Battery pack

Abstract

To provide a battery pack which is installed on a frame member located in the left side or the right side of a vehicle and has high resistance to an external force inputted from the direction of the left or right of the vehicle.SOLUTION: A battery pack comprises an upper cover and a lower case. The upper cover is arranged opposite to a floor panel of a vehicle. The lower case is assembled with the upper cover. In the width direction of the vehicle, an opening edge part of the lower case is assembled with a left end part and a right end part of the upper cover and forms a left flange and a right flange respectively. In the width direction of the vehicle, the upper faces, respectively of the left flange and the right flange, are disposed below an upper face of the upper cover opposite to the floor panel. The upper face of the upper cover opposite to the floor panel forms a step from the upper faces, respectively of the left flange and the right flange.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a battery pack that houses a battery stack to be mounted on a vehicle. [Background technology]

[0002] Japanese Patent Publication No. 6451685 discloses a mounting structure for a battery pack that is mounted to an underbody of a vehicle. In this conventional structure, the underbody includes a floor panel that is spanned across a skeletal member of the vehicle. The battery pack includes an upper cover that is disposed opposite the floor panel, and a lower case that is combined with the upper cover. A battery stack is housed in a space formed between the upper cover and the lower case. In addition, frames are provided on the sides of the battery pack on the front and rear sides of the vehicle, respectively. The battery pack is attached to the skeletal member via these frames. That is, in the conventional structure, the battery pack is attached to the underbody at the positions of the skeletal members on the front and rear sides of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6451685 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider attaching a battery pack to the left and right frame members of a vehicle. In this case, it is important to maintain the structure of the battery pack when an external force is applied from the left or right direction. However, the upper cover of a battery pack with a conventional structure is a simple plate-like member, and there is an issue that the mating surface of the upper cover with the lower case is easily opened.

[0005] One objective of the present disclosure is to provide a battery pack that is highly resistant to external forces input from the left or right direction of the vehicle when the battery pack is attached to left and right skeletal members of the vehicle. [Means for solving the problem]

[0006] The present disclosure relates to a battery pack that houses a battery stack to be mounted on a vehicle, and has the following features: The battery pack includes an upper cover and a lower case. The upper cover is disposed opposite a floor panel of the vehicle. The lower case is combined with the upper cover. In the width direction of the vehicle, an opening edge portion of the lower case is combined with a left end portion and a right end portion of the upper cover to form a left flange and a right flange, respectively. The left flange is attached to a left frame member of the vehicle provided to the left of the floor panel. The right flange is attached to a right frame member of the vehicle provided to the right of the floor panel. In the width direction, upper surfaces of the left and right flanges are located lower than an upper surface of the upper cover facing the floor panel. The upper surface of the upper cover facing the floor panel forms a step with the upper surfaces of the left and right flanges. Effect of the Invention

[0007] According to the battery pack of the present disclosure, the top surface of the upper cover forms a step with the top surfaces of the left flange and the right flange, and therefore, the step resists an external force input from the left or right direction of the vehicle, making it possible to prevent the mating surfaces of the upper cover and the lower case from opening apart. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram showing an example of an arrangement of a battery pack according to an embodiment of the present disclosure. [Diagram 2] 1 is a diagram illustrating an example of the configuration of a battery pack according to an embodiment; [Diagram 3]3 is a diagram showing characteristic parts of the battery pack shown in FIG. 2. [Figure 4] 10A to 10C are diagrams illustrating the effects of the battery pack according to the embodiment. [Diagram 5] 10A to 10C are diagrams illustrating the effects of the battery pack according to the embodiment. [Figure 6] 10A to 10C are diagrams illustrating the effects of the battery pack according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the structures and the like described in the following embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

[0010] 1. Battery pack Fig. 1 is a diagram showing an example of the arrangement of a battery pack 1 according to an embodiment of the present disclosure. Fig. 2 is a diagram for explaining an example of the configuration of the battery pack 1. The X-axis shown in Fig. 1 corresponds to the front-rear direction (length direction) of the vehicle VH, the Y-axis shown in Figs. 1 and 2 corresponds to the left-right direction (width direction) of the vehicle VH, and the Z-axis shown in Fig. 2 corresponds to the up-down direction (height direction) of the vehicle VH. More specifically, the positive direction of the X-axis corresponds to the forward direction, the positive direction of the Y-axis corresponds to the rightward direction, and the positive direction of the Z-axis corresponds to the upward direction.

