Vehicle battery pack and electric truck

Abstract

To increase energy density while securing rigidity in a vehicle battery pack.SOLUTION: A vehicle battery pack 10 includes a battery module 1 having a plurality of battery cells that supply power to a motor that drives a vehicle, a bottom plate 31 installed below the battery module 1, and a frame 32 disposed above the bottom plate 31 and surrounding the battery module 1. The frame 32 includes an extension 35 extending inward and connected to the bottom plate 31. The battery module 1 includes an L-shaped module end portion 1a facing the bottom plate 31 and supported by the extension 35.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This case relates to a vehicle battery pack that supports a battery module with a frame, and an electric truck equipped with this vehicle battery pack.

Background Art

[0002] In recent years, from the perspective of reducing environmental impact, the development of electric vehicles (electric cars, hybrid cars) that run on an electric motor has been carried out not only in the field of passenger cars but also in the field of commercial vehicles such as trucks (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] In a drive battery pack (vehicle battery pack) mounted on an electric vehicle as described above, it is an issue to increase the energy density (the amount of energy per unit volume or unit weight) from the viewpoints of extending the cruising range and ensuring mountability. Therefore, in order to reduce the volume and weight, it is conceivable to thin the constituent members of the battery pack. However, when the constituent members are thinned, it becomes difficult to ensure rigidity. Therefore, in the battery pack, it is required to increase the energy density while ensuring rigidity. This case was devised in view of the above problems, and one of the objectives is to increase the energy density while ensuring rigidity in a vehicle battery pack.

Means for Solving the Problems

[0005] This case was made to solve at least part of the above problems and can be realized as the following aspects or application examples. (1) The vehicle battery pack according to this application example includes a battery module having a plurality of battery cells that supply power to a motor driving the vehicle, a bottom plate installed below the battery module, and a frame body disposed above the bottom plate and surrounding the battery module. The frame body has an extending portion that extends inward and is connected to the bottom plate. The battery module is characterized by having an L-shaped module end portion that faces the bottom plate and is supported by the extending portion. According to such a vehicle battery pack, the load of the battery module can be received by the frame body. Thereby, the burden on the bottom plate can be reduced, so that the bottom plate can be made thinner and the weight reduction of the bottom plate can be realized. Therefore, in the vehicle battery pack, the energy density can be increased while ensuring rigidity.

[0006] (2) In the vehicle battery pack according to this application example, the bottom plate may be a cooling plate that cools the battery module and has a cooling passage inside which a refrigerant flows. According to the bottom plate that is a cooling plate, the battery module can be cooled by the refrigerant flowing through the internal cooling passage. By cooling the battery module in the vehicle battery pack in this way, the temperature management of the battery module can be efficiently performed, which contributes to the extension of the cruising range of the vehicle.

[0007] (3) In the vehicle battery pack according to this application example, the module end portion may be coupled to the extending portion via a spacer and disposed with a gap between the extending portion. According to such a configuration, the heat transfer from the module end portion to the extending portion can be suppressed by the gap, so that the influence of the heat of the battery module on the frame body can be reduced. Thereby, while the frame body supports the battery module, the frame body can be protected from the heat of the battery module.

[0008] (4) In the vehicle battery pack according to this application example, the battery module may include a cell stack in which the battery cells are stacked in a predetermined stacking direction, and a pair of end plates that are disposed on both end faces of the cell stack in the stacking direction and form the module end portions. According to the above end plates, the cell stack can be supported from both sides in the stacking direction, and an L-shaped module end portion can be easily formed. Therefore, while enhancing the rigidity of the battery module, the battery module can be easily supported by the frame body.

[0009] (5) The vehicle battery pack according to this application example includes a first reinforcing plate that extends along an intersection direction intersecting the stacking direction and is fixed to at least one of the bottom plate and the frame body. The battery module may have an intermediate plate that is disposed at an intermediate portion of the cell stack in the stacking direction and is fixed to the first reinforcing plate. According to the above intermediate plate, the rigidity can be enhanced at the intermediate portion of the cell stack in the stacking direction. Also, according to the above first reinforcing plate, the rigidity of the vehicle battery pack can be enhanced. Furthermore, according to the configuration in which the intermediate plate is fixed to the first reinforcing plate, displacement of the intermediate plate with respect to the bottom plate or the frame body can be suppressed. Thereby, displacement of the battery module with respect to the bottom plate or the frame body can be suppressed, and thus the reliability of the vehicle battery pack can be enhanced.

[0010] (6) In the vehicle battery pack according to this application example, the intermediate plate may have a pair of main surfaces facing the battery cells, a plurality of side surfaces connecting the outer edges of the main surfaces, and a recess that extends in the intersection direction at one of the side surfaces and houses the first reinforcing plate. If the above-mentioned concave portion is provided in the intermediate plate, the concave portion can be used as the accommodation space for the first reinforcing plate, so that space saving can be achieved. Therefore, while increasing the rigidity of the vehicle battery pack with the first reinforcing plate, it is possible to increase the output while avoiding an increase in the size and weight of the vehicle battery pack because the first reinforcing plate is accommodated in the concave portion, so that the energy density can be further increased.

[0011] (7) The vehicle battery pack according to this application example includes a plurality of the battery modules arranged in parallel in a posture in which the stacking directions in which the battery cells are stacked are parallel to each other, and a second reinforcing plate that extends along the stacking direction between adjacent battery modules and is fixed to the frame body. The second reinforcing plate may have an L-shaped plate end portion that faces the bottom plate and is supported by the extending portion. According to such a configuration, the second reinforcing plate can be arranged by utilizing the dead space between the battery modules. Further, according to the configuration in which the L-shaped plate end portion is supported by the extending portion of the frame body, the load of the second reinforcing plate and the members supported by the second reinforcing plate can also be received by the frame body. Thereby, the burden on the bottom plate can be further reduced, so that the bottom plate can be made thinner. Therefore, the energy density can be further increased while ensuring rigidity.

[0012] (8) In the vehicle battery pack according to this application example, the frame body may be an aluminum extrusion product and may have a hollow portion formed in the extending portion. According to such a configuration, in the frame body, it is possible to suppress an increase in weight while ensuring the rigidity for supporting the module end portion. Therefore, the energy density can be further increased.

