Power storage device

Abstract

A power storage device capable of improving vibration resistance is obtained. [Solution] The energy storage device 10 includes a lower-layer battery stack group 26, an upper-layer battery stack group 24, and a frame member 32, and is arranged such that the longitudinal direction of the battery stacks 14 that make up the lower-layer battery stack group 26 intersects with the longitudinal direction of the battery stacks 12 that make up the upper-layer battery stack group 24. This makes it possible to change and offset the directions in which the vibration resistance of the lower-layer battery stack group 26 and the upper-layer battery stack group 24 weakens. As a result, it is possible to improve the vibration resistance of the energy storage device 10 and suppress the effects of resonance.

Description

[Technical Field]

[0001] The present disclosure relates to an electricity storage device. [Background technology]

[0002] The following Patent Document 1 discloses technology related to a battery pack (hereinafter referred to as an "electricity storage device") that holds a battery module (hereinafter referred to as a "battery stack") that houses multiple battery cells. In this prior art, multiple battery stacks are stacked vertically, which makes it possible to increase the battery capacity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-134809 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned prior art, since the same battery stacks are stacked vertically, there are concerns about vibration resistance.

[0005] In consideration of the above, an object of the present invention is to provide an electricity storage device that can improve vibration resistance. [Means for solving the problem]

[0006] The energy storage device according to the first aspect includes a first battery stack group in which first battery stacks, each of which has a substantially rectangular parallelepiped shape and is generally rectangular in plan view, are stacked vertically; a second battery stack group in which second battery stacks, each of which has a substantially rectangular parallelepiped shape and is generally rectangular in plan view, are stacked vertically and are arranged below the first battery stack group with their longitudinal direction intersecting the longitudinal direction of the first battery stack group; and a first frame member arranged between the first battery stack group and the second battery stack group, to which the first battery stack group and the second battery stack group are respectively fixed and which is fixed directly or indirectly to a vehicle frame.

[0007] The energy storage device according to the first aspect includes a first battery stack group, a second battery stack group, and a first frame member. In the first battery stack group, first battery stacks each having a substantially rectangular parallelepiped shape in a plan view are stacked vertically. In the second battery stack group, second battery stacks each having a substantially rectangular parallelepiped shape in a plan view are stacked vertically. The second battery stack group is disposed below the first battery stack group, with its longitudinal direction intersecting the longitudinal direction of the first battery stack group. The first frame member is disposed between the first and second battery stack groups, and the first and second battery stack groups are fixed to the first frame member, which is directly or indirectly fixed to the vehicle frame.

[0008] For example, in a comparative example, when battery stacks each having a substantially rectangular parallelepiped shape in a plan view are stacked vertically with the longitudinal direction of each battery stack being the same, the battery stack has low vibration resistance in the width direction (the short direction perpendicular to the longitudinal direction). Therefore, in the comparative example, there is a concern about the vibration resistance to vibration G in a specific direction.

[0009] In contrast, in this embodiment, the first frame members, which are fixed to the first and second battery stack groups in a state where their longitudinal directions cross, are fixed directly or indirectly to the vehicle frame, making it possible to change the direction in which the vibration resistance of the first and second battery stack groups is weak, thereby balancing the directions in which the vibration resistance is strong and weak and canceling out the weak direction.As a result, this embodiment makes it possible to improve the vibration resistance of the power storage device and suppress the effects of resonance.

[0010] Here, "intersect" means not only completely perpendicular but also so-called nearly perpendicular. Also, "fixed directly or indirectly" means not only a configuration in which the first frame member is directly fixed to the vehicle frame but also a configuration in which it is indirectly fixed via a bracket or the like. Furthermore, examples of the "vehicle frame" include vehicle frames such as a cross member extending in the vehicle width direction and a side member extending in the vehicle longitudinal direction depending on the location where the power storage device is disposed.

[0011] The energy storage device of the second aspect is the energy storage device of the first aspect, wherein in the first battery stack, a plurality of first battery cells are stacked along the longitudinal direction of the first battery stack, and in the second battery stack, a plurality of second battery cells are stacked along the longitudinal direction of the second battery stack.

[0012] In the energy storage device according to the second aspect, the first battery stack has a plurality of first battery cells stacked along the longitudinal direction of the first battery stack, and the second battery stack has a plurality of second battery cells stacked along the longitudinal direction of the second battery stack, i.e., the direction along the stacking direction of the first battery cells and the second battery cells is the longitudinal direction of the first battery stack and the second battery stack.

