Battery mounting structure of electric vehicles

Abstract

The objective is to provide a battery mounting structure for electric vehicles that can improve NVH (noise, vibration, and harshness) performance. [Solution] The battery module 10 mounted on the vehicle body 1 comprises a battery housing 21, a plurality of cells 22 arranged in series in the longitudinal direction of the vehicle, and an elastic member 24 that covers at least one of the upper and lower surfaces of each of the plurality of cells 22 and connects the cells to each other. The elastic modulus of the elastic member 24 is E[N / m 2 ], the second moment of area of ​​the aggregate of multiple cells 22 and elastic member 24 is I[m 4 When the total length of the multiple cells 22 in the longitudinal direction of the vehicle is L [m], and the value of tanδ, which is the loss coefficient of the elastic member 24, is x, then EI / L 3 However, A ≤ EI / L 3 ≤ B, where A = 4320x -0.44 B = 41812x 0.0931 E, I, L, and x are set to satisfy the following condition.

Description

[Technical Field]

[0001] This invention relates to a battery mounting structure for an electric vehicle. [Background technology]

[0002] Conventionally, in electric vehicles where a battery module containing multiple cells housed inside a battery casing is mounted on the vehicle body, vibrations input to the vehicle body from the suspension supporting the wheels during vehicle operation cause the multiple cells inside the battery casing to vibrate individually in the vertical direction, and these vibrations are transmitted to the cabin. This results in noise, vibration, and harshness (roughness / unpleasantness) that affect the ride comfort inside the cabin. Therefore, improving NVH performance, which is the ability to reduce these noise, vibration, and harshness, has become a challenge for electric vehicles.

[0003] Therefore, in order to improve NVH performance, the structure described in Patent Document 1 includes a pair of C-shaped side plates in the battery housing to prevent multiple cells of the battery module from vibrating vertically. Each of the pair of side plates has an upper flange portion and a lower flange portion that support the cells from both the upper and lower sides. By having the pair of C-shaped side plates restrain both the left and right sides of multiple cells together, the upper and lower flange portions suppress vertical vibration of each cell, thereby improving NVH performance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-46644 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the above structure, a pair of C-shaped side plates restrain both the left and right sides of multiple cells together, and the flanges on both the top and bottom sides suppress vertical vibrations of each cell. However, the influence of resonance of each cell on vibrations during vehicle operation is not considered, and there is room for improvement in NVH performance.

[0006] This invention has been made in view of the circumstances described above, and aims to provide a battery mounting structure for an electric vehicle that can improve NVH performance. [Means for solving the problem]

[0007] To solve the aforementioned problems, the battery mounting structure for an electric vehicle of the present invention comprises a vehicle body, at least one battery module fixed to the vehicle body, and a pair of left and right front wheels rotatably mounted on both the left and right sides of the front of the vehicle body, wherein the battery module comprises a battery housing, a plurality of cells housed within the battery housing and arranged in series in the longitudinal direction of the vehicle, and an elastic member that covers at least one of the upper and lower surfaces of each of the plurality of cells, connects the cells to each other, and is connected to both ends of the battery housing in the longitudinal direction of the vehicle, and the modulus of elasticity of the elastic member is E[N / m 2 ], the second moment of area of ​​the aggregate of the plurality of cells and the elastic member is I[m 4 When the total length of the multiple cells in the vehicle's longitudinal direction is L [m], and the value of tanδ, which is the loss coefficient of the elastic member, is x, then EI / L 3 E, I, L, and x are set such that the following equation is satisfied: A ≤ EI / L 3 ≤ B, Here, A = 4320x -0.44 B = 41812x 0.0931 It is characterized by the following:

[0008] According to such a configuration, when the electric vehicle is running, the vibration waves input from the pair of left and right front wheels to the vehicle body are transmitted to the battery module fixed to the vehicle body. At this time, in the battery module, elastic waves are sequentially transmitted to a plurality of cells arranged in the vehicle front-rear direction through elastic members connected to both end portions of the battery housing in the vehicle front-rear direction.

