Battery mounting structure of electric vehicle

Abstract

The purpose of the present invention is to provide a battery mounting structure for an electric vehicle capable of improving NVH performance. A battery module (10) mounted on a vehicle body (1) is provided with: a battery case (21); a plurality of battery cells (22) arranged in series in the front-rear direction of the vehicle; and an elastic member (24) that covers at least one of the upper surface and the lower surface of each of the plurality of battery cells (22) and connects the battery cells. When the elastic modulus of the elastic member (24) is E [N / m2], the moment of inertia of the cross section of the assembly of the plurality of battery cells (22) and the elastic member (24) is I [m4], the length of the entire plurality of battery cells (22) in the front-rear direction of the vehicle is L [m], and the value of the loss coefficient tan [delta] of the elastic member (24) is x, E, I, L, and x are set such that EI / L3 satisfies A < = EI / L3 < = B, where A = 4320 x-0.44 and B = 41812 x 0.0931.

Description

TECHNICAL FIELD

[0001] The present application relates to a battery mounting structure of an electric vehicle. BACKGROUND

[0002] In the past, in an electric vehicle in which a battery module in which a plurality of battery cells are housed inside a battery case is mounted to a vehicle body, due to vibrations input to the vehicle body from a suspension or the like that supports a wheel while the vehicle is running, the plurality of battery cells inside the battery case vibrate in the up-and-down direction, and the vibrations are transmitted to the cabin. As a result, noise, vibration, and harshness that affect the ride comfort in the cabin are generated. Therefore, in an electric vehicle, improving the NVH performance, which is the performance of reducing the noise, vibration, and harshness described above, has been a technical problem.

[0003] Here, in order to improve the NVH performance, in the structure described in Patent Document 1, in order to make the plurality of battery cells of the battery module not vibrate in the up-and-down direction, the battery case is provided with a pair of side plates of a cross-sectional C shape. The pair of side plates each has an upper flange portion and a lower flange portion that support the battery cells from both the upper and lower sides. The pair of side plates of the cross-sectional C shape collectively restrain the left and right sides of the plurality of battery cells, and thus the flange portions on both the upper and lower sides suppress the vibration of each battery cell in the up-and-down direction, thereby improving the NVH performance.

[0004]

Prior Art Documents

Patent Documents

Patent Document 1

[0005]

Problems to be Solved by the Invention

[0006] The present application has been made in view of the above circumstances, and an object thereof is to provide a battery mounting structure of an electric vehicle that can improve the NVH performance.

[0007]

Means of Solving the Problems

[0008] According to the related structure, the vibration waves input to the vehicle body from the left and right pairs of front wheels during the running of the electric vehicle are transmitted to the battery module fixed to the vehicle body. At this time, in the battery module, the elastic waves are sequentially transmitted to the plurality of battery cells arranged in the vehicle front-rear direction via the elastic member connected to the vehicle front-rear direction both ends of the battery case.

[0009] In the above structure, the elastic modulus E of the elastic member, the cross-sectional moment of inertia I of the assembly of the plurality of battery cells and the elastic member, the length L of the plurality of battery cells as a whole in the vehicle front-rear direction, and the value x of the loss factor tan δ of the elastic member are set so that EI / L 3 satisfies the above formula, whereby the elastic waves are reduced by the interference of the plurality of battery cells resonating respectively.

[0010] In other words, under the frequency bandwidth of the vibrations input to the vehicle body during the running of the vehicle, the vibrations sequentially transmitted to the batteries arranged in series in the vehicle front-rear direction will cause the dissipation and interference of vibration energy. That is, by using the mass of the plurality of battery cells arranged in series and the loss factor or damping characteristics of the elastic member, continuous vibration attenuation is performed along the direction of transmission of the vibrations, and the vibration attenuation effect due to the so-called super damping is obtained.

[0011] Thus, for the vibration input from the front wheel to the vehicle body, the vibration is effectively blocked and suppressed from being transmitted into the cabin by the plurality of battery cells and the elastic member, and thus the NVH performance of the vehicle can be improved. Thus, the vibration of the frequency of the road noise band input to the vehicle body at the time of running can be suppressed.

[0012] In the battery mounting structure for the electric vehicle described above, it is preferable that when the value x of the loss tangent tan δ is 2, E, I, and L are set such that EI / L 3 satisfies the following equation: A ≦ EI / L 3 ≦ B Here, A = 3.18 x 10 3 , B = 4.46 x 10 4 .