[0013] (9) The electric truck according to this application example is characterized by including the vehicle battery pack according to any one of (1) to (8) above, and a pair of side rails that are arranged above the vehicle battery pack and suspend and support the vehicle battery pack. According to such an electric truck, since the rigidity is ensured and the energy density is increased in the vehicle battery pack as described above, the protection performance of the vehicle battery pack can be ensured even during a collision, and a good cruising range can be realized. Further, since the load of the battery module is received by the frame as described above, the bottom plate can be made thinner, so that the height dimension of the vehicle battery pack can be suppressed. Therefore, even for a vehicle battery pack suspended and supported by side rails, it is easy to secure the ground clearance.

Advantages of the Invention

[0014] According to the present case, in the vehicle battery pack, the energy density can be increased while ensuring the rigidity.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0016] Referring to the drawings, embodiments of the present invention will be described. The following embodiments are merely examples and are not intended to exclude various modifications and applications of technologies not explicitly stated in these embodiments. Each configuration of the following embodiments can be implemented with various modifications without departing from their gist. Also, they can be selectively adopted as necessary, or appropriately combined.

[0017] [1. Configuration] As shown in FIG. 1, an electric vehicle (vehicle) 20 according to this embodiment includes a driving battery pack (vehicle battery pack) 10, and is an electric vehicle or a hybrid vehicle that travels by driving a motor (electric motor) (not shown) with the electric power stored in the battery pack 10. Here, as the electric vehicle 20, an electric truck including a cab 21 and a cargo box 22 is exemplified. In FIG. 1, the cab 21 and the cargo box 22 are shown by two-dot chain lines.

[0018] The battery pack 10 of this embodiment has an outer shape that is substantially a rectangular parallelepiped and has a substantially rectangular shape when viewed from above. The battery pack 10 is disposed below a pair of side rails 23 extending in the vehicle length direction (front-rear direction) D1 and is suspended and supported by each side rail 23. Specifically, the battery pack 10 is supported by each side rail 23 in a state of being suspended from each side rail 23 via a bracket (not shown). However, the shape, arrangement, and support method of the battery pack 10 are not limited to those exemplified here. Also, here, an electric vehicle 20 equipped with one battery pack 10 is exemplified, but the number of battery packs 10 mounted on the electric vehicle 20 may be two or more.

[0019] The battery pack 10 of this embodiment includes a plurality of battery modules 1 and a housing 30 that houses the battery modules 1. In this embodiment, a battery pack 10 in which four battery modules 1 arranged in the vehicle length direction D1 are housed in a single housing 30 is exemplified.

[0020] Each battery module 1 is configured in the same manner as each other. As shown in FIGS. 2 and 3, each battery module 1 includes a cell stack 2 in which a plurality of battery cells 2a are stacked in a predetermined stacking direction Do, a pair of end plates 3 disposed on both end faces of the cell stack 2 in the stacking direction Do, and an intermediate plate 4 disposed in the middle portion of the cell stack 2 in the stacking direction Do. Further, each battery module 1 of the present embodiment further includes a first belt 5 and a second belt 6 that bundle a plurality of battery cells 2a.

[0021] The battery module 1 of the present embodiment has a dimension in the stacking direction Do that is longer than either the dimension in the width direction Dw orthogonal to the stacking direction Do or the dimension in the height direction Dh orthogonal to both the stacking direction Do and the width direction Dw, and has an elongated rectangular parallelepiped shape. However, the shape of the battery module 1 is not limited to the shape exemplified here.

[0022] The plurality of battery cells 2a stacked in the cell stack 2 are configured equally to each other. Each battery cell 2a of the present embodiment has a dimension in the stacking direction Do that is shorter than the dimensions in the width direction Dw and the height direction Dh, and has a thin rectangular plate shape. In the cell stack 2, the plurality of battery cells 2a are connected in series. The battery cell 2a supplies electric power to a motor that drives the electric vehicle 20. Note that heating foils 11 for heating individual battery cells 2a are disposed on both sides of the cell stack 2 in the width direction Dw.

[0023] The end plates 3 and the intermediate plate 4 are reinforcing members for suppressing deformation (increasing rigidity) of the cell stack 2. As shown in FIG. 3, each end plate 3 of the present embodiment has a thin rectangular plate-shaped thin portion 3a that is disposed in contact with the battery cell 2a, and a thick portion 3b that is smaller than the thin portion 3a in the height direction Dh and thicker in the stacking direction Do. The thin portions 3a of the pair of end plates 3 sandwich the cell stack 2 from both sides in the stacking direction Do. Further, the thick portion 3b of each end plate 3 serves as a tightening margin that is tightened by the first belt 5 and the second belt 6.

[0024] Each battery module 1 of the present embodiment has L-shaped module end portions 1a formed at both ends in the stacking direction Do by the step between the thin portion 3a and the thick portion 3b of the end plate 3. The module end portions 1a are preferably formed to have higher strength and rigidity than members (for example, battery cells 2a) other than the module end portions 1a in the battery module 1 in order to ensure the support rigidity of the battery module 1.

[0025] On the other hand, the intermediate plate 4 of the present embodiment has a shape in which a depression (a recess 4d described later) is provided in a part of a rectangular plate that is slightly thicker than the thick portion 3b of the end plate 3. The intermediate plate 4 divides the plurality of battery cells 2a of the cell stack 2 into a first group 2B and a second group 2C, and sandwiches each of the first group 2B and the second group 2C from both sides in the stacking direction Do together with the thin portion 3a of the end plate 3.

[0026] In the present embodiment, a battery module 1 is exemplified in which the intermediate plate 4 is provided at a position that bisects the cell stack 2 (the number of battery cells 2a is equal between the first group 2B and the second group 2C). However, the intermediate plate 4 may be provided in the middle portion of the cell stack 2 excluding both ends in the stacking direction Do, and the number of battery cells 2a may be different between the first group 2B and the second group 2C divided by the intermediate plate 4.

