Battery pack mounting structure

Abstract

The utility model provides a battery pack carrying structure which can restrain the change of a constraint load caused by temperature change. A battery pack mounting structure (1) in which a battery pack (10) and a vehicle body (20) are fastened by means of a plurality of brackets (21), the battery pack being provided with a battery module (11) in which a plurality of battery cells are stacked, and a case (12) that accommodates the battery module in a constrained state. Each of the plurality of brackets has a case fastening point (23) for fastening the case and the bracket and a vehicle body fastening point (22) for fastening the vehicle body and the bracket, and the vehicle body fastening point is positioned further inward than the case fastening point with respect to a first direction (100) in which the plurality of battery cells are stacked.

Description

Technical Field

[0001] The utility model relates to a battery pack mounting structure, in particular to a battery pack mounting structure which fastens the battery pack to a vehicle body through a plurality of brackets. Background Art

[0002] Battery packs, made up of multiple stacked battery cells, are used as high-capacity power supply devices in electric vehicles, etc. Because of their small footprint and light weight, these battery packs can be installed in limited spaces such as within vehicles.

[0003] Patent Document 1 discloses a battery pack including a battery module having a stacked body in which a plurality of battery cells are stacked, a bracket for fixing the battery module to a case at the battery cells at both ends of the stack, and a heat conducting member interposed between the stack and the case.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-041653.

[0005] To form a stack, a moderate restraining load must be applied to the battery cells to maintain them within the housing. On the other hand, in a battery pack comprising multiple stacked battery modules, the restraining load can fluctuate significantly due to fluctuations in ambient temperature or thermal expansion of the battery cells, which can cause the battery modules to flex.

[0006] To prevent deflection of the battery module, Patent Document 1 discloses a battery module equipped with a heat-conducting component to promote heat dissipation from the battery cells. Furthermore, Patent Document 1 discloses that, when the stack is secured to a housing, elastic components are provided to prevent deflection of the stack due to a reaction force exerted on the stack by the heat-conducting component. When the battery cells expand, the elastic components are compressed, allowing for a certain amount of expansion.

[0007] On the other hand, the structure of the battery module disclosed in Patent Document 1 requires components such as a heat conducting member and an elastic member, and is therefore disadvantageous in terms of cost. Utility Model Content

[0008] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a battery pack mounting structure that can suppress fluctuations in restraint load due to temperature fluctuations.

[0009] The battery pack mounting structure disclosed herein fastens the battery pack to the vehicle body via multiple brackets. The battery pack includes a battery module comprising a plurality of stacked battery cells and a housing that houses the battery module in a restrained state. The multiple brackets each have a housing fastening point for fastening the housing to the bracket and a vehicle body fastening point for fastening the vehicle body to the bracket. The vehicle body fastening points are located inward of the housing fastening points relative to a first direction in which the plurality of battery cells are stacked. This provides a battery pack mounting structure that suppresses fluctuations in restraint load due to temperature fluctuations.

[0010] Furthermore, the thermal expansion coefficient of the battery module may be greater than the thermal expansion coefficient of the housing. This provides a battery pack mounting structure that can suppress fluctuations in restraint load due to temperature fluctuations.

[0011] According to the present disclosure, it is possible to provide a battery pack mounting structure capable of suppressing fluctuations in the restraint load due to temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a top view of the battery pack mounting structure according to the present disclosure.

[0013] Figure 2A and Figure 2B This is a graph schematically illustrating load fluctuations during temperature fluctuations according to the present disclosure.

[0014] Figure 3 It is a diagram illustrating the positional relationship of the brackets according to the present disclosure. DETAILED DESCRIPTION

[0015] use Figure 1 A configuration example of the battery pack mounting structure according to the present disclosure will be described. Figure 1 The battery pack 10 shown in FIG. 1 includes at least a battery module 11 in which a plurality of battery cells are stacked and a housing 12 in which the battery module 11 is received in a restrained state. Figure 1 The battery module 11 is pressurized and constrained by applying a restraining load in the direction indicated by the arrow in FIG.

[0016] The battery pack mounting structure 1 according to the present disclosure is a structure in which a battery pack 10 is fastened to a vehicle body 20 via a plurality of brackets 21. The plurality of brackets 21 are fastened to the vehicle body 20 at vehicle body fastening points 22 and to the housing 12 at housing fastening points 23. Preferably, the vehicle body fastening points 22 are located inward of the housing fastening points 23 with respect to the first direction.

[0017] With this configuration, bracket 21 thermally expands in first direction 100 due to temperature rise, thereby assisting thermal expansion of case 12. This provides a battery pack mounting structure that can suppress fluctuations in restraint load due to temperature fluctuations.

[0018] use Figures 2A to 3 Explain the mechanism. Figure 2A To schematically illustrate the load variation during temperature fluctuations, a graph is plotted with the dimensions of the battery module 11 and the housing 12 as the horizontal axis and the load applied to them as the vertical axis. The intersection of the constraint load variation 111 of the battery module 11 and the constraint load variation 121 of the housing 12 is represented as the constraint load 101 at 25°C. Figure 2A This indicates that the thermal expansion coefficient of the battery module 11 is larger than the thermal expansion coefficient of the casing 12 .