[0013] According to the related structure, when the value x of the loss tangent tan δ of the elastic member is 2, the range of EI / L 3 , that is, the range between the minimum value A and the maximum value B, is maximized, and the elastic modulus E of the elastic member, the cross-sectional moment of inertia I of the assembly of the plurality of battery cells and the elastic member, and the length L of the entire plurality of battery cells in the front-rear direction of the vehicle that constitute EI / L 3 can be selected from a larger range to suppress the vibration of the road noise band. Thus, the design freedom of the battery mounting structure can be increased.

[0014] In the battery mounting structure for 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 battery cells.

[0015] In the related structure, the elastic member covers both the upper surface and the lower surface of each of the plurality of battery cells, and thus the plurality of battery cells can be stably supported. Thus, each battery cell can be made to actually resonate with the elastic wave to exert a stable vibration suppression effect.

[0016]

Effects of Invention

[0017] Figure 1 FIG. 1 is a plan view of the entire structure of the lower portion of a vehicle of an electric vehicle to which a battery mounting structure according to an embodiment of the present application is applied; Figure 2 is an exploded oblique view of the plurality of battery cells and the elastic member inside the battery module of Figure 1 Figure 3 is an oblique explanatory view showing the plurality of battery cells and the elastic member inside the battery module of Figure 2 ​The behavior of the assembly of multiple battery cells and elastic members deforming due to vibrations input during vehicle operation, with the upper surfaces of multiple battery cells connected by elastic members. Figure 4 for Figure 2 Enlarged cross-sectional view of the elastic component; Figure 5 To represent EI / L 3 Minimum values ​​A and EI / L 3 The range of the maximum value B, the loss coefficient tanδ of the elastic component and EI / L 3 The figure includes the loss coefficient tanδ and EI / L representing the components of this invention. 3 Distribution diagram of the combination (·) and the comparison example combination (×); Figure 6 To represent EI / L 3 The graph showing the relationship between the transfer function (FRF OA) and the function itself is used to represent... Figure 5 When the loss coefficient tanδ of the elastic component is 0.1, the loss coefficient tanδ and EI / L included in this invention are... 3 The graph shows the reduction in the transfer function resulting from the vibration damping effect of the combination (·); Figure 7 To represent EI / L 3 The graph showing the relationship between the transfer function (FRF OA) and the function itself is used to represent... Figure 5 When the loss coefficient tanδ of the elastic component is 0.4, the loss coefficient tanδ and EI / L included in this invention are... 3 The graph shows the reduction in the transfer function resulting from the vibration damping effect of the combination (·); Figure 8 To represent EI / L 3 The graph showing the relationship between the transfer function (FRF OA) and the function itself is used to represent... Figure 5 When the loss coefficient tanδ of the elastic component is 1.0, the loss coefficient tanδ and EI / L included in this invention are... 3 The graph shows the reduction in the transfer function resulting from the vibration damping effect of the combination (·); Figure 9 A schematic illustration of the desired overdamping phenomenon in the battery mounting structure of the present invention; Figure 10 The schematic diagram illustrates the resonance phenomenon as a comparative example with overdamped conditions. Figure 11 The figure illustrates the relationship between the frequency and the transfer function of the elastic wave blocking effect over a wide frequency range caused by the overdamping generated in this invention. Figure 12The figure illustrates the relationship between frequency and transfer function when using a dynamic vibration absorber to disperse the resonance peak at a specific frequency, as a comparative example with overdamping. Figure 13 The figure illustrates the relationship between frequency and transfer function when the resonance peak at a specific frequency is reduced only by attenuation, serving as a comparative example with overdamping. Detailed Implementation

[0018] The battery mounting structure of an electric vehicle according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] like Figure 1 As shown, the electric vehicle including the battery mounting structure according to an embodiment of the present invention has a structure in which the sleeve 20 of the battery pack 5 is integrated with the vehicle body 1 at the lower part of the vehicle. This structure, in which the battery module 10 is directly mounted on the vehicle body 1, is called a so-called skateboard structure.

