Battery pack

Abstract

The utility model relates to a battery pack which can be reinforced without arranging a reinforcing component on a battery shell. The battery pack provided by the utility model is provided with a battery unit group comprising a plurality of battery units and a battery shell for accommodating the battery unit group, the battery shell comprises a pair of cross beams, and the pair of cross beams are configured in a manner of clamping the battery unit group in the middle in a first direction; the battery cell group includes a plurality of battery cells stacked in a first direction and extending in a second direction orthogonal to the first direction, the plurality of battery cells being stacked in the second direction, and the battery cell group including a reinforcing plate stacked together with the plurality of battery cells. The reinforcing plate is located at a position at which the distance from the center of the battery cell group in the second direction is smaller than the distance from each end of the battery cell group in the second direction, and the reinforcing plate is arranged so as to bridge between the pair of cross beams.

Description

Technical Field

[0001] The utility model relates to a battery pack. Background Art

[0002] Patent Document 1 discloses a battery pack mounted on a vehicle. In this battery pack, battery cell groups are arranged on both sides via a reinforcement member extending in the front-rear direction of the vehicle.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-111531

[0004] In the battery pack described in Patent Document 1, the battery cell group monomer has no reinforcing member. Therefore, in the structure described in Patent Document 1, it is necessary to provide a reinforcing member (reinforcement member) on the battery case that accommodates the battery cell group. Utility Model Content

[0005] The utility model is completed in view of the above-mentioned technical problems, and an object of the utility model is to provide a battery pack that is reinforced without providing a reinforcing component on the battery housing.

[0006] The battery pack of the utility model comprises a battery cell group and a battery case. The battery cell group comprises a plurality of battery cells. The battery case accommodates the battery cell group. The battery case comprises a pair of cross beams, which are arranged in a manner of sandwiching the battery cell group in the first direction and extending in a second direction orthogonal to the first direction. The plurality of battery cells are stacked in the second direction. The battery cell group comprises a reinforcing plate stacked together with the plurality of battery cells, the reinforcing plate being located at a position where the distance from the center of the battery cell group in the second direction is smaller than the distance from each end of the battery cell group in the second direction. The reinforcing plate is arranged in a manner of bridging between the pair of cross beams.

[0007] In addition, in the battery pack of the present invention, the plurality of battery cells and the reinforcing plate may be joined to a pair of cross members.

[0008] Furthermore, in the battery pack of the present invention, the plurality of battery cells and the reinforcing plate may be bonded to the pair of cross members by an adhesive.

[0009] Furthermore, in the battery pack of the present invention, the battery cell group may include a heat insulating material interposed between the reinforcing plate and the battery cells in the second direction.

[0010] Furthermore, in the battery pack of the present invention, the reinforcing plate may be formed using a resin material.

[0011] According to the battery pack of the present invention, it is possible to realize a battery pack having a reinforcement structure against a load from the first direction without providing a reinforcement member in the battery case. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a diagram showing the configuration of a battery pack according to an embodiment.

[0013] Figure 2 Yes means Figure 1 Figure AA section in.

[0014] Figure 3 It is a diagram for explaining an electrical connection path between a plurality of battery cells in a battery pack according to an embodiment.

[0015] Figure 4 It is a diagram showing an example of a heat insulation structure of a battery cell group according to an embodiment.

[0016] Figure 5 It is a diagram showing another example of the heat insulation structure of the battery cell group according to the embodiment. DETAILED DESCRIPTION

[0017] Figure 1 1 is a diagram showing a configuration of a battery pack 1 according to an embodiment. The battery pack 1 is mounted on an electric vehicle such as a battery electric vehicle (BEV), for example. Figure 1 The direction of "FR" shown corresponds to the front of the vehicle on which the battery pack 1 is mounted. The direction of "RH" corresponds to the right side of the vehicle.

[0018] The battery pack 1 includes a plurality of battery cells 10 and a battery case 20. The battery case 20 accommodates the plurality of battery cells 10. The battery case 20 includes a lower case 21 and an upper case 22 (see below). Figure 2 ). Figure 1 Including from above the electric vehicle ( Figure 2 A diagram of a plurality of battery cells 10 placed on a lower housing 21 (in the direction of “UPR” shown in the figure) and a perspective exploded diagram for illustrating a restraint structure of the plurality of battery cells 10.

