Battery pack mounting structure

Abstract

To provide a battery pack mounting structure that suppresses fluctuations in restraining load due to temperature fluctuations.SOLUTION: A battery pack mounting structure 1 according to the present disclosure is a battery pack mounting structure that fastens a battery pack 10 and a body 20 via a plurality of brackets 21, and includes a battery module 11 having a plurality of stacked battery cells, and a housing 12 that houses the battery module in a constrained state, and each of the plurality of brackets has a housing fastening point 23 that fastens the housing to the bracket, where a body fastening point 22 that fastens the body to the bracket, and the body fastening points are located inward of the housing fastening points in a first direction 100 in which the plurality of battery cells are stacked.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery pack mounting structure, and more particularly to a battery pack mounting structure in which a battery pack and a body are fastened via a plurality of brackets. [Background technology]

[0002] Battery packs each including a plurality of stacked battery cells are used as large-capacity power supplies for electric vehicles, etc. Such battery packs are area-saving and lightweight, making them useful for installation in limited spaces such as inside a vehicle.

[0003] Patent document 1 discloses a battery pack including a battery module having a stack of multiple battery cells, brackets for fixing the battery module to a housing at the battery cells at both ends of the stack, and a heat conductive member interposed between the stack and the housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-041653 A Summary of the Invention [Problem to be solved by the invention]

[0005] To construct a stack, it is necessary to apply an appropriate restraining load to the battery cells to hold them in the housing. However, in a battery pack having a battery module in which multiple battery cells are stacked, the battery module may be deflected due to temperature, such as fluctuations in the environmental temperature or thermal expansion of the battery cells, and the restraining load may fluctuate significantly.

[0006] In order to suppress bending of the battery module, the battery module disclosed in Patent Document 1 is provided with a thermally conductive member to promote heat dissipation from the battery cells. It is also disclosed that when the stack is fixed to the housing, an elastic member is provided to suppress bending of the stack caused by a reaction force applied from the thermally conductive member to the stack, and that the elastic member is compressed when the battery cells expand, thereby allowing a certain amount of expansion of the battery cells.

[0007] On the other hand, the structure of the battery module disclosed in Patent Document 1 requires materials such as a heat conductive material and an elastic material, which is disadvantageous in terms of cost.

[0008] The present disclosure has been made to solve such problems, and has an object to provide a battery pack mounting structure that suppresses fluctuations in restraining load due to temperature fluctuations. [Means for solving the problem]

[0009] The battery pack mounting structure according to the present disclosure is a battery pack mounting structure in which a battery pack and a body are fastened via a plurality of brackets, the battery pack including a battery module in which a plurality of battery cells are stacked, and a housing that houses the battery module in a restrained state, the plurality of brackets each having a housing fastening point that fastens the housing to the bracket and a body fastening point that fastens the body to the bracket, the body fastening point being located on the inside of the housing fastening point in a first direction in which the plurality of battery cells are stacked. In this way, a battery pack mounting structure that suppresses fluctuations in restraining load due to temperature fluctuations can be provided.

[0010] The battery module may have a coefficient of thermal expansion greater than that of the housing, thereby providing a battery pack mounting structure that suppresses fluctuations in restraining load due to temperature fluctuations. Effect of the Invention

[0011] The present disclosure makes it possible to provide a battery pack mounting structure that suppresses fluctuations in restraining load due to temperature fluctuations. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a plan view of the battery pack mounting structure according to the present disclosure. [Diagram 2] 1 is a graph illustrating a load change during a temperature change according to the present disclosure. [Diagram 3] 1A and 1B are diagrams illustrating the positional relationship of brackets according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An example of the configuration of a battery pack mounting structure according to the present disclosure will be described with reference to Fig. 1. A battery pack 10 shown in Fig. 1 includes at least a battery module 11 in which multiple battery cells are stacked, and a housing 12 that houses the battery module 11 in a constrained state. Note that the battery module 11 is pressurized and constrained so that a constraining load is applied in the direction in which the multiple battery cells are stacked, as shown by the arrow in Fig. 1. Hereinafter, the direction in which the constraining load is applied is referred to as a first direction 100.

[0014] The battery pack mounting structure 1 according to the present disclosure is a structure in which a battery pack 10 and a body 20 are fastened via a plurality of brackets 21. The plurality of brackets 21 are fastened to the body 20 at body fastening points 22 and to the housing 12 at housing fastening points 23. Here, it is preferable that the body fastening points 22 are located more inward than the housing fastening points 23 in the first direction.

[0015] With the above-described configuration, bracket 21 thermally expands in first direction 100 due to an increase in temperature, thereby assisting the thermal expansion of housing 12, thereby providing a battery pack mounting structure that suppresses fluctuations in the restraining load due to temperature fluctuations.

[0016] This mechanism will be explained with reference to Figures 2 and 3. Figure 2(a) is a graph that illustrates the load fluctuations during temperature fluctuations, plotting the dimensions of the battery module 11 and the casing 12 on the horizontal axis and the load applied thereto on the vertical axis. The intersection of the restraining load fluctuations 111 of the battery module 11 and the restraining load fluctuations 121 of the casing 12 is shown as the restraining load 101 at 25°C. Figure 2(a) also illustrates a case where the thermal expansion coefficient of the battery module 11 is greater than that of the casing 12.

