Battery pack

Abstract

To provide a battery pack that enables a uniform restraint surface pressure to be applied to a stacked battery while suppressing increase in weight of a restraint plate, and impact resistance performance to be improved.SOLUTION: A battery pack includes a stacked battery and a pair of restraint plates. The stacked battery includes a plurality of battery cells stacked in a stacking direction parallel to a vehicle up-down direction. The pair of restraint plates has a quadrangular shape when viewed from the stacking direction and pressurize and restrains the stacked battery from both sides of the stacked battery in the stacking direction by a restraint load applied to both ends of each of the restraint plates in a specific direction parallel to one side of the quadrangular shape. At least one of the pair of restraint plates is a specific restraint plate including a first portion and a pair of second portions each having low rigidity against load input in the stacking direction as compared with the first portion. Each of the pair of second portions is disposed along a direction orthogonal to the specific direction. When viewed from the specific direction, the pair of second portions is disposed apart from each other at a location other than a center portion and both end portions of the specific restraint plate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery pack installed in a vehicle. [Background technology]

[0002] Patent Document 1 discloses a battery pack storage mechanism having a structure that absorbs and disperses impact energy during a side collision of a vehicle. This battery pack storage mechanism includes multiple cross members formed to extend in the width direction (left-right direction) of the vehicle, and is fastened to a vehicle body member. The multiple cross members function as partitions for the batteries housed in the battery pack storage mechanism, and also have the function of protecting the multiple batteries during a side collision. In addition, in this battery pack storage mechanism, a battery pack module consisting of multiple battery cells is arranged in each section partitioned by the multiple cross members. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-131486 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is conceivable to configure a battery pack to include a stacked battery including a plurality of battery cells stacked in a stacking direction parallel to the vertical direction of the vehicle, and a pair of restraining plates that have a rectangular shape when viewed from the stacking direction and pressurize and restrain the stacked battery from both sides in the stacking direction with a restraining load acting on both ends in a specific direction parallel to one side of the rectangle. In a battery pack having such a configuration, it is required to apply a uniform restraining surface pressure to the stacked battery by using the pair of restraining plates. In addition, due to the configuration of the battery pack, it is difficult to adopt inside the battery pack the collision prevention structure provided in the battery pack storage mechanism described in Patent Document 1.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a battery pack that can improve impact resistance while enabling the application of more uniform restraining surface pressure to stacked batteries while suppressing an increase in the weight of the restraining plates. [Means for solving the problem]

[0007] The length of the specific restraint plate in the specific direction is referred to as the specific direction length. The center of one of the pair of second parts in the specific direction may be located within a range of plus or minus 10% of the specific direction length centered at a position that is 1 / 4 of the specific direction length from one end of the specific restraint plate in the specific direction. The center of the other of the pair of second parts in the specific direction may be located within a range of plus or minus 10% of the specific direction length centered at a position that is 3 / 4 of the specific direction length from the one end.

[0010] The present disclosure No. 1 The battery pack according to the embodiment includes a stacked battery and a pair of restraining plates. The stacked battery includes a plurality of battery cells stacked in a stacking direction parallel to the vertical direction of the vehicle. The pair of restraining plates have a rectangular shape when viewed from the stacking direction, and pressurize and restrain the stacked battery from both sides in the stacking direction by a restraining load acting on both ends in a specific direction that is a direction parallel to one side of the rectangle. At least one of the pair of restraining plates is a specific restraining plate including a first portion and a pair of second portions having a lower rigidity against input of a load in the stacking direction compared to the first portion. Each of the pair of second portions is disposed along a direction perpendicular to the specific direction. When viewed in the specific direction, the pair of second portions are disposed apart from each other in locations excluding the center and both ends of the specific restraining plate. Each of the pair of second portions is formed using a material having a lower Young's modulus compared to the first portion.

[0011] The present disclosure SecondThe battery pack according to the embodiment includes a stacked battery and a pair of restraining plates. The stacked battery includes a plurality of battery cells stacked in a stacking direction parallel to the vertical direction of the vehicle. The pair of restraining plates has a rectangular shape when viewed from the stacking direction, and pressurizes and restrains the stacked battery from both sides in the stacking direction by a restraining load acting on both ends in a specific direction that is a direction parallel to one side of the rectangle. At least one of the pair of restraining plates is a specific restraining plate including a first portion and a pair of second portions having a lower rigidity against input of a load in the stacking direction compared to the first portion. Each of the pair of second portions is disposed along a direction perpendicular to the specific direction. When viewed in the specific direction, the pair of second portions are disposed apart from each other in places excluding a center portion and both ends of the specific restraining plate. The specific restraining plate includes a plurality of beads extending along the specific direction. Each of the pair of second portions is a portion having a cut formed along a direction perpendicular to the specific direction for at least one of the plurality of beads. Effect of the Invention

