Battery pack structure

Abstract

The present invention provides a battery pack structure that reliably discharges gas generated within a battery module due to thermal runaway to the outside of the battery pack, and also prevents thermal runaway in other battery modules. [Solution] The housing space 13 of the lower case member 4 is partitioned horizontally by the frame 5, forming a plurality of housing sections 12 capable of housing a battery module 2 inside each section. With the battery module 2 housed in each housing section 12, the lower case member 4 is covered with the upper case member 3 to constitute the battery pack 1. At least above the frame 5, a heat-expandable resin 11 is attached to the side surface of the lower case member 4 of the upper case member 3. The battery module 2 is provided with a gas discharge hole 7 on a surface other than the top surface for discharging gas generated inside, and at least one of the lower case member 4 and the upper case member 3 is provided with a gas discharge port 8 for discharging gas discharged from the battery module 2 to the outside.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a battery pack structure in which a thermally expandable resin is disposed between battery modules, and when a battery module undergoes thermal runaway (overheating), the space between the battery modules is blocked by the thermally expandable resin to suppress thermal runaway of other battery modules.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when a battery pack is disposed below the passenger compartment, in order to suppress heat transfer to the passenger compartment when a battery module housed in the battery pack undergoes thermal runaway, it may be considered to attach a thermally expandable resin to the lower surface of the upper case member constituting the battery pack housing. However, generally, since the gas discharge hole for discharging the gas generated when the battery module undergoes thermal runaway is provided on the upper surface of the battery module, when the battery module undergoes thermal runaway and the thermally expandable resin attached to the lower surface of the upper case member expands, the gas discharge hole is blocked by the expanded thermally expandable resin, and the gas cannot be discharged from the battery module. Of course, in that case, the gas generated inside the battery pack cannot be discharged to the outside of the battery pack either. An object of the present invention is to provide a battery pack structure capable of reliably discharging the gas generated in the battery module due to thermal runaway to the outside of the battery pack and preventing thermal runaway of other battery modules. [Means for solving the problem]

[0005] According to one aspect of the present invention, the invention comprises a lower case member capable of housing battery modules inside each of a plurality of housing sections partitioned in a horizontal plane by a frame, an upper case member covering the upper part of the lower case member when battery modules are housed in each housing section of the lower case member, and a heat-expandable resin attached to the surface of the upper case member on the lower case member side at least above the frame, wherein the battery module is provided with gas discharge holes on surfaces other than the top surface for discharging gas generated inside, and at least one of the lower case member and the upper case member is provided with a gas discharge port for discharging gas discharged from the battery module to the outside. [Effects of the Invention]

[0006] According to the present invention, it is possible to reliably discharge gas generated within the battery module due to thermal runaway to the outside of the battery pack, and to prevent thermal runaway in other battery modules. [Brief explanation of the drawing]

[0007] [Figure 1] This is a three-view drawing of the vehicle showing the battery pack configuration. [Figure 2] Figure 1 is a perspective view of the battery pack. [Figure 3] Figure 2 is a perspective view of the battery pack with the upper case component removed. [Figure 4] Figure 3 is a perspective view showing two examples of battery modules housed in the housing. [Figure 5] Figure 3 is a perspective view showing an example of a flow passage and gas outlet provided in the center frame. [Figure 6] Figure 3 is a perspective view showing an example of a flow passage and gas outlet provided in a cross frame. [Figure 7] Figures 5 and 6 are explanatory diagrams illustrating the operation of the flow path and gas outlet. [Figure 8] This is a perspective view showing another example of a gas outlet. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of the present invention described below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the structure, arrangement, etc., of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0009] Figure 1a is a left side view of the vehicle according to the embodiment, and Figure 1b is a bottom view. In this vehicle, an electric motor (not shown) is used to drive the vehicle, and the battery pack 1 for supplying power to this electric motor is located below the passenger compartment. By using this battery layout, the center of gravity of the vehicle can be lowered, thereby improving the vehicle's driving stability. The battery pack 1 shown in Figure 2 comprises a lower case member 4 of a lower container that constitutes a flat rectangular parallelepiped housing, and an upper case member 3 attached above it. The housing of the battery pack 1 formed by these members extends in the longitudinal direction and the width direction of the vehicle. The upper case member 3 is a so-called upper cover member, and in this embodiment, it has a side wall portion 3b that extends downward in the height direction from the outer peripheral edge of the upper plate portion 3a that constitutes the upper cover, and an upper flange portion 3c that extends to the outside of the housing from the lower outer peripheral edge thereof. Furthermore, the surface of the upper case member 3 facing the lower case member 4, i.e., the bottom surface and corresponding to the back surface, is coated with a heat-expandable resin 11 (see Figure 7). In this embodiment, the heat-expandable resin 11 is coated and attached to almost the entire back surface of the upper case member 3, but it must be attached at least above the frame 5 of the lower case member 4, which will be described later. On the upper surface of the upper case member 3, a connection portion 51 is exposed that electrically connects the battery module 2 inside the battery pack 1 to the outside.

