Battery module cooling structure

Abstract

The battery module cooling structure includes a battery pack case (20) having an internal space (20A) in which battery modules (30) are arranged side by side in a first direction, an air inlet (45B) to the internal space (20A), and an air outlet (46C) from the internal space (20A), and a partition portion (90) that extends in a horizontal second direction intersecting the first direction, is disposed between adjacent battery modules (30), stands upright upward from the inner bottom surface (51) of the battery pack case (20), and partitions a lower space (20L). The partition portion (90) is such that the distance from one end closer to the inlet (45B) in the second direction of the internal space (20A) to the other end closer to the inlet (45B) in the second direction of the internal space (20A) is longer for the partition portion (90) disposed closer to the inlet (45B) than to the outlet (46C) in the first direction.

Description

Technical Field

[0001] This invention relates to a battery module cooling structure for cooling a battery module mounted on a vehicle.

Background Art

[0002] Vehicles such as electric vehicles and hybrid electric vehicles are equipped with a large-capacity battery (also called a battery pack) as a power supply source for vehicle driving. As a large-capacity battery, a plurality of battery modules housed in the internal space of a battery pack case are known. The plurality of battery modules generate heat during power transfer such as during power running when supplying power to a driving motor and during regeneration when converting the braking energy of the vehicle into electric power for charging. As one of the structures for cooling the heat-generating battery module, a structure for cooling the battery module housed in the internal space of the battery pack case from below has been proposed. For example, a structure in which a water-cooling mechanism is provided in the lower space with respect to the battery module has been studied (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the structure of introducing a refrigerant into the lower space with respect to the battery module as described above, it is conceivable to use air (that is, cooling air) as the refrigerant. In this case, there may be a region where the air of the refrigerant is difficult to spread or a region where the air of the refrigerant is excessively supplied in the lower space (hereinafter also referred to as the "lower space"), and there is a risk that a plurality of battery modules cannot be cooled evenly. Therefore, there is room for improvement in cooling a plurality of battery modules evenly.

[0005] The battery module cooling structure of the present invention was invented in consideration of these problems, and one of its objectives is to cool multiple battery modules in a balanced manner. However, in addition to this objective, another objective of the present invention is to achieve effects derived from the configurations shown in the "Description of Embodiments" below, which are not obtainable with conventional technologies. [Means for solving the problem]

[0006] The disclosed battery module cooling structure can be realized as the following disclosed embodiments (application examples), which solve at least part of the above-mentioned problems. Each of the embodiments from embodiment 2 onwards is an embodiment that can be selected as an additional option, and each of the embodiments from embodiment 2 onwards is an embodiment that can be omitted. None of the embodiments from embodiment 2 onwards discloses an embodiment or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed battery module cooling structure includes a battery pack case and a partition. The battery pack case has an internal space in which three or more battery modules are arranged side by side in a horizontal first direction, an air inlet into the internal space, and an air outlet out of the internal space. The partitions extend in a horizontal second direction intersecting the first direction, are disposed between adjacent battery modules, and extend upward from the inner bottom surface of the battery pack case to separate a lower space between the electric module and the inner bottom surface. The inlet and the outlet are located at different positions in the first direction and the second direction, respectively, and the three or more battery modules are arranged on a path connecting the inlet and the outlet. The distance from one end of the partition closer to the inlet in the second direction to one end of the internal space closer to the inlet in the second direction is longer for the partitions located closer to the inlet in the first direction relative to the outlet.

[0008] Aspect 2. In the above aspect 1, it is preferable that the inlet is provided at least at one end and the other end in the first direction in the lower space. Aspect 3. In the above aspect 2, it is preferable that the inlet is provided at each of one end and the other end of the lower space in the first direction, and the outlet is provided in the center between the inlet located at one end of the lower space in the first direction and the inlet located at the other end of the lower space in the vehicle width direction.

[0009] Aspect 4. In any one of Aspects 1 to 3 above, it is preferable that the partition portion has at least one of a long partition portion that extends longer than the dimension of the battery module in the second direction and a short partition portion that extends shorter than the dimension of the battery module in the second direction.

[0010] Aspect 5. In any one of Aspects 1 to 4 above, it is preferable that a lower step portion is formed between a downstream bottom surface of the inner bottom surface that is located closer to the discharge outlet than the inlet in the second direction, and an upstream bottom surface of the inner bottom surface that is located closer to the inlet than the discharge outlet in the second direction and is lower than the downstream bottom surface.

[0011] Aspect 6. In any one of Aspects 1 to 5 above, it is preferable that the battery module cooling structure has an upper step portion formed between a downstream top surface of the inner top surface that defines the upper end of the internal space and that is located closer to the outlet than the inlet in the second direction, and an upstream top surface of the inner top surface that is located closer to the inlet than the outlet in the second direction and is lower than the downstream top surface.

[0012] Aspect 7. In any one of Aspects 1 to 6 above, it is preferable that the battery module cooling structure includes a baffle plate that is positioned above the battery module below a downstream top surface of the inner top surface that defines the upper end of the internal space and that is located closer to the outlet than the inlet in the second direction, and that obstructs the flow of air from below to above.

[0013] Aspect 8. In any one of Aspects 1 to 7 above, the partition section is preferably provided in a tapered shape in which the dimension in the first direction is longer on the side from the inlet toward the outlet in the second direction.

[0014] Aspect 9. In any one of Aspects 1 to 8 above, it is preferable that the battery pack case accommodates side modules, each of which is disposed at both ends of the battery modules in the first direction, and a center module, each of which is disposed centrally in the first direction, among the battery modules. In this case, it is preferable that the inner bottom surface has a side inner bottom surface located below the side modules and a center inner bottom surface located below the center module, and that the lower space has a side lower space formed between the side modules and the side inner bottom surface and provided with the inlet, and a center lower space formed between the center module and the center inner bottom surface, communicating with a lower part of the side lower space and having a smaller vertical dimension than the side lower space.

[0015] Aspect 10. In the above aspect 9, it is preferable that the side lower space is defined at its lower end by a slope surface that is positioned downward toward the center in the first direction in at least a portion of the side inner bottom surface. [Effects of the Invention]

[0016] According to the disclosed battery module cooling structure, a plurality of battery modules can be cooled in a balanced manner. [Brief explanation of the drawings]

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] With reference to the drawings, an embodiment of a structure relating to a battery mounted on a vehicle (including a battery module cooling structure) will be described. The embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly stated in the following embodiments. The configurations of the embodiments can be implemented in various modifications without departing from the spirit thereof. Furthermore, they can be selected or combined as needed.

[0019] In the following description, the forward direction of the vehicle is defined as the front, and the backward direction is defined as the rear, and left and right are defined based on the front. Since the left and right direction (first direction) is the width direction of the vehicle, in this embodiment, the left and right direction is referred to as the "vehicle width direction" of the vehicle. Furthermore, the up and down direction is defined with the direction of gravity as downward and the opposite as upward, and in this embodiment, the position in the up and down direction is referred to as the "height position." Note that the up and down direction does not have to completely coincide with the vertical direction, and may be slightly inclined relative to the vertical direction. Similarly, the front and back direction of the vehicle (second direction, hereinafter simply referred to as the "front and back direction") and the vehicle width direction do not have to completely coincide with the horizontal direction.

[0020] Vehicle structures are often formed with near bilateral symmetry (mirror symmetry about a plane including the yaw axis and roll axis passing through the center of gravity of the vehicle), but a completely symmetrical shape is not required. Furthermore, the type of vehicle to which the structure according to the embodiment is applied is not particularly limited, and the structure can be applied to, for example, an electric vehicle (EV), a hybrid vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or the like. A plug-in hybrid vehicle is a hybrid vehicle that can externally charge the battery or receive external power from the battery. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility, and a power outlet (outlet) for external power supply.

[0021] I. ONE EMBODIMENT In the following embodiment, as a structure related to a battery (also called a battery pack), a battery mounting structure for mounting a battery on a vehicle, a battery pack intake structure for taking in air into the internal space of a battery pack case mounted on the vehicle, and a battery module cooling structure for cooling the battery mounted on the vehicle will be described for three structures. Note that since the three structures of the battery mounting structure, the battery pack intake structure, and the battery module cooling structure are structures related to the vehicle's battery, they can be collectively referred to as the vehicle's battery structure, and when the battery is mounted at the lower part of the passenger compartment, it can also be called the vehicle lower structure with the mounting location of the battery as the prefix. These three structures can also be extended and referred to as the vehicle structure.

[0022] [1. Configuration] [1-1. Basic Structure] FIG. 1 is a longitudinal sectional view showing a battery pack 10 to which the battery module cooling structure according to the embodiment is applied and a part of the structure provided around the battery pack 10, and is a view seen from the front side of the vehicle. FIG. 2 is a cross-sectional view of the battery pack 10 and is a view seen from above the vehicle. FIG. 3 is a schematic diagram showing a path through which cooling air (hereinafter referred to as "cooling air") of the refrigerant flows in the internal space 20A of the battery pack 10, and is a view seen from the left side of the vehicle. FIG. 4 is an exploded perspective view showing an overview of the battery pack 10. As shown in FIG. 1, a battery pack 10 is provided in the passenger compartment 1, and various structures and members are provided around the battery pack 10.

[0023] <Peripheral Configuration of Battery Pack> Above the battery pack 10, a seat 2 on which a passenger sits is provided. Here, the seat 2 shown as an example is a front seat (front-side seat) among seats arranged in at least two rows in the front-rear direction. For example, the driver's seat and the front passenger seat are the seat 2. However, the seat 2 may be any front-side seat except the last-row seat among the seats arranged in multiple rows in the front-rear direction, and may be the frontmost seat or the second-row seat from the front in a vehicle in which three rows of seats are arranged side by side.