[0012] According to the battery pack of the present disclosure, at least one of the pair of constraining plates has a pair of second portions that have a lower rigidity against input of a load in the stacking direction compared to the first portion. This makes it possible to equalize the constraining surface pressure acting on the stacked battery while suppressing an increase in the weight of the constraining plate. Furthermore, by providing the pair of second portions with low rigidity in this manner, it is possible to increase the amount of impact energy absorbed (consumed) by utilizing the deformation of the constraining plate when an impact load acts from one end side in a specific direction. This makes it possible to improve impact resistance performance. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view showing a schematic configuration of a battery pack according to a first embodiment. [Diagram 2] 2 is an exploded perspective view showing an example of the configuration of the stacked battery shown in FIG. 1. FIG. [Diagram 3] 3 is a cross-sectional view that illustrates an example of the structure of the cell stack shown in FIG. 2. [Figure 4]10 is a diagram for explaining a preferable arrangement range R of a pair of second portions according to the present disclosure. FIG. [Diagram 5] 4A to 4C are diagrams illustrating specific configuration examples of a pair of second portions according to the first embodiment. [Figure 6] 5A to 5C are diagrams for explaining the effect of uniforming the restraining surface pressure by the rigidity reducing structure according to the first embodiment. [Figure 7] 5A to 5C are diagrams for explaining the effect of uniforming the restraining surface pressure by the rigidity reducing structure according to the first embodiment. [Figure 8] 5A to 5C are diagrams for explaining the effect of improving impact resistance performance by the rigidity reducing structure according to the first embodiment. [Figure 9] 13A and 13B are diagrams illustrating a specific configuration example of a restraint plate according to a first modified example of the first embodiment. [Figure 10] 13 is a diagram showing a specific configuration example of a restraint plate according to a second modified example of the first embodiment. FIG. [Figure 11] 13A and 13B are diagrams illustrating a specific configuration example of a restraint plate according to a third modified example of the first embodiment. [Figure 12] 13A and 13B are diagrams illustrating a specific configuration example of a restraint plate according to a fourth modified example of the first embodiment. [Figure 13] 13 is a diagram showing a specific configuration example of a restraint plate according to the second embodiment. FIG. [Figure 14] 13 is a diagram showing a specific configuration example of a restraint plate according to the third embodiment. FIG. [Figure 15] 13 is a diagram showing a specific configuration example of a restraint plate according to the fourth embodiment. FIG. [Figure 16] 13 is a diagram showing a specific configuration example of a restraint plate according to a modified example of the fourth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In each embodiment described below, elements common to each drawing are given the same reference numerals, and duplicated descriptions are omitted or simplified. In addition, when the number, quantity, amount, range, etc. of each element is mentioned in the embodiments described below, the technical idea of ​​the present disclosure is not limited to the mentioned number, unless otherwise specified or clearly specified in principle. In addition, the structures, etc. described in the embodiments described below are not necessarily essential to the technical idea of ​​the present disclosure, unless otherwise specified or clearly specified in principle.

[0015] 1. First embodiment 1-1. Overall configuration of the battery pack 1 is a perspective view showing a schematic configuration of a battery pack 10 according to embodiment 1. The battery pack 10 is mounted on a vehicle and supplies power to the vehicle. The battery pack 10 includes a stacked battery 20 and a pair of restraint plates 12 and 14.

[0016] The stacked battery 20 is a stacked body including a plurality of battery cells 34 (see FIG. 3 described below) stacked in a stacking direction D1 parallel to the vertical direction of the vehicle. The stacked battery 20 has a rectangular parallelepiped shape that is thinner in the stacking direction D1 than in the vehicle front-rear direction D2 and the vehicle width direction D3.

[0017] The pair of restraint plates 12 and 14 have a quadrilateral shape (e.g., a rectangular or square shape) when viewed from the stacking direction D1. The restraint plate 12 is disposed above the stacked battery 20, and the restraint plate 14 is disposed below the stacked battery 20. An insulating sheet 16 is interposed between the restraint plate 12 and the stacked battery 20, and between the stacked battery 20 and the restraint plate 14. Instead of the insulating sheet 16, each of the restraint plates 12 and 14 may be coated with an insulating paint.