[0010] Figure 3 shows the battery pack 1 in Figure 2 with the upper case member 3 removed. The lower case member 4, which serves as the lower container for housing the battery module 2, has a flat rectangular parallelepiped-shaped housing space 13 that extends in the vehicle's longitudinal and vehicle width directions. Multiple housing sections 12 for housing the battery module 2 are formed by dividing this housing space 13 vertically and horizontally with a frame 5. This frame 5 is a metal framework structure that supports the mass of the battery module 2, which is a considerably heavy object. It is constructed by combining metal hollow rectangular members with a rectangular cross-sectional outer shape of a predetermined height vertically and horizontally in a horizontal plane from the upper surface of the bottom plate portion 4a of the lower case member 4, i.e., the lower surface of the housing space 13. The metal rectangular cross-sectional members that make up the frame 5 have a shape such that, for example, as shown in Figure 7, a reinforcing plate member is added to the center in the height direction of the metal hollow rectangular members that make up the periphery of the rectangular cross-section.

[0011] This frame 5 has cross frame sections 5b that extend in the vehicle width direction to both ends of the vehicle width direction of the housing space 13 of the lower case member 4 at two locations in the vehicle front-rear direction of the housing space 13 of the lower case member 4, a center frame section 5a that extends from the vehicle front end of the lower case member 4 to the second cross frame section 5b in the vehicle width direction of the central part of the vehicle width direction of the housing space 13 of the lower case member 4, and a branch frame section 5c that extends from a predetermined distance from both ends of the vehicle width direction of the second cross frame section 5b from the vehicle front to the vehicle rear end of the housing space 13 of the lower case member 4.Therefore, the housing space 13 of the lower case member 4 is divided into a plurality of rectangular housing sections 12 in plan view by these frame sections 5a to 5c of the frame 5, and a battery module 2 is housed in each of these housing sections 12. Although the storage compartment 12 partitioned by the branch frame section 5c and the storage compartment 12 partitioned by the center frame section 5a have slightly different shapes, both storage compartments 12 are formed as rectangles in plan view, with the vehicle's front-rear direction being the longitudinal direction and the vehicle's width direction being the shortest direction.

[0012] Furthermore, this frame 5 has an outer shell frame portion 6 that surrounds a plurality of housing portions 12 at the outer peripheral edge of the housing space 13 of the lower case member 4. This outer shell frame portion 6 includes side frame portions 6a that extend in the vehicle front-rear direction at positions on both sides of the housing space 13 in the vehicle width direction, a front frame portion 6b that extends in the vehicle width direction at the vehicle front end of the housing space 13, and a rear frame portion (not shown) that extends in the vehicle width direction at the vehicle rear end of the housing space 13. Accordingly, this outer shell frame portion 6 constitutes the four side wall portions 4b of the lower case member 4, and its height is set slightly lower than the frame portions 5a to 5c that partition the housing space 13. Furthermore, a lower flange portion 4c is formed on the side wall portion 4b of the lower case member 4, that is, on the upper outer edge of the outer shell frame portion 6, extending outward from the housing space 13. The upper flange portion 3c of the upper case member 3 is mounted on the upper surface of this lower flange portion 4c, and the lower case member 4 and the upper case member 3 are joined by, for example, connecting and fixing the lower flange portion 4c and the upper flange portion 3c. In addition, cooling liquid passages (not shown) are laid out in a complex manner on the upper surface of the bottom plate portion 4a of the lower case member 4, and therefore the bottom surface of the housing space 13 is cooled by the cooling liquid, and the battery module 2 is cooled by contact with this bottom surface. When the lower case member 4 and the upper case member 3 are joined, the internal space of the housing is airtight and liquid-tight.