[0019] The plurality of battery cells 10 are, for example, rectangular batteries. When a predetermined number of battery cells 10 stacked along the second direction D2 is referred to as a battery cell group 12, Figure 1 In the example shown, as a plurality of battery cells 10, a plurality of (four in one example) battery cell groups 12 are arranged along the first direction D1. More specifically, the plurality of battery cells 10 are placed on the lower case 21 and accommodated in the battery case 20 without being modularized. In this way, the battery pack 1 involved in this embodiment has a so-called CTP (Cell To Pack) structure. According to the CTP structure, there is no need for a modular structure, so the space utilization and energy density of the battery pack 1 can be effectively improved.

[0020] In addition, Figure 1In the example shown, the first direction D1 is parallel to the front-rear direction of the vehicle. Figure 1 When the battery pack 1 is viewed from above, the first direction D1 is a direction orthogonal to the second direction D2, which is the stacking direction of the battery cells 10 in each battery cell group 12. The second direction D2 is parallel to the left-right direction of the vehicle (the vehicle width direction). Figure 1 , Figure 2 The reinforcement plate 13 shown is related to the “reinforcement structure for front and rear loads” described later, and the details of the reinforcement plate 13 will be described later.

[0021] The lower case 21 includes a pair of side reinforcements 23 and a plurality of cross members 24 as members for reinforcing the lower case 21. The side reinforcements 23 and cross members 24 are fixed to the main body of the lower case 21 so as to surround the plurality of battery cells 10 (each battery cell group 12).

[0022] More specifically, if Figure 1 As shown, the side reinforcements 23 are respectively arranged on the outer sides of each end of the battery cell group 12 in the second direction D2 (vehicle width direction) and extend along the first direction D1 (vehicle front-rear direction). In addition, a part of the plurality of cross beams 24 is arranged between two battery cell groups 12 adjacent to each other in the first direction D1 and extends along the second direction D2. The remaining cross beams 24 extend along the second direction D2 adjacent to the battery cell groups 12 located at each end of the first direction D1. In addition, both ends of each cross beam 24 are connected to a pair of side reinforcements 23. In other words, focusing on one battery cell group 12, the lower shell 21 includes a pair of cross beams 24 that are arranged in a manner that sandwiches the battery cell group 12 in the first direction D1 and are formed in a manner that extends along the second direction D2 that is orthogonal to the first direction D1.

[0023] In order to constrain the plurality of battery cells 10 (each battery cell group 12 ) in the second direction D2 (stacking direction), the battery pack 1 has a hybrid constraining structure in which a cross beam as a reinforcing member and a restraining band of the battery cell group 12 are integrally provided as the cross beam 24 .

[0024] Specifically, Figure 1 As shown, each beam 24 has an opposing wall 24a facing the adjacent battery cell group 12. Furthermore, a beam 24 located between two battery cell groups 12 in the first direction D1 has two opposing walls 24a. The beam 24 is bonded to the battery cell group 12 by an adhesive 30 applied to the opposing walls 24a.

[0025] In addition, an engaging portion 24b is formed at each end of each cross beam 24 in the second direction D2. The engaging portion 24b engages with the engaging portion 31a of the restraining member 31 on the battery cell group 12 side. The restraining member 31 is provided at each end of the battery cell group 12 in the second direction D2. By engaging the engaging portion 24b with the engaging portion 31a in a state where a compressive load along the second direction D2 acts on the battery cell group 12, the battery cell group 12 is restrained by the cross beam 24 in the second direction D2 with a predetermined restraining force.

[0026] As described above, according to the hybrid restraint structure, the battery cell group 12 is restrained in the second direction D2 (stacking direction) by restraint using the adhesive 30 and mechanical restraint using the engaging portion 24b and the engaging portion 31a (double structure). As a result, the number of components can be reduced, and the gap between the cross beam 24 and the battery cell group 12 can be reduced well, so that restraint in the second direction D2 can be achieved with excellent space efficiency.

