Battery pack

Abstract

This battery pack is provided with: a plurality of battery cells; a lower case in which the plurality of battery cells are arranged and placed; and a plurality of cross beams erected on the frame of the lower shell. The plurality of cross beams are configured to fasten the plurality of battery cells from both side surfaces. And each battery unit in the plurality of battery units is respectively adhered to the cross beams positioned on two side surfaces of the plurality of cross beams through an adhesive. As a result, it is possible to achieve a high space utilization rate and a highly safe constraining force for a battery pack that accommodates a plurality of battery cells.

Description

Technical Field

[0001] The present invention relates to a battery pack accommodating a plurality of battery cells, and more particularly to a battery pack mounted on a vehicle. Background Art

[0002] For a battery pack mounted on a vehicle, it is conceivable that a considerable amount of external force will be input due to impact or road interference during vehicle driving. Therefore, in order to ensure the safety of the battery pack, it is required to fully restrain the multiple battery cells housed in the battery pack. Patent document 1 discloses a prior art for restraining multiple battery cells. This prior art discloses that a battery stack composed of multiple battery cells is restrained by a pair of end plates arranged at both ends in the stacking direction and connecting rods that fix the pair of end plates.

[0003] In addition, as other documents indicating the technical level in this technical field, there are the following Patent Document 2 and Patent Document 3.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2021-026875

[0005] Patent Document 2: Japanese Patent Application Publication No. 2022-079016

[0006] Patent Document 3: Japanese Patent Application Publication No. 2023-046945

[0007] In the technology disclosed in Patent Document 1, a connecting rod is used to constrain a plurality of battery cells. In order to ensure mechanical strength, the connecting rod needs to be sufficiently thick. Therefore, when the technology disclosed in Patent Document 1 is used, the thickness of the connecting rod will squeeze the space in the battery pack accordingly. This is the main reason for the reduction in the space utilization of the battery pack. In turn, the energy density of the battery pack is reduced. Summary of the invention

[0008] In view of the above technical problems, an object of the present invention is to provide a technology for a battery pack that can achieve high space utilization and high safety restraint.

[0009] The battery pack of the present invention comprises: a plurality of battery cells; a lower shell, the plurality of battery cells are arranged and placed on the lower shell; and a plurality of cross beams mounted on the frame of the lower shell. The plurality of cross beams are configured to fasten the plurality of battery cells from both sides. Each of the plurality of battery cells is bonded to the cross beams located on both sides of the plurality of cross beams by an adhesive.

[0010] The plurality of cross beams function as reinforcing components for reinforcing the shell. According to the present invention, each battery cell is restrained by the plurality of cross beams. That is, the plurality of cross beams are also used as a restraining structure for the plurality of battery cells. In addition, each battery cell is bonded to the cross beams located on both sides thereof by an adhesive. Thus, according to the present invention, a battery pack having a high space utilization rate and a high safety restraining force can be realized.

[0011] In addition, each of the plurality of cross beams may be fastened to the lower housing by a fastening component.

[0012] The battery pack may further include a cooling device mounted on the lower side of the lower case to cool the plurality of battery cells via the lower case, wherein the lower surface of each of the plurality of battery cells is bonded to the lower case with a thermally conductive adhesive.

[0013] In addition, the battery pack may also include: an upper shell covering multiple battery cells; a cooling device installed on the upper side of the upper shell to cool the multiple battery cells through the upper shell, and the upper surface of each of the multiple battery cells is bonded to the upper shell by a thermally conductive adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing the overall structure of a battery pack according to an embodiment.

[0015] Figure 2 It is a diagram showing a portion related to a lower case of a battery pack according to an embodiment.

[0016] Figure 3 FIG. 1 is a diagram showing a partial cross-sectional view of the battery pack according to the embodiment when viewed from the left and right direction.

[0017] Figure 4 FIG. 1 is a diagram showing a partial cross-sectional view of a battery pack according to a modification of the embodiment, as viewed from the left and right direction. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0019] Figure 1 1 is a diagram showing the overall structure of a battery pack 100 according to the present embodiment. Typically, the battery pack 100 according to the present embodiment is mounted on a vehicle. For example, the battery pack 100 is used as a power source for electric vehicles including BEV (Battery Electric Vehicle), PHEV (Plug in Hybrid Electric Vehicle) and HEV (Hybrid Electric Vehicle).