[0009] In the above configuration, EI / L 3 The elastic modulus E of the elastic member, the second moment of area I of the aggregate of the plurality of cells and the elastic member, the length L in the vehicle front-rear direction of the entire plurality of cells, and the value x of tanδ which is the loss coefficient of the elastic member are set so as to satisfy the above formula, and the plurality of cells resonate respectively to interfere with the elastic waves and reduce the elastic waves.

[0010] In other words, in the frequency band of the vibration input to the vehicle body during vehicle running, dissipation and interference of vibration energy occur with respect to the vibration transmitted sequentially for each cell in series in the vehicle front-rear direction. That is, a vibration damping effect by so-called metamaterial damping that performs continuous vibration damping along the vibration transmission direction by utilizing the mass of a plurality of cells arranged in series and the loss coefficient or attenuation characteristics of the elastic member is obtained.

[0011] In this way, by effectively blocking the vibration input from the front wheels to the vehicle body by using a plurality of cells and elastic members and suppressing the transmission into the vehicle interior, it is possible to improve the NVH performance of the vehicle. Thereby, it is possible to suppress the vibration of the frequency of the road noise band input to the vehicle body during running.

[0012] In the battery mounting structure of the above electric vehicle, when x = 2 which is the value of tanδ, E, I, and L are set so that EI / L 3 satisfies the following formula: A ≦ EI / L 3 ≦ B, Here, A = 3.18×10 3 and B = 4.46×10 4 is preferable.

[0013] According to such a configuration, when x = 2 which is the value of tanδ that is the loss factor of the elastic member, EI / L 3 range, that is, the range between the minimum value A and the maximum value B can be made the widest, and EI / L 3 the elastic modulus E of the elastic member constituting it, the second moment of area I of the aggregate of the plurality of cells and the elastic member, and the length L in the vehicle front-rear direction of the entire plurality of cells can be selected from a wide range to suppress the vibration in the load noise band. As a result, the design freedom of the battery mounting structure is expanded.

[0014] In the battery mounting structure of the electric vehicle described above, it is preferable that the elastic member covers both the upper surface and the lower surface of each of the plurality of cells.

[0015] In such a configuration, the elastic member can stably support the plurality of cells by covering both the upper surface and the lower surface of each of the plurality of cells. Thereby, it is possible to surely resonate each cell with elastic waves and exhibit a stable vibration suppression effect.

Effect of the Invention

[0016] As described above, according to the battery mounting structure of the electric vehicle of the present invention, the NVH performance can be improved.

