Battery pack

Abstract

To provide a battery pack housing multiple battery cells capable of achieving a high space utilization rate and highly safe restraining force.SOLUTION: A battery pack 100 includes: multiple battery cells 20; a lowercase 10 in which multiple battery cells 20 are placed; and multiple cross members 41 cross-bridging between frames of the lowercase 10. The multiple cross members 41 are placed so as to fasten multiple battery cells 20 from both sides. Each of the multiple battery cells 20 is bonded to the cross members 41a and 41b which are located on both sides in multiple cross members 41 via adhesives 51a and 51b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a battery pack that houses a plurality of battery cells, and more particularly to a battery pack that is mounted on a vehicle. [Background technology]

[0002] A battery pack mounted on a vehicle is expected to be subjected to a considerable amount of external force due to impacts and road surface interference while the vehicle is traveling. Therefore, in order to ensure the safety of the battery pack, it is necessary to sufficiently restrain the multiple battery cells contained in the battery pack within the battery pack. Patent Document 1 discloses one conventional technique for restraining multiple battery cells. This conventional technique discloses that a battery stack consisting of multiple battery cells is restrained by a pair of end plates arranged at both ends in the stacking direction and a bind bar that fixes the pair of end plates.

[0003] Other documents that demonstrate the technical level of this technical field include the following Patent Documents 2 and 3. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-026875 [Patent Document 2] Patent Publication No. 2022-079016 [Patent Document 3] JP 2023-046945 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology disclosed in Patent Document 1, a bind bar is used to restrain multiple battery cells. The bind bar needs to be thick enough to ensure mechanical strength. Therefore, when the technology disclosed in Patent Document 1 is used, the space inside the battery pack is compressed by the thickness of the bind bar. This causes a decrease in the space utilization rate of the battery pack. As a result, the energy density of the battery pack decreases.

[0006] In view of the above-mentioned problems, one object of the present disclosure is to provide a technology that can realize high space utilization rate and highly safe restraining force for a battery pack. [Means for solving the problem]

[0007] The battery pack according to the present disclosure includes a plurality of battery cells, a lower case in which the plurality of battery cells are arranged and mounted, and a plurality of cross members that span the frame of the lower case. The cross members are arranged to fasten the plurality of battery cells from both side surfaces. Each of the plurality of battery cells is bonded to one of the cross members located on both side surfaces via an adhesive. Effect of the Invention

[0008] The multiple cross members function as reinforcing members that reinforce the case. According to the present disclosure, each battery cell is restrained by the multiple cross members. That is, the multiple cross members are also used as a restraining structure for the multiple battery cells. Also, each battery cell is bonded to the cross members located on both sides thereof via an adhesive. In this way, according to the present disclosure, it is possible to realize a battery pack that has a high space utilization rate and a restraining force that is highly safe. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an overall configuration of a battery pack according to an embodiment; [Diagram 2] 4A and 4B are diagrams showing parts related to a lower case of the battery pack according to the embodiment; [Diagram 3] FIG. 2 is a diagram showing a partial cross-sectional view of the battery pack according to the embodiment, as viewed from the left and right direction. [Figure 4] 13 is a diagram showing a partial cross-sectional view of a battery pack according to a modified example of the embodiment, as viewed from the left and right direction. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] 1 Battery pack 1 is a diagram showing an overall configuration of a battery pack 100 according to the present embodiment. The battery pack 100 according to the present embodiment is typically mounted on a vehicle. For example, the battery pack 100 is used as a power source for electric vehicles including a BEV (Battery Electric Vehicle), a PHEV (Plug in Hybrid Electric Vehicle), and an HEV (Hybrid Electric Vehicle).

[0012] The battery pack 100 contains a plurality of battery cells 20 for achieving a desired output. The plurality of battery cells 20 are appropriately connected by bus bars. Each of the plurality of battery cells 20 is typically a rechargeable secondary battery. For example, the battery cells 20 may be a lithium ion secondary battery, a nickel-metal hydride battery, a nickel-cadmium storage battery, or the like. In this embodiment, each of the plurality of battery cells 20 is rectangular. However, within the scope of the applicability of the contents described below, the shape of each of the plurality of battery cells 20 may be suitably selected.