[0011] As shown in Figs. 1 and 2, the battery pack 1 is attached to the underbody 2 of the vehicle VH. The underbody 2 includes a right skeletal member (right side frame) 21, a left skeletal member (left side frame) 22, and a floor panel 23. The floor panel 23 is bridged between the right skeletal member 21 and the left skeletal member 22. The battery pack 1 and the underbody 2 are attached to the lower surfaces of the right skeletal member 21 and the left skeletal member 22 (i.e., positions outside the passenger compartment). For example, the battery pack 1 is attached to the underbody 2 by fastening members that connect the lower surface of the battery pack 1 to the upper surface of the underbody 2.

[0012] As shown in FIG. 2, the battery pack 1 includes an upper cover 11 and a lower case 12. The upper cover 11 is composed of a central portion 11a, a right end portion 11b, and a left end portion 11c. The central portion 11a faces the floor panel 23. The right end portion 11b faces the right skeletal member 21. The left end portion 11c faces the left skeletal member 22. The top surface of the central portion 11a is located higher than the top surfaces of the right end portion 11b and the left end portion 11c. The top surface of the central portion 11a forms a step with the top surfaces of the right end portion 11b and the left end portion 11c.

[0013] The lower case 12 is composed of a case portion 12a and an opening edge portion 12b extending in the left-right direction of the vehicle VH at the opening position of the case portion 12a. The lower case 12 is combined with the upper cover 11. A battery stack 3 is housed in a space 13 surrounded by the lower surface of the central portion 11a and the upper and side surfaces of the case portion 12a. The battery stack 3 is composed of a large number of unit cells stacked one on top of the other. In the example shown in FIG. 2, the stacking direction of the large number of unit cells is the width direction of the vehicle VH. The battery stack 3 is a secondary battery that can be charged and discharged, and an example of such a secondary battery is a lithium-ion secondary battery.

[0014] The upper cover 11 and the lower case 12 are assembled at a position where the right end 11b and the left end 11c face the opening edge 12b. The right end 11b assembled with the opening edge 12b forms a right flange 6, and the left end 11c assembled with the opening edge 12b forms a left flange 7 (see FIG. 3). At the position of the right flange 6, a seal member (e.g., seal rubber) 4 is provided between the underside of the right end 11b and the surface of the opening edge 12b to seal the space formed therebetween. At the position of the left flange 7, a seal member 5 having the same function as the seal member 4 is provided.

[0015] For ease of explanation, FIG. 3, which is a simplified version of the battery pack 1 shown in FIG. 2, will be referred to below. FIG. 3 is a diagram showing characteristic parts of the battery pack 1 shown in FIG. 2. FIG. 3 shows the positions of the right flange 6 and the left flange 7. As can be seen from this figure, the right flange 6 and the left flange 7 are located above the battery stack 3, and when the battery pack 1 is viewed from a direction parallel to the Y axis, these flanges do not appear to overlap with the battery stack 3. FIG. 3 also shows an upper surface 31 of the battery stack 3. This upper surface 31 is located below the surface of the opening edge portion 12b that contacts the seal members 4 and 5.

[0016] 2.Effects 4 to 6 are diagrams for explaining the effects of the battery pack 1 according to the embodiment. In Figs. 4 and 5, simplified battery packs 8 and 9 are respectively depicted, similar to the battery pack 1 shown in Fig. 3. The battery packs 8 and 9 correspond to comparative examples of the battery pack 1 according to the embodiment. The difference between the configurations of the battery packs 8 and 9 and that of the battery pack 1 shown in Fig. 3 is the positions of the right and left flanges. The right and left flanges of the battery pack 8 are located higher than those of the battery pack 1. On the other hand, the right and left flanges of the battery pack 9 are located lower than those of the battery pack 1.