[0013] Figure 4 shows two examples of the battery module 2. As mentioned above, the housing 12 is a rectangle in plan view with the vehicle's front-rear direction being the longitudinal direction and the vehicle's width direction being the short direction. Therefore, the battery module 2 housed in it is also a rectangular parallelepiped in plan view with the vehicle's front-rear direction being the longitudinal direction and the vehicle's width direction being the short direction. In this embodiment, the height of the battery module 2 is equal to the height of the frame 5 excluding the outer shell frame 6, i.e., the center frame 5a, cross frame 5b, and branch frame 5c. In the example in Figure 4a, the gas exhaust hole 7 is provided in the side wall portion 2a (side wall portion facing the vehicle's width direction) that forms the longitudinal direction (long side) of the rectangle in plan view, and in the example in Figure 4b, the gas exhaust hole 7 is provided in the side wall portion 2b (side wall portion facing the vehicle's front-rear direction) that forms the short side (short side) of the rectangle in plan view. Note that gas exhaust holes 7 may be formed in both the side wall portion 2a shown in Figure 4a and the side wall portion 2b shown in Figure 4b. These gas exhaust holes 7 are for venting gas generated inside the battery module 2 when it experiences thermal runaway. The battery module 2 is housed in the housing 12 and connected to the frame 5, thereby fixing it to the lower case member 4. When connected to the frame 5, a gap is formed between the side walls 2a, 2b of each battery module 2 and the center frame 5a, cross frame 5b, and branch frame 5c. A gap may also be formed between the side walls 2a, 2b of each battery module 2 and the outer shell frame 6.

[0014] Figure 5 shows an example in which a gas outlet 8 is formed in the bottom plate portion 4a of the lower case member 4 located below the center frame portion 5a, for discharging gas discharged from the battery module 2 to the outside of the battery pack 1. If the center frame portion 5a remains above the gas outlet 8, the internal space of the housing portion 12 cannot be connected to the outside via the gas outlet 8. Therefore, a flow passage 9 is formed at the location where the gas outlet 8 is formed, passing through the center frame portion 5a. That is, for example, when gas is discharged from the battery module 2 housed in the housing portion 12 in the center in the left-right direction of Figure 5, the gas flows into the flow passage 9 provided in the center frame portion 5a, and then the gas is discharged to the outside from the gas outlet 8 below the center frame portion 5a. Since the center frame portion 5a faces the longitudinal direction of the housing portion 12, which is rectangular in plan view, in this case, a battery module 2 in which the gas outlet hole 7 is provided on the longitudinal surface of the rectangular housing portion 12, as shown in Figure 4a, would be preferable. Furthermore, this example can be applied not only to the center frame section 5a but also to the branch frame section 5c.

[0015] In contrast, Figure 6 shows an example in which a gas outlet 8 is formed in the bottom plate portion 4a of the lower case member 4 located below the cross frame portion 5b, for discharging gas discharged from the battery module 2 to the outside of the battery pack 1. Similar to the case of the center frame portion 5a, a flow passage 9 is formed at the location where the gas outlet 8 is formed, passing through the cross frame portion 5b. That is, for example, when gas is discharged from the battery module 2 housed in the housing portion 12 in the left-right center of Figure 6, the gas flows into the flow passage 9 provided in the cross frame portion 5b, and then the gas is discharged to the outside from the gas outlet 8 below the cross frame portion 5b. Since the cross frame portion 5b faces the shorter side of the housing portion 12 which is rectangular in plan view, in this case, a battery module 2 in which the gas outlet hole 7 is provided on the shorter side of the rectangular housing portion 12, as shown in Figure 4b, would be preferable.