[0027] As shown in FIG. 4, the intermediate plate 4 has a pair of main surfaces 4a facing the battery cells 2a, a plurality of side surfaces 4b, 4c connecting the outer edges of the main surfaces 4a, and a recess 4d provided in at least one of the side surfaces 4b, 4c. The intermediate plate 4 of the present embodiment has a rectangular main surface 4a, four side surfaces 4b, 4c connecting the four sides corresponding to the outer edges of the main surface 4a, respectively, and a recess 4d provided only in one of the side surfaces 4b, 4c.

[0028] Both of the pair of main surfaces 4a form a plane extending along the width direction Dw and the height direction Dh. On the other hand, the four side surfaces 4b are divided into two transverse surfaces 4b extending along the stacking direction Do and the width direction Dw, and two longitudinal surfaces 4c extending along the stacking direction Do and the height direction Dh. The recess 4d of the present embodiment extends in the width direction Dw (the intersection direction intersecting the stacking direction Do) on one (the lower side in FIG. 4) of the transverse surfaces 4b. The recess 4d forms a substantially rectangular parallelepiped-shaped space and opens in a substantially rectangular shape on each longitudinal surface 4c.

[0029] The recess 4d of the intermediate plate 4 functions as an accommodation space for arranging other members (for example, the first belt 5 and the first reinforcing plate 7 described later). Further, a pair of leg portions 4f formed between each main surface 4a and the recess 4d in the intermediate plate 4 of the present embodiment serve as a tightening margin to be tightened by the first belt 5.

[0030] The intermediate plate 4 of the present embodiment is an extrusion-molded product of aluminum and has a hollow portion 4e extending in the width direction Dw (the intersection direction). Here, an intermediate plate 4 provided with four hollow portions 4e opening in a substantially rectangular shape on each longitudinal surface 4c is exemplified. The intermediate plate 4 is manufactured by extruding aluminum with the width direction Dw as the extrusion direction.

[0031] As shown in FIGS. 2 and 3, both the first belt 5 and the second belt 6 are formed in an endless belt shape by, for example, metal. The first belt 5 bundles each of the first group 2B and the second group 2C separated by the intermediate plate 4 into one, while the second belt 6 bundles the entire cell stack 2 into one. In this way, the first belt 5 bundles a smaller number of battery cells 2a than the battery cells 2a bundled by the second belt 6.

[0032] The battery module 1 of the present embodiment includes a pair of first belts 5 provided on both sides in the stacking direction Do of the intermediate plate 4. One first belt 5 bundles a plurality of battery cells 2a forming the first group 2B into one, and the other first belt 5 bundles a plurality of battery cells 2a forming the second group 2C into one.

[0033] Specifically, the first belt 5 has a first outer belt portion 5a disposed outside the end plate 3 in the stacking direction Do and an inner belt portion 5b disposed in the concave portion 4d of the intermediate plate 4. Both the first outer belt portion 5a and the inner belt portion 5b of the present embodiment extend in the width direction Dw. The first outer belt portion 5a is disposed in contact with the thick portion 3b of the end plate 3, and the inner belt portion 5b is disposed in contact with the leg portion 4f (see FIG. 4) of the intermediate plate 4. In the first belt 5, the first intermediate portions 5c connecting both ends of the first outer belt portion 5a and the inner belt portion 5b extend in the stacking direction Do and are disposed outside the width direction Dw of the heating foil 11.

[0034] The first belt 5 tightens the thick portion 3b of the end plate 3 and the leg portion 4f of the intermediate plate 4 by the first outer belt portion 5a and the inner belt portion 5b, respectively. Thereby, the first belt 5 sandwiches a plurality of battery cells 2a (either one of the first group 2B and the second group 2C) laminated between the end plate 3 and the intermediate plate 4 from both sides in the stacking direction Do.

[0035] The second belt 6 of the present embodiment is disposed at a position different from that of the first belt 5 in the height direction Dh. Here, the second belt 6 disposed on the other lateral surface 4b side (the upper side in FIGS. 2 and 3) where the concave portion 4d is not provided with respect to the first belt 5 is exemplified. The second belt 6 has a pair of second outer belt portions 6a respectively disposed outside the pair of end plates 3 in the stacking direction Do. Both the second outer belt portions 6a of the present embodiment extend in the width direction Dw. The pair of second outer belt portions 6a are respectively disposed in contact with the thick portions 3b of the pair of end plates 3. In the second belt 6, the second intermediate portions 6c connecting both ends of the pair of second outer belt portions 6a extend in the stacking direction Do and are disposed outside the width direction Dw of the heating foil 11.

[0036] The second belt 6 fastens the thick portions 3b of the pair of end plates 3 with a pair of second outer belt portions 6a. Thereby, the second belt 6 sandwiches the cell laminate 2 (both the first group 2B and the second group 2C) disposed between the pair of end plates 3 from both sides in the stacking direction Do.

[0037] As shown in FIG. 5, in the battery pack 10, a plurality of battery modules 1 are arranged in parallel in a posture where the stacking directions Do are parallel to each other. In the present embodiment, an example of the battery pack 10 is illustrated in which the stacking direction Do coincides with the vehicle width direction (left - right direction) D2, the height direction Dh coincides with the vehicle height direction (up - down direction) D3, and each battery module 1 is arranged in a posture where the module end portion 1a and the recess 4d face downward (toward the bottom plate 31 described later). Note that in FIG. 5, each battery module 1 is shown in a simplified manner. Also, in the following description, the recess 4d provided in the intermediate plate 4 of the battery module 1 is also referred to as "the recess 4d of the battery module 1".

[0038] In the battery pack 10 of the present embodiment, the recesses 4d of each battery module 1 extend along the vehicle length direction D1. Also, the four recesses 4d provided in the four battery modules 1 are arranged along the vehicle length direction D1. Similarly, the module end portions 1a of the four battery modules 1 are arranged along the vehicle length direction D1.

[0039] The housing 30 has a bottom plate 31 installed below the battery module 1 and a frame body 32 disposed above the bottom plate 31 and surrounding the battery module 1. Here, an example is given of a bottom plate 31 having a rectangular shape and a frame body 32 standing upright from four sides corresponding to the outer edge of the bottom plate 31 and having a rectangular tube shape. The bottom plate 31 is formed thinner (with a smaller thickness) than the frame body 32 and the first reinforcing plate 7 and the second reinforcing plate 8 described later. Note that the housing 30 is provided with a lid plate (not shown) that closes the space surrounded by the bottom plate 31 and the frame body 32 from above.