[0024] Additionally, a panel member 3 and a carpet 4 of the vehicle interior 1 are provided above the battery pack 10. The panel member 3 is a sheet metal member that forms the floor surface on which the carpet 4 is placed. The carpet 4 is laid above the panel member 3, and seats 2 such as the driver's seat and passenger seat are arranged above the carpet 4 with a gap in the vehicle width direction. A console 5 is provided on the panel member 3 between the driver's seat and the passenger seat that make up the seat 2. The console 5 illustrated in Fig. 1 is provided separately from the panel member 3. This console 5 is provided with a cup holder 5H.

[0025] Below the battery pack 10, a body floor 6 extends in a planar shape. Below the body floor 6, a pair of left and right side members 7 are provided extending in the fore-and-aft direction to support from below a pair of left and right side floors 6X, which are the portions of the body floor 6 at the vehicle width end sides (hereinafter also referred to as the "vehicle width outer sides"). The center floor 6Y of this body floor 6, which is closer to the center of the vehicle width direction (inner side of the vehicle width direction) than the side floor 6X, is located lower than the side floor 6X, and the upper and lower cross sections along the vehicle width direction are shaped to be convex downward.

[0026] In the vehicle exemplified in this embodiment, an exhaust pipe 8 is provided extending in the front-rear direction below the body floor 6, on the inner side in the vehicle width direction of the right (one side in the vehicle width direction) side member 7. The exhaust pipe 8 is a duct member that circulates exhaust gas from an engine (internal combustion engine) not shown, and can also be considered a member that radiates exhaust heat. The space above the body floor 6 is the passenger compartment 1. In other words, since the lower end of the passenger compartment 1 is defined by the body floor 6, the battery pack 10 can also be said to be mounted in the lower part of the passenger compartment 1.

[0027] <Battery pack configuration> The battery pack 10 is a power storage device for a vehicle that houses a plurality of battery modules 30 in the internal space 20A of the battery pack case 20. Hereinafter, as the configuration of the battery pack 10, the configurations of the battery module 30, the battery system electrical components, and the cooling device will be described, then the internal arrangement will be described, and finally, the battery pack case 20 located below the seat 2 will be described.

[0028] ==Battery Module== The battery module 30 is a secondary battery that can not only supply power but also be charged. This battery module 30 generates heat during power transfer such as during power running when supplying power to the drive motor (not shown) of the vehicle or during regeneration when the braking energy of the vehicle is converted into electric power and charged. Note that the battery module 30 is a battery with a larger capacity than in-vehicle batteries such as so-called 12V batteries and 24V batteries.

[0029] Above and below the battery module 30 in the internal space 20A, a space (hereinafter referred to as the "lower space") 20L located below the battery module 30 and a space (hereinafter referred to as the "upper space") 20U located above the battery module 30 are formed. As shown in FIG. 3, each of the battery modules 30 is a battery pack formed by connecting a plurality of battery cells 30C (single cells, only one location is labeled in FIG. 3) to each other. These battery cells 30C are connected by combining series connections and parallel connections according to the design voltage, design capacity, etc. of the battery module 30.

[0030] FIGS. 1 and 2 illustrate a form in which a plurality of battery modules 30 having the same size are arranged side by side in the vehicle width direction in the same posture. Specifically, six battery modules 30 having the same dimensions in the vehicle width direction, front-rear direction, and vertical direction (i.e., proportions) and having a rectangular parallelepiped shape are arranged side by side in the same posture with the front-rear direction as the longitudinal direction. That is, the plurality of battery modules 30 have the same length in the vertical direction and the same length in the front-rear direction. In the battery module 30 illustrated in this embodiment, the first battery module 31, the second battery module 32, the third battery module 33, the fourth battery module 34, the fifth battery module 35, and the sixth battery module 36 are provided in order from left to right.

[0031] Among these six battery modules 31 to 36, the four battery modules 32 to 35 arranged at the center in the vehicle width direction are collectively referred to as the center module 15 without distinction. Also, among the six battery modules 31 to 36, the battery modules 31 and 36 respectively arranged at both ends in the vehicle width direction are collectively referred to as the side module 16 without distinction. That is, the ones located on the outermost sides on one side and the other side in the vehicle width direction among the six battery modules 30 are referred to as the side module 16.

[0032] In the internal space 20A that houses the above-described battery module 30, various battery-related electrical components and cooling devices are housed. ==Battery-related Electrical Components== As shown in FIG. 1, examples of the battery-related electrical components housed in the internal space 20A include a BMU 40 (Battery Management Unit, battery management device), a transformer 41, a harness 42, and a junction box 43 (see FIGS. 2 to 4). The BMU 40 is an electronic control device that comprehensively manages all the battery modules 30 and has functions such as managing and monitoring the states of the individual battery modules 30 and an A / D conversion (analog / digital conversion) function for control signals.

[0033] The transformer 41 is a device that converts voltage. This transformer 41 is, for example, a DC / DC converter that steps down the voltage applied from the battery module 30 and outputs it, and generates heat during voltage conversion. The harness 42 is an electric wire connected to the BMU 40, the transformer 41, the junction box 43, etc. The junction box 43 is a device that performs functions such as monitoring the amount of electric power transmitted outside the battery pack 10 for high-voltage electric power, cutting off the power, and distributing power to the transformer 41.

[0034] ==Cooling equipment== 4, an example of the cooling device housed in the internal space 20A is an intake duct 45. Note that examples of cooling devices that are not housed in the internal space 20A but are attached to the outside of the battery pack case 20 include a fan 44 and an exhaust duct 46. The fan 44 is an air-cooling fan that supplies cooling air to cool the heat-generating battery modules 30 and the transformer 41. The intake duct 45 and the exhaust duct 46 are tubular members that form the flow passages for the cooling air supplied by the fan 44.

[0035] The cooling by the cooling device is performed in the internal space 20A of the battery pack case 20 as will be outlined below. As shown in FIG. 3 , cooling air taken in from the space of the vehicle interior 1 (vehicle interior space) flows through the intake duct 45. The cooling air that has flowed through the intake duct 45 is introduced into the lower space 20L. The cooling air in the lower space 20L flows into the upper space 20U through gaps between the multiple battery cells 30C that make up each battery module 30. The cooling air flows from the lower space 20L to the upper space 20U, thereby cooling the battery modules 30. After cooling the transformer 41, the cooling air in the upper space 20U is circulated through the exhaust duct 46 by the fan 44 and then discharged.

[0036] In the illustrated embodiment, as shown in FIG. 4, a pair (two) of left and right intake ducts 45 are provided in the interior space 20A, and a fan 44 and an exhaust duct 46 are provided above the battery pack 10 in the center in the vehicle width direction. In the intake duct 45, an intake port 45A is formed at the upstream end in the flow direction of the cooling air, and an introduction port 45B is formed at the downstream end in the flow direction of the cooling air. The intake port 45A is an opening for taking in cooling air from the space of the passenger compartment 1 (the passenger compartment space) into the internal space 20A. The introduction port 45B is an opening for introducing cooling air into the internal space 20A. Specifically, the introduction port 45B for the cooling air into the internal space 20A is an opening for introducing the cooling air into the lower space 20L. That is, the cooling air for cooling the battery module 30 is introduced from the introduction port 45B in the lower space 20L.

[0037] Each of the intake port 45A and the introduction port 45B is provided at two locations, similar to the number of installed intake ducts 45. Specifically, the intake ports 45A are provided at the left and right ends respectively on the upper surface of the battery pack case 20. Also, the introduction ports 45B are provided at the left and right ends (one end and the other end in the first direction) respectively in the lower space 20L. However, only one intake duct 45 may be provided, and the introduction port 45B may be provided at either the left end or the right end in the lower space 20L.

[0038] The exhaust duct 46 extends outside the battery pack case 20. A fan 44 is connected to the upstream end in the flow direction of the cooled air (hereinafter, this is also referred to as "cooling air") in this exhaust duct 46, and an exhaust port 46D through which the cooling air pumped by the fan 44 is exhausted is formed at the downstream end in the flow direction. The cooling air in the exhaust duct 46 is exhausted from the exhaust port 46D into, for example, the inside of an instrument panel (not shown).

[0039] In addition, as shown in FIG. 3, the cooling air in the upper space 20U flows from the discharge port 46C communicating with the upper space 20U to the fan 44. The discharge port 46C is an opening for discharging the cooling air outside the internal space 20A. Specifically, the discharge port 46C for the cooling air outside the internal space 20A is an opening for discharging the cooling air from the upper space 20U. That is, the cooling air that has cooled the battery module 30 is discharged from the discharge port 46C in the upper space 20U.

[0040] Here, as shown by the thick dashed line in FIG. 2, the exemplified discharge port 46C is arranged such that both the position in the vehicle width direction and the position in the front-rear direction are different from those of the inlet port 45B. Specifically, the discharge port 46C is arranged on the center side and rear side in the vehicle width direction with respect to the inlet port 45B. In other words, focusing on the position in the vehicle width direction, the discharge port 46C is provided at the center between the inlet port 45B located on the left side and the inlet port 45B located on the right side in the vehicle width direction.

[0041] A plurality of battery modules 30 are arranged on a linear path (hereinafter referred to as the "linear path") 49 that virtually connects the inlet port 45B and the discharge port 46C. In other words, the inlet port 45B, the discharge port 46C, and the battery modules 30 are provided in a relative arrangement such that the virtual linear path 49 crosses all the battery modules 30.