[0020] Specifically, such as Figure 1 As shown, the lower part of the vehicle has a body 1 integrated with the sleeve 20, and a plurality of sleeves 20 mounted on the body 1. Figure 1 The battery pack 5 consists of 8 battery modules 10, paired front wheels 3, paired rear wheels 7, and a drive unit P including an electric motor that drives the paired front wheels 3. The battery pack 5 comprises a plurality of battery modules 10 and a sleeve 20 for housing the battery modules 10. The plurality of battery modules 10 are respectively fixed inside the sleeve 20. At least one battery module 10 is required.

[0021] like Figure 1 As shown, the vehicle body 1 includes a pair of front lower control arms 2, a pair of front suspensions 4 fixed to the pair of front lower control arms 2 and rotatably supporting the pair of front wheels 3, a sleeve 20 for the battery pack 5 located on the rear side X2 of the pair of front lower control arms 2, a pair of rear lower control arms 6 located on the rear side X2 of the sleeve 20, a pair of rear suspensions 8 fixed to the pair of rear lower control arms 6 and rotatably supporting the pair of rear wheels 7, and a floor (not shown) covering the upper part of the battery pack 5 and forming the floor of the cabin.

[0022] The sleeve 20 of the battery pack 5 includes left and right paired side beams 11 that are separated from each other in the vehicle width direction Y and extend in the vehicle front-rear direction X, a front crossbeam 12 that extends in the vehicle width direction Y and is connected to the front end of the paired side beams 11, and a rear crossbeam 13 that extends in the vehicle width direction Y and is connected to the rear end of the paired side beams 11.

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

[0024] In the present embodiment, as shown in Figure 1 two rows of groups each including eight battery modules 10 are arranged separately in the vehicle width direction Y. The four battery modules 10 of each row are arranged separately in the vehicle front-rear direction X at equal intervals.

[0025] As shown in Figure 2 each battery module 10 is provided with a battery case 21, a plurality of battery cells 22 arranged in the vehicle front-rear direction X inside the battery case 21, a separator 23 present between adjacent battery cells 22, and an elastic member 24 connecting between the plurality of battery cells 22.

[0026] The battery case 21 is a hollow substantially rectangular parallelepiped case, and specifically, is provided with a front wall 21a extending in the vehicle width direction Y, a rear wall 21b extending in the vehicle width direction Y in parallel with the front wall 21a on the vehicle rear side of the front wall 21a, and left and right pair of side walls 21c connecting the left and right end portions of the front wall 21a and the rear wall 21b and extending in the vehicle front-rear direction X. The actual battery case 21 has a top wall and a bottom wall covering the upper and lower sides of the plurality of battery cells 22 and the elastic member 24, but in order to be able to see the plurality of battery cells 22 and the elastic member 24, the top wall and the bottom wall are omitted from Figures 2-3 illustration.

[0027] The battery cell 22 is composed of a secondary battery such as a lithium ion battery, and is a plate-shaped or thin pouch-shaped battery, but can also be a cylindrical battery. The plurality of plate-shaped battery cells 22 are arranged in parallel with each other in the vehicle front-rear direction X, that is, each extend in the vehicle width direction Y.

[0028] The separator 23 is a thin plate or film-shaped member present between adjacent two battery cells 22. The separator 23 can be present between the two battery cells 22, for example, adhered to at least one of the opposing faces. The separator 23 is made of a material lighter in weight than the battery cell 22. Therefore, when the total weight of the plurality of battery cells 22 and the elastic member 24 is considered, the weight of the separator 23 can not be considered in particular.

[0029] As shown in Figures 2-3 the elastic member 24 is disposed in the battery case 21 (but as described above, the top wall and the bottom wall of the battery case 21 are not illustrated in order to see the elastic member 24).

[0030] The elastic member 24 covers at least one of the upper surface and the lower surface of each of the plurality of battery cells 22, Figures 2-3The middle part only covers the upper surface and is fixed to the upper surface by means of adhesive or other methods. Thus, the elastic member 24 connects each battery cell 22.

[0031] Furthermore, the elastic member 24 is securely connected to the front wall 21a and rear wall 21b at both ends of the battery casing 21 in the vehicle longitudinal direction X by means of bolt fastening or welding. Thus, as... Figure 3 As shown, with the upper surfaces of a plurality of battery cells 22 connected by an elastic member 24, the assembly of the plurality of battery cells 22 and the elastic member 24 deforms in the vertical direction due to vibrations input during vehicle operation. Figure 3 The diagram exaggerates the vertical behavior of the plurality of battery cells 22 and the elastic member 24. The actual vertical behavior is a tiny behavior contained inside the battery casing 21.