[0040] As shown in FIGS. 6 and 8, the bottom plate 31 of the present embodiment is a cooling plate for cooling the battery module 1, and has a cooling passage 38 through which a refrigerant flows inside. Specifically, the bottom plate 31 is composed of an upper plate 31A and a lower plate 31B stacked in the vehicle height direction D3, and has a hollow portion serving as the cooling passage 38 between these plates 31A and 31B. Such a bottom plate 31 as a cooling plate is provided with an inlet and an outlet (both not shown) for the refrigerant. Note that a protection plate (not shown) may be further provided below the bottom plate 31 to increase the rigidity of the battery pack 10 or to protect the bottom plate 31 from flying stones. In FIGS. 6 to 9, the hatching of the cross section of the battery cell 2a is omitted.

[0041] As shown in FIG. 5, specifically, the frame body 32 includes a pair of vertical wall portions 33 extending in the vehicle length direction D1 and a pair of horizontal wall portions 34 extending in the vehicle width direction D2. The pair of vertical wall portions 33 are arranged at intervals in the vehicle width direction D2, and the pair of horizontal wall portions 34 are arranged at intervals in the vehicle length direction D1. The vertical wall portions 33 face each battery module 1 from the outside in the vehicle width direction D2 (the outside in the stacking direction Do).

[0042] The frame body 32 of the present embodiment has an extension portion 35 that extends inward (toward the battery module 1 side) from each vertical wall portion 33 and is connected to the bottom plate 31. The extension portion 35 extends over the entire length of the vertical wall portion 33 in the vehicle length direction D1. As shown in FIG. 6, the extension portion 35 extends inward from the lower end portion of the vertical wall portion 33. Here, an example is given of an extension portion 35 having a rectangular cross section (a cross section along the vehicle width direction D2 and the vehicle height direction D3) and forming an L shape (a single-step staircase shape) together with the vertical wall portion 33.

[0043] The frame body 32 of the present embodiment is an aluminum extrusion product. The vertical wall portions 33 and the extension portion 35 are manufactured by extruding aluminum with the vehicle length direction D1 as the extrusion direction. On the other hand, the horizontal wall portion 34 is manufactured by extruding aluminum with the vehicle width direction D2 as the extrusion direction.

[0044] The frame body 32 has hollow portions 36 formed in each of the vertical wall portion 33, the horizontal wall portion 34, and the extension portion 35. In each of the vertical wall portion 33 and the horizontal wall portion 34, a plurality of hollow portions 36 are provided side by side in the vehicle height direction D3. On the other hand, in the extension portion 35, a plurality of hollow portions 36 are provided side by side in the vehicle width direction D2. Each of the vertical wall portion 33, the horizontal wall portion 34, and the extension portion 35 is coupled to the bottom plate 31 by a screw member 12 inserted from below the bottom plate 31.

[0045] As shown in FIG. 7, the L-shaped module end portion 1a faces the bottom plate 31 and is supported by the extension portion 35. In the module end portion 1a of the present embodiment, the thin-walled portion 3a of the end plate 3 is located inside the extension portion 35 in the vehicle width direction D2, and the thick-walled portion 3b of the end plate 3 is located above the extension portion 35, so that the module end portion 1a is positioned with respect to the extension portion 35.

[0046] The module end portion 1a of the present embodiment is coupled to the extension portion 35 via a spacer 13. That is, the module end portion 1a is disposed with a gap G1 between it and the extension portion 35 by the thickness of the spacer 13. Here, an example is given of the module end portion 1a coupled to the extension end portion (the right end portion in FIG. 7) of the extension portion 35 via the spacer 13.

[0047] Specifically, the spacer 13 is a flange portion of a rivet nut 14 fixed to the extension portion 35. The rivet nut 14 is fitted into a through hole 37 formed in the upper surface of the extension portion 35, and the flange portion functioning as the spacer 13 is disposed so as to overlap the upper surface of the extension portion 35. A bolt 15 inserted from above the thick-walled portion 3b of the end plate 3 is fastened to the rivet nut 14.

[0048] Each battery module 1 is fixed to the frame body 32 in a state where a gap G1 is secured between the module end portion 1a and the extension portion 35 by fastening the above-described rivet nut 14 and bolt 15. Thereby, the battery module 1 is housed in the housing 30 in a state where the module end portion 1a is supported by the extension portion 35 of the frame body 32.

[0049] Further, each battery module 1 of the present embodiment is arranged with the battery cell 2a in contact with the bottom plate 31 which is a cooling plate. However, the battery module 1 may be provided in a state where the module end portion 1a is supported by the extending portion 35 of the frame body 32, and the battery cell 2a may be arranged with a gap (in a state floating from the bottom plate 31) between the battery cell 2a and the bottom plate 31.

[0050] As shown in FIG. 5, the battery pack 10 of the present embodiment includes a plate-shaped first reinforcing plate 7 and a second reinforcing plate 8 that reinforce the housing 30. The first reinforcing plate 7 and the second reinforcing plate 8 are arranged on the bottom plate 31 and intersect each other. Here, the first reinforcing plate 7 extending along the vehicle length direction D1 (i.e., the intersection direction) and the two second reinforcing plates 8 extending along the vehicle width direction D2 (i.e., the stacking direction Do) are exemplified.

[0051] The first reinforcing plate 7 is accommodated (arranged) in the recess 4d of each battery module 1. In other words, the first reinforcing plate 7 extends along the vehicle length direction D1 so as to penetrate the recesses 4d of the four battery modules 1. On the other hand, the two second reinforcing plates 8 are provided at intervals from each other in the vehicle length direction D1 and are arranged between adjacent battery modules 1. That is, each second reinforcing plate 8 extends along the vehicle width direction D2 between adjacent battery modules 1.