[0042] ==Internal Arrangement== Next, the arrangement of the battery modules 30, battery system electrical components, and cooling equipment in the battery pack 10 will be described. As shown in FIG. 4, the BMU 40, the transformer 41, and the junction box 43 are collectively arranged in the center or front in the vehicle width direction in the internal space 20A.

[0043] FIGS. 1 and 4 show an example in which the BMU 40 and the transformer 41 are arranged above the center module 15 in the internal space 20A. Here, an arrangement in which the transformer 41 is located above the BMU 40 is exemplified. Also, as shown in FIG. 2, the junction box 43 is arranged in front of the center module 15. Note that the BMU 40, the transformer 41, and the junction box 43 are not arranged above or in front of the side module 16. Therefore, it can be said that the side module 16 has a higher degree of freedom in arrangement setting than the center module 15, and the center module 15 has more restrictions on arrangement changes than the side module 16.

[0044] The harness 42 is connected to the BMU 40, the transformer 41, the junction box 43, and the like, and is therefore routed at least above or in front of the center module 15. 4, the intake duct 45 extends outward in the vehicle width direction and forward of each of the left and right side modules 16. In the illustrated intake duct 45, an intake port 45A is disposed on the outer side of each side module 16 in the vehicle width direction in a plan view, and an introduction port 45B is disposed on the front side of each side module 16 in a plan view.

[0045] In addition, the fan 44 and the exhaust duct 46 are arranged above the battery pack case 20 rather than in the internal space 20A. Here, the fan 44 is arranged above the transformer 41, and the exhaust duct 46 extends forward from the fan 44. 1, the seat 2 is not installed in the interior space 20A but above the battery pack 10, and above the outer half of the second battery module 12 and fifth battery module of the center module 15 in the vehicle width direction, and above the entire side module 16. The battery pack case 20 thus mounted below the seat 2 will be described next.

[0046] ==Battery pack case== The battery pack case 20, in which the battery module 30, battery-related electrical components, and cooling equipment are arranged as described above, is mounted in the lower part of the vehicle interior 1 (lower part of the vehicle interior), and as shown in Fig. 1, is composed of a tray 21 and a lid 22. The tray 21 is a cylindrical casing member with a bottom and an opening at the top. The lid 22 is a cover member that closes the opening of the tray 21.

[0047] The tray 21 has a bottom wall portion 50 and a side wall portion 60 standing upright from the periphery of the bottom wall portion 50 . The bottom wall 50 has an inner bottom surface 51 that defines the lower end of the internal space 20A. The "inner bottom surface 51" here refers to a planar portion exposed to the lower space 20L. The wall-like (plate-like) portion having the inner bottom surface 51 defined in this way is the bottom wall 50. The inner bottom surface 51 extends below the battery module 30 via the lower space 20L. That is, the battery module 30 and the inner bottom surface 51 are separated from each other.

[0048] In the present embodiment, the inner bottom surface 51 is divided into two regions: a center inner bottom surface 51C located below the center module 15 and a side inner bottom surface 51S located below the side module 16. Similarly, the lower space 20L is also divided into two regions: a center lower space 20C formed below the center module 15 and above the center inner bottom surface 51C, and a side lower space 20S formed below the side module 16 and above the side inner bottom surface 51S. The center lower space 20C and the side lower space 20S are provided in communication with each other, and cooling air can flow through the entire lower space 20L.

[0049] Note that the exhaust pipe 8 described above is disposed directly below the vehicle-width direction end portion of the tray 21 (battery pack case 20). The lid 22 is a member that forms the upper surface of the battery pack case 20. As shown in FIG. 4, an air intake port 45A for taking in cooling air into the internal space 20A is formed in the lid 22. Here, an upward air intake port 45A is provided on the upper surface of the battery pack case 20, and an air intake port cover 70 that covers the air intake port 45A is provided.

[0050] [1-2. Battery mounting structure] Hereinafter, the battery mounting structure related to the layout of the battery module 30 will be described in detail. In a structure where all battery modules arranged in a predetermined direction are disposed at the same height position (hereinafter referred to as "comparative structure 1"), a surface on which all battery modules can be placed at the same height position (i.e., a placement surface of a region where all battery modules extend at a certain height position) is required, and there is a risk of interference with the peripheral structure of the battery module. For example, when existing structures such as side members 7 and exhaust pipes 8 exist outside the vehicle width direction of the battery pack 10 as in the present embodiment, in comparative structure 1, the battery modules outside the vehicle width direction may interfere with these existing structures. Therefore, measures such as redesigning the arrangement of the peripheral structure of the battery module or reducing the number of battery modules are required.

[0051] Therefore, in the battery mounting structure of the present embodiment, all the battery modules 30 are not deliberately arranged at the same height position, and the height position is set according to the arrangement location of the battery module 30, thereby ensuring the degree of freedom in the layout of the peripheral structure with respect to the battery module 30.

[0052] In the battery mounting structure of the present embodiment, as shown in FIGS. 1 and 4, the side module 16 is disposed so as to protrude upward with respect to the center module 15. In other words, the height position of the side module 16 is offset upward with respect to the center module 15. Conversely, the center module 15 is disposed so as to protrude downward with respect to the side module 16. In other words, the height position of the center module 15 is offset downward with respect to the side module 16. Such an offset arrangement in the vertical direction can be rephrased as an arrangement in which the position of the side module 16 is raised among a plurality (for example, six) of battery modules 30 (31 to 36), and can also be rephrased as an arrangement in which the side module 16 protrudes upward more than the center module 15.

[0053] Here, the exemplary side module 16 is arranged at a position where it partially overlaps with the center module 15 in the vertical direction when viewed from the vehicle width direction. Such an arrangement can be rephrased as an arrangement in which all of the battery modules 30 wrap around at least a partial region in the vertical direction, and it can also be said that the side module 16 is not raised too high above the entire center module 15. In addition, the center modules 15 are arranged at equal height positions. The side modules 16 are also arranged at equal height positions.

[0054] Regarding the battery module 30 in which the relative height positions of the center module 15 and the side module 16 are set as described above, with reference to FIG. 1, an explanation of the height position with respect to the side member 7 among the peripheral structures of the battery pack 10 will be appended. The lower part (a part) of the center module 15 is arranged at a height position that overlaps with the side member 7 when viewed from the vehicle width direction. On the other hand, the side module 16 does not overlap with the side member 7 when viewed from the vehicle width direction and is arranged at a height position above the side member 7. Such an arrangement of the battery module 30 with respect to the side member 7 can be said to be an arrangement in which the center module 15 fits between the side members 7, and it can also be said to be a recessed arrangement in which the side module 16 retreats upward to avoid interference with the side member 7 (peripheral structure).

[0055] In addition, regarding the height position of the lower end surface 30L of the battery module 30 with reference to the upper end 7U of the side member 7, the lower end surface 30L of the center module 15 (only one location is labeled in FIG. 1) is arranged below the upper end 7U of the side member 7. On the other hand, the lower end surface 30L of the side module 16 is arranged above the upper end 7U of the side member 7.

[0056] The side lower space 20S formed below the side module 16, which is disposed offset upward as described above, has a larger vertical dimension than the center lower space 20C formed below the center module 15. In other words, the vertical dimension of the center lower space 20C is smaller than that of the side lower space 20S. The lower part of the side lower space 20S is in communication with the center lower space 20C.

[0057] The lower end of the side lower space 20S is defined by a slope surface 51X that is positioned (inclined downward) in at least a portion of the side inner bottom surface 51S and that is positioned downward toward the center in the vehicle width direction. In other words, the slope surface 51X is a planar portion that slopes downward from the outer side toward the inner side in the vehicle width direction.

[0058] Furthermore, the side modules 16 provided in the battery mounting structure exemplified in this embodiment are disposed so as to protrude forward relative to the center module 15, as shown in Fig. 2. In other words, this arrangement means that the position of the side modules 16 in the front-to-rear direction is offset forward relative to the center module 15. Conversely, the center module 15 is disposed so as to protrude rearward relative to the side modules 16. In other words, this arrangement means that the position of the center module 15 in the front-to-rear direction is offset rearward relative to the side modules 16. This offset arrangement in the front-to-rear direction can also be said to be an arrangement in which the side modules 16 are positioned forward among the multiple (e.g., six) battery modules 30 (31-36).

[0059] A rear wall portion 61 is provided on the side wall portion 60 of the battery pack case 20 so as to extend upright behind the battery module 30 in accordance with the outer shape of the battery module 30 in which the relative longitudinal positions of the center module 15 and the side modules 16 are set as described above. Specifically, of the rear wall 61, a portion (hereinafter referred to as a "side portion") 61S erected on the rear side of the side module 16 is positioned further forward than a portion (hereinafter referred to as a "center portion") 61C erected on the rear side of the center module 15. In other words, the center portion 61C of the rear wall 61, which is in the center in the vehicle width direction, is formed in a shape that convex rearward.

[0060] The side portions 61S extend to the rear and left and right corners of the tray 21 of the battery pack case 20. Therefore, the rear and left and right corners of the tray 21 are formed at positions shifted forward. The front wall 62 of the side wall 60, which is erected in front of the battery module 30, extends in a flat plate shape along the vehicle width direction. The junction box 43 is housed between the front wall 62, which does not have any concave or convex shapes in the front and rear directions, and the center module 15. In other words, the side module 16 is disposed offset forward without changing the layout of the junction box 43 disposed in front of the center module 15.