[0027] In addition, in order to restrain the battery cell group 12 in the second direction D2, the restraining band 32 may be used. By using the restraining band 32, the battery cell group 12 can be restrained from above by engaging the engaging portions 32a at each end of the restraining band 32 with the engaging portions 31b of the restraining member 31. In order to achieve more reliable restraint, the restraining band 32 may be bonded to the battery cell group 12 by an adhesive 33 (see Figure 2 ) is joined to the upper surface 10a of each battery cell 10 included in the battery cell group 12.

[0028] Next, the relationship between the plurality of battery cells 10 and the battery case 20 (lower case 21) will be described. Figure 2 As shown in FIG. 1 , the lower surface 10b of each battery cell 10 is bonded to the lower case 21 by the thermally conductive adhesive 34. That is, each battery cell 10 is restrained by the adhesive force of the thermally conductive adhesive 34 and does not come off the lower case 21. Figure 2 As shown, each cross beam 24 is disposed on the lower housing 21 (more specifically, the reinforcing member 25 included in the lower housing 21). In order to make the assembly of the battery cell group 12 and the cross beam 24 more secure, each cross beam 24 can also be fixed to the lower housing 21 (reinforcing member 25) using fasteners such as bolts and nuts. In addition, by using a thermally conductive adhesive 34, in the case Figure 2 When the cooler 40 is provided so as to be in contact with the lower surface of the lower case 21 as in the illustrated example, the heat dissipation from the lower surface 10 b of each battery cell 10 can be promoted by the thermally conductive adhesive 34 .

[0029] In addition, in order to achieve more reliable constraints, such as Figure 2As shown in the example, the upper surface 10a of each battery cell 10 may be bonded to the upper case 22 via a thermally conductive adhesive 35. Figure 2 When the cooler 41 is provided in contact with the upper surface of the upper case 22 as in the example shown, the heat dissipation from the upper surface 10a of each battery cell 10 can be promoted by the thermally conductive adhesive 35. In addition, in order to constrain the upper surface 10a side of each battery cell 10, it is also possible to use only the thermally conductive adhesive 35 without using the adhesive 33.

[0030] Next, the reinforcement structure for the front and rear loads will be described.

[0031] To illustrate the reinforcing plate 13, Figure 1 Additional reference Figure 2 . Figure 2 To express Figure 1 The AA cross-sectional view in FIG. 1 shows the structure of the reinforcing plate 13 and its surroundings as viewed from the second direction D2.

[0032] Each battery cell group 12 includes a reinforcing plate 13. Figure 1 As shown, the reinforcing plate 13 is arranged at the center of the battery cell group 12 in the second direction D2, and is stacked together with the plurality of battery cells 10 constituting the battery cell group 12. The reinforcing plate 13 is formed using, for example, a metal material. In addition, the arrangement location of the reinforcing plate 13 in the battery cell group 12 is not necessarily limited to the center in the second direction D2, as long as it is a position where the distance from the center of the battery cell group 12 is less than the distance from each end of the battery cell group 12 in the second direction D2. In addition, the configuration position of the reinforcing plate 13 in the second direction D2 is a structure close to the center as described above, compared with the example in which the configuration position is close to one end of the battery cell group 12, from the perspective of effectively bearing the front and rear loads together with the skeleton structural components (side reinforcement 23 and cross beam 24) of the battery case 20.

[0033] Each reinforcing plate 13 is arranged to bridge between the pair of cross members 24. More specifically, the reinforcing plate 13 has the same size as the battery unit 10 at least in the first direction D1 and the vehicle front-rear direction (height direction). Figure 2 As shown, the lateral beams 24 (a pair of lateral beams) are connected to each end of the lateral beams 24 located in the first direction D1. Figure 2 In the example shown, the joining of the reinforcing plate 13 and the cross beam 24 is also as shown in FIG. Figure 2 As shown, the bonding is performed by using an adhesive 30. In a broad sense, the bonding between the reinforcing plate 13 and the cross member 24 does not necessarily have to be performed by bonding, and other bonding methods such as fastening with fasteners (for example, bolts and nuts) may be used.