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

[0033] (Instructions related to the settings of E, I, L, and x) In the battery mounting structure of this embodiment, such as Figures 1-3 As shown, in the structure of the battery module 10 having a plurality of battery cells 22 and elastic members 24 supporting the plurality of battery cells 22 respectively, the elastic modulus of the elastic member 24 is E [N / m]. 2 The moment of inertia of the cross section of the assembly of a plurality of battery cells 22 and elastic member 24 is I [m]. 4 When the length of the plurality of battery cells 22 as a whole in the longitudinal direction of the vehicle is L [m], and the loss coefficient tanδ of the elastic member 24 is x, set E, I, L, and x such that EI / L 3 Satisfy the following formula: A≦EI / L 3 ≦B、 Here, A = 4320x －0.44 B = 41812x 0.0931 .

[0034] In the battery module 10 of this embodiment, although there is a separator 23 between adjacent battery cells 22, the separator 23 is very thin and light compared to the battery cells 22, so it does not affect the above E, I, L.

[0035] The loss coefficient tanδ and elastic modulus E in this embodiment are the loss coefficient and elastic modulus at 10-60℃ and 100Hz.

[0036] Figure 5 It represents EI / L 3 Minimum values ​​A and EI / L 3 The range of the maximum value B, the loss coefficient tanδ of elastic member 24 and EI / L 3 The figure shows the loss coefficient tanδ and EI / L included in this invention. 3 Distribution diagram of the combination (·) and the combination (×) of the comparison example.

[0037] according to Figure 5 The above EI / L figure 3 The minimum value A lies on a downward-curving curve, meaning that as the loss coefficient tanδ increases, it decreases rapidly below approximately 0.2, and then gradually decreases after exceeding approximately 0.2. Conversely, the maximum value B lies on an upward-curving curve, meaning that as the loss coefficient tanδ increases, it increases rapidly below approximately 0.2, and then gradually increases after exceeding approximately 0.2. It can be seen that the loss coefficient tanδ and EI / L included in this invention... 3 The combination (·) is distributed in Figure 5 The range enclosed by the curves of minimum value A and maximum value B, and the combination of comparative examples (×) is distributed outside this range.

[0038] like Figure 5 As in the present invention, E, I, L, x (=tanδ) are set such that EI / L 3 Satisfying A≦EI / L 3 The formula ≦B means that, relative to the vibration input to the vehicle body when the vehicle is in motion, i.e., road noise (vibration waves of about 100Hz (100Hz~400Hz)), the plurality of battery cells 22 can resonate separately to continuously dampen the vibration.

[0039] from Figures 6-8 As shown in the graph, the vibration attenuation effect is clear. Here, Figures 6-8 These represent EI / L 3 The graph showing the relationship between the transfer function (FRF OA) and the function itself is used to represent... Figure 5 For the elastic component with loss coefficients tanδ = 0.1, 0.4, and 1.0, the loss coefficients tanδ and EI / L included in this invention are... 3 The graph shows the reduction in the transfer function resulting from the vibration damping effect of the combination (·). From... Figures 6-8 As can be seen from the diagram, in Figure 5loss coefficient tan δ and EI / L 3 In the combination (·) of the present application, due to the vibration damping effect, the transfer function is reduced to a level lower than the transfer function C at which a passenger in the vehicle can feel the vibration damping. On the other hand, in the combination (x) of the comparative example, it is known that the level is higher than the above-mentioned transfer function C, and the vibration damping effect is not obtained. Figures 6-8 The vibration damping effect shown above has been confirmed by computer analysis by the present inventors.

[0040] It is known from the above results that the vehicle battery mounting structure of the present embodiment can obtain the following effects.

[0041] Vibration waves input to the vehicle body 1 from the left and right pair of front wheels 3 during running of the electric vehicle are transmitted to the plurality of battery modules 10 fixed to the vehicle body 1, respectively. At this time, in each battery module 10, the elastic waves are sequentially transmitted to the plurality of battery cells 22 arranged in the vehicle front-rear direction X via the elastic member 24. In the above battery mounting structure, E, I, L, x are set so that EI / L 3 satisfies A≦EI / L 3 ≦B, whereby the elastic waves are interfered with by causing the plurality of battery cells 22 to resonate, respectively, and the elastic waves are reduced.

