Battery mounting structure

Abstract

A battery mounting structure comprises: a center module (15) which is among a plurality of battery modules (30) that are disposed side by side in the vehicle width direction of a vehicle in an internal space (20A) of a battery pack case (20) mounted in the vehicle and that are of equal length in the vertical direction of the vehicle, and which is disposed in a center part in the vehicle width direction; and side modules (16) which are among the plurality of battery modules (30), which are respectively disposed at both ends in the vehicle width direction, and which are disposed so as to protrude upward with respect to the center module (15).

Description

Battery mounting structure

[0001] The present invention relates to a battery mounting structure for mounting a battery on a vehicle.

[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 source for driving the vehicle. A known example of a large-capacity battery is a plurality of battery modules housed in the internal space of a battery pack case. For example, a technology has been proposed in which all battery modules are arranged side by side at the same height and in the same orientation (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2014-207237

[0004] However, in the above-described structure in which all battery modules aligned in a predetermined direction are positioned at the same height, a surface (mounting surface) is required on which all battery modules can be mounted at the same height, which may cause interference with the surrounding structures of the battery modules. For example, when multiple battery modules aligned in the vehicle width direction and positioned at the same height are mounted on a vehicle, the battery modules on the outer side of the vehicle width may interfere with existing structures such as side members and exhaust pipes located on the outer side of the vehicle width. This may result in layout constraints, such as the need to redesign the arrangement of structures located around the battery modules or the inability to mount the desired number of battery modules. Therefore, there is room for improvement in ensuring layout flexibility for the surrounding structures around the battery modules.

[0005] The battery mounting structure of the present invention was invented in consideration of these problems, and one of its objectives is to ensure flexibility in the layout of the peripheral structure of the battery module. However, in addition to this objective, another objective of the present invention is to achieve effects derived from the configurations shown in the "Mode for Carrying Out the Invention" below, which are not obtainable with conventional technology.

[0006] The disclosed battery mounting structure can be realized as the following disclosed embodiments (application examples) and solves 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 mounting structure includes a plurality of battery modules arranged side by side in the vehicle width direction in the internal space of a battery pack case mounted on a vehicle and having equal lengths in the vehicle up-down direction, the plurality of battery modules including a center module arranged in the center of the vehicle width direction, and side modules arranged at both ends of the plurality of battery modules in the vehicle width direction and protruding upward relative to the center module.

[0008] Aspect 2. In Aspect 1 above, it is preferable that the side module is disposed in a position that partially overlaps the center module in the up-down direction when viewed from the vehicle width direction. Aspect 3. In Aspect 1 or 2 above, it is preferable that a plurality of center modules are provided, and that the center modules are positioned at the same height, and that the side modules are positioned at the same height.

[0009] Aspect 4. In any one of Aspects 1 to 3 above, it is preferable that the side modules are positioned outermost on one and the other sides of the plurality of battery modules in the vehicle width direction.

[0010] Aspect 5. In any one of Aspects 1 to 4 above, it is preferable that the battery pack case is provided in the vehicle interior space and is mounted below a front seat excluding a rearmost seat among a plurality of rows of seats aligned in the longitudinal direction of the vehicle. Aspect 6. In any one of Aspects 1 to 5 above, it is preferable that the plurality of battery modules have the same length in the longitudinal direction of the vehicle, and that the side module is disposed so as to protrude forward relative to the center module.

[0011] Aspect 7. In any one of Aspects 1 to 6 above, it is preferable that the battery pack case has a side lower space formed between the side module and a side inner bottom surface located below the side module and into which air is introduced, and a center lower space formed between the center module and a center inner bottom surface located below the center module, communicating with a lower part of the side lower space and having a vertical dimension smaller than that of the side lower space.

[0012] Aspect 8. In the above-mentioned Aspect 7, it is preferable that the lower end of the side lower space is defined by a slope surface that is positioned downward toward the center in the vehicle width direction on at least a portion of the side inner bottom surface. Aspect 9. In any one of the above-mentioned Aspects 1 to 8, it is preferable that an exhaust pipe is disposed directly below the vehicle width direction end of the battery pack case.