[0016] The operation of the flow passage 9 and gas outlet 8 in Figures 5 and 6 will be explained using Figure 7. As shown in Figure 7, the aforementioned gas outlet 8 is equipped with a check valve 10 that opens when the internal pressure of the battery pack 1 exceeds a predetermined value, allowing only the internal gas to be discharged to the outside. As mentioned earlier, the side surface, i.e., the back surface, of the lower case member 4 of the upper case member 3 is coated with a thermally expandable resin 11 over almost the entire back surface. This is also necessary to suppress the transfer of heat to the vehicle compartment in the event of thermal runaway of the battery module 2, which will be described later. Therefore, the thermally expandable resin 11 is also present above the center frame portion 5a, the cross frame portion 5b, and the branch frame portion 5c. When not heated, the thermally expandable resin 11 does not come into contact with the upper surfaces of the center frame portion 5a, the cross frame portion 5b, and the branch frame portion 5c, as shown in Figure 7a, and there is a gap between the lower surface of the thermally expandable resin 11 and the upper surfaces of these frame portions 5a to 5c. If thermal runaway occurs in any of the battery modules 2 from this state, the heat generated there travels through the gap below the thermally expandable resin 11, causing the internal temperature of the battery pack 1 to rise. When the internal temperature of the battery pack 1 exceeds the thermal expansion start temperature of the thermally expandable resin 11, the thermally expandable resin 11 expands and eventually comes into contact with the upper surfaces of the center frame portion 5a, cross frame portion 5b, and branch frame portion 5c, as shown in Figure 7b, sealing and closing each housing portion 12 that houses the battery modules 2.

[0017] In the housing portion 12 where the battery module 2 has experienced thermal runaway, the pressure in the internal space increases due to the gas discharged from the gas discharge hole 7 of the battery module 2. The gas discharged from the battery module 2 also flows into the flow path 9 provided in the center frame portion 5a, the cross frame portion 5b, and the branch frame portion 5c. When the check valve 10 at the gas discharge port 8 of the lower case member 4 where the flow path 9 communicates opens due to the increase in pressure in the internal space of the housing portion 12, as shown in Fig. 7b, the gas in the housing portion 12 is discharged to the outside of the battery pack 1 through the gas discharge port 8. As can be inferred from the name "thermal runaway", the gas discharged from the battery module 2 during thermal runaway is at a high temperature. If other battery modules 2 are heated by this high-temperature gas, a chain reaction of thermal runaway called thermal chain occurs, and other battery modules 2 also experience thermal runaway. By discharging the high-temperature internal gas of the housing portion 12 to the outside of the battery pack 1, the thermal chain of other battery modules 2 can be prevented. At this time, since it is desirable for the gas discharged from the battery module 2 to be discharged to the outside as quickly as possible, it is preferable to provide the gas discharge hole 7 on the surface of the battery module 2 facing the frame 5 where the gas discharge port 8 is provided, that is, where the flow path 9 opens. The flow path 9 through which the gas flows penetrates the center frame portion 5a, the cross frame portion 5b, and the branch frame portion 5c and communicates with the adjacent housing portion 12. However, for the following reasons, the high-temperature internal gas does not easily flow into the adjacent housing portion 12.

[0018] In other words, since the inside of the battery pack 1 is hot and the outside is cold, heat exchange occurs easily, and since the resistance at the gas outlet 8 is relatively low, most of the internal gas is discharged to the outside through the gas outlet 8. Also, in parts where the cross-sectional area of ​​the gas flow path is large, the pressure loss is small, and in such parts, the gas tends to flow from the hot side to the cold side. However, the cross-sectional area of ​​the flow passage 9 is limited, and the pressure loss is large between the housing section 12 from which the gas is discharged and the adjacent housing section 12 connected by the flow passage 9. As a result, the gas flow rate and velocity toward the adjacent housing section 12 decrease, making it difficult for the gas to flow toward the adjacent housing section 12. In addition, the heat from the hot gas discharged from the thermally runaway battery module 2 is transferred to the center frame section 5a, cross frame section 5b, and branch frame section 5c, and since the temperature of the internal gas decreases, the effect of the hot gas flowing toward the cold side, i.e., the adjacent housing section 12, is small.