[0034] As described above, in the battery pack 1 involved in the present embodiment, the battery cell group 12 includes a reinforcing plate 13 stacked together with a plurality of battery cells 10, and the reinforcing plate 13 is located at a position where the distance from the center of the battery cell group 12 in the second direction D2 is smaller than the distance from each end of the battery cell group 12 in the second direction D2. Moreover, the reinforcing plate 13 is configured to bridge between a pair of cross beams 24. As a result, when a load (front and rear load) from the front and rear direction (first direction D1) of the vehicle acts on the battery pack 1, each reinforcing plate 13 functions as a reinforcing member that bears the load. In this way, in the battery pack 1, the battery cell group 12 itself is provided with a reinforcing structure for the front and rear loads. Therefore, it is possible to well realize a battery pack 1 having a reinforcing structure for the front and rear loads without providing a reinforcing member in the battery case 20.

[0035] In the battery pack 1 according to the present embodiment, the reinforcing plate 13 is bonded to each of the pair of beams 24 together with the plurality of battery cells 10 by the adhesive 30. That is, like the plurality of battery cells 10, the reinforcing plate 13 is arranged without a gap with each of the pair of beams 24. Figure 2 As shown, in the first direction D1 (vehicle front-rear direction), a plurality of reinforcing plates 13 and the cross beam 24 interposed between the reinforcing plates 13 are continuously arranged without gaps. According to such a reinforcing structure, as described below, it is possible to obtain an excellent effect in improving the resistance to crushing of the battery pack 1 accompanied by front-rear loads or front-rear collisions (front collisions or rear collisions of electric vehicles).

[0036] In order to illustrate the above effect, a battery pack in which a battery cell group including a reinforcing plate similar to the reinforcing plate 13 does not have a CTP structure but is modularized as a battery module is referred to as a comparative example. In the battery pack of the comparative example, in order to assemble the battery module in the space in the battery case divided by a plurality of cross beams, it is necessary to ensure a gap between the battery module and the cross beam. The gap is generated between each battery module arranged in a row in the first direction D1 (vehicle front and rear direction) and the cross beam. As a result, when the above-mentioned front and rear loads act on the battery pack, the reinforcing plate in each battery module that receives the front and rear loads has a stroke of the amount of the above-mentioned gap in the first direction D1. With the stroke of the reinforcing plate, the battery module is deformed. More specifically, when the battery pack is viewed from above, the battery module is deformed into a horizontal V-shape. Therefore, in the structure of the comparative example, it is difficult to appropriately improve the resistance to crushing or front and rear collisions accompanied by front and rear loads. In contrast, according to the reinforcing structure of the battery pack 1 involved in this embodiment, the reinforcing plate 13 is arranged in a manner without a gap with the cross beam 24. Therefore, compared with the above-mentioned comparative example, the resistance to crushing or front-rear collision caused by front-rear loads can be greatly improved.

[0037] Next, refer to Figure 3 Other effects brought about by the reinforcement plates 13 being provided to each battery cell group 12 will be described. Figure 3 1 is a diagram for explaining an electrical connection path between a plurality of battery cells 10 in a battery pack 1 according to an embodiment. The electrical connection path here is formed by a bus bar 54 connected between a positive electrode terminal 50 and a negative electrode terminal 52 of the battery pack 1.

[0038] As an electrical connection path in a battery pack having a plurality of battery cell groups such as the battery cell groups 12, it is also possible to adopt the same Figure 3 The following structure is different from the structure shown in the figure: first, the plurality of battery cells included in each battery cell group are electrically connected in series, and then the adjacent battery cell groups are electrically connected in series. However, if such a structure is adopted, the length of the busbar connecting the battery cell groups becomes longer. From the perspective of, for example, the cost of the battery pack increases and from the perspective of protecting the busbar from external input, it is not preferable that the length of the busbar of the battery pack as a whole becomes longer.