[0013] The disclosed battery mounting structure ensures a degree of freedom in the layout of the peripheral structure relative to the battery module.

[0014] It is a longitudinal cross-sectional view seen from the front side of a vehicle, showing a battery pack to which a battery mounting structure according to an embodiment is applied and a part of a structure provided around the battery pack. It is a transverse cross-sectional view seen from above the vehicle of the battery pack of Figure 1. It is a schematic diagram showing a path through which cooling air circulates in the internal space of the battery pack of Figure 1. It is an exploded perspective view showing an overview of the battery pack of Figure 1.

[0015] With reference to the drawings, embodiments of a structure (including a battery mounting structure) related to a battery mounted on a vehicle 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.

[0016] 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 direction 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.

[0017] Vehicle structures are often formed with near bilateral symmetry (mirror symmetry with respect to a plane including the yaw axis and roll axis passing through the center of gravity of the vehicle), but perfect symmetry 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 may 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 capable of externally charging the battery or externally receiving 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 for external power supply.

[0018] [I. One Embodiment] In the following one embodiment, a battery mounting structure for mounting a battery (also called a battery pack) on a vehicle will be described.

[0019] [1. Configuration] Fig. 1 is a longitudinal cross-sectional view showing a battery pack 10 to which a battery mounting structure according to an embodiment is applied and a portion of the structure provided around the battery pack 10, as viewed from the front side of the vehicle. Fig. 2 is a transverse cross-sectional view of the battery pack 10, as viewed from above the vehicle. Fig. 3 is a schematic diagram showing the path through which cooling air circulates in the internal space 20A of the battery pack 10, as viewed 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, the battery pack 10 is provided in a vehicle interior 1, and various structures and members are provided around the battery pack 10.

[0020] <Peripheral Configuration of Battery Pack> A seat 2 for a passenger is provided above the battery pack 10. The seat 2 illustrated here is a front seat (front seat) among at least two rows of seats arranged in the longitudinal direction. For example, the driver's seat or the passenger seat is the seat 2. However, the seat 2 may be any front seat among multiple rows of seats arranged in the longitudinal direction, excluding the rearmost seat, and may be the frontmost seat or the second-to-front seat in a vehicle with three rows of seats arranged side by side.

[0021] In addition, 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 a driver's seat and a passenger seat, are arranged above the carpet 4 with a gap in the vehicle width direction. A console 5 is provided between the driver's seat and the passenger seat that form the seats 2. The console 5 illustrated in FIG. 1 is provided separately from the panel member 3. This console 5 is provided with cup holders 5H.

[0022] A body floor 6 extends in a planar shape below the battery pack 10. A pair of left and right side members 7 extend in the front-rear direction below the body floor 6 and support from below a pair of left and right side floor members 6X, which are portions of the body floor 6 on the vehicle widthwise end sides (hereinafter also referred to as "outside sides in the vehicle width direction"). A center floor 6Y, which is a portion of the body floor 6 closer to the vehicle widthwise center (inner side in the vehicle width direction) than the side floors 6X, is located lower than the side floors 6X, and the upper and lower cross sections along the vehicle width direction are formed in a downwardly convex shape.

[0023] In the vehicle exemplified in this embodiment, an exhaust pipe 8 is provided below the body floor 6, extending in the longitudinal direction, on the inside 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 be considered to be mounted in the lower part of the passenger compartment 1.

[0024] <Configuration of Battery Pack> The battery pack 10 is a power storage device for a vehicle that houses multiple battery modules 30 in the internal space 20A of a battery pack case 20. Below, the configuration of the battery pack 10 will be described, including the configuration of the battery modules 30, the battery-related electrical components, and the cooling equipment, followed by the internal layout, and finally the battery pack case 20 located below the seat 2.

[0025] ==Battery Module== The battery module 30 is a secondary battery that can not only supply power but also charge. This battery module 30 generates heat when receiving and supplying power, such as during power running to supply power to the vehicle's drive motor (not shown) or during regeneration, when the vehicle's braking energy is converted into power and charged. The battery module 30 has a larger capacity than on-board batteries such as so-called 12V batteries and 24V batteries.