[0019] As can be inferred from the above, in the battery pack structure of this embodiment, the gas discharge port 8 may be provided at any location other than the upper plate portion 3a of the upper case member 3. FIG. 8 shows an example thereof (the upper flange portion and the lower flange portion are not shown). The gas discharge port 8 is provided in the front frame portion 6b, the side frame portion 6a, which constitute the side wall portion 4b of the lower case member 4, or a rear frame portion (not shown) or the side wall portion 3b of the upper case member 3. In this case, in the front frame portion 6b, the side frame portion 6a, and the rear frame portion, a flow passage 9 is opened from the accommodating portion 12 facing inside the housing to the outer shell frame portion 6 (frame 5), and the gas discharge port 8 is formed in the portion outside the housing of this flow passage 9. However, in the examples shown in FIGS. 5 and 6, a common gas discharge port 8 may be provided via the flow passage 9 provided in the frame 5 (frame portions 5a to 5c) for adjacent accommodating portions 12, whereas in the example of FIG. 8, it is necessary to provide a gas discharge port 8 for each accommodating portion 12. Since the gas discharge port 8 itself is an opening, the cost is small, but a check valve 10 is required for each gas discharge port 8, so the more gas discharge ports 8 there are, the greater the cost. Further, since the gas discharge port 8 is a so-called recessed portion, there is a possibility of affecting the strength and rigidity of the upper case member 3, the lower case member 4, or the frame 5 constituting the housing. As in the examples shown in FIGS. 5 and 6, sharing the gas discharge port 8 in adjacent accommodating portions 12 can reduce such concerns.

[0020] Although the battery pack structure according to the embodiment has been described above, the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, in the above embodiment, the housing space 13 inside the housing was divided vertically and horizontally in a horizontal plane to form the housing section 12 for the battery module 2, but it is also possible to have a layout in which the housing section 12 is formed in a single row using, for example, a ladder-shaped frame 5. Furthermore, the shapes of the upper case member 3 and lower case member 4 that constitute the housing are not limited to those of the embodiment, and the present invention can be applied to any housing configuration as long as the upper case member 3 covers the upper part of the lower case member 4 that constitutes the container. Also, as can be seen from the above description, if the only purpose is to prevent heat chain from occurring in battery modules 2 other than the battery module 2 that has overheated, it is sufficient that the thermally expandable resin 11 is present at least above the frame 5. However, if it is to suppress the transfer of heat generated in the battery pack 1 to the vehicle compartment, as in the above embodiment, it is desirable to attach the thermally expandable resin 11 as an insulating material to the entire back surface of the upper case member 3.

[0021] In this embodiment, the housing space 13 within the lower case member 4 is partitioned horizontally by the frame 5, forming a plurality of housing sections 12 capable of housing battery modules 2 inside each section. With the battery modules 2 housed in each housing section 12, the upper part of the lower case member 4 is covered with the upper case member 3 to constitute the battery pack 1. At least above the frame 5, a heat-expandable resin 11 is attached to the side surface of the lower case member 4 of the upper case member 3. The battery module 2 is provided with gas discharge holes 7 on surfaces other than the top surface for discharging gas generated inside, and at least one of the lower case member 4 and the upper case member 3 is provided with a gas discharge port 8 for discharging gas discharged from the battery module 2 to the outside. Therefore, even if any of the battery modules 2 overheat and the heat expandable resin 11 expands due to the heat, the gas discharge holes 7 of the battery module 2 will not be blocked, and the gas inside the overheated battery module 2 will be discharged into the housing section 12 and further discharged to the outside through the gas discharge port 8. At this time, the thermally expandable resin 11 expands and comes into contact with the upper surface of the frame 5 that partitions the housing section 12, sealing each housing section 12. This suppresses heat transfer to the battery modules 2 in adjacent housing sections 12, thereby preventing thermal runaway of the other battery modules 2.