[0019] When the ambient temperature rises from 25° C. to 60° C., the size of the battery module 11 increases due to the temperature fluctuation, as shown by the restraint load fluctuation 112 . This increase is represented as the thermal expansion 110 of the battery module 11 .

[0020] Likewise, due to the temperature variation, the size of the housing 12 may increase, as indicated by the restraint load variation 122. This increase is represented as the thermal expansion 120 of the housing 12.

[0021] The intersection of the restraint load variation 112 of the battery module 11 and the restraint load variation 122 of the housing 12 is represented as the restraint load 202 at 60°C. It can be seen that the difference in expansion between the battery module 11 and the housing 12 due to temperature rise increases the restraint load.

[0022] The housing 12 of the present disclosure is further Figure 3 The thermal expansion 210 between brackets 21A and 21B shown here increases in size due to the effect of the temperature change, as shown by the restraint load change 123, when the ambient temperature rises from 25° C. to 60° C. The details of brackets 21A and 21B will be described later.

[0023] Depending on the presence or absence of thermal expansion 210 between brackets 21A and 21B, the intersections of the restraint load variation 112 of the battery module 11 and the restraint load variations 122 and 123 of the housing 12 are represented as restraint loads 202 and 102 at 60°C, respectively. The restraint load 202 can be considered as the restraint load when the vehicle body fastening point 22 is located at the same position as or outside the housing fastening point 23 with respect to the first direction 100.

[0024] On the other hand, restraint load 102 is the restraint load generated by adding thermal expansion 210 between brackets 21A and 21B by positioning the housing 12, or the vehicle body fastening point 22, inward relative to the housing fastening point 23 in the first direction 100. Comparing restraint loads 202 and 102 reveals that positioning the vehicle body fastening point 22 inward relative to the housing fastening point 23 in the first direction 100 suppresses the increase in restraint load. Therefore, it can be seen that the effects of the battery pack mounting structure of the present disclosure can be achieved if the thermal expansion coefficient of the battery module 11 is greater than that of the housing 12.

[0025] in addition, Figure 2B This indicates a case where the thermal expansion coefficient of the battery module 11 is smaller than that of the housing 12. Even in this case, a comparison of the restraint loads 202 and 102 shows that the battery pack mounting structure according to the present disclosure can suppress an increase in the restraint load.

[0026] Figure 3 It means Figure 1 The diagram shows the positional relationship of the brackets in the battery pack mounting structure 1. The brackets 21A and 21B according to the present disclosure can be made of various materials, but as an example, a bracket made of cast iron can be used.

[0027] In any bracket 21A, assuming that the distance L between the vehicle body fastening point 22A and the housing fastening point 23A in the first direction 100 is 50 mm and the ambient temperature rises from 25°C to 60°C, the amount of expansion ΔL (mm) of the bracket 21 is calculated as follows: 0.0184 (mm).

[0028] ΔL=αLΔT=10.5×10 6 ×50×(60-25)≈0.0184(mm)

[0029] Where α is the linear expansion coefficient of cast iron and ΔT is the temperature difference.

[0030] The distance between the vehicle body fastening points 22A and 22B of the pair of brackets 21A and 21B of the housing 12 facing each other in the first direction 100 expands by 0.0368 (=0.0184×2) mm. The load fluctuation reduction ΔF obtained by this expansion is calculated as 46 (N) as shown below.

[0031] ΔF=kΔL×2=2500×0.0184×2=46 (N)

[0032] Where k is the module spring constant (N / mm).

[0033] Therefore, by applying the battery pack mounting structure disclosed herein, the fluctuation in the restraint load can be reduced by 46 (N). It should be noted that while this effect is calculated for rising temperatures, the same effect is also achieved when the temperature drops. Furthermore, the battery pack mounting structure disclosed herein achieves even greater effects when the restraint load increases with rising temperatures and decreases with falling temperatures.

[0034] In this way, it is possible to provide a battery pack mounting structure that can suppress fluctuations in the restraint load due to temperature fluctuations.

[0035] In addition, the present disclosure is not limited to the above-mentioned contents, and can be appropriately modified within the scope not departing from the gist.

Claims

1. A battery pack mounting structure for fastening a battery pack to a vehicle body via a plurality of brackets, characterized in that: The battery pack comprises: a battery module in which a plurality of battery cells are stacked; and a housing for accommodating the battery module in a restrained state, The plurality of brackets respectively have: a housing fastening point for fastening the housing to the bracket; and A body fastening point for fastening the body and the bracket, The vehicle body fastening point is located inside the case fastening point with respect to a first direction in which the plurality of battery cells are stacked.

2. The battery pack mounting structure according to claim 1, wherein: The thermal expansion coefficient of the battery module is greater than the thermal expansion coefficient of the housing.

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