Brief Description of the Drawings

[0017] [Figure 1] It is a plan view showing the overall configuration of the lower part of an electric vehicle to which the battery mounting structure of the electric vehicle according to an embodiment of the present invention is applied. [Figure 2] It is an exploded perspective view showing a plurality of cells and elastic members inside the battery module of FIG. 1. [Figure 3] It is a perspective explanatory view showing the behavior in which the aggregate of the plurality of cells and the elastic member is deformed by the vibration input during vehicle travel in a state where the upper surfaces of the plurality of cells of FIG. 2 are connected by the elastic member. [Figure 4] It is an enlarged cross-sectional view of the elastic member of FIG. 2. [Figure 5] This graph shows the range of the minimum value A and maximum value B of EI / L3 for an elastic member, and the relationship between the loss coefficient tanδ and EI / L3, and the distribution of combinations of loss coefficient tanδ and EI / L3 included in the present invention (·) and combinations of comparative examples (×). [Figure 6] This graph shows the relationship between EI / L3 and the transfer function (FRF OA), and illustrates the reduction in the transfer function due to the vibration damping effect of the combination of loss coefficient tanδ and EI / L3 (·) included in the present invention, in the case of the elastic member with a loss coefficient tanδ = 0.1 shown in Figure 5. [Figure 7] This graph shows the relationship between EI / L3 and the transfer function (FRF OA), and illustrates the reduction in the transfer function due to the vibration damping effect of the combination of loss coefficient tanδ and EI / L3 (·) included in the present invention, in the case of the elastic member with a loss coefficient tanδ = 0.4 shown in Figure 5. [Figure 8] This graph shows the relationship between EI / L3 and the transfer function (FRF OA), and illustrates the reduction in the transfer function due to the vibration damping effect of the combination of loss coefficient tanδ and EI / L3 (·) included in the present invention, in the case of the elastic member loss coefficient tanδ = 1.0 shown in Figure 5. [Figure 9] This is a schematic diagram illustrating the meta-damping phenomenon that we want to induce in the battery mounting structure of the present invention. [Figure 10] This is a schematic diagram illustrating the resonance phenomenon, which is a comparative example with metadamping. [Figure 11] This graph shows the relationship between frequency and transfer function to explain the shielding of elastic waves over a wide frequency range due to metadamping in the present invention. [Figure 12] This graph shows the relationship between frequency and transfer function to explain the dispersion of the resonance peak at a specific frequency using a dynamic vibration absorber, which is a comparative example with metadamping. [Figure 13] This graph shows the relationship between frequency and transfer function to illustrate how the resonance peak at a specific frequency can be reduced solely by damping, as a comparative example with metadamping. [Modes for carrying out the invention]

[0018] Hereinafter, a battery mounting structure for an electric vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0019] As shown in Figure 1, the underside of an electric vehicle, including a battery mounting structure which is one embodiment of the present invention, has a structure in which the casing 20 of the battery pack 5 is integrated with the vehicle body 1. Such a structure is one in which the battery module 10 is directly mounted on the vehicle body 1 and is called a so-called skateboard structure.

[0020] Specifically, as shown in Figure 1, the lower part of the vehicle comprises a body 1 integrated with a casing 20, a plurality of battery modules 10 (eight in Figure 1) mounted on the casing 20 of the body 1, a pair of left and right front wheels 3, a pair of left and right rear wheels 7, and a drive unit P including an electric motor that drives the pair of front wheels 3. The battery pack 5 consists of a plurality of battery modules 10 and a casing 20 that houses the battery modules 10. The plurality of battery modules 10 are individually fixed inside the casing 20. Note that at least one battery module 10 is sufficient.

[0021] As shown in Figure 1, the vehicle body 1 comprises a pair of front lower arms 2, a pair of front suspensions 4 fixed to the pair of front lower arms 2 and rotatably supporting a pair of front wheels 3, a casing 20 of the battery pack 5 located on the rear X2 side of the vehicle of the pair of front lower arms 2, a pair of rear lower arms 6 located on the rear X2 side of the vehicle of the casing 20, a pair of rear suspensions 8 fixed to the pair of rear lower arms 6 and rotatably supporting a pair of rear wheels 7, and a floor plate (not shown) that covers the top of the battery pack 5 and forms the floor of the passenger compartment.

[0022] The casing 20 of the battery pack 5 comprises a pair of left and right side members 11 that are spaced apart from each other in the vehicle width direction Y and extend in the vehicle longitudinal direction X, a front cross member 12 that extends in the vehicle width direction Y and connects to the front ends of the pair of side members 11, and a rear cross member 13 that extends in the vehicle width direction Y and connects to the rear ends of the pair of left and right side members 11.

[0023] The rear ends of a pair of front lower arms 2 are connected to the front cross member 12. The front ends of a pair of rear lower arms 6 are connected to the rear cross member 13.

[0024] In this embodiment, as shown in Figure 1, two rows of eight battery modules 10 are arranged spaced apart in the vehicle width direction Y. The four battery modules 10 in each row are arranged spaced equally apart in the vehicle longitudinal direction X.