[0017] Specifically, in battery pack 8, upper cover 81 extends linearly in a direction parallel to the Y-axis, and there is no step at the end of upper cover 81. Instead, the opening edge of lower case 82 moves in the positive direction of the Z-axis. On the other hand, in battery pack 9, the right end of upper cover 91 and the opening edge of lower case 92, which contact seal member 4, are located below top surface 31. The left end of upper cover 91 and the opening edge of lower case 92, which contact seal member 5, are also located below top surface 31.

[0018] FIG. 4 shows (i) an example of the transmission of external force F input to battery pack 8 when a side collision occurs. In the positive direction of the Y axis, the right flange of battery pack 8 is located at the outermost position. Therefore, when a side collision occurs, external force F acts on the right flange first. If this happens, the mating surfaces of the opening edges of upper cover 81 and lower case 82 that make up the right flange will easily open, which may make it impossible to maintain the seal structure of the right flange.

[0019] (i) An example of the transmission of an external force F in the event of a side collision is also shown in FIG. 5. In this example, the right flange may move in the negative direction of the Y axis, causing the upper cover 91 and the lower case 92 connected to the right flange to be wedged into the battery stack 3. FIG. 5 also shows (ii) an example of the movement of gas G (e.g., flammable gas) ejected from a cell constituting the battery stack 3. In this example, the gas G generated in a position close to the right flange may be ejected directly onto the sealing member 4, impairing the function of the sealing member 4, causing the gas G to leak out of the battery pack 1. FIG. 5 also shows (iii) an example of the movement of heat H generated from the battery stack 3. In this example, the heat H may easily accumulate between the underbody 2 and the right and left flanges, making it necessary to cool the battery stack 3.

[0020] In this regard, the battery pack 1 according to the embodiment can reduce the defects described in Figs. 4 and 5. As shown in Fig. 6, (i) in the event of a side collision, the step formed in the upper cover 11 resists the external force F, making it possible to suppress the opening of the mating surfaces described in Fig. 4. It is also possible to avoid the wedgie described in Fig. 5. In addition, (ii) even if gas G is ejected at a position close to the right flange, it is possible to prevent the gas G from being ejected directly onto the seal member 4. Furthermore, (iii) heat H generated from the battery stack 3 is easily released into the atmosphere, making it possible to suppress the buildup of heat described in Fig. 5. [Explanation of symbols]

[0021] 1,8,9...battery pack, 2...underbody, 3...battery stack, 4,5...sealing member, 6...right flange, 7...left flange, 11,81,91...upper cover, 11a...center, 11b...right end, 11c...left end, 12,82,92...lower case, 12a...case, 12b...opening edge, 13...space, 21...right skeletal member, 22...left skeletal member, 23...floor panel, 31...top surface of battery stack, F...external force, G...gas, H...heat, VH...vehicle

Claims

1. A battery pack that houses a battery stack to be mounted on a vehicle, an upper cover disposed opposite a floor panel of the vehicle; a lower case combined with the upper cover; Equipped with an opening edge portion of the lower case is combined with a left end portion and a right end portion of the upper cover to form a left flange and a right flange, respectively, in a width direction of the vehicle; the left flange is attached to a left frame member of the vehicle provided to the left of the floor panel, and the right flange is attached to a right frame member of the vehicle provided to the right of the floor panel, In the width direction, upper surfaces of the left flange and the right flange are located lower than an upper surface of the upper cover that faces the floor panel, An upper surface of the upper cover facing the floor panel forms a step with each of the upper surfaces of the left flange and the right flange. A battery pack characterized by:

2. 2. The battery pack according to claim 1, The left flange and the right flange are located above the battery stack in the width direction. A battery pack characterized by:

3. 3. The battery pack according to claim 1, The upper surface of the battery stack is located below the surfaces of the opening edge portions that face the lower surfaces of the left end portion and the right end portion at the respective positions of the left flange and the right flange. A battery pack characterized by:

4. 4. The battery pack according to claim 3, a seal member is provided between a lower surface of the left end portion and a surface of the opening edge portion facing the lower surface of the left end portion, the seal member sealing a gap formed between these surfaces; A seal member is provided between the lower surface of the right end portion and a surface of the opening edge portion facing the lower surface of the right end portion to seal a gap formed between these surfaces. A battery pack characterized by:

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