[0052] The first reinforcing plate 7 and the second reinforcing plate 8 are fixed to at least one of the bottom plate 31 and the frame body 32. In the present embodiment, both end portions of the first reinforcing plate 7 in the vehicle length direction D1 and both end portions of the second reinforcing plate 8 in the vehicle width direction D2 are fixed to the frame body 32 by welding. Further, the intersecting (overlapping) portions of the first reinforcing plate 7 and the second reinforcing plate 8 are fixed to each other by welding.

[0053] The second reinforcing plate 8 of the present embodiment has an L-shaped plate end portion 8a that faces the bottom plate 31 and is supported by the extending portion 35 of the frame body 32. The plate end portion 8a corresponds to both end portions of the second reinforcing plate 8 in the vehicle width direction D2. The plate end portion 8a of the present embodiment is connected to the extending portion 35 over the entire length of the extending portion 35 in the vehicle width direction D2.

[0054] As shown in FIG. 8, the cross section (a cross section orthogonal to the vehicle length direction D1) of the first reinforcing plate 7 of the present embodiment forms a rectangular closed cross section corresponding to the concave portion 4d of the intermediate plate 4. However, a gap G2 is secured between the first reinforcing plate 7 and the leg portion 4f of the intermediate plate 4 to prevent interference between the intermediate plate 4 and the first belt 5 with respect to the first reinforcing plate 7.

[0055] The first reinforcing plate 7 of the present embodiment is an extrusion-molded product of aluminum and has a hollow portion 7a extending in the vehicle length direction D1. Here, an example of the first reinforcing plate 7 provided with two hollow portions 7a arranged in the vehicle height direction D3 is illustrated. Each hollow portion 7a has a rectangular shape when viewed from the vehicle length direction D1. The first reinforcing plate 7 is coupled to the bottom plate 31 by a screw member 16 inserted from below the bottom plate 31.

[0056] In the present embodiment, the second reinforcing plate 8 is also an extrusion-molded product of aluminum and has a hollow portion (not shown) extending in the vehicle width direction D2. Each hollow portion of the second reinforcing plate 8 has, for example, the same rectangular shape as the hollow portion 7a of the first reinforcing plate 7 when viewed from the vehicle width direction D2. Note that a plurality of hollow portions arranged in the vehicle height direction D3 may also be provided in the second reinforcing plate 8.

[0057] The battery pack 10 of the present embodiment includes a fastening structure 9 that fastens the intermediate plate 4 and the first reinforcing plate 7 to each other. The fastening structure 9 is composed of, for example, a through hole 9a formed in the intermediate plate 4, a screw hole 9b formed in the first reinforcing plate 7 so as to communicate with the through hole 9a, and a bolt 9c inserted through the through hole 9a and screwed into the screw hole 9b.

[0058] The through-hole 9a extends in the vehicle height direction D3 (height direction Dh) at a location different from the hollow portion 4e in the intermediate plate 4. The screw hole 9b extends in the vehicle height direction D3 at a location different from the hollow portion 7a in the first reinforcing plate 7. The bolt 9c is inserted into the through-hole 9a from above. In the fastening structure 9, the lower part of the bolt 9c inserted into the through-hole 9a is screwed into the screw hole 9b, thereby fastening the intermediate plate 4 and the first reinforcing plate 7 to each other.

[0059] [2. Function and Effect] (1) In the battery pack 10, since the L-shaped module end portion 1a is supported by the extending portion 35 of the frame body 32, the load of the battery module 1 can be received by the frame body 32. Thereby, compared with the case where the entire battery module 1 is placed on the bottom plate 31, the burden on the bottom plate 31 can be reduced. As a result, since the load resistance required for the bottom plate 31 is reduced, the bottom plate 31 can be made thinner, and the weight reduction of the bottom plate 31 can be realized. Therefore, the energy density can be increased while ensuring the rigidity in the battery pack 10.

[0060] (2) According to the bottom plate 31 which is a cooling plate for cooling the battery module 1 and has a cooling passage 38 through which a refrigerant flows inside, the battery module 1 can be cooled by the refrigerant flowing through the cooling passage 38. By cooling the battery module 1 in the battery pack 10 in this way, the temperature management of the battery module 1 can be efficiently performed, which contributes to the extension of the cruising range of the electric vehicle 20.

[0061] Further, if the battery module 1 is arranged in contact with the bottom plate 31, direct heat exchange can be performed between the bottom plate 31 and the battery module 1, so that the cooling efficiency of the battery module 1 can be enhanced. Therefore, it contributes to the further extension of the cruising range of the electric vehicle 20.

[0062] (3) If the module end portion 1a is coupled to the extending portion 35 via the spacer 13 and is disposed with a gap G1 therebetween, heat transfer from the module end portion 1a to the extending portion 35 can be suppressed by the gap G1. For this reason, the influence of the heat of the battery module 1 on the frame body 32 can be reduced. Thereby, while supporting the battery module 1 with the frame body 32, the frame body 32 can be protected from the heat of the battery module 1.

[0063] (4) According to the pair of end plates 3 that are disposed on both end faces in the stacking direction Do of the cell stack 2 and form the module end portion 1a, the cell stack 2 can be supported from both sides in the stacking direction Do, and the L-shaped module end portion 1a can be easily formed. Therefore, while increasing the rigidity of the battery module 1, the battery module 1 can be easily supported by the frame body 32. Thus, the rigidity of the battery pack 10 can be further increased.

[0064] (5) If, in addition to the pair of end plates 3, an intermediate plate 4 is disposed with respect to the cell stack 2 of the battery module 1, both end faces in the stacking direction Do of the cell stack 2 can be supported by the end plates 3, and the intermediate portion in the stacking direction Do of the cell stack 2 can be supported by the intermediate plate 4. Thereby, the rigidity can be increased not only at both end faces but also at the intermediate portion in the stacking direction Do of the cell stack 2.

[0065] In particular, according to the intermediate plate 4, since the rigidity of the intermediate portion in the stacking direction Do where the cell stack 2 is likely to undergo bending deformation can be increased, deformation of the cell stack 2 can be effectively suppressed. Therefore, even if the number of battery cells 2a stacked in the cell stack 2 is increased, bending deformation of the cell stack 2 in the stacking direction Do can be suppressed. Also, even if a plurality of battery cells 2a are individually deformed, for example, due to thermal expansion, distortion of the cell stack 2 can be suppressed. Therefore, the reliability of the battery module 1 can be increased.