[0026] 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 above and below the battery module 30. As shown in Fig. 3, each battery module 30 is an assembled battery formed by connecting multiple battery cells 30C (single cells; only one cell is marked in Fig. 3). These battery cells 30C are connected in a combination of series and parallel connections depending on the design voltage, design capacity, etc. of the battery module 30.

[0027] 1 and 2 illustrate an example in which multiple battery modules 30 of the same size are arranged side by side in the vehicle width direction in the same orientation. Specifically, six rectangular parallelepiped battery modules 30 with the same dimensions in the vehicle width direction, front-rear direction, and up-down direction (i.e., proportions) are arranged side by side in the same orientation with the front-rear direction as the longitudinal direction. That is, the multiple battery modules 30 have the same length in the up-down direction and the same length in the front-rear direction. The battery modules 30 illustrated in this embodiment include, in order from left to right, a first battery module 31, a second battery module 32, a third battery module 33, a fourth battery module 34, a fifth battery module 35, and a sixth battery module 36.

[0028] Of these six battery modules 31 to 36, the four battery modules 32 to 35 arranged in the center in the vehicle width direction are referred to indistinguishably as the center module 15. Of the six battery modules 31 to 36, the battery modules 31 and 36 arranged at both ends in the vehicle width direction are referred to indistinguishably as the side modules 16. In other words, of the six battery modules 30, the ones located outermost on one and the other sides in the vehicle width direction are referred to as the side modules 16.

[0029] The internal space 20A housing the battery modules 30 houses various battery-related electrical components and cooling devices. ==Battery-related Electrical Components== As shown in Figure 1, the battery-related electrical components housed in the internal space 20A include a BMU (Battery Management Unit) 40, a transformer 41, a harness 42, and a junction box 43 (see Figures 2 to 4). The BMU 40 is an electronic control device that manages all of the battery modules 30, and has functions such as managing and monitoring the status of each battery module 30 and A / D conversion (analog-to-digital conversion) of control signals.

[0030] The transformer 41 is a device that converts voltage. This transformer 41 is, for example, a DC / DC converter that steps down and outputs the voltage applied from the battery module 30, 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 power transmitted from the battery pack 10 to the outside, cutting off the power, and distributing power to the transformer 41.

[0031] Cooling Equipment As shown in Fig. 4, an example of a cooling equipment housed in the internal space 20A is an intake duct 45. Examples of cooling equipment that is not housed in the internal space 20A but is 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-cooled 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 a flow path for the cooling air supplied by the fan 44.

[0032] Cooling by the cooling equipment is performed in the internal space 20A of the battery pack case 20 as 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 discharged through the exhaust duct 46 by the fan 44.

[0033] In the illustrated embodiment, as shown in FIG. 4 , a pair 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 of the vehicle width direction. The intake duct 45 has an intake port 45A formed at its upstream end in the direction of flow of cooling air and an inlet port 45B formed at its downstream end in the direction of flow of cooling air. The intake port 45A is an opening that takes in cooling air from the space of the vehicle interior 1 (vehicle interior space) into the interior space 20A. The inlet port 45B is an opening that introduces cooling air into the lower space 20L. That is, cooling air that cools the battery module 30 is introduced from the inlet port 45B in the lower space 20L.

[0034] The air intake port 45A and the introduction port 45B are each provided in two locations, the same as the number of installed air intake ducts 45. Specifically, the air intake port 45A is provided at each of the left and right ends of the top surface of the battery pack case 20. Also, the introduction port 45B is provided at each of the left and right ends (one end and the other end in the first direction) of the lower space 20L. However, only one air intake duct 45 may be provided, and the introduction port 45B may be provided at either the left end or the right end of the lower space 20L.