[0018] The pair of restraint plates 12 and 14 are formed using a metal material such as iron or aluminum. The pair of restraint plates 12 and 14 may also be formed using a fiber-reinforced plastic such as glass fiber reinforced plastic (GFRP) or carbon fiber reinforced plastic (CFRP) instead of a metal material.

[0019] The pair of restraint plates 12 and 14 pressurize and restrain the stacked battery 20 from both sides in the stacking direction D1. Specifically, the battery pack 10 includes sidewall members (not shown) that cover the four side surfaces of the stacked battery 20. The restraint plates 12 and 14 are fastened together using bolts (not shown) via the sidewall members located between them.

[0020] 1, the plurality of bolt holes 18 for the above fastening are formed at a predetermined pitch in the vehicle front-rear direction D2 at both ends of each of the restraint plates 12 and 14 in the vehicle width direction D3, as an example. Therefore, by passing bolts through the plurality of bolt holes 18 and fastening the pair of restraint plates 12 and 14 via the above-mentioned side wall members, a restraining load for pressurizing and restraining the stacked battery 20 from both sides in the stacking direction D1 acts on both ends of the pair of restraint plates 12 and 14 in the vehicle width direction D3. As a result, a restraining surface pressure is applied to each of the upper and lower surfaces of the stacked battery 20.

[0021] In the example of the battery pack 10 shown in FIG. 1, the vehicle width direction D3 corresponds to the "specific direction that is a direction parallel to one side of the rectangle of the pair of restraining plates having a rectangular shape" according to the present disclosure. However, the "specific direction" is not limited to the vehicle width direction D3. That is, the "specific direction" differs depending on the direction in which the restraining load is applied to both ends of the pair of restraining plates 12 and 14. Therefore, in another example in which the above-mentioned bolt holes 18 are provided in the pair of restraining plates 12 and 14 at both ends in the vehicle front-rear direction D2 rather than in the vehicle width direction D3, the vehicle front-rear direction D2 corresponds to another example of the "specific direction". In addition, the joining of the restraining plates 12 and 14 via the four side walls is not limited to the example of fastening with bolts, and may be performed using other methods such as welding.

[0022] In the battery pack 10, the restraining plates 12 and 14 and the side wall members form a battery case that covers the laminated battery 20. The battery pack 10 is attached to the vehicle by, for example, joining (for example, by bolting or welding) the lower restraining plate 14, which functions as part of the battery case, to a predetermined vehicle body member. However, the restraining plates 12 and 14 do not necessarily have to also function as the case (battery case) of the battery pack 10. In other words, an upper cover may be provided above the restraining plate 12 in the vehicle, and a lower case may be provided below the restraining plate 14 in the vehicle.

[0023] In addition, in the example shown in Fig. 1, the vehicle is equipped with one battery pack 10 that houses one stacked battery 20 having upper and lower surfaces with large surface areas as shown in Fig. 1. Note that as the capacity (amount of power) of the battery pack 10 required for the vehicle increases, the surface areas of the upper and lower surfaces of the stacked battery 20 also increase.

[0024] 1-2. Structure of stacked battery Fig. 2 is an exploded perspective view showing a schematic example of the configuration of the stacked battery 20 shown in Fig. 1. The stacked battery 20 (hereinafter also simply referred to as "battery 20") is a rechargeable secondary battery. The battery 20 includes a cell stack 22, a positive current collector plate 24, a negative current collector plate 26, a positive current collector terminal 28, and a negative current collector terminal 30.

[0025] In the example shown in Fig. 2, the battery 20 includes a plurality of stacked cell stacks 22. The positive electrode current collector 24 and the negative electrode current collector 26 are arranged to sandwich the plurality of cell stacks 22. The number of cell stacks 22 arranged between the positive electrode current collector 24 and the negative electrode current collector 26 is not particularly limited, and may be one. In the example shown in Fig. 2, the cell stacks 22 are alternately stacked with cooling plates 32 for cooling the cell stacks 22. The cooling plates 32 are made of a metal such as aluminum or copper, and electrically connect the adjacent cell stacks 22 in series.

[0026] Fig. 3 is a cross-sectional view that shows a schematic example of the structure of the cell stack 22 shown in Fig. 2. The cell stack 22 is configured by stacking a plurality of battery cells 34 in one direction. Each battery cell 34 is configured such that the positive electrode layer 38 and the negative electrode layer 40 of adjacent bipolar electrode plates 36 face each other with a separator (electrolyte layer) 42 interposed therebetween.