[0013] Generally, when battery cells are stacked along the width direction perpendicular to the longitudinal direction of the battery stack, that is, when the longitudinal direction of the battery stack and the longitudinal direction of the battery cells are the same, the battery stack is prone to bending at approximately the center in the longitudinal direction. In this aspect, the first battery cell and the second battery cell are stacked along the longitudinal directions of the first battery stack and the second battery stack, respectively, making it possible to suppress bending at approximately the center in the longitudinal direction of the first battery stack and the second battery stack.

[0014] The first battery cell and the second battery cell may be battery cells having the same configuration, or may be battery cells having different configurations.

[0015] The energy storage device according to the third aspect is the energy storage device according to the first or second aspect, wherein an upper layer battery stack group made up of the first battery stack group is arranged along the vehicle width direction, and a lower layer battery stack group made up of the second battery stack group is arranged along the vehicle width direction, and a plurality of the second battery stack groups are arranged so that the projected dimensions of the lower layer battery stack group are larger than the projected dimensions of the upper layer battery stack group.

[0016] In a power storage device according to a third aspect, an upper layer battery stack group made up of a first battery stack group is arranged along the vehicle width direction, and a lower layer battery stack group made up of a second battery stack group is arranged along the vehicle width direction, and a plurality of second battery stack groups are arranged in the lower layer battery stack group so that the projected dimensions of the lower layer battery stack group are larger than the projected dimensions of the upper layer battery stack group.

[0017] In this way, since the lower battery stack group has a larger projected dimension than the upper battery stack group, it is possible to position the center of gravity of the storage device on the lower battery stack side, thereby improving the vibration stability of the storage device.

[0018] The energy storage device according to a fourth aspect is the energy storage device according to any one of the first to third aspects, further comprising a housing case that houses the upper battery stack group and the lower battery stack group, a lower case that forms the bottom wall of the housing case, and second frame members that are fixed to the lower case, are arranged between the second battery stack groups, and are respectively fixed to the second battery stack groups.

[0019] A fourth aspect of the present invention provides an energy storage device including a housing case that houses an upper battery stack group and a lower battery stack group. A second frame member is fixed to a lower case that forms a bottom wall of the housing case. The second frame member is disposed between the second battery stack groups, and the second battery stack groups are fixed to the second frame member.

[0020] In this aspect, the second battery stack groups constituting the lower battery stack group are each fixed to the second frame member fixed to the lower case, which makes it possible to further improve the vibration stability of the power storage device. [Effects of the Invention]

[0021] As described above, the electricity storage device according to the present invention can improve vibration resistance. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic perspective view showing an electricity storage device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating the power storage device shown in FIG. [Figure 3] 2A and 2B are schematic diagrams showing the electricity storage device shown in FIG. 1, in which (A) is a front view of the electricity storage device and (B) is a side view of the electricity storage device. [Figure 4] FIG. 3 is a schematic diagram corresponding to FIG. 2 as a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0023] An electric storage device according to one embodiment of the present invention will be described with reference to the drawings. Note that arrows UP, L, and W shown as appropriate in each drawing indicate the upward direction, longitudinal direction, and width direction, respectively, of a battery stack (first battery stack) 12 and a battery stack (second battery stack) 14 that constitute an electric storage device 10 according to this embodiment. Furthermore, the vehicle to which the electric storage device according to this embodiment is applied is an electric vehicle.

[0024] (Configuration of the power storage device) First, the configuration of the power storage device according to this embodiment will be described.

[0025] As shown in Figures 1 and 2, the power storage device 10 is configured to include a plurality of battery stacks 12 and 14, respectively, and is disposed, for example, on the rear side of a vehicle. Note that Figure 2 is a schematic diagram that shows the power storage device 10 shown in Figure 1. As shown in Figures 1 and 2, the battery stacks 12 and 14 each have a substantially rectangular parallelepiped shape, the battery stack 12 is configured to include a plurality of battery cells (first battery cells) 20, and the battery stack 14 is configured to include a plurality of battery cells (second battery cells) 22.

[0026] The battery cells 20, 22 can be selected from secondary batteries such as lithium ion secondary batteries (including liquid batteries and all-solid-state batteries), lead acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, and cobalt-titanium lithium secondary batteries.

[0027] The battery cells 20, 22 each have a flattened rectangular parallelepiped shape and are stacked along the longitudinal direction of the battery stacks 12, 14. In other words, the longitudinal direction of the battery stacks 12, 14 is the direction along the stacking direction of the battery cells 20, 22. Highly rigid plate-like end plates 15 are provided at both ends of the battery stacks 12, 14 in the longitudinal direction. The battery cells 20 and 22 may have the same configuration or different configurations. For example, the battery cells 20 and 22 may have different external dimensions.