[0035] Exhaust duct 46 extends to the outside of battery pack case 20. A fan 44 is connected to the upstream end of exhaust duct 46 in the direction of flow of cooled air (hereinafter also referred to as "cooled air"), and an exhaust port 46D is formed at the downstream end in the flow direction, through which the cooled air compressed by fan 44 is exhausted. The cooled air in exhaust duct 46 is exhausted from exhaust port 46D, for example, into the interior of an instrument panel (not shown).

[0036] In addition, as shown in FIG. 3 , the cooling air in the upper space 20U flows to the fan 44 through an exhaust port 46C that communicates with the upper space 20U. That is, the cooling air that has cooled the battery module 30 is exhausted from the exhaust port 46C of the upper space 20U. The illustrated exhaust port 46C is positioned differently from the inlet 45B in both the vehicle width direction and the front-to-rear direction, as shown by the thick dashed line in FIG. 2 . Specifically, the exhaust port 46C is positioned toward the center and rear of the inlet 45B in the vehicle width direction. In other words, focusing on the position in the vehicle width direction, the exhaust port 46C is located midway between the inlet 45B at the left end and the inlet 45B at the right end in the vehicle width direction.

[0037] Each battery module 30 is arranged on a straight line path 49 that virtually connects the inlet 45B and the outlet 46C. In other words, the inlet 45B, the outlet 46C, and the battery modules 30 are arranged in a relative position such that the virtual straight line path 49 crosses all of the battery modules 30.

[0038] Internal Arrangement Next, we will explain the arrangement of the battery modules 30, battery-related electrical components, and cooling equipment of the battery pack 10. As shown in Figure 4, the BMU 40, transformer 41, and junction box 43 are all arranged together in the center or front of the vehicle width direction in the internal space 20A.

[0039] 1 and 4 show an example in which the BMU 40 and 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 illustrated. Furthermore, as shown in FIG. 2, the junction box 43 is arranged in front of the center module 15. Note that the BMU 40, transformer 41, and junction box 43 are not arranged above or in front of the side module 16. For this reason, it can be said that the side module 16 has a higher degree of freedom in setting the arrangement than the center module 15, but the center module 15 has more restrictions on changing the arrangement than the side module 16.

[0040] The harness 42 is connected to the BMU 40, the transformer 41, the junction box 43, etc., and is therefore routed at least above and in front of the center module 15. As shown in Fig. 4, the intake duct 45 extends outward in the vehicle width direction and forward of each of the left and right side modules 16. The intake duct 45 illustrated here has an intake port 45A located on the outer side of each side module 16 in the vehicle width direction in a plan view, and an inlet 45B located on the front side of each side module 16 in a plan view.

[0041] In addition, the fan 44 and exhaust duct 46 are disposed above the battery pack case 20 rather than in the interior space 20A. Here, the fan 44 is disposed above the transformer 41, and the exhaust duct 46 extends forward from the fan 44. As shown in FIG. 1 , the seat 2 is disposed above the battery pack 10 rather than the interior space 20A, and is installed above the outer half of the second battery module 32 and fifth battery module 35 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.

[0042] ==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 Figure 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.

[0043] The tray 21 has a bottom wall 50 and side walls 60 extending from the periphery of the bottom wall 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 manner is the bottom wall 50. The inner bottom surface 51 extends below the battery module 30 through the lower space 20L. In other words, the battery module 30 and the inner bottom surface 51 are spaced apart.

[0044] In this embodiment, the inner bottom surface 51 is subdivided 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. The lower space 20L is similarly subdivided 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, allowing cooling air to circulate throughout the entire lower space 20L.

[0045] The exhaust pipe 8 is disposed directly below the end of the tray 21 (battery pack case 20) in the vehicle width direction. The lid 22 is a member that forms the top surface of the battery pack case 20. As shown in Figure 4, the lid 22 is provided with an air intake port 45A that takes in cooling air into the internal space 20A. Here, the air intake port 45A is provided on the top surface of the battery pack case 20 and faces upward, and an air intake port cover 70 is provided to cover the air intake port 45A.