[0025] As shown in Figure 2, each battery module 10 comprises a battery housing 21, a plurality of cells 22 housed inside the battery housing 21 and arranged in a line in the vehicle's longitudinal direction X, a separator 23 interposed between adjacent cells 22, and an elastic member 24 connecting the plurality of cells 22 to each other.

[0026] The battery housing 21 is a hollow, roughly rectangular housing, and specifically comprises a front wall 21a extending in the vehicle width direction Y, a rear wall 21b extending in the vehicle width direction Y parallel to the front wall 21a on the rear side of the front wall 21a, and a pair of left and right side walls 21c that connect the left and right ends of the front wall 21a and the rear wall 21b and extend in the vehicle longitudinal direction X. In reality, the battery housing 21 has a top wall and a bottom wall that cover both the upper and lower sides of the multiple cells 22 and elastic members 24, but these are omitted in Figures 2 and 3 to show the multiple cells 22 and elastic members 24.

[0027] Cell 22 consists of a secondary battery such as a lithium-ion battery and has a plate-like or thin pouch-like shape, but may also be cylindrical. Multiple plate-like cells 22 are arranged in the vehicle's longitudinal direction X so as to be parallel to each other, that is, each extending in the vehicle width direction Y.

[0028] The separator 23 is a thin plate or film-like member interposed between two adjacent cells 22. The separator 23 only needs to be interposed between the two cells 22, for example, by being bonded to at least one of their opposing surfaces. The separator 23 is made of a lightweight material compared to the weight of the cells 22. Therefore, when considering the total weight of the assembly of multiple cells 22 and elastic members 24, the weight of the separator 23 does not need to be specifically considered.

[0029] As shown in Figures 2-3, the elastic member 24 is disposed inside the battery housing 21 (however, as mentioned above, the top and bottom walls of the battery housing 21 are not shown in order to display the elastic member 24).

[0030] The elastic member 24 covers at least one of the upper and lower surfaces of each of the multiple cells 22, and in Figures 2-3, only the upper surface, and is fixed to the upper surface by adhesive or other means. In this way, the elastic member 24 connects the cells 22 to each other.

[0031] Furthermore, the elastic member 24 is firmly connected to the front wall 21a and rear wall 21b, which are the front and rear ends of the battery housing 21 in the vehicle's longitudinal direction X, by bolting or welding. As a result, as shown in Figure 3, with the upper surfaces of the multiple cells 22 connected by the elastic member 24, the assembly of the multiple cells 22 and the elastic member 24 behaves in a way that deforms vertically in response to vibrations input during vehicle operation. Note that in Figure 3, the vertical behavior of the multiple cells 22 and the elastic member 24 is exaggerated, but the actual vertical behavior is a minute movement contained within the battery housing 21.

[0032] As shown in Figure 4, the elastic member 24 is composed of a thin plate 25 made of metal or resin and a damping adhesive 26 made of a polymer material. The damping adhesive 26 is, for example, a sealer or rubber-based adhesive, and is a polymer adhesive that has vibration damping characteristics by having a Young's modulus of 500 MPa or less and a loss coefficient of 0.1 or more at a temperature of 20°C. Each of the multiple cells 22 is bonded to the thin plate 25 by the damping adhesive 26 made of a polymer adhesive or the like.

[0033] (Explanation of settings E, I, L, and x) In the battery mounting structure of this embodiment, as shown in Figures 1 to 3, the battery module 10 has a configuration in which a plurality of cells 22 and an elastic member 24 that individually supports the plurality of cells 22, and the modulus of elasticity of the elastic member 24 is E[N / m 2 ], the second moment of area of ​​the aggregate of multiple cells 22 and elastic member 24 is I[m 4 When the total length of the multiple cells 22 in the longitudinal direction of the vehicle is L [m], and the value of tanδ, which is the loss coefficient of the elastic member 24, is x, then EI / L 3 E, I, L, and x are set such that the following equation is satisfied. A ≤ EI / L 3 ≤ B, Here, A = 4320x -0.44 B = 41812x 0.0931

[0034] In this embodiment, the battery module 10 has a separator 23 interposed between adjacent cells 22. However, since the separator 23 is much thinner and lighter than the cells 22, it does not affect the above-mentioned E, I, and L.