[0027] More specifically, the cell stack 22 includes a frame 44 along with a plurality of bipolar electrode plates 36 and a plurality of separators 42. The bipolar electrode plates 36 are supported by the frame 44 so as to be spaced apart in the stacking direction D1. The separators 42 are disposed between adjacent bipolar electrode plates 36.

[0028] Each bipolar electrode plate 36 includes an electrode plate portion 46, a positive electrode layer 38, and a negative electrode layer 40. The electrode plate portion 46 is formed of a metal material such as nickel. The positive electrode layer 38 includes a positive electrode active material. For example, nickel hydroxide is used as the positive electrode active material. The negative electrode layer 40 includes a negative electrode active material. For example, a hydrogen-absorbing alloy is used as the negative electrode active material. As shown in FIG. 3, only one of the positive electrode layer 38 and the negative electrode layer 40 is formed on the electrode plate portions 46 located at both ends in the stacking direction D1. The separator 42 is formed in a sheet shape. The separator 42 is formed using a porous film formed of, for example, a polyolefin resin.

[0029] Inside the cell stack 22 configured as described above, an accommodation space 48 is formed by the adjacent electrode plate parts 46 and the frame body 44. In this accommodation space 48, a separator 42, a positive electrode layer 38, a negative electrode layer 40, and an electrolyte (not shown) are arranged. The electrolyte is, for example, an alkaline solution such as an aqueous potassium hydroxide solution. A battery cell 34 is formed by the separator 42, the negative electrode layer 40, the positive electrode layer 38, and the electrolyte. A plurality of battery cells 34 are arranged in the stacking direction D1. The battery cells 34 are connected in series by the electrode plate parts 46. When the battery 20 is discharged, a current flows inside the cell stack 22 from the upper side (the negative electrode collector plate 26 side) to the lower side (the positive electrode collector plate 24 side) in FIG. 3.

[0030] In the example shown in FIG. 3, the separator 42 impregnated with an electrolytic solution is exemplified as the electrolyte layer, but instead of the separator 42, for example, a solid electrolyte or a gel electrolyte may be used. In addition, in the example shown in FIG. 3, a bipolar battery 20 is exemplified. However, the "stacked battery" according to the present disclosure is not limited to a bipolar type, and may be a monopolar type. In other words, the cell stack included in the "stacked battery" according to the present disclosure may be configured by stacking a plurality of battery cells configured such that the positive electrode layer of one of adjacent electrode plates and the negative electrode layer of the other electrode plate face each other via an electrolyte layer.

[0031] 1-3.Reduced rigidity structure of restraining plate In a battery pack including a stacked battery, it is required to uniformly apply a restraining surface pressure of a certain threshold value TH (see FIG. 7 described later) or more to the upper and lower surfaces of the stacked battery. Here, when a restraining load is applied to the pair of restraining plates at both ends in the vehicle width direction D3 (specific direction) as described above, bending deformation occurs in the pair of restraining plates. Unlike the restraining plates 12 and 14 of this embodiment having a "rigidity reduction structure" described below, if the pair of restraining plates for applying the restraining surface pressure to the stacked battery were simple flat plates, the central part of the pair of restraining plates in the vehicle width direction D3 would be easily lifted by the bending change (see FIG. 6(A) described later). As a result, the restraining surface pressure in the central part would be easily released, making it difficult to apply a uniform restraining surface pressure to the stacked battery regardless of the position in the vehicle width direction D3. In addition, if the thickness of the pair of restraining plates is increased to suppress bending deformation and ensure a uniform restraining surface pressure, the weight of the pair of restraining plates would increase.

[0032] Therefore, a battery pack including a stacked battery is required to be able to apply a more uniform surface pressure to the stacked battery while suppressing an increase in the weight of the pair of restraint plates.The battery pack is also required to be able to improve impact resistance performance in the event of a vehicle collision.

[0033] In consideration of the above-mentioned problems, the pair of restraining plates 12 and 14 of this embodiment are provided with the following "rigidity reducing structure."

[0034] 1, the restraint plate 12 includes a first portion 12a and a pair of second portions 12b. The pair of second portions 12b are portions having a lower rigidity (more specifically, bending rigidity) against input of a load in the stacking direction D1 than the first portions 12a. More specifically, the first portions 12a are portions of the restraint plate 12 other than the pair of first portions 12a.