[0066] In addition, if a first reinforcing plate 7 fixed to at least one of the bottom plate 31 and the frame body 32 is provided, the rigidity of the battery pack 10 can be increased. Thereby, while ensuring the required rigidity of the battery pack 10, it is possible to reduce the thickness of the bottom plate 31 or avoid increasing the size of the second reinforcing plate 8. Furthermore, if the intermediate plate 4 is fixed to the first reinforcing plate 7, displacement of the intermediate plate 4 with respect to the bottom plate 31 and the frame body 32 can be suppressed. Thereby, displacement of the battery module 1 with respect to the bottom plate 31 and the frame body 32 can be suppressed, so that the reliability of the battery pack 10 can be further enhanced.

[0067] (6) If at least one of the side surfaces 4b and 4c of the intermediate plate 4 is provided with a recess 4d, the recess 4d can be used as a housing space for other members (in this embodiment, the first belt 5 and the first reinforcing plate 7). As in this embodiment, if the inner belt portion 5b of the first belt 5 is disposed in the recess 4d, a plurality of battery cells 2a laminated between the end plate 3 and the intermediate plate 4 can be clamped by the first belt 5 from both sides in the lamination direction Do, so that the rigidity of the battery module 1 can be further increased.

[0068] In addition, by using the recess 4d as a housing space for other members, it is not necessary to separately secure a space for arranging other members, so that space saving can be realized. Thereby, it is possible to increase the output while avoiding an increase in size and weight of the battery module 1, so that the energy density can be further increased.

[0069] Also, if the first reinforcing plate 7 is housed in the recess 4d of the intermediate plate 4, it is not necessary to separately secure a space for arranging the first reinforcing plate 7 inside the frame body 32, so that space saving can be realized. Therefore, while increasing the rigidity of the battery pack 10 by the first reinforcing plate 7, it is possible to increase the output while avoiding an increase in size and weight of the battery pack 10 by housing the first reinforcing plate 7 in the recess 4d, so that the energy density can be further increased.

[0070] If the second reinforcing plate 8 extends along the stacking direction Do between adjacent battery modules 1, the second reinforcing plate 8 can be arranged by utilizing the dead space between the battery modules 1. As a result, while further enhancing the rigidity of the battery pack 10 with the second reinforcing plate 8, it is possible to increase the output while avoiding an increase in the size of the battery pack 10, so that the energy density can be further increased. Also, according to the second reinforcing plate 8 fixed between adjacent battery modules 1, displacement between adjacent battery modules 1 can be suppressed. Therefore, the reliability of the battery pack 10 can be enhanced.

[0071] Furthermore, if the L-shaped plate end 8a is supported by the extending portion 35 of the frame body 32, the load of the second reinforcing plate 8 (and the members supported by the second reinforcing plate 8) can also be received by the frame body 32. Thereby, compared with the case where the entire second reinforcing plate 8 is placed on the bottom plate 31, the burden on the bottom plate 31 can be further reduced. As a result, since the required load-bearing capacity of the bottom plate 31 is further reduced, the bottom plate 31 can be made thinner. Therefore, the energy density can be further increased while ensuring the rigidity in the battery pack 10. In addition, according to the first reinforcing plate 7 and the second reinforcing plate 8 that cross each other, the rigidity of the battery pack 10 can be enhanced in two different directions. Therefore, even when the electric vehicle 20 collides, deformation of the battery pack 10 can be effectively suppressed. Therefore, the protection performance of the battery pack 10 can be ensured.

[0072] (8) According to the frame body 32 which is an aluminum extrusion product and has a hollow portion 36 formed in the extending portion 35, it is possible to suppress an increase in weight while ensuring the rigidity for supporting the module end 1a. Therefore, the energy density of the battery pack 10 can be further increased.

[0073] If an endless belt-shaped first belt 5 is provided to sandwich a plurality of battery cells 2a laminated between the end plate 3 and the intermediate plate 4 from both sides in the lamination direction Do, the plurality of battery cells 2a can be constrained by the first belt 5. In particular, since the first belt 5 sandwiches only a part (either the first group 2B or the second group 2C) of the battery cells 2a laminated in the cell laminate 2, rather than all of them, the individual battery cells 2a can be effectively constrained as compared with the second belt 6 that sandwiches the entire cell laminate 2.

[0074] Also, according to the first belt 5, since a plurality of battery cells 2a are sandwiched from both sides in the lamination direction Do, it becomes easier to absorb the deformation due to the thermal expansion of the individual battery cells 2a, and the vibration in the lamination direction Do can be suppressed. Furthermore, according to the first intermediate portion 5c that connects the first outer belt portion 5a and the inner belt portion 5b in the first belt 5, the vibration in the direction orthogonal to the lamination direction Do (the width direction Dw in this embodiment) can also be suppressed. Therefore, if the first belt 5 is provided, the rigidity of the battery module 1 can be further increased. As a result, the deformation of the cell laminate 2 is further suppressed, and the reliability of the battery module 1 can be further enhanced.

[0075] If the inner belt portion 5b of the first belt 5 is disposed in the concave portion 4d of the intermediate plate 4, it is not necessary to separately secure a space for disposing the inner belt portion 5b of the first belt 5, so that space saving can be achieved. Therefore, a further decrease in energy density can be suppressed.

[0076] (10) If a pair of first belts 5 are respectively provided on both sides of the intermediate plate 4 in the lamination direction Do, the first group 2B and the second group 2C of the cell laminate 2 can be respectively constrained by the pair of first belts 5 on both sides of the intermediate plate 4 in the lamination direction Do. In addition to this, if an endless belt-shaped second belt 6 that sandwiches the cell laminate 2 from both sides in the lamination direction Do is provided, the entire cell laminate 2 can be constrained by one second belt 6.

[0077] In this way, by combining a pair of first belts 5 and one second belt 6, while effectively restraining each individual battery cell 2a with each first belt 5, the relative displacement between the first group 2B and the second group 2C can be suppressed with the second belt 6. Therefore, the rigidity of the battery module 1 can be further enhanced.