[0061] [1-3. Battery pack air intake structure] The battery pack air intake structure that takes in cooling air into the internal space 20A of the battery pack case 20 will be described in detail below. In a structure in which air from the vehicle interior is drawn into the battery pack case 20 to cool the battery module 30, as in this embodiment, the air intake 45A serving as the intake for the cooling air needs to be open to the vehicle interior. However, if the air intake for drawing in the cooling air is directly exposed to the vehicle interior (hereinafter referred to as "Comparative Structure 2"), there is a risk that foreign objects from the vehicle interior may enter the internal space of the battery pack case. For example, in Comparative Structure 2 in which the air intake formed on the top surface of the battery pack case is exposed to the vehicle interior, there is a risk that a small object dropped by an occupant may roll into the air intake, or that a drink spilled by an occupant may run down the seat and enter the air intake.

[0062] Therefore, the battery pack air intake structure of this embodiment is designed so that the air intake port 45A that takes in cooling air is not exposed to the vehicle interior space, thereby preventing foreign objects from entering the internal space 20A of the battery pack case 20. This will be described in detail below with reference to FIGS. 5 and 6. FIG. 5 is a cross-sectional view of the main part of the structure surrounding the air intake port 45A located on the left side of the vehicle, as seen from the front of the vehicle, and FIG. 6 shows an air intake port cover 70 that covers the air intake port 45A from above. In the description using FIGS. 5 and 6, the "right side" refers to the inside in the vehicle width direction, and the "left side" refers to the outside in the vehicle width direction. In this embodiment, a pair of left and right air intake ducts 45 are provided, so the surrounding structure of the air intake port 45A on the right side of the vehicle and the air intake port cover 70 (not shown) have the same configuration (bilateral symmetry) as will be described below.

[0063] As shown in Fig. 5, the battery pack air intake structure of this embodiment includes an air intake cover 70 that covers the air intake 45A from above. The air intake cover 70 is disposed above and spaced apart from the air intake 45A, and a horizontal gap 47 is provided between the air intake cover 70 and the upper surface 20F of the battery pack case 20. That is, the cover lower surface 70L of the air intake cover 70 faces the upper surface 20F and the air intake 45A via the gap 47. The upper surface 70J of the air intake cover 70 (hereinafter referred to as the "cover upper surface") is exposed to the vehicle interior 1.

[0064] Gap 47 communicates with the vehicle interior space via air intake 71. That is, air intake cover 70 forms air intake 71 and also forms gap 47 with the upper surface 20F of battery pack case 20 (which may also be called the "case upper surface"). Here, three intakes 71A, 71B, and 71C are shown as examples of air intakes 71. Of the three intakes 71A, 71B, and 71C, one is a right intake 71A facing the right of the vehicle, another is a rear intake 71B facing the left of the vehicle, and the remaining one is an upper intake 71C facing upward.

[0065] The right intake port 71A and the left intake port 71B are each defined by the upper edge at the right and left edges of the intake port cover 70, and are provided horizontally (in a direction different from the direction of the intake port 45A). Describing the arrangement of the right intake port 71A and the left intake port 71B with reference to the position of the intake port 45A, the right intake port 71A is formed on the right side (one side in a predetermined direction) of the intake port 45A, and the left intake port 71B is formed on the left side (the other side in the predetermined direction) of the intake port 45A.

[0066] In the intake port cover 70 that forms the right intake port 71A and the left intake port 71B on the right and left sides sandwiching the intake port 45A as described above, an upper intake port 71C is formed in a region that does not overlap the intake port 45A in a top view. Here, the exemplified upper intake port 71C is provided on the right side with respect to the intake port 45A and is arranged in the vicinity of the right intake port 71A. FIG. 6 exemplifies the upper intake port 71C with a mesh-like mesh member 72 stretched thereover.

[0067] The right intake port 71A and the left intake port 71B do not include a mesh member 72 such as the upper intake port 71C and form merely openings. The three air intake ports 71A, 71B, and 71C are arranged such that the distances (separation distances) from the intake port 45A are different. FIG. 5 exemplifies a form in which the separation distance of the air intake port 71 with respect to the intake port 45A is such that the right intake port 71A is the farthest and the left intake port 71B is the closest. In addition, the three air intake ports 71A, 71B, and 71C are arranged at a distance from the edge 4E (opening edge) of the carpet 4. Note that the edge 4E of the carpet 4 is a location where, for example, warm air heated from the exhaust system of the vehicle may leak.

[0068] Incidentally, if liquid is spilled on the intake port cover 70, for example, the liquid may pool on the cover upper surface 70J depending on the shape of the cover upper surface 70J of the intake port cover 70. Furthermore, if liquid spills on the cover upper surface 70J and seeps in through the air intake 71, the seeping liquid may be easily guided along the cover lower surface 70L toward above the intake port 45A depending on the shape of the cover lower surface 70L of the intake port cover 70. In particular, if the cover lower surface 70L is configured to be positioned lower as it approaches the intake port 45A from the air intake 71, the seeping water may be guided by gravity along the cover lower surface 70L toward above the intake port 45A, resulting in the water seeping into the intake port 45A.

[0069] Therefore, the cover upper surface 70J and the cover lower surface 70L are provided at an incline to ensure that liquid that may adhere to the intake port cover 70 is properly disposed of. The cover upper surface 70J is inclined downward toward the air intake 71. The cover upper surface 70J illustrated here is provided in a roof shape (a downwardly inclined eave shape) that is positioned lower (downwardly inclined) as it approaches each of the left and right edges.

[0070] The cover lower surface 70L is provided with an upwardly sloping portion 70G that is positioned upward (inclined upward) as it approaches the air intake 45A from the air intake 71. Fig. 5 shows an example in which an upwardly sloping portion 70G that is positioned upward (inclined upward) is provided as it approaches the air intake 45A from each of the right air intake 71A and the left air intake 71B.

[0071] The illustrated air intake cover 70 extends from above to an area that covers the metal sheet edge 3E, which is the edge portion of the panel member 3 that is provided around the air intake 45A. In other words, the air intake cover 70 extends from the air intake 45A to the metal sheet edge 3E of the panel member 3 when viewed from above the vehicle. However, the air intake cover 70 does not overlap the edge 4E of the carpet 4 when viewed from above.

[0072] The battery pack air intake structure of this embodiment includes not only the air intake cover 70 but also a rib 80 that structurally prevents foreign matter that has entered the gap 47 from entering the air intake 45A. The rib 80 stands upright in the gap 47 from the upper surface 20F of the battery pack case 20. The rib 80 is provided with a gap (a gap that connects the air intake 71 and the air intake 45A) from the air intake cover 70 (i.e., not in contact with the cover lower surface 70L of the air intake cover 70).

[0073] Although not shown, as another form of rib, a rib may be erected from the intake port cover 70 into the gap 47. In this case, the rib may be provided with a gap from the upper surface 20F of the battery pack case 20. The former rib 80 (rib 80 erected from the upper surface 20F) and the latter rib (rib erected from the intake port cover 70) may be provided side by side. Furthermore, the rib may be provided with a gap that at least connects the air intake 71 and the intake port 45A, and may be erected from both the upper surface 20F of the battery pack case 20 and the intake port cover 70.

[0074] In the configuration illustrated in this embodiment, the air intake port 45A, the rib 80, and the air intake port 71 are arranged side by side in the vehicle width direction. The rib 80 illustrated here is formed as a peripheral wall surrounding the periphery of the intake port 45A in top view, as shown in Fig. 6. In other words, the rib 80 standing so as to surround the periphery of the intake port 45A is provided on both sides of the intake port 45A, and in other words, the entire area of the rib 80 is arranged to overlap with the intake port 45A in the front-to-rear direction.

[0075] The rib 80 includes a right rib 81 (first rib) located on the right side of the intake port 45A, and a left rib 82 (second rib) located on the left side of the intake port 45A. These ribs 81, 82 have different distances from the air intake port 71. Specifically, the distance L1 between the right rib 81 and the right intake port 71A is longer than the distance L2 between the left rib 82 and the left intake port 71B (satisfying the inequality "L1>L2").

[0076] Although the ribs 81 and 82 are more effective in structurally suppressing the intrusion of foreign matter as they are longer in the vertical direction, they structurally block the air flow path from the passenger compartment space, leading to a decrease in the intake efficiency of the cooling air. Therefore, in order to achieve both the suppression of the intrusion of foreign matter and the suppression of the decrease in the intake efficiency of the cooling air, the dimensions and arrangements of the ribs 81 and 82 are set.

[0077] Here, the exemplified ribs 81 and 82 are, as shown in FIG. 5, such that the height dimensions G1 and G2 from the adjacent surfaces 9A and 9B immediately adjacent to the ribs 81 and 82 are set according to the separation distances L1 and L2 from the air inlets 71A and 71B close to the ribs 81 and 82. Specifically, the first height dimension G1 from the right adjacent surface 9A (first adjacent surface) adjacent to the right side of the right rib 81 to the upper end 81U of the right rib 81 is smaller than the second height dimension G2 from the left adjacent surface 9B (second adjacent surface) adjacent to the left side of the left rib 82 to the upper end 82U of the left rib 82. That is, the inequality "G1 < G2" is satisfied, and the height dimensions G1 and G2 (so-called "gaps") from the adjacent surfaces 9A and 9B adjacent to the opposite side of the air inlet 45A with respect to the ribs 81 and 82 are smaller for the farther separation distances L1 and L2. That is, the gap of the right rib 81 arranged deeper among the ribs 81 and 82 is suppressed. In this embodiment, the right adjacent surface 9A is the upper surface of another panel member to which the panel member 3 is fixed, and the left adjacent surface 9B is the upper surface 20F of the battery pack case 20.