[0039] In contrast, in the electrical connection path of this embodiment, Figure 3 As shown, the busbar 54 is not a unit of the battery cell group 12, but a plurality of battery cells 10 are electrically connected in series according to each of the eight divisions A, B, C, D, E, F, G, and H divided by the cross beam 24 and the reinforcing plate 13. In addition, the busbar 54 connects the divisions A, B, C, D, E, F, G, and H in series in sequence. According to the electrical connection path formed in this way, the length of the busbar 54 as the battery group 1 as a whole can be effectively shortened. In more detail, the busbar 54 is formed as follows: after the four divisions A, B, C, and D located on one side in the second direction D2 are connected in series in sequence with the reinforcing plate 13 of each battery cell group 12 as the boundary, the four divisions E, F, G, and H located on the other side in the second direction D2 are connected in series in sequence.

[0040] On this basis, according to Figure 3 The electrical connection path shown in the figure increases the potential difference between the partitions separated as the electrical connection path (for example, between partition A and partition H, between partition B and partition G, and between partition C and partition F). Therefore, when an electrical short circuit occurs due to the action of external input or thermal runaway of the battery cell 10, a thermal chain reaction or spark of the battery cell 10 caused by the high potential difference may be easily generated. Regarding such a technical problem, in the battery pack 1 involved in the present embodiment, a reinforcing plate 13 is sandwiched between the partitions where the high potential difference is generated. Therefore, by the presence of the reinforcing plate 13, it is possible to fully ensure the insulation distance between the battery cells 10 of the two partitions where the high potential difference is generated, and in addition, it is possible to enhance the resistance to the above-mentioned thermal chain reaction and spark generation.

[0041] The thermal insulation structure of the battery cell group will be described.

[0042] In having Figure 3 In the case of the busbar 54 of the electrical connection path shown, the battery pack 1 may also have Figure 4 The battery cell group 14 or Figure 5 A battery cell group 16 is shown in place of the battery cell group 12 .

[0043] Figure 4 It is a diagram showing an example of a heat insulation structure of a battery cell group according to an embodiment. Figure 4 The battery cell group 14 shown includes a heat insulating material 15 interposed between the reinforcing plate 13 and the battery cell 10 in the second direction D2 (stacking direction). More specifically, the heat insulating material 15 is disposed between the adjacent battery cells 10 at both ends of the reinforcing plate 13 in the second direction D2. According to the heat insulating structure using the heat insulating material 15, when thermal runaway occurs in the battery cell 10, it is possible to more reliably suppress the occurrence of a thermal chain reaction beyond the division in the same battery cell group 12.

[0044] Figure 5 It is a diagram showing another example of the heat insulation structure of the battery cell group according to the embodiment. Figure 5 The battery cell group 16 shown includes a reinforcing plate 17 instead of the reinforcing plate 13. The reinforcing plate 17 is formed of a resin material. More specifically, the reinforcing plate 17 is formed of, for example, a fiber-reinforced resin material with high thermal resistance. According to the present heat insulation structure using the reinforcing plate 17 having a higher thermal resistance than the metal reinforcing plate 13, when thermal runaway occurs in the battery cell 10, it is possible to more reliably suppress the occurrence of a thermal chain reaction beyond the division in the same battery cell group 12.

Claims

1. A battery pack, characterized in that: A battery cell group including a plurality of battery cells and a battery case accommodating the battery cell group are provided. The battery case includes a pair of beams, the pair of beams being arranged so as to sandwich the battery cell group in a first direction and extending in a second direction orthogonal to the first direction. The plurality of battery cells are stacked along the second direction, The battery cell group includes a reinforcing plate stacked together with the plurality of battery cells, the reinforcing plate being located at a position where a distance from a center of the battery cell group in the second direction is smaller than a distance from each end of the battery cell group in the second direction. The reinforcing plate is arranged so as to bridge between the pair of cross beams.

2. The battery pack according to claim 1, characterized in that: The plurality of battery cells and the reinforcing plate are joined to the pair of cross beams.

3. The battery pack according to claim 2, characterized in that: The plurality of battery cells and the reinforcing plate are bonded to the pair of cross members by an adhesive.

4. The battery pack according to any one of claims 1 to 3, characterized in that: The battery cell group includes a heat insulating material interposed between the reinforcing plate and the battery cells in the second direction.

5. The battery pack according to any one of claims 1 to 3, characterized in that: The reinforcing plate is formed using a resin material.

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