[0035] In this embodiment, the conditions for the loss coefficient tanδ and the elastic modulus E are those for 10-60°C and 100Hz.

[0036] Figure 5 shows EI / L 3 The minimum values ​​of A and EI / L 3The loss coefficients tanδ and EI / L of the elastic member 24, which show the range of the maximum value B. 3 The graph shows the loss coefficients tanδ and EI / L included in the present invention. 3 This graph shows the distribution of combinations (·) and comparative example combinations (×).

[0037] According to the graph in Figure 5, the above EI / L 3 The minimum value A lies on a downward-curving curve, i.e., a curve where the value decreases rapidly as the loss coefficient tanδ increases below approximately 0.2, and then gradually decreases above approximately 0.2. On the other hand, the maximum value B lies on an upward-curving curve, i.e., a curve where the value increases rapidly as the loss coefficient tanδ increases below approximately 0.2, and then gradually increases above approximately 0.2. The loss coefficients tanδ and EI / L included in this invention 3 The combination (·) is distributed within the range enclosed by the curves for the minimum value A and the maximum value B in Figure 5, while the combination of the comparative example (×) is distributed outside that range.

[0038] As shown in the combination (·) of the present invention in Figure 5, EI / L 3 A ≤ EI / L 3 By setting E, I, L, and x (=tanδ) to satisfy the equation ≤B, multiple cells 22 can resonate with each other and continuously dampen vibrations in response to road noise (vibration waves of approximately 100Hz (100Hz~400Hz)), which is vibration input to the vehicle body when the vehicle is in motion.

[0039] The vibration damping effect is evident from the graphs in Figures 6-8. Here, each of the figures in Figures 6-8 represents EI / L 3 A graph showing the relationship between the transfer function (FRF OA) and the loss coefficients tanδ and EI / L included in the present invention for each case of the loss coefficients tanδ = 0.1, 0.4, and 1.0 of the elastic member in Figure 5. 3 This graph shows the reduction in the transfer function due to the vibration damping effect of the combination (·). Looking at the graphs in Figures 6-8, we can see the loss coefficients tanδ and EI / L included in the present invention shown in Figure 5. 3In combination (·), the vibration damping effect reduces the transfer function to a level lower than the level of transfer function C at which vehicle occupants can feel the vibration damping. On the other hand, in the comparative example combination (×), the level of transfer function C is higher than the above level, and no vibration damping effect is obtained. The vibration damping effect shown in Figures 6-8 has been confirmed by computer analysis conducted by the inventors.

[0040] From the above results, it can be seen that the vehicle battery mounting structure of this embodiment provides the following effects and advantages.

[0041] During the operation of an electric vehicle, vibration waves input to the vehicle body 1 from the pair of front wheels 3 are transmitted to multiple battery modules 10 fixed to the vehicle body 1. At that time, in each battery module 10, elastic waves are sequentially transmitted to multiple cells 22 arranged in the longitudinal direction X of the vehicle via an elastic member 24. In the above battery mounting structure, as described above, EI / L 3 A ≤ EI / L 3 Because E, I, L, and x are set to satisfy ≤B, multiple cells 22 resonate with each other, interfering with the elastic wave and reducing its elasticity.

[0042] In other words, in the frequency band of vibrations input to the vehicle body 1 when the vehicle is in motion, vibration energy dissipation and interference occur for vibrations transmitted sequentially for each series-connected cell 22 in the longitudinal direction X of the vehicle. That is, a vibration damping effect is obtained by so-called meta-damping (meta-resonance), which utilizes the mass of two or more series-connected cells 22 and the loss coefficient or damping characteristics of the elastic member 24 to perform continuous vibration damping along the vibration transmission direction.