[0013] The multiple battery cells 20 are housed in a battery case that is made up of a lower case 10 and an upper case 30. The lower case 10 and the upper case 30 are made of, for example, light metal or resin, or a steel plate.

[0014] A plurality of cross members 41 that span the frame of the lower case 10 are attached to the lower case 10. The plurality of cross members 41 are reinforcing members that reinforce the battery case. In particular, the plurality of cross members 41 have the effect of greatly improving the durability of the battery case against impacts from the left and right directions.

[0015] The lower case 10 is divided by a plurality of cross members 41. A certain number of the plurality of battery cells 20 are placed side by side in each space divided by the plurality of cross members 41. Then, the upper case 30 that covers the plurality of battery cells 20 is assembled to the lower case 10. In this manner, a battery case that houses the plurality of battery cells 20 is constructed.

[0016] Particularly in this embodiment, the multiple battery cells 20 are housed in the battery case in a state in which they are directly placed on the lower case 10 without being modularized. In other words, the battery pack 100 according to this embodiment employs a so-called CTP (Cell To Pack) structure. Since the CTP structure does not require a structure associated with modularization, it is possible to effectively improve the space utilization rate and energy density of the battery pack 100.

[0017] The battery pack 100 further includes a cooling device 61 (hereinafter referred to as the "first cooling device 61") attached to the underside of the lower case 10, a cooling device 62 (hereinafter referred to as the "second cooling device 62") attached to the upper side of the upper case 30, and a share panel 70 attached to the underside of the first cooling device 61.

[0018] The first cooling device 61 and the second cooling device 62 exchange heat with the plurality of battery cells 20 to adjust the temperature of the plurality of battery cells 20 .

[0019] The first cooling device 61 exchanges heat from the underside of the multiple battery cells 20 across the lower case 10. That is, the first cooling device 61 cools the underside of the multiple battery cells 20. For example, the first cooling device 61 has a cooling circuit that is arranged to pass through the undersides of the multiple battery cells 20 across the lower case 10. The first cooling device 61 exchanges heat with the multiple battery cells 20 via a refrigerant that flows through the cooling circuit. The lower case 10 may be formed to have a space on the underside to pass the cooling circuit of the first cooling device 61 through.

[0020] The second cooling device 62 exchanges heat from the top surfaces of the multiple battery cells 20 across the upper case 30. That is, the second cooling device 62 cools the top surfaces of the multiple battery cells 20. For example, the second cooling device 62 has a cooling circuit that is arranged to pass through the top surfaces of the multiple battery cells 20 across the upper case 30. The second cooling device 62 exchanges heat with the multiple battery cells 20 via a refrigerant that flows through the cooling circuit. The upper case 30 may be formed to have a space on the upper side for passing the cooling circuit of the second cooling device 62.

[0021] The share panel 70 protects the battery pack 100 against external forces input from below due to road interference, etc. The share panel 70 is provided with a gap between it and the lower case 10 and the first cooling device 61. The share panel 70 is made of, for example, light metal or resin, or a steel plate.

[0022] The battery pack 100 may include other components (not shown). For example, the battery pack 100 may include various sensors and wiring components for a battery management system.

[0023] 2 Battery cell restraint structure The battery pack 100 mounted on a vehicle is expected to be subjected to a considerable amount of external force due to shocks and road surface interference while the vehicle is traveling. Vibrations of the multiple battery cells 20 in the battery pack 100 due to external forces input to the battery pack 100 are problematic from the viewpoint of the safety of the battery pack 100. For this reason, it is necessary to sufficiently restrain each of the multiple battery cells 20 within the battery pack 100.

[0024] Battery cells expand and contract depending on the deterioration state and SOC (State Of Charge). The load generated by a battery cell changes depending on the expansion and contraction of the battery cell. Therefore, in order to safely restrain the battery cell, the expansion and contraction of the battery cell must be taken into consideration. In other words, the battery cell must be restrained in such a way that the minimum load required for restraint is maintained, while the restraint is not released even under conditions where the load generated by the battery cell is at its maximum.