[0078] Also, according to the second belt 6, similar to the first belt 5, since a plurality of battery cells 2a are clamped from both sides in the stacking direction Do, it becomes easier to absorb the deformation due to the thermal expansion of each individual battery cell 2a, and the vibration in the stacking direction Do can be suppressed. Furthermore, according to the second intermediate portion 6c that connects the second outer belt portions 6a to each other in the second belt 6, the vibration in the direction orthogonal to the stacking direction Do (the width direction Dw in this embodiment) can also be suppressed. Thus, the rigidity of the battery module 1 can be further enhanced.

[0079] (11) If the intermediate plate 4 is an extruded product of aluminum and has a hollow portion 4e extending in the width direction Dw (the intersecting direction) in which the concave portion 4d extends, the intermediate plate 4 can be easily manufactured by extrusion molding with the width direction Dw as the extrusion direction. Therefore, the manufacturability of the intermediate plate 4 can be enhanced, and the weight reduction of the intermediate plate 4 can be achieved by the hollow portion 4e.

[0080] (12) If a fastening structure 9 for fastening the intermediate plate 4 and the first reinforcing plate 7 to each other is provided, the displacement of the intermediate plate 4 with respect to the first reinforcing plate 7 can be prevented. For this reason, the position of the battery module 1 in the housing 30 can be stabilized, and the deformation of the battery module 1 itself can be further suppressed by the stabilization of the position of the intermediate plate 4. Thus, the reliability of the battery pack 10 can be enhanced.

[0081] (13) According to the electric vehicle 20 equipped with the battery pack 10, as described above, since the rigidity is ensured and the energy density is increased in the battery pack 10, the protection performance of the battery pack 10 can be ensured even during a collision, and a good cruising range can be realized. In general, electric trucks are heavier than passenger cars, so they require a large battery pack to ensure a sufficient cruising range. On the other hand, in electric trucks, it is necessary to ensure a distance (ground clearance) from the road surface to the battery pack of a predetermined value or more, so the height dimension (dimension in the vehicle height direction) of the battery pack may not be increased. In particular, a battery pack that is disposed below the side rail and is suspended and supported by the side rail is difficult to ensure a sufficient ground clearance, and a high rigidity is required for the bottom plate that supports the battery module, so the bottom plate tends to be thickened. Therefore, it has been an issue to increase the energy density while suppressing the height dimension of the battery pack.

[0082] On the other hand, in the electric vehicle 20, since the load of the battery module 1 is received by the frame body 32 as described above, the bottom plate 31 can be thinned, so that the energy density can be increased while suppressing the height dimension of the battery pack 10. Therefore, even for the battery pack 10 that is suspended and supported by the side rail 23, it is easy to ensure a sufficient ground clearance, and the cruising range of the electric vehicle 20 can be ensured.

[0083] [3. Modification Example] The above-described extension portion 35 is an example. As shown in FIG. 9, the cross section of the extension portion 35 may be stepped. Here, an extension portion 35 having an L-shaped cross section is illustrated. When such a stepped extension portion 35 is formed, the plate end portion 8a of the second reinforcing plate 8 is also formed in a corresponding shape. Specifically, the plate end portion 8a is formed in a stepped shape having a plurality of L-shaped configurations. In FIG. 9, elements that are the same as or corresponding to the elements shown in the above-described embodiment are denoted by the same reference numerals.

[0084] According to such a stepped extension portion 35, the rigidity can be increased compared to the rectangular extension portion 35 shown in the above embodiment. Therefore, the module end portion 1a can be supported more stably, and the deformation of the bottom plate 31 and the vertical wall portion 33 can be suppressed. Thus, the rigidity of the battery pack 10 can be further increased. On the other hand, according to the rectangular extension portion 35 shown in the above embodiment, space saving can be achieved compared to the stepped extension portion 35 as shown in FIG. 9, so it is easier to avoid an increase in the size of the frame body 32.

[0085] Note that the extension portion 35 only needs to extend inward of the frame body 32 so as to support the module end portion 1a. Instead of extending over the entire length of the vertical wall portion 33 in the vehicle length direction D1, it may be provided pinpoint only at the location corresponding to the module end portion 1a. Also, the two extension portions 35 provided on the frame body 32 may have different configurations from each other.

[0086] Also, the module end portion 1a only needs to be L-shaped so as to face the bottom plate 31 and be supported by the extension portion 35, and it may be formed of a member other than the end plate 3, or may be arranged in contact with the extension portion 35 (without leaving the above gap G1). The recess 4d of the intermediate plate 4 only needs to extend in the intersecting direction intersecting the stacking direction Do. For example, it may extend in a direction slightly inclined with respect to the width direction Dw. Also, when the recess 4d is provided on the vertical surface 4c as described above, for example, it may extend in the height direction Dh.

[0087] The recess 4d may be provided on two or more of the plurality of side surfaces 4b, 4c. When a plurality of recesses 4d are provided in the intermediate plate 4, each of the plurality of recesses 4d can be used as a housing space for other members, so further space saving can be achieved. Also, if the plurality of recesses 4d are used as a housing space for arranging the inner belt portion 5b of the first belt 5, it becomes possible to arrange more first belts 5, so that the rigidity of the battery module 1 can be further improved. On the one hand, according to the intermediate plate 4 provided with only one recess 4d as in the above embodiment, compared with the case where a plurality of recesses 4d are provided, rigidity is more easily ensured, so that deformation of the cell laminate 2 can be further suppressed.

[0088] The shapes of the end plate 3 and the intermediate plate 4 described above are merely examples. The shapes of the end plate 3 and the intermediate plate 4 may be appropriately set according to the shape of the battery cell 2a. Further, the shape of the recess 4d provided in the intermediate plate 4 may be appropriately set according to the shape of other members housed in the recess 4d. Note that the shape, number, and arrangement of the hollow portions 4e of the intermediate plate 4 are not limited to the above examples. The intermediate plate 4 does not have to be an extrusion-molded product of aluminum, and the recess 4d and the hollow portion 4e may be omitted.