[0043] In this way, vibrations input from the front wheels 3 to the vehicle body 1 are effectively blocked using multiple cells 22 and elastic members 24, and transmission to the passenger compartment is suppressed, thereby improving the vehicle's NVH performance. This makes it possible to suppress vibrations in the road noise frequency range that are input to the vehicle body 1 during driving.

[0044] Here, in the case where x = 2, which is the value of the loss coefficient tanδ of the elastic member 24, EI / L 3 It is preferable that E, I, and L be set such that the following equation is satisfied. A ≤ EI / L 3 ≤ B, Here, A = 3.18 × 10 3 B = 4.46 × 10 4 With this configuration, when x=2, which is the value of tanδ, the loss coefficient of the elastic member 24, EI / L 3 This makes it possible to make the range, that is, the range between the minimum value A and the maximum value B, as wide as possible, EI / L 3 By selecting from a wide range of values ​​for the elastic modulus E of the elastic member 24, the second moment of area I of the aggregate of the multiple cells 22 and the elastic member 24, and the overall length L in the vehicle's longitudinal direction, it is possible to suppress vibrations in the road noise range. As a result, the design freedom of the battery mounting structure is expanded.

[0045] (Explanation of meta-damping) The inventors have devised a configuration that induces meta-damping (meta-resonance) within each battery module 10 by carefully devising the elastic modulus E of the elastic member 24, the second moment of area I of the aggregate of the multiple cells 22 and the elastic member 24, the total length L of the multiple cells 22 in the longitudinal direction of the vehicle, and the value x of the loss coefficient tanδ of the elastic member 24, in order to effectively dampen vibrations input from the front wheel 3 to the vehicle body 1 by a multi-mass point dispersion type vibration model using multiple cells 22 inside the battery module 10 shown in Figures 1 and 2 above.

[0046] Here, meta-damping, as shown in Figure 9, is the process of generating multiple resonances under the same excitation frequency in a multi-mass dispersion type vibration model, thereby blocking the vibrations transmitted to the output destination (i.e., creating a band gap).

[0047] For example, in a typical resonance phenomenon, as shown in Figure 10, if the input wave is continuously excited at the same frequency, the vibration reaching the output is amplified as the input wave resonates with the reflected wave from the output.

[0048] However, in the meta-damping shown in Figure 9, even when the input wave is continuously excited at the same frequency, the input wave interferes with each set of cells 22 and elastic members 24 (with spring constant K and damping rate C) within each battery module 10, causing vibration energy to dissipate (i.e., vibration damping), thus blocking vibrations from reaching the output destination. In other words, meta-damping continuously interferes and dampens to prevent amplification due to resonance. Looking at the vehicle body 1 as a whole in Figure 1, vibrations input from the front wheels 3 during vehicle operation are transmitted to the eight battery modules 10 through the front suspension 4, front lower arm 2, front cross member 12, and bottom wall. At this time, the multiple cells 22 within each battery module 10 and the elastic members 24 supporting them (see Figures 2-3) interfere with the vibrations and dissipate vibration energy, so the vibrations gradually decrease as they move towards the rear X2 of the vehicle.

[0049] In order to generate the damping caused by meta-damping as described above in each battery module 10, the modulus of elasticity E of the elastic member 24, the second moment of area I of the aggregate of the multiple cells 22 and the elastic member 24, the length L of the entire group of multiple cells 22 in the vehicle longitudinal direction, and the value x of the loss coefficient tanδ of the elastic member 24 are set as described above.

[0050] The meta-damping achieved in the battery mounting structure of this embodiment as described above controls the vibration level by a resonant structure of a metamaterial that combines a local resonant element and a damping element (specifically, the structure of the battery module 10, which is composed of multiple cells 22 and elastic members 24 combined). Therefore, within the target frequency band (bandgap), vibrations are not transmitted into the cabin (inside the vehicle) due to the interaction of the above-mentioned resonant structure.