[0025] As described above, the battery pack 100 according to the present embodiment has a CTP structure in which a plurality of battery cells 20 are directly mounted on the lower case 10. While the CTP structure can improve the space utilization rate and the energy density, how to ensure the restraint of the battery cells is an issue. Using additional members to restrain the battery cells reduces the space utilization rate of the battery pack 100, which goes against the purpose of the CTP structure. On the other hand, there is a concern that the adhesion peeling under the maximum load condition occurs when the battery cells are restrained only by the adhesive force using an adhesive. This makes it difficult to adopt battery cells with a large expansion amount, narrowing the range of battery cell selection.

[0026] The battery pack 100 according to this embodiment has a restraining structure for a plurality of battery cells 20 that can realize a highly safe restraining force while achieving a high space utilization rate by the CTP structure. Hereinafter, the restraining structure for a plurality of battery cells 20 according to this embodiment will be described with reference to Figs. 2 and 3. Fig. 2 shows a top view of a portion of the battery pack 100 related to the lower case 10. Fig. 2 further includes a diagram showing a more detailed configuration. Fig. 3 shows a partial cross-sectional view of the battery pack 100 as viewed from the left and right direction.

[0027] In the battery pack 100 according to this embodiment, the multiple cross members 41 that are attached to the lower case 10 as reinforcing members are also used as a restraining structure for the multiple battery cells 20.

[0028] As described above, a certain number of the battery cells 20 are placed side by side in each space partitioned by the cross members 41. Here, the cross members 41 are arranged so as to fasten the battery cells 20 from both side surfaces (see FIG. 2). In this way, the cross members 41 mechanically restrain each battery cell 20 from both side surfaces.

[0029] Furthermore, each battery cell 20 is adhered to cross members 41a, 41b located on both sides thereof via adhesives 51a, 51b (see FIG. 3). By combining mechanical restraint and adhesion by adhesive, each battery cell 20 can be more firmly restrained. In particular, even if adhesion peels off, the application of load by mechanical restraint is maintained, enabling highly safe restraint. There are no particular limitations on the type or standard of the adhesives 51a, 51b. The adhesive strength of the adhesives 51a, 51b may be determined according to the required restraining force.

[0030] The restraint structure for the multiple battery cells 20 according to this embodiment further restrains the multiple battery cells 20 at their bottom and top surfaces.

[0031] The underside of each battery cell 20 is bonded to the lower case 10 via a thermally conductive adhesive 52a (see FIG. 3). The adhesive strength of the thermally conductive adhesive 52a restrains the underside of each battery cell 20. The underside of each battery cell 20 is cooled by the first cooling device 61 with the lower case 10 sandwiched therebetween. The thermal conductivity of the thermally conductive adhesive 52a promotes heat dissipation from the underside of each battery cell 20. Therefore, by using the thermally conductive adhesive 52a, it is possible to improve the cooling performance of the underside cooling by the first cooling device 61. The type and specifications of the thermally conductive adhesive 52a are not particularly limited. The adhesive strength and thermal conductivity performance of the thermally conductive adhesive 52a may be determined according to the required restraint force and cooling performance.

[0032] The battery cells 20 are fastened from the top by a plurality of band members 42 in units of a certain number (see FIG. 2). In FIG. 2, each band member 42 fastens a certain number of battery cells 20 from the top for each space partitioned by the plurality of cross members 41. Each band member 42 is formed of, for example, steel or carbon fiber. Each band member 41 may be subjected to insulating coating such as cationic coating to ensure insulation. The band members 42 mechanically restrain each battery cell 20 from the top. The top surface of each battery cell 20 is also bonded to the band member 42 via an adhesive 51c (see FIG. 3). In this way, each battery cell 20 is restrained at the top by the mechanical restraint by the band members 42 and the adhesive force of the adhesive 51c. The type and standard of the adhesive 51 are not particularly limited.

[0033] The top surface of each battery cell 20 is further adhered to the upper case 30 via a thermally conductive adhesive 52b (see FIG. 3). The adhesive force of the thermally conductive adhesive 52b restrains the top surface of each battery cell 20. The top surface of each battery cell 20 is cooled by the second cooling device 62 with the upper case 30 sandwiched therebetween. The thermal conductivity of the thermally conductive adhesive 52b promotes heat dissipation from the top surface of each battery cell 20. Therefore, by using the thermally conductive adhesive 52b, it is possible to improve the cooling performance of the top surface cooling by the second cooling device 62. There are no particular limitations on the type or specification of the thermally conductive adhesive 52b.