[0022] Furthermore, by providing a check valve 10 at the gas outlet 8 that can discharge gas to the outside when the internal pressure increases, the inside of the housing can be maintained in an airtight and liquid-tight state except when gas discharge is necessary, and the generated gas can be discharged to the outside only when the battery module 2 experiences thermal runaway. Furthermore, by providing gas exhaust holes 7 on surfaces other than the top and bottom of the battery module 2, and by providing a gas exhaust port 8 in at least one of the lower case member 4 and the upper case member 3 near the battery module 2, the gas generated in the battery module 2 can be reliably discharged into the housing 12, and furthermore, the gas can be quickly discharged to the outside of the housing. Furthermore, by providing a flow passage 9 in the frame 5 that communicates with the housing section 12 and through which gas flows, and configuring the flow passage 9 to communicate with the gas outlet 8, the gas outlet 8 can be formed in the lower case member 4 without unnecessarily reducing the strength or rigidity of the lower case member 4. Also, if the frame 5 has an outer shell frame section 6 that surrounds a plurality of housing sections 12 partitioned in a horizontal plane, it is possible to provide the gas outlet 8 on the outside by forming the flow passage 9 in this outer shell frame section 6.

[0023] Furthermore, by opening a flow passage 9 on the surface of the frame 5 opposite the gas exhaust hole 7 of the battery module 2, and providing a gas exhaust port 8 of the lower case member 4 on the underside of the frame 5 at the location of the opening, it becomes possible to discharge the gas discharged from the gas exhaust hole 7 of the battery module 2 to the outside of the housing as quickly as possible. At the same time, by forming the flow passage 9 through the frame 5 to connect adjacent housing sections 12, it becomes possible to reduce the number of gas exhaust ports 8. Furthermore, in each of the adjacent housing sections 12 partitioned by the frame 5, a gas exhaust hole 7 is provided on the surface facing the frame 5 of the battery module 2, a flow passage 9 is provided that penetrates the frame 5 and connects the adjacent housing sections 12, and the gas exhaust port 8 of the lower case member 4 is provided on the underside of the frame 5 at the location of the flow passage 9. This allows the gas discharged from the gas exhaust hole 7 of the battery module 2 to be discharged to the outside of the housing as quickly as possible, reducing the number of gas exhaust ports 8 and lowering costs. Furthermore, by applying the thermally expandable resin 11 to the lower surface of the upper case member 3 and then attaching it, the attachment of the thermally expandable resin 11 becomes easier. [Explanation of Symbols]

[0024] 1...Battery pack, 2...Battery module, 3...Upper case member, 4...Lower case member, 5...Frame, 6...Outer shell frame section, 7...Gas exhaust hole, 8...Gas outlet, 9...Flow passage, 10...Check valve, 11...Thermally expandable resin, 12...Housing section

Claims

1. A lower case member capable of housing battery modules inside each of the multiple housing sections partitioned horizontally by a frame, An upper case member that covers the upper part of the lower case member with the battery module housed in each of the housing sections of the lower case member, It comprises a heat-expandable resin attached to the surface of the upper case member on the lower case member side at least above the frame, The battery module has gas exhaust holes on surfaces other than the top surface for releasing gas generated internally. A battery pack structure characterized in that at least one of the lower case member and the upper case member is provided with a gas outlet for discharging gas discharged from the battery module to the outside.

2. The battery pack structure according to claim 1, characterized in that the gas outlet has a check valve that can discharge the gas to the outside only when the internal pressure increases.

3. The gas exhaust holes are provided on surfaces other than the top and bottom surfaces of the battery module. The battery pack structure according to claim 1, characterized in that the gas outlet is provided in at least one of the lower case member and the upper case member in the vicinity of the battery module.

4. The frame is provided with a flow passage through which the gas flows, communicating with the housing section. The battery pack structure according to claim 1, characterized in that the flow passage is connected to the gas outlet.

5. The battery pack structure according to claim 4, characterized in that the frame has an outer shell frame portion that surrounds the plurality of housing portions partitioned in a horizontal plane.

6. The battery pack structure according to claim 4, characterized in that the flow passage opens to the surface of the frame facing the gas exhaust hole of the battery module, and the gas exhaust port of the lower case member is provided on the lower side of the frame at the position of the opening.

7. The battery pack structure according to claim 4, wherein in each of the adjacent housing sections partitioned by the frame, the battery module is provided with the gas exhaust hole on the surface facing the frame, the flow passage is provided so as to penetrate the frame and connect the adjacent housing sections, and the gas exhaust port of the lower case member is provided on the lower side of the frame at the location of the flow passage.

8. The battery pack structure according to claim 1, characterized in that the thermally expandable resin is applied to the lower surface of the upper case member before attachment.

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