such as to partition the housing area enclosed by the enclosure wall in the stacking direction of the plurality of battery cells included in the battery cell group. The reinforcing plate includes a metal plate, The aforementioned enclosure wall is composed of four flat wall sections. The battery cell group includes a plurality of battery cells stacked along the stacking direction, The at least one reinforcing plate is interposed between adjacent battery cells among the plurality of battery cells, The pair of end plates are facing each other in the stacking direction, A battery pack in which the group of battery cells and the at least one reinforcing plate are sandwiched between the pair of end plates.

2. The battery pack according to claim 1, wherein the at least one reinforcing plate is located in the center of the storage area in the stacking direction.

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