[0035] Each of the pair of second portions 12b is disposed along the vehicle front-rear direction D2, which is a direction perpendicular to the vehicle width direction D3 (specific direction). More specifically, in the example shown in Fig. 1, each of the pair of second portions 12b extends from one end to the other end of the restraining plate 12 in the vehicle front-rear direction D2. When viewed in the vehicle width direction D3, the pair of second portions 12b are disposed apart from each other in locations of the restraining plate 12 excluding the center and both ends.

[0036] The other restraining plate 14 has a first portion 14a and a pair of second portions 14b. This restraining plate 14 also has a rigidity reducing structure. The rigidity reducing structure of the restraining plate 14 is the same as that of the restraining plate 12, so a detailed description thereof will be omitted here.

[0037] Next, with reference to FIG. 4, an example of a preferred arrangement range of the pair of second portions 12b in the vehicle width direction D3 will be described. FIG. 4 is a view of the restraining plate 12 looking down from above the vehicle. In this embodiment, the pair of second portions 12b are arranged symmetrically with respect to the center position of the restraining plate 12 in the vehicle width direction D3 (specific direction). The length of the restraining plate 12 in the vehicle width direction D3 is referred to as the "specific direction length L". As shown in FIG. 4, the center C1 in the vehicle width direction D3 of the portion 12b1, which is one of the pair of second portions 12b, is provided at a position 1 / 4 of the specific direction length L from one end E in the vehicle width direction D3. In addition, the center C2 in the vehicle width direction D3 of the other portion 12b2 is provided at a position 3 / 4 of the specific direction length L from the one end E.

[0038] A preferred arrangement of the pair of second portions 12b in the vehicle width direction D3 is not limited to the example of the portions 12b1 and 12b2 shown in Fig. 4, and may be within the following arrangement range R. That is, the center of the portion 12b1 may be located within a range of plus or minus 10% of the specific direction length L centered at a position 1 / 4 of the specific direction length L from one end E in the vehicle width direction D3. Also, the center of the other portion 12b2 may be located within a range of plus or minus 10% of the specific direction length L centered at a position 3 / 4 of the specific direction length L from the one end E.

[0039] Fig. 5 is a diagram showing a specific configuration example of the pair of second portions 12b according to the first embodiment. Fig. 5 is a diagram showing the restraining plate 12 as viewed from the vehicle longitudinal direction D2. As shown in Fig. 5, each of the pair of second portions has a groove having a semicircular cross section. As a result, each of the pair of second portions has a smaller thickness in the stacking direction D1 than the first portion 12a. Note that a specific configuration example of the restraining plate 14 can be obtained by inverting the restraining plate 12 shown in Fig. 5 in the stacking direction D1.

[0040] 1-4.Effects First, the effect of equalizing the restraining surface pressure by the rigidity reduction structure according to the first embodiment will be described with reference to Fig. 6 and Fig. 7. Fig. 6(A) and Fig. 6(B) show cross sections of the restraining plate cut along the vehicle width direction D3 (specific direction). The horizontal axis of these figures indicates the position on the restraining plate in the vehicle width direction D3. The comparative example shown in Fig. 6(A) and Fig. 7 corresponds to a configuration including a flat-shaped restraining plate 100 without a rigidity reduction structure.

[0041] In the comparative example, when the above-mentioned restraining load is applied to both ends of the restraining plate 100, the restraining plate 100 deforms so as to generate a peak at the center position in the vehicle width direction D3 as shown in Fig. 6(A). As a result, as shown in Fig. 7, the restraining surface pressure in the comparative example decreases from each end of the restraining plate 100 toward the center position while maintaining a high rate of decrease.

[0042] In contrast, the restraining plate 12 of this embodiment has a rigidity reduction structure that utilizes a pair of second portions 12b that are less rigid than the surrounding first portions 12a. The deformation of the sections from each end of the restraining plate 12 to the pair of second portions 12b is equivalent to that of the comparative example. However, by reducing the rigidity of the pair of second portions 12b, the deformation of the central portion of the restraining plate 12 located between the pair of second portions 12b is suppressed. Therefore, as shown in FIG. 6(B), the flat area increases at the central side compared to the comparative example. As a result, the restraining surface pressure at the central position is lowered as in the comparative example, but as shown by hatching in FIG. 7, the change in the restraining surface pressure according to the position in the vehicle width direction D3 at the central side can be effectively suppressed. Therefore, compared to the comparative example (flat plate), the restraining surface pressure can be made uniform.