[0089] The first belt 5 may be arranged so as to sandwich a plurality of battery cells 2a from both sides in the stacking direction Do. For example, both the first outer belt portion 5a and the inner belt portion 5b may extend in the height direction Dh, and the first intermediate portion 5c may extend in the stacking direction Do and be arranged outside the battery cells 2a in the height direction Dh. Similarly, the arrangement of the second belt 6 is not limited to the above examples. Note that the end plate 3, the intermediate plate 4, the first belt 5, and the second belt 6 may be omitted from the battery module 1.

[0090] The configuration of the battery pack 10 described above is merely an example. The number of battery modules 1 provided in the battery pack 10 may be one or more. Further, the posture of the battery module 1 in the battery pack 10 is not particularly limited. For example, the battery module 1 may be housed in the housing 30 in a posture where the stacking direction Do coincides with the vehicle length direction D1, or may be housed in the housing 30 in a posture where the recess 4d faces the side (frame body 32 side) or the upper side (lid plate side).

[0091] The specific structure of the bottom plate 31 is not limited to the above example. The bottom plate 31 may not have the function as a cooling plate. That is, the bottom plate 31 may not have the cooling passage 38 inside. In this case, further thinning of the bottom plate 31 becomes possible. The structure of the above-described frame body 32 is also an example. The frame body 32 may have a shape other than a rectangular tube shape. Also, the frame body 32 may not be an extruded product of aluminum, or the hollow portion 36 may be omitted.

[0092] The extending direction, number, and arrangement of the first reinforcing plate 7 and the second reinforcing plate 8 are not limited to the above examples. The first plate 7 and the second reinforcing plate 8 may not be extruded products of aluminum, or the hollow portion may be omitted. Also, either one or both of the first reinforcing plate 7 and the second reinforcing plate 8 may be omitted from the battery pack 10.

[0093] The above-described fastening structure 9 is an example. As the fastening structure 9, various structures for fastening the intermediate plate 4 and the first reinforcing plate 7 to each other can be applied. Note that the fastening structure 9 can also be omitted from the battery pack 10. The application target of the battery pack 10 is not limited to the above-described electric vehicle 20. Also, the battery pack 10 may be applied to, for example, an electric vehicle other than a truck.

Explanation of Reference Numerals

[0094] 1 Battery module 1a Module end 2 Cell stack 2a Battery cell 2B First group 2C Second group 3 End plate 3a Thin portion 3b Thick portion 4 Intermediate plate 4a Main surface 4b Lateral surface (side surface) 4c Longitudinal surface (side surface) 4d Recess 4e Hollow portion 4f Foot part 5 First belt 5a First outer belt part 5b Inner belt part 5c First intermediate part 6 Second belt 6a Second outer belt part 6c Second intermediate part 7 First reinforcing plate 7a Hollow part 8 Second reinforcing plate 8a Plate end part 9 Fastening structure 9a Through hole 9b Threaded hole 9c Bolt 10 Battery pack 11 Heating foil 12 Screw member 13 Spacer 14 Rivet nut 15 Bolt 16 Screw member 20 Electric vehicle (vehicle, electric truck) 21 Cab 22 Cargo box 23 Side rail 30 Housing 31 Bottom plate 31A Upper plate 31B Lower plate 32 Frame body 33 Vertical wall part 34 Horizontal wall part 35 Extension part 36 Hollow part 37 Through hole 38 Cooling passage D1 Vehicle length direction D2 Vehicle width direction D3 Vehicle height direction Dh Height direction Do Laminating direction Dw Width direction (cross direction) G1 Gap between module end part 1a and extension part 35 G2 Gap between first reinforcing plate 7 and foot part 4f of intermediate plate 4

Claims

1. A battery module having a plurality of battery cells that supply power to a motor for driving a vehicle, A bottom plate installed below the battery module, A frame body disposed above the bottom plate and surrounding the battery module, and includes: The frame body has an extending portion that extends inward and is connected to the bottom plate, The battery module has a surface facing the bottom plate and supported by the extending portion, and has a module end portion with a cross section recessed in an L shape A vehicle battery pack, characterized in that.

2. The bottom plate is a cooling plate for cooling the battery module, and has a cooling passage inside through which a refrigerant flows The vehicle battery pack according to claim 1, characterized in that.

3. The module end portion is coupled to the extending portion via a spacer and is disposed with a gap between the module end portion and the extending portion The vehicle battery pack according to claim 1 or 2, characterized in that.

4. The battery module has a cell stack in which the battery cells are stacked in a predetermined stacking direction, and a pair of end plates disposed on both end faces of the cell stack in the stacking direction and forming the module end portion The vehicle battery pack according to any one of claims 1 to 3, characterized in that.

5. Including a first reinforcing plate extending along an intersecting direction intersecting the stacking direction and fixed to at least one of the bottom plate and the frame body, The battery module has an intermediate plate disposed in the middle portion of the cell stack in the stacking direction and fixed to the first reinforcing plate The vehicle battery pack according to claim 4, characterized in that.

6. The intermediate plate has a pair of main surfaces facing the battery cells, a plurality of side surfaces connecting the outer edges of the main surfaces, and a recess extending in the intersecting direction on one of the side surfaces and accommodating the first reinforcing plate The vehicle battery pack according to claim 5, characterized in that.

7. The end plate has a thin portion with a small thickness and a thick portion with a larger thickness than the thin portion, Due to the step between the thin portion and the thick portion, the module end portion with a cross section recessed in an L shape is formed The vehicle battery pack according to any one of claims 4 to 6, characterized in that.

8. A plurality of the battery modules arranged in parallel in a posture in which the stacking directions of the battery cells are parallel to each other; A second reinforcing plate that extends along the stacking direction between adjacent battery modules and is fixed to the frame body; The second reinforcing plate has a surface that faces the bottom plate and is supported by the extending portion, and has a plate end portion with a cross section recessed in an L shape. The vehicle battery pack according to any one of claims 1 to 7, characterized in that.

9. The vehicle battery pack according to any one of claims 1 to 8, characterized in that the frame body is an extruded aluminum product and has a hollow portion formed in the extending portion.

10. A vehicle battery pack according to any one of claims 1 to 9; A pair of side rails arranged above the vehicle battery pack to suspend and support the vehicle battery pack; An electric truck characterized by that.

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