[0042] In other words, at the frequency bandwidth of the vibration input to the vehicle body 1 during running of the vehicle, the vibration transmitted to each battery cell 22 arranged in series in the vehicle front-rear direction X sequentially causes dissipation and interference of vibration energy. That is, by the mass of two or more battery cells 22 arranged in series and the loss coefficient or damping characteristics of the elastic member 24, continuous vibration damping is performed along the transmission direction of the vibration, and a vibration damping effect due to so-called super-damping (super-resonance) is obtained.

[0043] Thus, for the vibration input to the vehicle body 1 from the front wheels 3, the plurality of battery cells 22 and the elastic member 24 are used to effectively block and suppress the transmission of the vibration into the cabin, whereby the NVH performance of the vehicle can be improved. Thus, the vibration at the frequency of the road noise band input to the vehicle body 1 during running can be suppressed.

[0044] Here, it is preferable that, when the value x of the loss coefficient tan δ of the elastic member 24 is 2, E, I, L are set so that EI / L 3 satisfies the following equation: A≦EI / L 3 ≦B Here, A = 3.18 x 10 3 , B = 4.46 x 10 4 According to the related structure, when the value x of the loss coefficient tan δ of the elastic member 24 is 2, it is possible to make EI / L3 The range, that is, the range between the minimum value A and the maximum value B, reaches its maximum, allowing selection from a larger range to constitute EI / L. 3 The elastic modulus E of the elastic member 24, the moment of inertia I of the assembly of the plurality of battery cells 22 and the elastic member 24, and the length L of the plurality of battery cells as a whole in the longitudinal direction of the vehicle are used to suppress vibrations of road noise bands. As a result, the design freedom of the battery mounting structure can be increased.

[0045] (Explanation of overdamping) In order to achieve the above Figures 1-2 The multi-mass dispersed vibration model composed of a plurality of battery cells 22 inside the battery module 10 shown is used to effectively attenuate the vibration input to the vehicle body 1 from the front wheel 3. The inventors carefully studied the elastic modulus E of the elastic member 24, the moment of inertia I of the cross section of the plurality of battery cells 22 and the elastic member 24, the length L of the plurality of battery cells 22 as a whole in the longitudinal direction of the vehicle, and the value x of the loss coefficient tanδ of the elastic member 24, and conceived a structure that induces meta-damping (meta-resonance) in each battery module 10.

[0046] Here, overdamping refers to, for example, Figure 9 As shown, in a multi-particle dispersed vibration model, multiple resonances are induced under the same excitation frequency, blocking the vibration transmitted to the output end (i.e., generating a band gap).

[0047] For example, under typical resonance phenomena, such as Figure 10 As shown, if excitation is applied continuously at the same frequency, the input wave will resonate with the reflected wave from the output end, thereby causing the vibration reaching the output end to be gradually amplified.

[0048] However, in Figure 9 Under the overdamped condition shown, through the plurality of battery cells 22 (with mass M) within each battery module 10 and the elastic members 24 (with stiffness coefficient K and decay rate C) supporting them respectively, even when excitation is continuously applied at the same frequency, the input wave will interfere with the combination of each battery cell 22 and the elastic member 24, causing vibration energy to dissipate (i.e., vibration decay). Thus, the vibration reaching the output end is blocked. In other words, under overdamped conditions, continuous interference is applied to attenuate the vibration in order to prevent amplification due to resonance. Figure 1 Looking at the vehicle body 1 as a whole, when the vehicle is in motion, the vibration input from the front wheel 3 is transmitted to the eight battery modules 10 through the front suspension 4, front lower control arm 2, front crossbeam 12, and bottom wall. At this time, the plurality of battery cells 22 in each battery module 10 and the elastic members 24 supporting them (see reference) Figures 2-3The vibration is disturbed and its energy is dissipated, so that the vibration gradually decreases as it is transmitted toward the rear of the vehicle (X2).

[0049] In order to induce the attenuation caused by the super-damping in each battery module 10, the elastic modulus E of the elastic member 24, the moment of inertia I of the cross section of the assembly of the plurality of battery cells 22 and the elastic member 24, the length L of the plurality of battery cells 22 as a whole in the longitudinal direction of the vehicle, and the value x of the loss coefficient tanδ of the elastic member 24 are set as described above.