[0046] The battery mounting structure related to the layout of the battery modules 30 will be described in detail below. A structure in which all battery modules aligned in a predetermined direction are arranged at the same height (hereinafter referred to as the "comparative structure") requires a surface on which all battery modules can be mounted at the same height (i.e., a mounting surface in an area where all battery modules extend at a certain height), which may cause interference with the surrounding structures of the battery modules. For example, if existing structures such as side members 7 and exhaust pipes 8 are present on the outer side of the battery pack 10 in the vehicle width direction, as in this embodiment, the comparative structure may cause the outer battery modules in the vehicle width direction to interfere with these existing structures. Therefore, measures such as redesigning the layout of the surrounding structures of the battery modules or reducing the number of battery modules are required.

[0047] Therefore, in the battery mounting structure of this embodiment, all battery modules 30 are not placed at the same height position, but the height position is set depending on the placement location of the battery module 30, thereby ensuring freedom in the layout of the surrounding structure for the battery module 30.

[0048] In the battery mounting structure of this embodiment, as shown in Figures 1 and 4, the side modules 16 are arranged to protrude upward relative to the center module 15. In other words, the height position of the side modules 16 is offset (shifted) upward relative to the center module 15. Conversely, the center module 15 is arranged to protrude downward relative to the side modules 16. In other words, the height position of the center module 15 is offset downward relative to the side modules 16. This vertically offset arrangement can also be said to be an arrangement in which the position of the side module 16 is raised among the multiple (e.g., six) battery modules 30 (31 to 36).

[0049] The side modules 16 illustrated here are arranged in a position where they partially overlap the center module 15 in the vertical direction when viewed from the vehicle width direction. This arrangement can be said to be an arrangement in which all of the battery modules 30 overlap at least a portion of the vertical area, and can also be said to be an arrangement in which the side modules 16 are not elevated 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.

[0050] With respect to the battery module 30 in which the relative height positions of the center module 15 and side modules 16 are set as described above, the height positions relative to the side members 7 among the peripheral structures of the battery pack 10 will be described with reference to Figure 1. The lower part (part) of the center module 15 is disposed at a height position that overlaps with the side members 7 when viewed from the vehicle width direction. On the other hand, the side modules 16 are disposed at a height position higher than the side members 7 without overlapping with them when viewed from the vehicle width direction. This arrangement of the battery module 30 relative to the side members 7 can be said to be an arrangement in which the center module 15 is fitted between the side members 7, and can also be said to be a recessed arrangement in which the side modules 16 are set back upward to avoid interference with the side members 7 (peripheral structures).

[0051] Regarding the height position of the lower end surfaces 30L of the battery modules 30 relative to the upper ends 7U of the side members 7, the lower end surface 30L of the center module 15 (only one location is marked with a reference symbol in FIG. 1 ) is located below the upper ends 7U of the side members 7. Meanwhile, the lower end surfaces 30L of the side modules 16 are located above the upper ends 7U of the side members 7.

[0052] The side lower space 20S, which is formed below the side modules 16 that are offset upward as described above, has a larger vertical dimension than the center lower space 20C, which is formed below the center module 15. In other words, the center lower space 20C has a smaller vertical dimension than the side lower space 20S. This makes it easier for cooling air to accumulate in the side lower space 20S than in the center lower space 20C, allowing the portion of the lower part of the battery module 30 that is closer to the inlet 45B than the outlet 46C to exchange heat sufficiently with the cooling air. The lower part of the side lower space 20S is connected to the center lower space 20C.

[0053] The lower end of the side lower space 20S is defined by a slope surface 51X that is located downward (inclined downward) on at least a portion of the side inner bottom surface 51S 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 to the inner side in the vehicle width direction.

[0054] Furthermore, as shown in FIG. 2 , 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. 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 described as an arrangement in which the side modules 16 are positioned forward among the multiple (e.g., six) battery modules 30 (31 to 36).