[0078] Also, the height positions of the upper ends 81U and 82U of the ribs 81 and 82 (shown by a one-dot chain line in FIG. 5) and the height positions of the upper ends of the air inlets 71A and 71B (shown by a one-dot chain line in FIG. 5) are provided to be substantially equal to each other. That is, the ribs 81 and 82 are erected on each path straight from each of the air inlets 71A and 71B to the air inlet 45A. Therefore, the air taken in from the air inlets 71A and 71B flows upward in a meandering manner over the ribs 81 and 82 and then to the air inlet 45A, and a complex path that is not straight (so-called "labyrinth structure") is formed by the ribs 81 and 82 and the air inlet cover 70.

[0079] To increase the efficiency of cooling air intake, the height positions of the upper ends 81U, 82U of the ribs 81, 82 may be set lower than the height positions of the upper ends of the air intakes 71A, 71B. Conversely, to ensure a more reliable effect of suppressing the intrusion of foreign matter, the height positions of the upper ends 81U, 82U of the ribs 81, 82 may be set higher than the height positions of the upper ends of the air intakes 71A, 71B. Additionally, from the viewpoint of ensuring the efficiency of intake of cooling air, the rib 80 is provided in the area of the gap 47 excluding the space above the intake port 45A.

[0080] [1-4. Battery module cooling structure] The battery module cooling structure for cooling the battery module 30 will be described in detail below. In a structure in which cooling air is introduced into the lower space 20L below the battery modules 30, as in this embodiment, if the lower space is not partitioned (hereinafter referred to as "Comparative Structure 3"), there is a risk that areas in the lower space will be poorly circulated by the cooling air or that an excessive amount of cooling air will be supplied. Therefore, in Comparative Structure 3, there is a risk that the multiple battery modules will not be cooled in a balanced manner.

[0081] Therefore, the battery module cooling structure of this embodiment achieves well-balanced cooling of the battery modules 30 by using a structure that partitions the lower space 20L into which cooling air is introduced. As shown in Figures 7 and 8, the battery module cooling structure of this embodiment is provided with multiple partition sections 90 that partially divide the lower space 20L and extend in the front-to-rear direction, and the length of the partition section 90 extending in the front-to-rear direction is determined by the location of the partition section 90.

[0082] The partition portions 90 are respectively arranged between adjacent battery modules 30. Specifically speaking, at least a part of the partition portion 90 is arranged between two battery modules 30 adjacent in the vehicle width direction in a plan view, and as shown in FIG. 8, it stands upright upward from the inner bottom surface 51 of the tray 21 (battery pack case 20). Note that, as shown in FIG. 8, the partition portion 90 may be erected upward from the inner bottom surface 51 by bending the bottom wall portion 50 of the tray 21 itself, or the lower surface of the bottom wall portion 50 may be flush and erected on the inner bottom surface 51. Further, the partition portion 90 may be integrated with the battery pack case 20, or may be provided separately from the battery pack case 20. Here, each of the illustrated partition portions 90 is provided in a shape with a constant or substantially constant dimension in the vehicle width direction regardless of the front-rear direction position. Further, the upper end of the partition portion 90 is in surface contact with the lower end surfaces 30L of the battery modules 30 on both sides of the partition portion 90, respectively. Thereby, the lower space 20L is partitioned.

[0083] If the space below each battery module 30 and above the inner bottom surface 51 is called a "small space", and the lower space 20L is called a "large space" in which the small spaces are arranged in the vehicle width direction, then the large space is partitioned into small spaces by the partition portion 90 while the small spaces are partially communicated with each other. The size of the region where the small spaces communicate with each other partially is adjusted by the length of the extension dimension (that is, the dimension in the front-rear direction) of the partition portion 90.

[0084] The battery module cooling structure in FIG. 7 exemplifies a form in which six battery modules 30 and five partition portions 90 are provided. The five partition portions 90 are provided with a first partition portion 91, a second partition portion 92, a third partition portion 93, a fourth partition portion 94, and a fifth partition portion 95 in order from left to right. Among these five partition portions 90, the third partition portion 93 is provided at the center in the vehicle width direction, the first partition portion 91 and the fifth partition portion 95 are provided symmetrically left and right, and the second partition portion 92 and the fourth partition portion 94 are provided symmetrically left and right.

[0085] The first partition 91 is disposed between the first battery module 31 and the second battery module 32 in a plan view. The second partition 92 is disposed between the second battery module 32 and the third battery module 33 in a plan view. Similarly, the third partition 93 is disposed between the third battery module 33 and the fourth battery module 34 in a plan view. The fourth partition 94 is disposed between the fourth battery module 34 and the fifth battery module 35 in a plan view. The fifth partition 95 is disposed between the fifth battery module 35 and the sixth battery module 36 in a plan view.

[0086] Explaining the arrangement of the partitions 90 based on the inlet 45B and the outlet 46C (shown by thick dashed lines in FIG. 7), the third partition 93 is arranged on the side closest to the outlet 46C than the inlet 45B in the vehicle width direction. Next, the second partition 92 and the fourth partition 94 are arranged on the side closer to the outlet 46C than the inlet 45B. The first partition 91 and the fifth partition 95 are arranged on the side farthest from the outlet 46C than the inlet 45B.

[0087] The distance from the front end 90F of the partition 90 (one end closer to the inlet 45B in the second direction) to the front end of the lower space 20L (internal space 20A) (one end closer to the inlet 45B in the second direction) is longer for partitions 90 that are located closer to the inlet 45B than the outlet 46C in the vehicle width direction. By setting the length of the partitions 90 in this way, the area that connects the small spaces below each battery module 30 and above the inner bottom surface 51 becomes smaller the closer the area that connects the small spaces is to the outlet 46C. In other words, the area that connects the small spaces becomes larger the closer it is to the inlet 45B.

[0088] Of the five partition members 90 illustrated here, the positions of the ends in the front-rear direction that are closer to the discharge outlet 46C than the inlet 45B are aligned in the front-rear direction. Specifically, the rear ends 90B of the partition members 90 (the ends that are closer to the discharge outlet 46C than the inlet 45B) are aligned in the front-rear direction. For example, the rear ends 90B of the partition members 90 are disposed in contact with the rear end of the lower space 20L (the end that is closer to the discharge outlet 46C in the second direction). Furthermore, the partition portions 90 are set so that the closer to the side of the exhaust port 46C where the inlet port 45B is located in the vehicle width direction, the shorter the dimension in the front-rear direction.

[0089] As illustrated in this embodiment, when the discharge port 46C is provided in the center between the inlet 45B located on the left side of the lower space 20L in the vehicle width direction and the inlet 45B located on the right side of the lower space 20L in the vehicle width direction, the partitions 90 are configured to have a longer longitudinal dimension as they are disposed closer to the center in the vehicle width direction. In other words, the partitions 90 are configured to have a shorter longitudinal dimension as they are disposed closer to the outside in the vehicle width direction. That is, the partitions 90 are configured to have a front end 90F located rearward as they are disposed closer to the outside in the vehicle width direction. Specifically, of the partitions 90, the third partition 93 has the longest dimension in the front-to-rear direction, and the second partition 92 and the fourth partition 94 have shorter dimensions in the front-to-rear direction than the third partition 93. In addition, the first partition 91 and the fifth partition 95 have shorter dimensions in the front-to-rear direction than the second partition 92 and the fourth partition 94.

[0090] The first partition 91 and the fifth partition 95 extend in the front-rear direction with dimensions shorter than the front-rear dimension of each battery module 30. In contrast, the second partition 92, the fourth partition 94, and the third partition 93 extend in the front-rear direction with dimensions longer than the front-rear dimension of each battery module 30. Based on the length of the partition 90 based on the front-to-rear dimension of the battery module 30, the first partition 91 and the fifth partition 95 may be called "short partitions," and the second partition 92, the fourth partition 94, and the third partition 93 may be called "long partitions."

[0091] In addition to the partition section 90, the battery module cooling structure illustrated in this embodiment is provided with a structure that ensures appropriate circulation of cooling air in the lower space 20L and the upper space 20U in order to distribute air evenly to each battery cell 30C (see Figure 9) in the battery module 30 and equalize the temperature of each battery cell 30C. The side closer to the inlet 45B than the outlet 46C in the front-rear direction can be said to be the upstream side in the flow direction of the cooling air, which is the front side in this embodiment. The side closer to the outlet 46C than the inlet 45B in the front-rear direction can be said to be the downstream side in the flow direction of the cooling air, which is the rear side in this embodiment.

[0092] If the inner bottom surface of the tray were flat, cooling air would flow more easily through the lower space closer to the exhaust port, making it less likely for cooling air to stagnate in the upstream region of the lower space closer to the inlet. If cooling air does not stagnate sufficiently in the upstream region of the lower space, the lower portion of the battery module closer to the inlet port than the exhaust port may not be able to exchange heat sufficiently with the cooling air. Therefore, there is room for improvement in cooling the lower portion of the battery module closer to the inlet port than the exhaust port.

[0093] To address this issue, the battery module cooling structure exemplified in this embodiment has a step on the inner bottom surface 51 that defines the lower end of the lower space 20L, thereby ensuring reliable cooling of the lower part of the battery module 30, that part closer to the inlet than the outlet. Specifically, as shown in FIG. 9, the battery pack case 20 has a lower step portion 52 on the inner bottom surface 51 that is higher on the downstream side than on the upstream side in the direction of cooling air flow.

[0094] The lower step portion 52 is formed between an upstream bottom surface 53 located on the front side of the inner bottom surface 51 and a downstream bottom surface 54 located on the rear side. The upstream bottom surface 53 is located lower than the downstream bottom surface 54. In other words, the downstream bottom surface 54 is closer to the horizontal bottom surface 30L of the battery module 30 than the upstream bottom surface 53. In light of the difference in the distance between the bottom surfaces 53, 54 and the bottom surface 30L of the battery module 30, the lower step portion 52 can also be said to have a structure that narrows the downstream side of the direction in which cooling air flows in the lower space 20L.