[0043] More specifically, the threshold value TH in Fig. 7 is the threshold value of the restraining surface pressure that is required to be applied to the stacked battery 20. In the battery pack 10, the restraining surface pressure only needs to satisfy the threshold value TH. Compared to the comparative example, the restraining plate 12 of this embodiment reduces the magnitude of the restraining surface pressure itself near the central position, but can equalize the restraining surface pressure while ensuring the necessary surface pressure value (threshold value TH). In addition, the restraining surface pressure can be equalized without relying on an increase in the thickness of the restraining plate 12 to improve rigidity, that is, while suppressing an increase in the weight of the restraining plate 12. The same is true for the restraining plate 14 having the same rigidity-reducing structure.

[0044] Next, Fig. 8 is a diagram for explaining the effect of improving impact resistance performance by the rigidity reduction structure according to the first embodiment, and is a diagram of the restraining plates 100 and 12 viewed from the vehicle longitudinal direction D2, similar to Fig. 6. More specifically, the upper, middle and lower diagrams in Fig. 8(A) and Fig. 8(B) respectively show how deformation of the restraining plates 100 and 12 progresses in response to input of an impact load from one side in the vehicle transverse direction D3.

[0045] First, a comparative example (flat plate) will be described. When a flat constraining plate 100 can no longer withstand the impact load, the constraining plate 100 begins to deform, as shown in the upper part of Fig. 8(A). Once deformation occurs, the constraining plate 100 becomes less able to generate a reaction force against the impact load. As a result, the deformation progresses, as shown in the middle and lower parts of Fig. 8(A).

[0046] On the other hand, in the constraining plate 12 having the rigidity reduction structure, as shown in the upper part of FIG. 8(B), deformation is easily caused in the pair of second portions 12b at the beginning of input of the impact load. In this way, by intentionally making deformation (bending) easily occur in the pair of second portions 12b, the length of each portion of the constraining plate 12 (three portions including the portion on the central side and the portions on each end side) that is distinguished by each bending point becomes shorter than that of the comparative example after bending. Therefore, the rigidity of each portion after the occurrence of the bending becomes higher. As a result, the constraining plate 12 can increase the reaction force against the impact load after the occurrence of the bending compared to the comparative example. In other words, the amount of absorption (consumption) of the impact energy utilizing the deformation of the constraining plate 12 can be increased compared to the comparative example. This makes it possible to improve the impact resistance performance. The same is true for the constraining plate 14 having the same rigidity reduction structure.

[0047] As described above, according to the battery pack 10 of the present embodiment, it is possible to apply a more uniform restraining surface pressure to the stacked battery 20 while suppressing an increase in the weight of the pair of restraining plates 12 and 14, and it is possible to improve impact resistance.

[0048] In addition, if the "pair of second portions" in the "specific direction (e.g., vehicle width direction D3)" according to the present disclosure are too close to the center position of the "specific direction," the range in which the restraining surface pressure can be made uniform becomes shorter. Conversely, if the "pair of second portions" are too far from the center position, even if the restraining surface pressure of the portion located between the "pair of second portions" can be made uniform, the restraining surface pressure itself will be weak. In regard to these points, according to the above-mentioned arrangement range R, the location of the pair of second portions can be appropriately selected so as to more effectively apply a uniform restraining surface pressure at a value equal to or greater than the above-mentioned threshold value TH.

[0049] 1-5. Variations The "pair of second portions" according to the present disclosure may be formed so as to have a smaller thickness in the stacking direction D1 than the "first portion" by adopting, for example, the shape examples shown in the following Figures 9 to 12 instead of the example shown in Figure 5.

[0050] 9 is a diagram showing a specific configuration example of a restraint plate 50 according to a first modified example of embodiment 1. The restraint plate 50 includes a first portion 50a and a pair of second portions 50b. In this first modified example, each of the pair of second portions 50b is a portion having a groove having a semicircular cross section on both sides in the stacking direction D1.

[0051] 10 is a diagram showing a specific configuration example of a restraint plate 52 according to a second modified example of the first embodiment. The restraint plate 52 includes a first portion 52a and a pair of second portions 52b. In this second modified example, each of the pair of second portions 52b is a portion having a plurality of (three, for example) small grooves having a semicircular cross section. Such grooves may be formed in the restraint plate 52 on both sides in the stacking direction D1.

[0052] FIG. 11 is a diagram showing a specific configuration example of the restraining plate 54 according to the third modified example of the first embodiment. The restraining plate 54 includes a first portion 54a and a pair of second portions 54b. In the example shown in FIG. 1 described above, each of the pair of second portions 12b extends from one end to the other end of the restraining plate 12 in the vehicle longitudinal direction D2. In contrast, in the third modified example, each of the pair of second portions 54b is a portion having a plurality of (for example, two) grooves partially arranged along the vehicle longitudinal direction D2 (i.e., a direction perpendicular to the "specific direction"). In other words, each of the pair of second portions 54b is formed as a portion divided into a plurality of (for example, two) portions along the vehicle longitudinal direction D2.