[0055] A rear wall portion 61 is provided on the side wall portion 60 of the battery pack case 20, extending rearward from the battery module 30, along the outer shape of the battery module 30, with the relative longitudinal positions of the center module 15 and the side modules 16 set as described above. Specifically, a portion 61S (hereinafter referred to as a "side portion") of the rear wall portion 61 extending rearward from the side module 16 is positioned further forward than a portion 61C (hereinafter referred to as a "center portion") extending rearward from the center module 15. In other words, a central portion 61C of the rear wall portion 61, which is located in the center of the vehicle width direction, is formed in a shape that protrudes rearward.

[0056] 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 positioned shifted forward. The front wall portion 62 of the side wall portion 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 center module 15 and the front wall portion 62, which does not have any concave or convex shapes in the front and rear directions. In other words, the side modules 16 are positioned offset forward without changing the layout of the junction box 43, which is positioned in front of the center module 15.

[0057] [2. Functions and Effects] As configured as described above, this embodiment provides the following functions and effects. (1) In the battery mounting structure of this embodiment, the side modules 16 are disposed to protrude upward relative to the center module 15. Therefore, when applying the above-described battery mounting structure to an existing structure that includes side members 7, an exhaust pipe 8, and the like, interference between the existing structure and the side modules 16 and center module 15 can be easily avoided. For example, the center module 15 fits between the side members 7, allowing the battery module 30 to be mounted 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 around the battery module 30 can be ensured.

[0058] (2) In this embodiment, the side modules 16 are disposed in positions that 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 flexibility in the layout of the surrounding structure for the battery module 30.

[0059] (3) The center modules 15 are arranged at equal heights, and the side modules 16 are also arranged at equal heights. This allows a space with a large bottom area where multiple top surfaces of the center modules 15 are lined up to be secured above the center modules 15 in the internal space 20A of the battery pack case 20. This space can be utilized to accommodate electrical components such as the BMU 40 and transformer 41. In addition, the center modules 15 arranged at equal heights 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 heights, the layout of the battery modules 30 can be prevented from becoming complicated.

[0060] (4) 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.

[0061] (5) The battery pack case 20 is mounted below the seat 2, and the side modules 16 are disposed in the internal space 20A of the battery pack case 20, offset forward in the fore-and-aft direction relative to the center module 15. Therefore, the side portions 61S erected on the rear side of the side modules 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 the seats immediately behind the seat 2. For example, it improves the legroom for passengers getting in the second-row rear seats relative to the driver's seat or passenger seat 2. Furthermore, 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 passenger compartment 1.

[0062] (6) Because the center lower space 20C is smaller than the side lower space 20S, cooling air is more likely to stagnate in the side lower space 20S than in the center lower space 20C. This allows the cooling air in the side lower space 20S to stagnate before flowing into the center lower space 20C, ensuring balanced cooling of the entire battery module 30. (7) The lower end of this side lower space 20S is defined by a slope surface 51X that is positioned downward toward the center in the vehicle width direction on at least a portion of the side inner bottom surface 51S. This ensures a volume of the side lower space 20S in which cooling air can stagnate, while suppressing interference with surrounding structures due to the side lower space 20S expanding toward the vehicle width direction end.

[0063] (8) In addition, because the side modules 16 are positioned with their height positions offset upward relative to the center module 15, the side modules 16 can be positioned away from the exhaust pipe 8, which reduces heating of the side modules 16 due to radiant heat from the exhaust pipe 8. In this way, reducing the heat received by the side modules 16 from the exhaust pipe 8 contributes to improving the cooling performance of the side modules 16.

[0064] [II. Modifications] The above-described embodiment is merely an example. For example, in a battery mounting structure, among a plurality of battery modules having the same vertical length, it is sufficient that the side modules are arranged to protrude upward relative to at least the center module, and the side modules and the center module may be arranged at equal positions in the front-to-rear direction. With a battery mounting structure in which only the height positions of the battery modules are offset, a simple modification to a structure in which the battery modules are arranged at equal positions in the front-to-rear direction and height positions can ensure flexibility in the layout of the surrounding structure around the battery modules.