[0095] Furthermore, if the surface defining the upper end of the internal space (hereinafter referred to as the "inner top surface") is flat, cooling air will be more likely to flow to the upstream region of the upper space in the internal space, closer to the inlet. If cooling air is unevenly supplied to the upstream region of the upper space in this way, there is a risk that the upper portion of the battery module, closer to the inlet than the outlet, will be overcooled. Therefore, there is room for improvement in preventing excessive cooling of the upper portion of the battery module, closer to the inlet than the outlet.

[0096] To address this issue, the battery module cooling structure illustrated in this embodiment has a step on the inner top surface 23 that defines the upper end of the upper space 20U (internal space 20A), thereby preventing excessive cooling of the upper part of the battery module 30 that is closer to the inlet than the outlet. An upper step portion 24 is formed on the inner top surface 23, with the upstream side positioned lower than the downstream side in the direction of cooling air flow.

[0097] The upper step portion 24 is formed between a downstream top surface 26 located on the rear side of the inner top surface 23 and an upstream top surface 27 located on the front side. The upstream top surface 27 is located lower than the downstream top surface 26. In other words, the upstream top surface 27 is located closer to the horizontal upper end surface 30U of the battery module 30 than the downstream top surface 26. Considering that the distances between the top surfaces 26 and 27 and the upper end surface 30U of the battery module 30 are different, the upper step portion 24 can also be said to have a structure that narrows the upstream side in the direction in which cooling air flows in the upper space 20U. The upper step portion 24 may be formed in the battery pack case 20, or may be provided in a component other than the battery pack case 20.

[0098] In the upper space 20U, as described above, cooling air tends to flow more easily into the space in the front upstream region in the longitudinal direction (i.e., the side closer to the inlet 45B) regardless of the position in the vehicle width direction. Due to this tendency, it is preferable that the upper step portion 24 be disposed on the inner top surface 23 that defines the upper space 20U above all of the battery modules 30. However, the upper step portion 24 may also be disposed on the inner top surface 23 that defines the upper space 20U above only some of the battery modules 30.

[0099] In addition, cooling air flows easily through the portion of the upper space 20U close to the outlet 46C, which may increase the flow rate of the cooling air. If excessive cooling air is supplied to the space close to the outlet 46C in this manner, the rear portion of the upper part of the battery module 30 (the side closer to the outlet 46C than the inlet 45B) may be excessively cooled, resulting in a localized increase in cooling performance.

[0100] Therefore, the battery module cooling structure exemplified in this embodiment is provided with a baffle plate 99 that reduces the flow rate and supply of cooling air in the space of the upper space 20U that is closer to the outlet 46C. The baffle plate 99 is disposed below the downstream top surface 26 and above the battery modules 30 in the upper space 20U, and is a component that obstructs the flow of cooling air from below to above.

[0101] In the upper space 20U, the cooling air tends to flow more easily toward the rear (closer to the outlet 46C in the front-to-rear direction) space as it moves toward the center in the vehicle width direction (closer to the outlet 46C in the vehicle width direction). Due to this tendency, it is preferable to dispose the baffle plate 99 in the upper space 20U above the third battery module 33 and the fourth battery module 34 (see FIGS. 2 and 7).

[0102] [2. Actions and Effects] Since this embodiment is configured as described above, the following actions and effects can be obtained.

[0103] [2-1.Battery mounting structure] (1A) In the battery mounting structure of this embodiment, the side modules 16 are arranged to protrude upward relative to the center module 15. Therefore, when the above-described battery mounting structure is applied to an existing structure that includes side members 7, an exhaust pipe 8, and the like, it becomes easier to avoid interference between the existing structure and the side modules 16 and center module 15. For example, the center module 15 fits between the side members 7, making it possible to mount the battery module 30 below the seat 2. In this way, the above-described battery mounting structure allows the battery module 30 to be mounted without modifying the existing structure. Therefore, flexibility in the layout of the surrounding structure for the battery module 30 can be ensured.

[0104] (2A) In this embodiment, the side modules 16 are disposed in a position where they partially overlap the center module 15 in the vertical direction when viewed in the vehicle width direction. This prevents the vertical dimension of the battery pack case 20 from increasing compared to an arrangement in which the side modules 16 are positioned higher than the entire center module 15. In this way, the ability to prevent the battery pack case 20 from becoming larger also ensures freedom in the layout of the surrounding structure for the battery module 30.

[0105] (3A) The center modules 15 are arranged at equal height positions, and the side modules 16 are also arranged at equal height positions. As a result, a space with a wide bottom surface where multiple top surfaces of the center modules 15 are lined up can be secured above the center module 15 in the internal space 20A of the battery pack case 20. This space can be used to accommodate electrical components such as the BMU 40 and the transformer 41. Additionally, the center modules 15 arranged at equal height positions contribute to improving the ease of routing the harnesses 42 connected to each center module 15. Furthermore, since the side modules 16 are also arranged at equal height positions, the layout of the battery modules 30 can be prevented from becoming complicated.

[0106] (4A) Of the six battery modules 30, two side modules 16 are located on the outermost sides of the vehicle width. Therefore, compared to a battery mounting structure with more than two side modules 16, it is possible to both prevent the vehicle's center of gravity from becoming high and ensure flexibility in the layout of the surrounding structure for the battery modules 30.

[0107] (5A) A battery pack case 20 is mounted below the seat 2, and a side module 16 is disposed in the internal space 20A of the battery pack case 20, offset forward in the front-to-rear direction relative to the center module 15. Therefore, the side portion 61S erected on the rear side of the side module 16 can be disposed forward of the central portion 61C erected on the rear side of the center module 15 in the battery pack case 20. This improves the ease of entry and exit for passengers getting in and out of seats immediately behind the seat 2. For example, it improves the legroom for passengers getting into the second-row rear seats relative to the driver's seat or passenger seat 2. It also makes it easier for passengers sitting in seats adjacent to the rear of the seat 2 (i.e., while riding) to stretch their legs, improving the livability of the vehicle interior 1.

[0108] Since the center lower space 20C is smaller than the side lower space 20S, cooling air is more likely to accumulate in the side lower space 20S than in the center lower space 20C. As a result, the cooling air in the side lower space 20S accumulates and then flows into the center lower space 20C, enabling the entire battery module 30 to be cooled evenly.

[0109] (7A) The lower end of this side lower space 20S is demarcated by a slope surface 51X that is positioned downward toward the center side in the vehicle width direction at at least a part of the side inner bottom surface 51S. Therefore, while securing the volume of the side lower space 20S where cooling air can accumulate, interference with the peripheral structure due to the bulging of the side lower space 20S toward the end side in the vehicle width direction can be suppressed.

[0110] (8A) In addition, since the height position of the side module 16 is offset upward with respect to the center module 15, the side module 16 can be arranged at a distance from the exhaust pipe 8, and heating of the side module 16 due to radiant heat from the exhaust pipe 8 can be suppressed. By suppressing the heat reception from the exhaust pipe 8 to the side module 16 in this way, it contributes to improving the cooling performance of the side module 16.

[0111] [2-2. Battery Pack Intake Structure] (1B) According to the battery pack intake structure of the present embodiment, since the intake port 45A is covered by the intake port cover 70, entry of foreign matter from above into the intake port 45A can be structurally suppressed. Furthermore, by erecting ribs 80 in the gap 47 between the air intake 71 and the intake port 45A, even if foreign matter enters the gap 47 from the air intake 71, entry of this foreign matter into the intake port 45A can be structurally suppressed by the ribs 80. Therefore, entry of foreign matter into the internal space 20A of the battery pack case 20 can be suppressed. By suppressing entry of foreign matter in this way, it is also possible to take in the air in the passenger compartment 1 into the intake port 45A through the gap communicating the air intake 71 and the intake port 45A.

[0112] (2B) The rib 80 is provided with a gap with respect to the intake port cover 70. Therefore, air in the passenger compartment 1 can be taken into the intake port 45A through the gap that communicates the air intake port 71 and the intake port 45A between the rib 80 and the intake port cover 70, and the intake efficiency of the intake port 45A can be ensured.

[0113] (3B) The above-mentioned rib 80 is erected in the gap 47 from the upper surface 20F of the battery pack case 20. Therefore, it is possible to structurally prevent foreign matter that rolls or is pushed along the upper surface 20F of the battery pack case 20 from entering the intake port 45A, and the foreign matter intrusion prevention effect is improved.

[0114] (4B) Further, in the above-described embodiment, the height positions of the upper ends 81U and 82U of the ribs 81 and 82 and the height positions of the upper ends of the air intake ports 7A and 7B are provided to be substantially equal to each other. With the ribs 81 and 82 that are neither too high nor too low in this way, it is possible to achieve both suppression of foreign matter intrusion and suppression of a decrease in the intake efficiency of the cooling air.

[0115] (5B) In the above-described embodiment, a right intake port 71A and an upper intake port 71C on the right side with respect to the intake port 45A and a left intake port 71B on the left side with respect to the intake port 45A are provided, and ribs 81 and 82 are provided on both the right side and the left side with the intake port 45A interposed therebetween. Therefore, by taking in air from the three (a plurality of) air intake ports 71A, 71B, and 71C, the intake efficiency of the cooling air can be ensured. Moreover, the intrusion of foreign matter from the right intake port 71A and the upper intake port 71C on the right side (inner side in the vehicle width direction) with respect to the intake port 45A can be suppressed by the right rib 81 (the rib 81 on the inner side in the vehicle width direction), and the intrusion of foreign matter from the left intake port 71B on the left side (outer side in the vehicle width direction) with respect to the intake port 45A can be suppressed by the left rib 82 (the rib 82 on the outer side in the vehicle width direction).