[0028] Here, in this embodiment, the energy storage device 10 is configured to include an upper layer battery stack group 24 that is stacked vertically and arranged on the upper side of the energy storage device 10, and a lower layer battery stack group 26 that is arranged on the lower side of the energy storage device 10.

[0029] The upper battery stack group 24 is configured by stacking a plurality of (here, three) battery stacks 12 in the vertical direction. Each battery stack 12 is arranged so that the stacking direction of the battery cells 20 (direction of arrow A) is the vehicle width direction (direction of arrow W). Vertically adjacent battery stacks 12 are fixed to each other, for example, by holes (not shown) and through bolts 28 formed in end plates 15 provided at both longitudinal ends of the battery stack 12.

[0030] The plurality of battery stacks 12 stacked in the vertical direction in this manner are referred to as a battery stack group (first battery stack group) 16. That is, in this embodiment, the upper layer battery stack group 24 is made up of the battery stack group 16.

[0031] Meanwhile, the lower battery stack group 26 has multiple (here, two) battery stacks 14 stacked vertically. Each battery stack 14 is arranged so that the stacking direction of the battery cells 22 (direction of arrow B) is the vehicle fore-and-aft direction (direction of arrow L). Furthermore, vertically adjacent battery stacks 14 are fixed to each other via holes and through-bolts 30 formed in end plates 15 provided at both ends of the battery stacks 14 in the longitudinal direction, similar to the battery stacks 12.

[0032] The plurality of battery stacks 14 stacked vertically in this manner are referred to as a battery stack group (second battery stack group) 18. In this embodiment, the lower-layer battery stack group 26 has a plurality of battery stack groups 18 arranged (here, two rows) along the vehicle width direction. That is, in this embodiment, the lower-layer battery stack group 26 is made up of two battery stack groups 18.

[0033] 3(A) and 3(B), in this embodiment, the projected dimensions (W1, L1) of the lower battery stack group 26 are set to be larger than the projected dimensions (W2, L2) of the upper battery stack group 26. W1 and W2 are width dimensions along the vehicle width direction, and L1 and L2 are length dimensions along the vehicle front-rear direction.

[0034] Furthermore, in this embodiment, a plate-shaped frame member (first frame member) 32 is provided between the upper battery stack group 24 and the lower battery stack group 26, and the upper battery stack group 24 and the lower battery stack group 26 are each fixed to the frame member 32.

[0035] In this embodiment, the upper battery stack group 24 and the lower battery stack group 26 can be housed within a housing case 34. The housing case 34 is configured to include a lower case 36 and an upper case 38. The lower case 36 is formed in a plate shape, and the upper battery stack group 24 and the lower battery stack group 26 are covered from the outside by the upper case 38, and the frame member 32 is fixed to the upper case 38.

[0036] As an example, the upper case 38 may be fixed to a cross member (vehicle frame) 35 extending along the vehicle width direction on the vehicle rear side of the upper case 38, and the frame member 32 and the upper case 38 may be fastened together to the cross member. Note that this cross member may be a rear cross member that forms part of a rear suspension member.

[0037] Meanwhile, the lower battery stack group 26 is fixed to the lower case 36. A plate-shaped frame member (second frame member) 40 is arranged between the battery stack groups 18 that make up the lower battery stack group 26. The frame member 40 is fixed in a state in which it stands upright relative to the lower case 36 and extends along the fore-and-aft direction of the vehicle, and the tip of the frame member 40 is joined to the frame member 32, for example, by adhesive, welding, or the like.

[0038] (Actions and Effects of the Electricity Storage Device) Next, the operation and effects of the electricity storage device according to this embodiment will be described.

[0039] As shown in FIGS. 1 and 2, in this embodiment, the energy storage device 10 includes an upper layer battery stack group 24, a lower layer battery stack group 26, and a frame member 32.

[0040] The upper-layer battery stack group 24 is configured by stacking battery stacks 12 vertically (battery stack group 16) with the vehicle width direction (arrow W direction) as the longitudinal direction. The lower-layer battery stack group 26 is configured by arranging battery stack groups 18 in two rows along the vehicle width direction, with the vehicle fore-aft direction (arrow L direction) as the longitudinal direction and battery stacks 14 stacked vertically. In other words, in this embodiment, the battery stacks 12 constituting the upper-layer battery stack group 24 and the battery stacks 14 constituting the lower-layer battery stack group 26 are arranged vertically with their longitudinal directions approximately perpendicular (intersecting).