[0053] FIG. 12 is a diagram showing a specific configuration example of a restraining plate 56 according to a fourth modified example of the first embodiment. The restraining plate 56 includes a first portion 56a and a pair of second portions 56b. In this fourth modified example, similarly to the third modified example, each of the pair of second portions 56b is partially disposed along the vehicle longitudinal direction D2. In the fourth modified example, each of the pair of second portions 56b is a portion having a plurality of through holes (for example, nine). The plurality of through holes are, for example, circular. Note that instead of the plurality of through holes, a plurality of spherical depressions may be used.

[0054] 2. Second embodiment The second embodiment differs from the first embodiment in the configuration method of the "pair of second portions." Fig. 13 is a diagram showing a specific configuration example of the restraining plate 60 according to the second embodiment. Fig. 13 shows a cross section of the restraining plate 60 along the vehicle width direction D3 (specific direction).

[0055] The restraining plate 60 includes a first portion 60a and a pair of second portions 60b. In the first embodiment, the pair of second portions 60b is configured by utilizing a difference in thickness of the restraining plate. In contrast, in the second embodiment, the pair of second portions 60b is configured by utilizing a change in cross-sectional shape that does not involve a change in the thickness of the restraining plate 60. That is, as shown in FIG. 13, in a cross section along the vehicle width direction D3, the first portion 60a is flat, and each of the pair of second portions is corrugated.

[0056] The pair of corrugated second portions 60b exhibit high rigidity against a load that bends the restraint plate 60, for example, when the load is applied to each end in the vehicle longitudinal direction D2. On the other hand, the pair of corrugated second portions 60b bend more easily (i.e., have lower rigidity) than a flat plate when the restraint load is applied to each end in the vehicle transverse direction D3, as shown in Fig. 13. Therefore, even when the restraint plate 60 is used instead of the restraint plates 12 and 14 of the first embodiment, the same effect as the first embodiment can be obtained.

[0057] 3. Third embodiment The third embodiment differs from the first and second embodiments in the configuration method of the "pair of second portions." Fig. 14 is a diagram showing a specific configuration example of the restraining plate 70 according to the third embodiment. Fig. 14 shows a cross section of the restraining plate 70 along the vehicle width direction D3 (specific direction).

[0058] The restraining plate 70 includes a first portion 70a and a pair of second portions 70b. In the third embodiment, the difference in rigidity between the first portion 70a and the pair of second portions 70b is imparted by utilizing the difference in material. That is, each of the pair of second portions 70b is formed using a material having a lower Young's modulus than the first portion 70a.

[0059] Specifically, for example, the first portion 70a and the pair of second portions 70b may both be formed using fiber-reinforced plastics such as GFRP or CFRP, etc. The fiber blending ratio of the pair of second portions 70b may be made lower than that of the first portion 70a, thereby providing the above-mentioned stiffness difference.

[0060] In order to provide the above-mentioned rigidity difference, the first portion 70a may be formed using a metal material, and the pair of second portions 70b may be formed using a resin material. In such an example, the restraint plate 70 may be formed using a resin-metal joining method such as insert molding.

[0061] In addition, instead of the above-mentioned specific example, the stiffness difference may be provided by using, for example, two kinds of metal materials having different Young's moduli. In such an example, the restraining plate 70 may be formed by any joining method, such as welding or a combination of bolts and nuts.

[0062] Even when the restraint plate 70 of the third embodiment described above is used in place of the restraint plates 12 and 14, the same effects as those of the first embodiment can be obtained.

[0063] 4. Fourth embodiment The fourth embodiment differs from the first to third embodiments in the configuration method of the "pair of second portions." Fig. 15 is a diagram showing a specific configuration example of a restraining plate 80 according to the fourth embodiment.

[0064] The restraining plate 80 includes a first portion 80a and a pair of second portions 80b. As shown in Fig. 15, the restraining plate 80 (specific restraining plate) includes a plurality of beads 82 extending along the vehicle width direction D3 (specific direction). As an example, the number of beads 82 is four. Such beads 82 are provided to increase the basic rigidity of the restraining plate 80.