[0034] By restraining the multiple battery cells 20 at their bottom and top surfaces in this manner, the restraining force can be further increased. In particular, the restraining structure for the battery cells 20 according to this embodiment can achieve both improved cooling performance and improved restraining force. Note that, in consideration of the necessary restraining force, the restraint of the multiple battery cells 20 at their top surfaces can also be performed only by adhesion with the thermally conductive adhesive 52b. This can further increase the space utilization rate.

[0035] 3. Effects As described above, according to the battery pack 100 of this embodiment, each battery cell 20 is restrained by the multiple cross members 41. This allows the multiple battery cells 20 to be restrained without the need for additional members for restraint. Each battery cell 20 is bonded to the cross members 41a, 41b located on both sides thereof via adhesives 51a, 51b. This allows restraint with little waste of space. Furthermore, since restraint is achieved by combining mechanical restraint and adhesion by adhesive, a large restraining force can be achieved. In particular, even if adhesion peels off, the application of load by mechanical restraint is maintained, making it possible to achieve highly safe restraint.

[0036] In this way, the battery pack 100 according to this embodiment achieves high space utilization rate and highly safe binding force. The bottom surface of each battery cell 20 is bonded to the lower case 10 via a thermally conductive adhesive 52a. The top surface of each battery cell 20 is bonded to the upper case 10 via a thermally conductive adhesive 52b. This makes it possible to improve the binding force and the cooling performance.

[0037] 4. Variations The battery pack 100 according to this embodiment may employ a restraining structure for the multiple battery cells 20, which will be described below.

[0038] Fig. 4 shows a partial cross-sectional view of a battery pack 100 according to a modified example. In the battery pack 100 according to the modified example, each of the multiple cross members 41 is fastened to the lower case 10 by fastening parts 80. In Fig. 4, the fastening parts 80 are, for example, composed of bolts and nuts, and each of the cross members 41a, 41b is fastened to the lower case 10 by fastening parts 80a, 80b. The fastening points may be provided at multiple points in the longitudinal direction of each cross member 41.

[0039] By adopting such a configuration, the multiple cross members 41 can be fixed to the battery case in the vertical direction. This makes it possible to maintain the restraint by the multiple cross members 41 more firmly. It is also possible to further strengthen the restraint by increasing the number of fastening points. In particular, even if the adhesives 51a, 51b, and 51c or the thermally conductive adhesives 52a and 52b are peeled off, it becomes possible to maintain a more secure restraint. [Explanation of symbols]

[0040] 10 lower case, 20 battery cell, 30 upper case, 41 cross member 42 band member, 51 adhesive, 52 thermally conductive adhesive, 61 first cooling device, 62 second cooling device, 70 share panel, 80 fastening parts, 100 battery pack

Claims

1. A plurality of battery cells; a lower case in which the plurality of battery cells are arranged and placed; A plurality of cross members that traverse the frame of the lower case; Equipped with the plurality of cross members are arranged to fasten the plurality of battery cells from both side surfaces, Each of the plurality of battery cells is bonded to one of the plurality of cross members located on both sides thereof via an adhesive. Battery pack.

2. 2. The battery pack according to claim 1, Each of the plurality of cross members is fastened to the lower case by a fastening part. Battery pack.

3. 3. The battery pack according to claim 1, a cooling device attached to a lower side of the lower case and configured to cool the plurality of battery cells by sandwiching the lower case therebetween; The bottom surface of each of the plurality of battery cells is bonded to the lower case via a thermally conductive adhesive. Battery pack.

4. 3. The battery pack according to claim 1, an upper case covering the plurality of battery cells; a cooling device attached to an upper side of the upper case and configured to cool the plurality of battery cells by sandwiching the upper case; Further equipped with The upper surface of each of the plurality of battery cells is bonded to the upper case via a thermally conductive adhesive. Battery pack.

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