[0020] The battery pack 100 accommodates 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 secondary battery capable of charge and discharge. For example, a lithium-ion secondary battery, a nickel-metal hydride battery, a nickel-cadmium storage battery, etc. In the present embodiment, the plurality of battery cells 20 are each square. However, the shape of each of the plurality of battery cells 20 can be appropriately selected within the scope of the contents described below.

[0021] The plurality of battery cells 20 are housed in a battery case composed 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, resin, or steel plate.

[0022] The lower case 10 is assembled with a plurality of beams 41 which are mounted on the frame of the lower case 10. The plurality of beams 41 are reinforcing members for reinforcing the battery case. In particular, the plurality of beams 41 have the effect of greatly improving the durability of the battery case against impacts from the left and right directions.

[0023] The lower case 10 is divided by a plurality of beams 41. A certain number of battery cells 20 are arranged and placed in each space divided by the beams 41. The upper case 30 covering the battery cells 20 is assembled to the lower case 10. In this way, a battery case accommodating the battery cells 20 is formed.

[0024] In particular, in this embodiment, a plurality of battery cells 20 are housed in the battery case without being modularized and directly placed on the lower case 10. That is, the battery pack 100 involved in this embodiment adopts the so-called CTP (Cell To Pack) structure. The CTP structure does not require a modular structure, so it can effectively improve the space utilization and energy density of the battery pack 100.

[0025] The battery pack 100 further includes a first cooling device 61 mounted on the lower side of the lower case 10 , a second cooling device 62 mounted on the upper side of the upper case 30 , and a shared panel 70 mounted on the lower side of the first cooling device 61 .

[0026] The first cooling device 61 and the second cooling device 62 adjust the temperature of the plurality of battery cells 20 by exchanging heat with the plurality of battery cells 20 .

[0027] The first cooling device 61 exchanges heat from the lower surfaces of the plurality of battery cells 20 via the lower housing 10. That is, the first cooling device 61 cools the lower surfaces of the plurality of battery cells 20. For example, the first cooling device 61 has a cooling circuit that is configured to pass through the lower surfaces of the plurality of battery cells 20 via the lower housing 10. The first cooling device 61 exchanges heat with the plurality of battery cells 20 via a refrigerant flowing in the cooling circuit. The lower housing 10 may be formed to have a space on the lower side for the cooling circuit of the first cooling device 61 to pass through.

[0028] The second cooling device 62 exchanges heat from the upper surfaces of the plurality of battery cells 20 via the upper housing 30. That is, the second cooling device 62 cools the upper surfaces of the plurality of battery cells 20. For example, the second cooling device 62 has a cooling circuit that is configured to pass through the upper surfaces of the plurality of battery cells 20 via the upper housing 30. The second cooling device 62 exchanges heat with the plurality of battery cells 20 via the refrigerant flowing in the cooling circuit. The upper housing 30 may be formed to have a space on the upper side for the cooling circuit of the second cooling device 62 to pass through.

[0029] The shared panel 70 protects the battery pack 100 from external force input from below due to road interference or the like. The shared panel 70 is provided with a gap between the lower case 10 and the first cooling device 61. The shared panel 70 is made of, for example, light metal, resin, or steel plate.

[0030] The battery pack 100 may include other structures not shown in the figure. For example, the battery pack 100 may include various sensors and wiring components used in the battery management system.

[0031] It is conceivable that a considerable amount of external force is input to the battery pack 100 mounted on a vehicle due to impact or road interference during vehicle travel. The external force input to the battery pack 100 may cause the plurality of battery cells 20 to shake inside the battery pack 100, which is a problem from the perspective of the safety of the battery pack 100. Therefore, it is required to fully restrain each of the plurality of battery cells 20 inside the battery pack 100.

[0032] The battery cell expands and contracts according to the state of degradation and SOC (State Of Charge). The load generated by the battery cell changes with the expansion and contraction of the battery cell. Therefore, in order to safely constrain the battery cell, it is necessary to consider the expansion and contraction of the battery cell. That is, the constraint of the battery cell needs to be performed while maintaining the application of the minimum load required for the constraint, while not releasing the constraint even when the load generated by the battery cell reaches the maximum load.