[0065] The battery modules may have different lengths in the front-to-rear direction as long as they have the same length in the up-to-down direction. Note that the "length in the up-to-down direction" referred to here is treated as being equal even if there are differences to a certain extent, such as variations due to manufacturing lots of the battery modules or variations within the tolerance range. In other words, even if the battery modules have slightly different lengths in the up-to-down direction, they are considered to have the same length in the up-to-down direction. Note that the "length in the front-to-rear direction" of the battery modules is also treated as being equal even if there are differences to a certain extent, such as variations due to manufacturing lots of the battery modules or variations within the tolerance range.

[0066] The side modules may be disposed in an upper position above the center module so as not to overlap with it in the up-down direction when viewed from the vehicle width direction. In this case, greater flexibility in the layout of the peripheral structure relative to the battery modules can be ensured. The center modules are not limited to being disposed at equal height positions, but may be disposed at different height positions. Furthermore, the side modules are not limited to being disposed at equal height positions, but may be disposed at different height positions. In these cases, greater flexibility in the layout of the peripheral structure relative to the center module and the peripheral structure relative to the side modules can be ensured.

[0067] The surface defining the lower end of the side lower space is not limited to the above-described sloped surface, and other forms 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, and further freedom in the layout of the surrounding structure for the side module can be ensured.

[0068] A vehicle to which the battery mounting structure is applied does not need to be provided with an exhaust pipe. In other words, 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, and the side modules may be located at both ends in the vehicle width direction. The center module is not limited to a configuration in which one is provided on each side (two in total), but may be provided with two on each side, or may have different numbers on each side (for example, one on the left and two on the right, for a total of three). Furthermore, the side lower space and the center lower space do not need to be provided in the internal space of the battery pack case.

[0069] This invention can be applied to the manufacturing industry of battery-powered vehicles.

[0070] REFERENCE SIGNS LIST 1 vehicle interior 2 seat (front seat) 8 exhaust pipe 10 battery pack 15 center module 16 side module 20 battery pack case 20A interior space 20C center lower space 20L lower space 20S side lower space 20U upper space 30 battery module 51 inner bottom surface 51C center inner bottom surface 51S side inner bottom surface 51X slope surface

Claims

1. A battery mounting structure comprising: a center module arranged in the center of the vehicle width direction among a plurality of battery modules arranged side by side in the internal space of a battery pack case mounted on a vehicle and having equal lengths in the vertical direction of the vehicle; and side modules arranged at both ends of the plurality of battery modules in the vehicle width direction, each side module projecting upward relative to the center module.

2. The battery mounting structure according to claim 1, characterized in that the side modules are arranged in a position where they partially overlap the center module in the vertical direction when viewed from the vehicle width direction.

3. The battery mounting structure according to claim 1 or 2, wherein a plurality of center modules are provided, and the height positions of the center modules are equal to each other, and the height positions of the side modules are equal to each other.

4. The battery mounting structure described in any one of claims 1 to 3, characterized in that the side modules are located on the outermost sides of the plurality of battery modules on one and the other sides in the vehicle width direction.

5. The battery mounting structure described in any one of claims 1 to 4, characterized in that the battery pack case is provided in the vehicle interior space and is mounted below the front seats excluding the rearmost seats among multiple rows of seats lined up in the longitudinal direction of the vehicle.

6. The battery mounting structure described in any one of claims 1 to 5, wherein the plurality of battery modules have the same length in the longitudinal direction of the vehicle, and the side module is disposed so as to protrude forward relative to the center module.

7. A battery mounting structure as claimed in any one of claims 1 to 6, characterized in that the battery pack case has: a side lower space formed between the side inner bottom surface located below the side module and the side module, and into which air is introduced; and a center lower space formed between the center inner bottom surface located below the center module and the center module, communicating with the lower part of the side lower space and having a smaller vertical dimension than the side lower space.

8. The battery mounting structure according to claim 7, wherein the side lower space is defined at its lower end by a sloped surface that is positioned downwards towards the center of the vehicle width on at least a portion of the bottom surface of the inner side of the side.

9. A battery mounting structure as claimed in any one of claims 1 to 8, characterized in that an exhaust pipe is disposed directly below the end of the battery pack case in the vehicle width direction.

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