[0041] For example, as a comparative example, in a power storage device 100, when the battery stacks 108 of the lower-layer battery stack group 106 and the battery stacks 104 of the upper-layer battery stack group 102 are stacked vertically with their longitudinal directions aligned as shown in Fig. 4, the vibration resistance in the width direction (the short-side direction perpendicular to the longitudinal direction) of the battery stack 104 is weakened. For this reason, in the comparative example, there are concerns about the vibration resistance to vibration G in a specific direction. In this case, the fixing portion of the lower-layer battery stack group 106 is subjected to stress, and it becomes necessary to increase the fixing strength by increasing the number of fixing points in the fixing portion, for example.

[0042] In contrast, in this embodiment, as described above, the longitudinal direction of the battery stacks 12 constituting the upper-layer battery stack group 24 and the longitudinal direction of the battery stacks 14 constituting the lower-layer battery stack group 26 are arranged substantially perpendicular to each other. This makes it possible to change the direction in which vibration resistance is weak between the upper-layer battery stack group 24 and the lower-layer battery stack group 26, thereby balancing the directions in which vibration resistance is strong and weak, and canceling out the weak directions. As a result, in this embodiment, it is possible to improve the vibration resistance of the energy storage device 10 and suppress the effects of resonance.

[0043] Generally, when battery cells are stacked along a width direction perpendicular to the longitudinal direction of the battery stack, the longitudinal direction of the battery stack and the longitudinal direction of the battery cells are in the same direction, and the approximate center of the longitudinal direction of the battery stack is prone to bending.

[0044] In contrast, in the present embodiment, the battery stack 12 has the battery cells 20 stacked along the longitudinal direction of the battery stack 12, and the battery stack 14 has the battery cells 22 stacked along the longitudinal direction of the battery stack 14. Therefore, in the present embodiment, the longitudinal directions of the battery cells 20 and 22 are different from the longitudinal directions of the battery stack 12 and the battery stack 14, making it possible to suppress bending of the battery stack 12 and the battery stack 14 at approximately the center.

[0045] Furthermore, for example, although not shown, in a battery stack in a so-called double-end fixed state in which both longitudinal ends are fixed, the central portion in the longitudinal direction may bend due to repeated vibrations caused by vehicle travel. In this case, it is conceivable to fix the battery stack at the longitudinal center portion with fastening members such as bolts.

[0046] However, in this embodiment, it is possible to suppress the effects of resonance in the energy storage device 10 in the first place, and therefore it is possible to suppress deformation of the battery stacks 12, 14. Therefore, fastening members for suppressing deformation are not required in the longitudinal center portions of the battery stacks 12, 14. In other words, in this embodiment, it is possible to realize an energy storage device 10 in which multiple battery stacks 12, 14 are stacked using a minimum number of fastening members.

[0047] As a result, in this embodiment, compared to when the longitudinal center of the battery stacks 12, 14 is fixed with fastening members, it is possible to reduce the number of parts, and since there is no need to reserve space for the fastening members, it is possible to improve the volumetric efficiency of the battery cells 20, 22.

[0048] In this embodiment, the battery stack groups 16 in the upper battery stack group 24 are arranged along the vehicle width direction, and the battery stack groups 18 in the lower battery stack group 26 are arranged along the vehicle front-rear direction. In the lower battery stack group 26, multiple battery stack groups 16 are arranged along the vehicle width direction, and as shown in Figures 3(A) and 3(B), the projected dimensions (W1, L1) of the lower battery stack group 26 are set to be larger than the projected dimensions (W2, L2) of the upper battery stack group.

[0049] As described above, in this embodiment, the lower battery stack group 26 has a larger arrangement space than the upper battery stack group 24, so that the center of gravity of the energy storage device 10 can be positioned on the lower battery stack group 26 side, thereby further improving the vibration stability of the energy storage device 10.

[0050] Furthermore, this embodiment includes a housing case 34 that houses the upper battery stack group 24 and the lower battery stack group 26. The bottom wall of the housing case 34 is formed by a lower case 36, and a frame member 40 is fixed to the lower case 36. The frame member 40 is disposed between adjacent battery stack groups 18 that make up the lower battery stack group 26, and each battery stack group 18 is fixed to the frame member 40.

[0051] In this manner, in this embodiment, the plurality of battery stack groups 18 are each fixed to the frame member 40 fixed to the lower case 36, so that the vibration stability of the energy storage device 10 can be further improved.

