Battery pack

Abstract

To provide a battery pack that can improve rigidity while suppressing an increase in weight.SOLUTION: A battery pack is mounted on a vehicle and includes a battery cell and a case that houses the battery cell. The case is provided with a side frame member 3a. The side frame member 3a has an outer member 31 made of steel and an inner member 32 made of an aluminum alloy. The outer member 31 has a cylindrical portion 311, and the inner member 32 is disposed in an internal space S of the cylindrical portion 311.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] Conventionally, a battery pack mounted on a vehicle is known (see, for example, Patent Document 1). The battery pack includes a battery cell and a case that houses the battery cell. The case is provided with a skeletal structure, which makes it possible to improve the resistance of the battery pack to impacts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-147509 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when a skeletal structure is provided in the case as in the above-mentioned battery pack, it is desirable to suppress an increase in weight while improving rigidity.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a battery pack that can improve rigidity while suppressing an increase in weight. [Means for solving the problem]

[0006] A battery pack according to the present invention is mounted on a vehicle and includes a battery cell and a case that houses the battery cell. The case is provided with a skeletal member. The skeletal member has an outer member made of steel and an inner member made of an aluminum alloy. The outer member has a cylindrical portion, and the inner member is disposed in the internal space of the cylindrical portion. Effect of the Invention

[0007] According to the battery pack of the present invention, it is possible to improve the rigidity while suppressing an increase in weight. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram for explaining a battery pack according to an embodiment of the present invention; [Diagram 2] 2(a) is a cross-sectional view taken along line AA in FIG. 1, and (b) is a plan view showing a side framework member of the battery pack. [Diagram 3] 13(a) is a first modified example of the inner member of the side frame member, and FIG. 13(b) is a second modified example of the inner member of the side frame member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment of the present invention will be described.

[0010] First, the battery pack according to the present embodiment will be described with reference to FIGS.

[0011] The battery pack is mounted on a vehicle and configured to store power for driving a driving motor (not shown). The battery pack is disposed under a floor panel (not shown) of the vehicle and is provided between a pair of left and right side members (not shown). As shown in FIG. 1, the battery pack includes a plurality of battery stacks 1 and a case that houses the plurality of battery stacks 1.

[0012] A plurality of battery stacks 1 are connected in series or parallel. Each battery stack 1 has a plurality of battery cells (not shown), which are connected in series, for example. Each battery cell is a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery, and is formed in a rectangular shape. The battery stack 1 is formed by stacking the plurality of battery cells in the thickness direction.

[0013] The case includes a lower case 2 and an upper case (not shown), and the lower case 2 and the upper case are assembled together to form an accommodation space. The accommodation space of the case accommodates a plurality of battery stacks 1. The lower case 2 is formed, for example, from a steel plate.

[0014] The lower case 2 is formed in a rectangular box shape with an open upper end. The battery stack 1 is placed on a bottom surface 21 of the lower case 2 and is fixed to the bottom surface 21. The lower case 2 is provided with a skeletal structure 3 for reinforcing the case. The skeletal structure 3 is housed inside the lower case 2 and attached to the lower case 2. For example, the battery stack 1 is disposed in a space partitioned by the skeletal structure 3. The battery stack 1 is disposed so that its longitudinal direction (thickness direction of the battery cells) faces the vehicle width direction.

[0015] The skeleton structure 3 includes a side skeleton member 3a, a center skeleton member 3b, and a cross skeleton member 3c. The side skeleton member 3a is formed so as to extend in the vehicle front-rear direction (X direction) and is disposed at both ends in the vehicle width direction (Y direction). The center skeleton member 3b is formed so as to extend in the vehicle front-rear direction and is disposed at the center in the vehicle width direction. The cross skeleton member 3c is formed so as to extend in the vehicle width direction and is configured to connect the side skeleton member 3a and the center skeleton member 3b. A plurality of cross skeleton members 3c are provided at intervals in the vehicle front-rear direction. The center skeleton member 3b and the cross skeleton member 3c are formed, for example, from a steel plate.

[0016] The side framework member 3a is set to have higher rigidity than the center framework member 3b and the cross framework member 3c. As shown in Fig. 2(a), the side framework member 3a is provided so as to follow the side surface 22 of the lower case 2. The side surface 22 is formed so as to extend upward from the end of the bottom surface 21 in the vehicle width direction. A flange 23 is formed at the upper end of the side surface 22, protruding outward in the vehicle width direction. The side framework member 3a is disposed between the side surface 22 and the battery stack 1, and is provided over the entire length of the side surface 22.