[0017] When the environmental temperature rises from 25° C. to 60° C., the battery module 11 increases in size due to the effect of temperature fluctuation, as shown by the restraining load fluctuation 112. The amount of this increase is shown as the thermal expansion 110 of the battery module 11.

[0018] Similarly, the housing 12 increases in dimension due to the effect of temperature fluctuations as shown by the restraint load fluctuations 122. This increase is shown as thermal expansion 120 of the housing 12.

[0019] The intersection of the restraint load variation 112 of the battery module 11 and the restraint load variation 122 of the casing 12 is shown as the restraint load 202 at 60° C., and it can be seen that the restraint load increases due to the difference in the amount of expansion between the battery module 11 and the casing 12 due to an increase in temperature.

[0020] 3 between brackets 21A and 21B, when the environmental temperature rises from 25° C. to 60° C., the dimensions of the housing 12 according to the present disclosure increase due to the effect of temperature fluctuations as shown by restraining load fluctuations 123. Details of brackets 21A and 21B will be described later.

[0021] Depending on the presence or absence of thermal expansion 210 between brackets 21A and 21B, the intersections of restraint load fluctuations 112 of battery module 11 and restraint load fluctuations 122 and 123 of housing 12 are shown as restraint loads 202 and 102 at 60° C., respectively. The restraint load 202 can be considered as the restraint load when body fastening point 22 is located on the same side as or outside housing fastening point 23 in the first direction 100.

[0022] On the other hand, the restraining load 102 is a restraining load when thermal expansion 210 between brackets 21A and 21B is added because the housing 12 according to the present disclosure, i.e., the body fastening point 22, is located more inward than the housing fastening point 23 in the first direction 100. As can be seen by comparing the restraining loads 202 and 102, the increase in the restraining load can be suppressed by the body fastening point 22 being located more inward than the housing fastening point 23 in the first direction 100. Therefore, it can be seen that the effect of the battery pack mounting structure according to the present disclosure can be obtained when the thermal expansion coefficient of the battery module 11 is greater than that of the housing 12.

[0023] 2(b) shows a case where the thermal expansion coefficient of the battery module 11 is smaller than that of the housing 12. Even in this case, as can be seen by comparing the restraining loads 202 and 102, the battery pack mounting structure according to the present disclosure makes it possible to suppress an increase in the restraining load.

[0024] Fig. 3 is a diagram for explaining the positional relationship of brackets in the battery pack mounting structure 1 shown in Fig. 1. Brackets 21A and 21B according to the present disclosure can be made of various materials, but as an example, a case in which a cast iron bracket is used will be considered.

[0025] In any one bracket 21A, assuming that the distance L between the body fastening point 22A and the housing fastening point 23A in the first direction 100 is 50 mm and the environmental temperature rises from 25°C to 60°C, the expansion amount ΔL (mm) of the bracket 21 is calculated to be 0.0184 (mm) as follows. ΔL=αLΔT=10.5×10 6 ×50×(60-25)≒0.0184(mm) Here, α is the linear expansion coefficient of cast iron and ΔT is the temperature difference.

[0026] The distance between the body fastening points 22A and 22B of the pair of brackets 21A and 21B facing each other in the first direction 100 of the housing 12 expands by 0.0368 (=0.0184×2) (mm). The load fluctuation reduction amount ΔF obtained by this expansion is calculated to be 46 (N) as follows. ΔF=kΔL×2=2500×0.0184×2=46(N) where k is the modular spring constant (N / mm).

[0027] Therefore, by applying the battery pack mounting structure according to the present disclosure, it is possible to reduce the restraint load fluctuation by 46 (N). Note that although the effect when the temperature rises is calculated, the same effect is obtained when the temperature drops. Furthermore, the battery pack mounting structure according to the present disclosure is more effective in a configuration in which the restraint load increases with an increase in temperature and decreases with a decrease in temperature.

[0028] In this way, it is possible to provide a battery pack mounting structure that suppresses fluctuations in the restraining load due to temperature fluctuations.

[0029] The present disclosure is not limited to the above, and can be modified as appropriate without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0030] 1 Battery pack mounting structure 10 Battery pack 11 Battery module 12. Chassis 20 Body 21, 21A, 21B bracket 22, 22A Body fastening points 23, 23A Housing fastening point 100 First Direction 110 Thermal expansion of battery modules 120 Thermal expansion of the housing 210 Thermal expansion between brackets 101, 102, 202 Restraint load 111, 112 Battery module restraint load fluctuation 121, 122, 123 Housing restraint load fluctuation

Claims

1. A battery pack mounting structure for fastening a battery pack and a body via a plurality of brackets, wherein the battery pack comprises: a battery module in which a plurality of battery cells are stacked; and a housing that houses the battery module in a constrained state, wherein each of the plurality of brackets has: a housing fastening point for fastening the housing and the bracket; and a body fastening point for fastening the body and the bracket, wherein the battery module has a coefficient of thermal expansion greater than that of the housing, and the body fastening point is located closer to the inside than the housing fastening point with respect to a first direction in which the plurality of battery cells are stacked. A battery pack mounting structure.

2. The battery module has a coefficient of thermal expansion greater than that of the housing. The battery pack mounting structure according to claim 1.

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