[0052] (Supplementary information about this embodiment)

[0053] In this embodiment, the energy storage device 10 shown in FIG. 1 is disposed on the rear side of the vehicle, and the upper case 38 (see FIG. 3(A)) of the energy storage device 10 is fixed to a cross member 35 serving as a vehicle frame, and the cross member 35 is described as being a rear cross member of a rear suspension member. However, the vehicle frame is not limited to this. For example, it may be a rear side member, rocker, or the like extending in the fore-and-aft direction of the vehicle. In this case, both ends of the energy storage device 10 in the vehicle width direction are fixed. Furthermore, the energy storage device 10 is not limited to being disposed on the rear side of the vehicle, but may also be disposed on the front side of the vehicle.

[0054] In addition, in this embodiment, the upper case 38 is configured to externally cover the upper battery stack group 24, the lower battery stack group 26, and the frame member 32, but this is not limited to this. For example, the upper case 38 may be configured to be divided into upper and lower parts by the frame member 32. Furthermore, the frame member 32 may form a floor panel, with the upper battery stack group 24 provided above the floor panel and the lower battery stack group 26 provided below the floor panel.

[0055] Furthermore, in this embodiment, the upper battery stack group 24 is made up of one battery stack group 16, and the battery stack group 16 is made up of three battery stacks 12 stacked in the vertical direction. Also, the lower battery stack group 26 is made up of two battery stack groups 18 lined up in the vehicle width direction, and the battery stack group 18 is made up of two battery stacks 14 stacked in the vertical direction.

[0056] However, in this embodiment, the number of battery stacks 12 and 14 is not particularly limited as long as they are arranged such that the longitudinal direction of the battery stacks 12 and the longitudinal direction of the battery stacks 14 are substantially perpendicular to each other. For example, the battery stack group 16 may be composed of two battery stacks 12 stacked in the vertical direction, and the battery stack group 18 may be composed of three battery stacks 14 stacked in the vertical direction.

[0057] Also, for example, the battery stack groups 16 may be arranged along the vehicle longitudinal direction in the upper battery stack group 24, and the battery stack groups 18 may be arranged along the vehicle width direction in the lower battery stack group 26. Furthermore, a plurality of battery stack groups 16 may be arranged along the vehicle longitudinal direction in the upper battery stack group 24, and three or more battery stack groups 18 may be arranged along the vehicle width direction in the lower battery stack group 26.

[0058] Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment may be appropriately combined with various modified examples, and the present invention may of course be embodied in various forms as long as it does not deviate from the gist of the present invention. [Explanation of symbols]

[0059] 10. Energy storage device 12 Battery stack (first battery stack) 14 Battery stack (second battery stack) 16 Battery Stack Group (1st Battery Stack Group) 18 Battery Stack Group (Second Battery Stack Group) 20 battery cells (first battery cell) 22 Battery cell (second battery cell) 24 Upper battery stacks 26 Lower Battery Stacks 32 Frame member (first frame member) 34 Storage Case 35 Cross member (vehicle frame) 36 Lower case 38 Upper Case 40 Frame member (second frame member)

Claims

1. a first battery stack group in which first battery stacks each having a substantially rectangular parallelepiped shape that is substantially rectangular in plan view are stacked in a vertical direction; a second battery stack group in which a second battery stack having a substantially rectangular parallelepiped shape that is substantially rectangular in a plan view is stacked in a vertical direction and is disposed below the first battery stack group with its longitudinal direction intersecting the longitudinal direction of the first battery stack group; a first frame member disposed between the first battery stack group and the second battery stack group, to which the first battery stack group and the second battery stack group are respectively fixed, and which is fixed directly or indirectly to a vehicle frame; A power storage device comprising:

2. 2. The energy storage device according to claim 1, wherein in the first battery stack, a plurality of first battery cells are stacked along a longitudinal direction of the first battery stack, and in the second battery stack, a plurality of second battery cells are stacked along a longitudinal direction of the second battery stack.

3. 2. The energy storage device according to claim 1, wherein an upper layer battery stack group made up of the first battery stack group is arranged along the vehicle width direction, and a lower layer battery stack group made up of the second battery stack group is arranged along the vehicle width direction, and a plurality of the second battery stack groups are arranged so that the projected dimensions of the lower layer battery stack group are larger than the projected dimensions of the upper layer battery stack group.

4. a housing case that houses the upper layer battery stack group and the lower layer battery stack group; a lower case that constitutes a bottom wall portion of the storage case; a second frame member fixed to the lower case, disposed between the second battery stack groups, and to which the second battery stack groups are respectively fixed; The electricity storage device according to claim 3 , further comprising:

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