[0051] (A comparative explanation of metadamping, dynamic vibration absorbers, and damping) Here, we will explain the differences between meta-damping, dynamic vibration absorbers, and damping as vibration reduction methods.

[0052] In meta-damping, as shown by curve C1 in the graph of Figure 11, the input elastic wave C0 (an elastic wave with peaks P1 and P2) is blocked and attenuated by interference due to the interaction between the input elastic wave C0 (an elastic wave with peaks P1 and P2) and the meta-resonator (the multi-mass point dispersion type vibration model in Figure 9 above), thereby expanding the band gap BG (i.e., the frequency band in which the vibration is blocked and attenuated) and forming a single, connected, wide BG.

[0053] In dynamic vibration absorbers, the vibration of the main vibration system is damped by adding an auxiliary mass and transferring energy to the auxiliary vibration system. Specifically, in dynamic vibration absorbers, as shown by curve C2 in the graph of Figure 12, vibrations are damped by splitting the single large peak P1 of the transfer function of the input elastic wave C0 into two smaller peaks. Therefore, a wide band gap BG (see Figure 11) like that of metadamping does not occur.

[0054] Furthermore, in damping, the energy generated by vibration is dissipated by the damping material into heat or fluid resistance, thereby reducing the vibration. Specifically, in damping, as shown by curve C3 in the graph of Figure 13, the vibration is attenuated by lowering one large peak P1 in the transfer function of the input elastic wave C0. Therefore, a wide band gap BG, as seen in metadamping, does not occur.

[0055] (modified version) In the battery module 10 shown in Figures 2-3 above, the elastic member 24 is connected to the upper surface of each of the multiple cells 22. However, in a modified example of the present invention, it is preferable that the elastic member 24 covers both the upper and lower surfaces of each of the multiple cells 22 and is connected to both the upper and lower surfaces of the multiple cells 22.

[0056] As shown in this modified example, the elastic member 24 covers both the upper and lower surfaces of each of the multiple cells 22, thereby stably supporting the multiple cells 22. This makes it possible to reliably resonate each cell 22 with elastic waves and exert a stable vibration suppression effect. [Explanation of Symbols]

[0057] 1. Vehicle body 3 Front wheels 10 Battery Modules 21 Battery enclosure 22 cells 23 Separator 24 Elastic members 25 plates 26 Damping Adhesive

Claims

1. In the battery mounting structure of an electric vehicle, The car body and, At least one battery module fixed to the vehicle body, The vehicle body is equipped with a pair of left and right front wheels that are rotatably mounted on both the left and right sides of the front of the vehicle body, The aforementioned battery module is Battery housing and The battery housing comprises a plurality of cells arranged in series in the front-rear direction of the vehicle, An elastic member that covers at least one of the upper and lower surfaces of each of the plurality of cells, connects the cells to each other, and is connected to both ends of the battery housing in the vehicle's front-rear direction. Equipped with, The elastic modulus of the elastic member is E [N / m] ２ ], the second moment of area of ​​the aggregate of the plurality of cells and the elastic member is I [m ４ When the length of the entire plurality of cells in the longitudinal direction of the vehicle is L [m], and the value of tanδ, which is the loss coefficient of the elastic member, is x, then EI / L ３ E, I, L, and x are set such that the following equation is satisfied: A≦EI / L ３ ≦B、 Here, A = 4320x －０．４４ B = 41812x ０．０９３１ A battery mounting structure for an electric vehicle characterized by the following features.

2. In the battery mounting structure for an electric vehicle according to claim 1, In the case where x = 2, which is the value of tanδ, EI / L ３ E, I, and L are set such that the following equation is satisfied: A≦EI / L ３ ≦B、 Here, A = 3.18×10 ３ , B = 4.46×10 ４ A battery mounting structure for an electric vehicle characterized by the following features.

3. In the battery mounting structure for an electric vehicle according to claim 1 or 2, The elastic member covers both the upper and lower surfaces of each of the plurality of cells. A battery mounting structure for an electric vehicle characterized by the following features.

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