[0033] However, as described above, the battery pack 100 of the present embodiment has a CTP structure in which a plurality of battery cells 20 are directly placed on the lower housing 10. On the one hand, the CTP structure can improve space utilization and energy density, but on the other hand, how to ensure the constraint of the battery cells becomes a technical problem. The use of additional components to constrain the battery cells will result in a decrease in the space utilization of the battery pack 100, which violates the purpose of the CTP structure. On the other hand, if only the constraint is based on the adhesive force of the adhesive, there is a concern that the adhesive will peel off under the condition of maximum load. This makes it difficult to use battery cells with large expansion, and the range of selectable battery cells is narrow.

[0034] The battery pack 100 according to the present embodiment has a restraint structure for a plurality of battery cells 20 that can achieve high space utilization of a CTP structure and a high safety restraint force. Figure 2 and Figure 3 The restraint structure of the plurality of battery cells 20 according to the present embodiment will be described. Figure 2 A top view showing a portion of the battery pack 100 associated with the lower case 10 . Figure 2 It also includes diagrams showing more detailed structures. Figure 3 FIG. 1 is a partial cross-sectional view of the battery pack 100 as viewed from the left and right directions.

[0035] The battery pack 100 according to the present embodiment further uses a plurality of cross members 41 assembled to the lower case 10 as reinforcement members as a restraining structure for the plurality of battery cells 20 .

[0036] As described above, a certain number of the plurality of battery cells 20 are arranged in each space divided by the plurality of beams 41. Here, the plurality of beams 41 are configured to fasten the plurality of battery cells 20 from both sides (see Figure 2 ). In this way, the plurality of cross beams 41 mechanically constrain each battery cell 20 from both sides.

[0037] Furthermore, each battery cell 20 is bonded to the cross beams 41a and 41b located on both sides thereof by adhesives 51a and 51b (see Figure 3 ). By combining mechanical restraint with bonding by adhesive, each battery cell 20 can be restrained more firmly. In particular, even if adhesive peeling occurs, the load based on the mechanical restraint is maintained, so that highly safe restraint can be performed. The type and specification of the adhesives 51a and 51b are not particularly limited. The adhesive strength of the adhesives 51a and 51b can be determined according to the required restraining force.

[0038] The restraining structure of the plurality of battery cells 20 in the present embodiment restrains the plurality of battery cells 20 also on the lower and upper surfaces thereof.

[0039] The lower surface of each battery cell 20 is bonded to the lower case 10 via a thermally conductive adhesive 52a (see Figure 3 ). Each battery cell 20 is constrained on the lower surface by the adhesive force of the thermally conductive adhesive 52a. In addition, the lower surface of each battery cell 20 is cooled by the first cooling device 61 through the lower shell 10. The thermal conductivity of the thermally conductive adhesive 52a promotes heat dissipation from the lower surface of each battery cell 20. Therefore, by using the thermally conductive adhesive 52a, the cooling performance of the lower surface cooling performed by the first cooling device 61 can be improved. The type and specification of the thermally conductive adhesive 52a are not particularly limited. The adhesive force and thermal conductivity of the thermally conductive adhesive 52a can be determined according to the required restraining force and cooling performance.

[0040] The plurality of battery cells 20 are fastened from the upper surface by a plurality of band members 42 at regular intervals (see Figure 2 ).exist Figure 2 In the embodiment, each band member 42 fastens a certain number of battery cells 20 from the upper surface according to each space divided by the plurality of cross beams 41. Each band member 42 is formed, for example, of steel or carbon fiber. In order to ensure insulation, each band member 42 may be subjected to an insulating coating based on a cationic coating or the like. The plurality of band members 42 mechanically constrain each battery cell 20 from the upper surface. In addition, the upper surface of each battery cell 20 is bonded to the band member 42 by an adhesive 51c (see Figure 3 ). In this way, each battery cell 20 is constrained on the upper surface by the mechanical constraints of the plurality of band members 42 and the adhesive force of the adhesive 51c. The type and specification of the adhesive 51c are not particularly limited.