[0017] The side frame member 3a is provided to improve resistance to side collisions. The side frame member 3a has an outer member 31 made of steel and an inner member 32 made of aluminum alloy. The outer member 31 and the inner member 32 improve rigidity, while the inner member 32 is made of aluminum alloy, making it possible to suppress an increase in weight. The side frame member 3a is an example of the "frame member" of the present invention.

[0018] The outer member 31 is formed of a plate material and joined to the lower case 2. The outer member 31 has a cylindrical portion 311, a lower flange 312, and an upper flange 313. The cylindrical portion 311 has a substantially rectangular cross-sectional shape and is formed so as to extend in the vehicle front-rear direction. The cylindrical portion 311 is placed on the bottom surface 21 and disposed so as to be adjacent to the side surface 22. In other words, the cylindrical portion 311 is disposed in the corner formed by the bottom surface 21 and the side surface 22.

[0019] Lower flange 312 is formed to extend inward in the vehicle width direction from the lower end of cylindrical portion 311, and is provided along bottom surface 21. Upper flange 313 has an L-shaped cross section, and is provided along side surface 22 and flange 23. In other words, upper flange 313 extends upward from the upper end of cylindrical portion 311 and is bent outward in the vehicle width direction.

[0020] The inner member 32 is formed into a rectangular tubular shape by extrusion molding. The inner member 32 is disposed in the internal space S of the tubular portion 311, and disposed so that the longitudinal direction faces the vehicle front-rear direction. That is, the inner member 32 is inserted into the tubular portion 311. Two partition portions 321 are provided inside the inner member 32. The two partition portions 321 are horizontal and disposed at an interval in the up-down direction. That is, the inner member 32 has three rectangular closed cross-sectional portions integrally formed.

[0021] 2(b), one end 322 in the longitudinal direction (X direction) of the inner member 32 is immovably attached to the cylindrical portion 311. In contrast, the other end 323 in the longitudinal direction of the inner member 32 is movably attached to the cylindrical portion 311. In other words, the other end 323 is slidably engaged with the cylindrical portion 311.

[0022] For example, a round hole (not shown) is formed in one end 322 of the inner member 32 and in the cylindrical portion 311, and a fastening member 33 is inserted into the round hole to make the one end 322 immovable. On the other hand, a round hole (not shown) is formed in the other end 323 of the inner member 32, and an elongated hole 311a is formed in the cylindrical portion 311, and a fastening member 34 is inserted into the round hole and the elongated hole 311a to make the fastening member 34 movable together with the other end 323 along the elongated hole 311a.

[0023] -effect- In this embodiment, as described above, the outer member 31 made of steel and the inner member 32 made of aluminum alloy are provided, the cylindrical portion 311 is formed in the outer member 31, and the inner member 32 is disposed in the internal space S of the cylindrical portion 311. With this configuration, it is possible to improve rigidity while suppressing an increase in weight. Also, it is possible to suppress an increase in size of the side frame member 3a.

[0024] In addition, in this embodiment, the other end 323 of the inner member 32 is movably attached to the tubular portion 311, so that the difference between the linear expansion coefficient of the outer member 31 and the linear expansion coefficient of the inner member 32 can be absorbed. That is, even if the amount of expansion of the inner member 32 is larger than that of the outer member 31, the other end 323 is movable, so that it is possible to suppress the load on the fastening portion.

[0025] -Other embodiments- It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above-described embodiments, but is defined by the claims. The technical scope of the present invention includes all modifications within the scope and meaning equivalent to the claims.

[0026] For example, in the above embodiment, the present invention is applied to the side frame member 3a, but the present invention is not limited to this, and may be applied to the cross frame member or the center frame member.

[0027] In the above embodiment, the cross-sectional shape of the inner member 32 may be any shape. For example, as in the inner member 32a according to a first modified example shown in FIG. 3(a), one partition portion 321a may be provided. In the inner member 32a, two rectangular closed cross-sectional portions are integrally formed. Also, as in the inner member 32b according to a second modified example shown in FIG. 3(b), two partition portions 321b may be provided. The partition portion 321b is provided so as to be inclined with respect to the horizontal. In the inner member 32b, three triangular closed cross-sectional portions are integrally formed. [Explanation of symbols]

[0028] 1... battery stack, 2... lower case, 3a... side frame member (frame member), 31...Outer member, 32, 32a, 32b...Inner member, 311...Cylindrical part

Claims

[Claim 1] A battery pack to be mounted on a vehicle, A battery cell; a case that houses the battery cell; The case is provided with a framework member, The framework member has an outer member made of steel and an inner member made of an aluminum alloy, The battery pack according to claim 1, wherein the outer member has a cylindrical portion, and the inner member is disposed in an internal space of the cylindrical portion.

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