[0065] Moreover, in the fourth embodiment, each of the pair of second portions 80b has a notch 84 formed along the vehicle longitudinal direction D2 (i.e., a direction perpendicular to the specific direction) with respect to each bead 82. The first portion 80a is a portion other than the pair of second portions 80b (i.e., a portion without a bead 82 and a portion of the bead 82 away from the notch 84). With this configuration, the rigidity of the second portion 80b having the notch 84 can be reduced compared to the other portions of the restraint plate 80 (i.e., the first portion 80a) with respect to the restraint load applied to the restraint plate 80 at both ends in the vehicle width direction D3.

[0066] Even when the restraint plate 80 of the fourth embodiment described above is used in place of the restraint plates 12 and 14, the same effects as those of the first embodiment can be obtained.

[0067] FIG. 16 is a diagram showing a specific configuration example of a restraining plate 90 according to a modified example of the fourth embodiment. The restraining plate 90 includes a first portion 90a and a pair of second portions 90b. In this modified example, the cuts 84 of the pair of second portions 90b are provided in some of the beads 82, not in all of them. More specifically, as a preferred example, the cuts 84 are formed in two of the four beads 82, such that the beads 82 without the cuts 84 and the beads 82 with the cuts 84 are arranged alternately. As in this example, the "cuts" according to the present disclosure may be formed in one or more of the beads, but not in all of the beads.

[0068] In the above-described first to fourth embodiments, a "rigidity reducing structure" is provided to both of the pair of restraining plates. In other words, both of the pair of restraining plates correspond to the "specific restraining plate" according to the present disclosure. However, the "rigidity reducing structure utilizing a pair of second portions" may be provided to only one of the pair of restraining plates. In other words, only one of the pair of restraining plates may correspond to the "specific restraining plate". [Explanation of symbols]

[0069] 10 Battery pack 12, 14, 50, 52, 54, 56, 60, 70, 80, 90 restraint plate 12a, 14a, 50a, 52a, 54a, 56a, 60a, 70a, 80a, 90a: First portion of restraining plate 12b, 14b, 50b, 52b, 54b, 56b, 60b, 70b, 80b, 90b Pair of second portions of restraining plates 18 Bolt holes 20 Stacked battery 34 Battery Cell 82 Bead 100 Restraint plate (comparison example)

Claims

1. a stacked battery including a plurality of battery cells stacked in a stacking direction parallel to the vertical direction of the vehicle; a pair of restraining plates each having a rectangular shape as viewed from the stacking direction, the restraining plates pressurizingly restraining the stacked battery from both sides in the stacking direction by a restraining load acting on both ends in a specific direction that is a direction parallel to one side of the rectangle; A battery pack comprising: At least one of the pair of restraining plates is A first portion; and a pair of second regions having a lower rigidity against an input of a load in the stacking direction than the first regions; A specific restraining plate including: Each of the pair of second portions is disposed along a direction perpendicular to the specific direction, When viewed in the specific direction, the pair of second portions are disposed apart from each other in a location excluding a center portion and both ends of the specific restraint plate, Each of the pair of second portions is formed using a material having a lower Young's modulus than the first portion. A battery pack characterized by:

2. a stacked battery including a plurality of battery cells stacked in a stacking direction parallel to the vertical direction of the vehicle; a pair of restraining plates each having a rectangular shape as viewed from the stacking direction, the restraining plates pressurizingly restraining the stacked battery from both sides in the stacking direction by a restraining load acting on both ends in a specific direction that is a direction parallel to one side of the rectangle; A battery pack comprising: At least one of the pair of restraining plates is A first portion; and a pair of second regions having a lower rigidity against an input of a load in the stacking direction than the first regions; A specific restraining plate including: Each of the pair of second portions is disposed along a direction perpendicular to the specific direction, When viewed in the specific direction, the pair of second portions are disposed apart from each other in a location excluding a center portion and both ends of the specific restraint plate, The specific restraint plate includes a plurality of beads extending along the specific direction, Each of the pair of second regions has a notch formed in at least one of the plurality of beads along a direction perpendicular to the specific direction. A battery pack characterized by:

3. When the length of the specific restraint plate in the specific direction is referred to as the specific direction length, a center of one of the pair of second portions in the specific direction is located within a range of ±10% of the specific direction length, the range being centered at a position that is ¼ of the specific direction length from one end of the specific restraint plate in the specific direction; The center of the other of the pair of second portions in the specific direction is located within a range of ±10% of the specific direction length, with the center being located at a position that is 3 / 4 of the specific direction length from the one end.

3. The battery pack according to claim 1 or 2.

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