[0116] (6B) Since the entire region of the rib 80 overlaps with the intake port 45A in the front-rear direction, the intrusion of foreign matter into the intake port 45A can be structurally suppressed in the entire region in the front-rear direction. (7B) Furthermore, the ribs 80 erected so as to surround the periphery of the intake port 45A structurally prevent foreign matter from entering the intake port 45A in all directions.

[0117] (8B) Cover top surface 70J of intake port cover 70 is inclined so as to be positioned downward toward air intake 71. Therefore, even if liquid is spilled on cover top surface 70J, the liquid flows down cover top surface 70J toward air intake 71. Therefore, the shape (structure) of cover top surface 70J can prevent liquid from accumulating on cover top surface 70J. This cover top surface 70J can also prevent dust from accumulating on cover top surface 70J.

[0118] (9B) Furthermore, cover underside 70L of intake port cover 70 is provided with an upwardly sloping portion 70G that rises upward as it approaches intake port 45A from air intake 71. Therefore, the shape (structure) of cover underside 70L can prevent liquid from flowing down cover underside 70L and entering intake port 45A.

[0119] (10B) In the ribs 81, 82 of the above-described embodiment, height dimensions G1, G2 from adjacent surfaces 9A, 9B adjacent to the ribs 81, 82 on the opposite side of the intake port 45A to the upper ends 81U, 82U of the ribs 81, 82 are set smaller when the separation distance L1, L2 is longer. In this way, by reducing the height dimension of one rib 81 that is recessed further than the other rib 82, it is possible to suppress a decrease in the intake efficiency of cooling air while suppressing the intrusion of foreign matter into the intake port 45A.

[0120] (11B) The air intake cover 70 described above extends to an area that covers from above the metal sheet edge 3E of the panel member 3. Because the metal sheet edge 3E is covered by the air intake cover 70 in this way, even if an occupant in the vehicle interior 1 drops something and searches for it by hand under the seat 2, the occupant can be structurally prevented from touching the metal sheet edge 3E, thereby improving the safety of the occupant.

[0121] (12B) The air intake cover 70 described above has an upward-facing upper intake 71C in an area that does not overlap with the air intake 45A in a top view. Therefore, even if this battery pack air intake structure is applied to a vehicle with a peripheral configuration in which warm air that may leak from the edge 4E (opening end) of the carpet 4 is taken in through the horizontally facing right intake 71A or left intake 71B, cool air can be taken in through the upward-facing upper intake 71C. This prevents warm air from being taken into the battery pack case 20, contributing to improved cooling efficiency.

[0122] (13B) According to the upper intake 71C on which the mesh member 72 described above is stretched, even if the upper intake 71C is provided facing upward, the mesh member 72 can capture foreign matter, thereby preventing foreign matter from entering through the upper intake 71C.

[0123] [2-3. Battery module cooling structure] (1C) According to the battery module cooling structure of this embodiment, the distance from the front end 90F of the partition 90 to the front end of the lower space 20L is longer for partitions 90 located closer to the inlet 45B than the outlet 46C in the vehicle width direction. This makes it easier for cooling air to accumulate in the region of the lower space 20L where the inlet 45B is located relative to the outlet 46C, and makes it easier for cooling air to spread evenly from this region to the region of the lower space 20L where the outlet 46C is located relative to the inlet 45B. By optimizing the extension dimension of the partition 90 in this way, cooling air is supplied to the lower space 20L in a balanced manner. Therefore, the plurality of battery modules 30 can be cooled in a balanced manner.

[0124] In the configuration exemplified in this embodiment, the rear ends 90B of the partitions 90 are provided at equal positions in the front-rear direction, and the partitions 90 that are disposed closer to the inlet 45B in the vehicle width direction relative to the outlet 46C have shorter front-rear dimensions. With partitions 90 positioned and sized like this, the length of the partition 90 extending in the front-rear direction corresponds to the size of the area in front of the partition 90 through which cooling air communicates in the vehicle width direction. Therefore, simply by setting the length of the partition 90 extending in the front-rear direction, the size of the area in the lower space 20L through which cooling air communicates in the vehicle width direction in front of the partition 90 can be set.

[0125] (2C) If the lower space extends to the left or right side of the inlet and the exhaust outlet is located toward the center of the vehicle width relative to the inlet, the cooling air introduced from the inlet will have difficulty reaching the space in the lower space that extends outward in the left-right direction from the inlet (opposite the exhaust outlet). In contrast, according to the battery module cooling structure described above, the inlet 45B is provided at the left end and the right end of the lower space 20L, which makes it easier for the cooling air in the lower space 20L to spread evenly in the vehicle width direction, thereby enabling the multiple battery modules 30 to be cooled in a balanced manner.

[0126] (3C) In this embodiment, the lower space 20L has an inlet 45B at each of the left and right ends, and an outlet 46C is provided in the center between the inlet 45B located on the left side and the inlet 45B located on the right side. Therefore, the partitions 90 located closer to the center in the vehicle width direction are set to have longer longitudinal dimensions. Therefore, the partitions 90 located in the center in the vehicle width direction, including the third partition 93, can prevent the cooling air introduced from the inlet 45B at the left end and the cooling air introduced from the inlet 45B at the right end from mixing within the lower space 20L. This also allows for balanced cooling of the multiple battery modules 30.

[0127] (4C) The first partition 91 and the fifth partition 95 (i.e., the “short partition”), which extend in the fore-and-aft direction with dimensions shorter than the battery module 30, can further promote the retention of cooling air in the area of the lower space 20L on the outer side of the vehicle width (the inlet 45B side). The second partition 92, fourth partition 94, and third partition 93 (i.e., "long partitions"), which extend in the fore-and-aft direction with dimensions longer than the battery module 30, allow the battery module 30 to be cooled entirely in the region of the lower space 20L toward the center of the vehicle width (the exhaust outlet 46C side). This contributes to improving the cooling performance of the battery module 30.

[0128] (5C) The lower step portion 52 formed between the downstream bottom surface 54 and the upstream bottom surface 53 narrows the rear space (closer to the exhaust port 46C) of the lower space 20L compared to the front space (closer to the inlet 45B). This prevents excessive flow of cooling air into the rear space of the lower space 20L, while ensuring sufficient flow of cooling air into the front space of the lower space 20L. This prevents excessive cooling of the rear portion of the lower part of the battery module 30, while allowing sufficient cooling of the front portion of the lower part of the battery module 30. In this way, the entire battery module 30 can be cooled in a balanced manner.

[0129] (6C) The upper step portion 24 formed between the downstream top surface 26 and the upstream top surface 27 narrows the space on the front side (the side closer to the inlet 45B) of the upper space 20U, which prevents excessive flow of cooling air into the front space of the upper space 20U and prevents excessive cooling of the front portion of the upper part of the battery module 30. In this way, the entire battery module 30 can be cooled in a balanced manner.

[0130] (7C) In addition, since the baffle plate 99 that obstructs the flow of cooling air from below to above extends below the downstream top surface 26 and above the battery module 30, the flow of cooling air to the discharge port 46C in the rear space of the upper space 20U is obstructed by the baffle plate 99. Therefore, the cooling air stays in the rear space of the upper space 20U, and the rear part of the upper part of the battery module 30 can be surely cooled. Also from this point, the entire battery module 30 can be cooled in a well-balanced manner.

[0131] (8C) Further, since the center lower space 20C is smaller than the side lower space 20S, the cooling air is more likely to stay in the side lower space 20S than in the center lower space 20C. Thereby, the cooling air in the side lower space 20S stays and then flows to the center lower space 20C, and the entire battery module 30 can be cooled in a well-balanced manner. With such a relationship between the sizes of the lower spaces 20C and 20S and the dimension setting of the partition portion 90, the plurality of battery modules 30 can be cooled more evenly.

[0132] (9C) The side lower space 20S is defined at the lower end by a slope surface 51X that is positioned downward toward the center in the vehicle width direction at least in a part of the side inner bottom surface 51S. Therefore, while securing the volume of the side lower space 20S where the cooling air can stay, it is possible to suppress the interference with the peripheral structure due to the bulge of the side lower space 20S toward the vehicle width direction end side.

[0133] [II. Modification Example] ==Battery Mounting Structure== The above-described battery mounting structure is an example. For example, in the battery mounting structure, among a plurality of battery modules having the same length in the vertical direction, it is sufficient that the side modules protrude upward at least with respect to the center module, and the side modules and the center module may be arranged at the same position in the front-rear direction. According to the battery mounting structure in which only the height positions of the battery modules are offset in this way, it is possible to secure the layout freedom of the peripheral structure with respect to the battery modules only by making a simple layout change to the structure in which the positions in the front-rear direction and the height positions are the same.

[0134] If the plurality of battery modules have the same length in the vertical direction, they may have different lengths in the front-rear direction. Here, the "length in the vertical direction" is regarded as equal even if there are differences to the extent of variations due to manufacturing lots of the battery modules or variations within the tolerance range. That is, even if the lengths in the vertical direction of the plurality of battery modules are somewhat different, they are regarded as having the same length in the vertical direction. Note that the "length in the front-rear direction" of the plurality of battery modules is also regarded as equal even if there are differences to the extent of variations due to manufacturing lots of the battery modules or variations within the tolerance range.