[0041] The upper surface of each battery cell 20 is also bonded to the upper case 30 by a thermally conductive adhesive 52b (see Figure 3 ). Each battery cell 20 is constrained on the upper surface by the adhesive force of the thermally conductive adhesive 52b. In addition, the upper surface of each battery cell 20 is cooled by the second cooling device 62 via the upper shell 30. The thermal conductivity of the thermally conductive adhesive 52b promotes heat dissipation on the upper surface of each battery cell 20. Therefore, by using the thermally conductive adhesive 52b, the cooling performance of the upper surface cooling performed by the second cooling device 62 can be improved. The type and specification of the thermally conductive adhesive 52b are not particularly limited.

[0042] By constraining the multiple battery cells 20 on the lower surface and the upper surface in this way, the restraining force can be further improved. In particular, according to the restraining structure of the battery cells 20 of this embodiment, it is possible to achieve both the promotion of cooling performance and the improvement of restraining force. In addition, in view of the required restraining force, it is also possible to restrain the multiple battery cells 20 on the upper surface only by bonding with the thermally conductive adhesive 52b. This can further improve the space utilization.

[0043] As described above, according to the battery pack 100 involved in this embodiment, each battery cell 20 is constrained by a plurality of beams 41. Thus, a plurality of battery cells 20 can be constrained without the need for additional components for the constraints. In addition, each battery cell 20 is bonded to the beams 41a, 41b located on both sides thereof by adhesives 51a, 51b. Thus, it is possible to perform constraints with less waste of space. Furthermore, since the constraints are performed by combining mechanical constraints with the bonding of adhesives, a large restraining force can be achieved. In particular, even if adhesive peeling occurs, the application of the load generated by the mechanical constraints is maintained, so that highly safe constraints can be achieved.

[0044] In this way, the battery pack 100 according to the present embodiment achieves high space utilization and high safety restraint. In addition, the lower surface of each battery cell 20 is bonded to the lower housing 10 by the thermally conductive adhesive 52a. And, the upper surface of each battery cell 20 is bonded to the upper housing 30 by the thermally conductive adhesive 52b. Thus, it is possible to improve the restraint while improving the cooling performance.

[0045] The battery pack 100 according to the present embodiment may also adopt a restraining structure for a plurality of battery cells 20 as described below.

[0046] Figure 4 FIG. 1 is 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, a plurality of cross members 41 are fastened to the lower case 10 by fastening components. The fastening components are composed of bolts and nuts, for example. Figure 4 In the embodiment, the cross beams 41a and 41b are fastened to the lower housing 10 by fastening components 80a and 80b, respectively. The fastening portions may be provided at multiple locations in the longitudinal direction of each cross beam 41.

[0047] By adopting such a structure, multiple beams 41 can be fixed to the battery case in the vertical direction. As a result, the constraints achieved by the multiple beams 41 can be more firmly maintained. The constraints can also be made more secure by increasing the number of fastening parts. In particular, even when the adhesives 51a, 51b, 51c or the thermally conductive adhesives 52a, 52b are peeled off, a safer constraint can be maintained.

Claims

1. A battery pack, characterized in that: have: a plurality of battery cells; a lower housing on which the plurality of battery cells are arranged and placed; and A plurality of beams are mounted on the frame of the lower shell. The plurality of cross beams are configured to fasten the plurality of battery cells from two sides. Each battery cell in the plurality of battery cells is bonded to a cross beam located on two side surfaces of the cross beams through an adhesive.

2. The battery pack according to claim 1, characterized in that: Each of the plurality of cross beams is fastened to the lower shell body through a fastening component.

3. The battery pack according to claim 1 or 2, characterized in that: A cooling device is also provided, the cooling device being installed on the lower side of the lower case and cooling the plurality of battery cells through the lower case. The lower surface of each of the plurality of battery cells is bonded to the lower case by a thermally conductive adhesive.

4. The battery pack according to claim 1 or 2, characterized in that: Also available: an upper housing covering the plurality of battery cells; and A cooling device is installed on the upper side of the upper shell to cool the plurality of battery cells through the upper shell. The upper surface of each of the plurality of battery cells is bonded to the upper case by a thermally conductive adhesive.

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