[0135] The side modules may be arranged at an upper position that does not overlap with the center module in the vertical direction when viewed from the vehicle width direction. In this case, the layout freedom of the peripheral structure with respect to the battery modules can be more ensured. The center modules are not limited to being arranged at the same height positions, and may be arranged at different height positions. Also, the side modules are not limited to being arranged at the same height positions, and may be arranged at different height positions. In these cases, the layout freedom of the peripheral structure with respect to the center module and the peripheral structure with respect to the side module can be more ensured.

[0136] The surface defining the lower end of the side lower space is not limited to the above-described sloped surface, and other shapes may be adopted. The center lower space is not limited to a space whose vertical dimension is smaller than that of the side lower space. For example, if the vertical dimension of the side lower space is kept the same as that of the center lower space, the inner bottom surface of the side can be brought closer to the side module than in the above-described embodiment, thereby ensuring greater flexibility in the layout of the surrounding structure for the side module.

[0137] The vehicle to which the battery mounting structure is applied does not need to be provided with an exhaust pipe, that is, the battery mounting structure may be applied to an electric vehicle that does not have an engine. It is sufficient that at least one center module is provided. The side modules are only required to be located at both ends in the vehicle width direction, and are not limited to a configuration in which one is provided on each side (two in total), but may be provided two on each side, or the number of modules provided on each side may be different (for example, one on the left and two on the right, three in total). In addition, the side lower space and the center lower space do not have to be provided in the internal space of the battery pack case.

[0138] ==Battery pack air intake structure== For example, the battery pack air intake structure may include at least an air intake port formed on the top surface of the battery pack case for taking in air into the internal space of the battery pack case, an air intake port cover for forming an air intake communicating with the vehicle interior space and covering the air intake port from above while forming a gap between the air intake port and the top surface of the battery pack case, and a rib provided with a gap communicating between the air intake port and the air intake port and extending from at least one of the top surface of the battery pack case and the air intake port cover into the gap.

[0139] The intake port cover only needs to form at least one air intake, and at least one rib may be provided. Also, the mesh member of the upper intake port may be omitted, and further, the upper intake port may be omitted. In these cases, it is possible to suppress foreign matter from entering the internal space of the battery pack case with a simple configuration.

[0140] Even when ribs are provided, the ribs are not limited to the form of being erected so as to surround the periphery of the intake port. They may be separately provided on the right side (one side in a predetermined direction) and the left side (the other side in the predetermined direction) of the intake port, and a pair of left and right ribs may be provided so as to be separated from each other. Alternatively, they may be provided only on the right side or the left side with respect to the intake port. Also, the entire area of the rib in the front-rear direction is not limited to the arrangement overlapping the intake port. In these cases, compared with the rib 80 of the above embodiment erected so as to surround the periphery of the intake port, the occupied area of the rib in the gap is suppressed, which contributes to an improvement in the intake efficiency of the cooling air from the intake port.

[0141] The shape of the intake port cover is not limited to a shape in which the upper surface of the cover is inclined downward toward the air intake 71 or a shape having an upward slope on the lower surface of the cover, and various shapes can be adopted according to the peripheral structure, design requirements, etc. Also, the extending range of the intake port cover is not limited to the range extending to the area covering the sheet metal edge from above, and can be set to various extending ranges according to the peripheral structure, design requirements, etc. Regarding the dimensions and arrangements of the ribs, various dimensions and arrangements can be adopted in consideration of the effect of suppressing the intrusion of foreign matter, the intake efficiency of the cooling air, etc.

[0142] In addition, as a modified example of the battery pack intake structure, instead of the rib 80 described in the above embodiment, a structure provided with a mesh-like mesh stretched across the air intake may be used. That is, as the battery pack intake structure according to the modified example, an intake port formed on the upper surface of the battery pack case for taking air into the internal space of the battery pack case, an air intake port communicating with the passenger compartment space, and a gap between the air intake port and the intake port are formed between the upper surface of the battery pack case. An intake port cover that covers the intake port from above, and a mesh-like mesh stretched across the air intake port may be provided. According to this structure, foreign matter attempting to enter the gap is captured by the mesh, so that the entry of foreign matter into the intake port can be suppressed. Therefore, the entry of foreign matter into the internal space of the battery pack case can be suppressed.

[0143] ==Battery Module Cooling Structure== This is an example of the battery module cooling structure described above. For example, the partition portion does not have to have a shape with a constant (or substantially constant) width dimension in the vehicle width direction regardless of the position in the front-rear direction. For example, like the partition portion 90' shown in FIG. 10, it may be provided in a tapered shape in which the width dimension in the vehicle width direction is longer toward the front side (the side from the inlet 45B to the outlet 46C) in the front-rear direction. According to the tapered partition portion 90' that tapers toward the front side in this way, the space on the rear side of the front side space in the lower space 20L is narrowed, and the same effect as the lower step portion 52 described in the above embodiment is achieved.

[0144] In the battery module cooling structure, at least three (one more than the number of partition portions provided) or more battery modules may be provided, and at least two (one less than the number of battery modules provided) partition portions may be provided. In addition, when integrated with a member such as a battery pack case provided around the partition portion, the number of partition portions provided may be single or plural.

[0145] Enumerating a form example in which the battery module cooling structure of the above-described embodiment is simplified, an inlet may be provided only at one of the left end portion and the right end portion in the lower space, and only a long partition portion or only a short partition portion may be provided as the partition portion. The lower step portion and the upper step portion may be omitted, or the baffle plate may be omitted. Regarding this battery module cooling structure, the vehicle width direction of the above-described embodiment may be read as an arbitrary first horizontal direction, and the front-rear direction described above in one embodiment may be read as a second horizontal direction intersecting the first direction.

Industrial Applicability

[0146] This case is applicable to the manufacturing industry of vehicles equipped with batteries.

Explanation of Reference Numerals

[0147] 10 Battery pack 15 Center module 16 Side module 20 Battery pack case 20A Internal space 20C Center lower space 20L Lower space 20S Side lower space 20U Upper space 23 Inner top surface 24 Upper step portion 26 Downstream top surface 27 Upstream top surface 30 Battery module 30C Battery cell 30L Lower end surface 30U Upper end surface 3E Sheet metal edge 45B Inlet 46C Outlet 49 Virtual straight path 51 Inner bottom surface 51C Center inner bottom surface 51S Side inner bottom surface 51X Slope surface 52 Lower step portion 53 Upstream bottom surface 54 Downstream bottom surface 90 Partition part 90B Rear end 90F Front end 91 First partition part (Short partition part) 92 Second partition part (Long partition part) 93 Third partition part (Long partition part) 94 Fourth partition part (Long partition part) 95 Fifth partition part (Short partition part) 99 Baffle plate

Claims

1. a battery pack case having an internal space in which three or more battery modules are arranged side by side in a horizontal first direction, an air inlet port into the internal space, and an air outlet port out of the internal space; partition portions extending in a horizontal second direction intersecting the first direction, disposed between adjacent battery modules, and erected upward from an inner bottom surface of the battery pack case to separate a lower space between the battery modules and the inner bottom surface; Equipped with the inlet and the outlet are located at different positions in the first direction and the second direction, three or more of the battery modules are arranged on a path connecting the inlet and the outlet, A distance from one end of the partition portion closer to the inlet in the second direction to one end of the internal space closer to the inlet in the second direction is longer for the partition portion disposed closer to the inlet with respect to the outlet in the first direction. A battery module cooling structure comprising:

2. The inlet is provided at least at one end and the other end of the lower space in the first direction. The battery module cooling structure according to claim 1 .

3. the inlet is provided at one end and the other end in the first direction in the lower space, The exhaust port is provided at a center between the inlet port located at one end side of the lower space in the first direction and the inlet port located at the other end side of the lower space in the first direction. The battery module cooling structure according to claim 2 .

4. The partitions include at least one of long partitions extending longer than the dimension of the battery module in the second direction and short partitions extending shorter than the dimension of the battery module in the second direction. The battery module cooling structure according to claim 1 .

5. A lower step portion is formed between a downstream bottom surface of the inner bottom surface that is located closer to the discharge outlet than the inlet in the second direction, and an upstream bottom surface of the inner bottom surface that is located closer to the inlet than the discharge outlet in the second direction and is located lower than the downstream bottom surface. The battery module cooling structure according to claim 1 .

6. An upper step portion is formed between a downstream top surface of the inner top surface that defines the upper end of the internal space and that is located closer to the discharge outlet than the inlet in the second direction, and an upstream top surface of the inner top surface that is located closer to the inlet than the discharge outlet in the second direction and that is located lower than the downstream top surface. The battery module cooling structure according to claim 1 .

7. An upper step portion is formed between a downstream top surface of the inner top surface that defines the upper end of the internal space and that is located closer to the discharge outlet than the inlet in the second direction, and an upstream top surface of the inner top surface that is located closer to the inlet than the discharge outlet in the second direction and that is located lower than the downstream top surface. The battery module cooling structure according to claim 1 .

8. The partition portion is provided in a tapered shape such that the dimension in the first direction is longer from the inlet toward the outlet in the second direction. The battery module cooling structure according to claim 1 .

9. the battery pack case accommodates side modules disposed at both ends of the battery modules in the first direction, and a center module disposed at a center of the battery modules in the first direction, the inner bottom surface includes a side inner bottom surface located below the side module and a center inner bottom surface located below the center module, The lower space includes a side lower space formed between the side module and the side inner bottom surface and provided with the inlet, and a center lower space formed between the center module and the center inner bottom surface, communicating with a lower portion of the side lower space and having a smaller vertical dimension than the side lower space. The battery module cooling structure according to any one of claims 1 to 8.

10. The side lower space has a lower end defined by a slope surface that is positioned downward toward the center in the first direction in at least a portion of the side inner bottom surface. The battery module cooling structure according to claim 9 .

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