[0050] The superdamping achieved by the battery mounting structure of this embodiment is controlled by a resonant structure of a meta-material that combines local resonance elements and attenuation elements (specifically, the structure of a battery module 10 composed of a plurality of battery cells 22 and elastic members 24). Therefore, within the target bandwidth (bandgap), the interaction of the above-mentioned resonant structure prevents vibration from being transmitted into the cabin (cockpit).

[0051] (Comparison of superdamping, dynamic vibration absorbers, and damping) Here, we will explain the differences between overdamping, dynamic vibration absorbers, and damping as methods to reduce vibration.

[0052] In superdamping technology, such as Figure 11 As shown by curve C1 in the figure, the input elastic wave C0 (an elastic wave with peaks P1 and P2) and the superresonator (as described above) Figure 9 The interaction of the multi-particle dispersed vibration model is used to interfere with the input elastic wave C0, thereby blocking and attenuating it, amplifying the band gap BG (i.e., the bandwidth for blocking and attenuating the vibration), and connecting them to form a broad BG.

[0053] In dynamic vibration absorber technology, energy is transferred to an auxiliary vibration system by adding an auxiliary mass, thereby attenuating the vibration of the main vibration system. Specifically, in a dynamic vibration absorber, such as... Figure 12 As shown by curve C2 in the figure, the large peak P1 of the transfer function of the input elastic wave C0 is divided into two smaller peaks, thereby damping the vibration. Therefore, a wide bandgap BG as that of overdamped waves will not be generated (see reference). Figure 11 ).

[0054] In addition, vibration damping techniques utilize damping materials to dissipate the energy generated by vibration as heat or fluid resistance, thereby achieving vibration attenuation. Specifically, in vibration damping techniques, such as... Figure 13 As shown by curve C3 in the figure, the vibration is attenuated by reducing the transfer function of the input elastic wave C0 by a large peak P1. Therefore, a wide bandgap BG, as seen with overdamping, is not generated.

[0055] (Modified example) In the battery module 10 shown above, the elastic member 24 is connected to the respective upper surfaces of the plurality of battery cells 22, but as a modified example of the present application, the elastic member 24 can cover both the respective upper surfaces and lower surfaces of the plurality of battery cells 22 and be connected to both the upper and lower surfaces of the plurality of battery cells 22. Figures 2-3 In the battery module 10 shown above, the elastic member 24 is connected to the respective upper surfaces of the plurality of battery cells 22, but as a modified example of the present application, the elastic member 24 can cover both the respective upper surfaces and lower surfaces of the plurality of battery cells 22 and be connected to both the upper and lower surfaces of the plurality of battery cells 22.

[0056] As in this modified example, the elastic member 24 covers both the respective upper surfaces and lower surfaces of the plurality of battery cells 22, whereby the plurality of battery cells 22 can be stably supported. As a result, each battery cell 22 can be brought into substantial resonance with the elastic wave, thereby exerting a stable vibration suppression effect.

[0057] [Numbering Explanation] 1 vehicle body 3 front wheel 10 battery module 21 battery case 22 battery cell 23 partition 24 elastic member 25 plate 26 damping adhesive

Claims

1. A battery mounting structure for an electric vehicle, characterized by: a vehicle body; at least one battery module fixed to the vehicle body; left and right pairs of front wheels rotatably mounted on left and right sides of a front portion of the vehicle body; wherein the battery module includes: a battery case; a plurality of battery cells housed in the battery case and arranged in series in a vehicle longitudinal direction; an elastic member covering at least one of upper and lower surfaces of each of the plurality of battery cells, connecting the battery cells, and connected to both end portions of the battery case in the vehicle longitudinal direction.

2. The battery mounting structure for an electric vehicle according to claim 1, characterized in that: In such a case, the elastic modulus of the elastic member is set to E [N / m 2 ], the total cross-sectional moment of inertia of the plurality of battery cells and the elastic member is set to I [m 4 ], the length of the plurality of battery cells as a whole in the vehicle longitudinal direction is set to L [m], and the value of the loss factor tan δ of the elastic member is set to x, such that EI / L 3 satisfies the following equation: A < EI / L 3 < B, Here, A = 4320 x －0.44 B = 41812 x 0.0931 . when the value of tan δ is x = 2, 3. The battery mounting structure for an electric vehicle according to claim 1 or 2, characterized in that: E, I, L are set such that EI / L 3 satisfies the following equation: A < EI / L 3 < B, Here, A = 3.18 x 10 3 , B = 4.46 x 10 4 . the elastic member covers both the upper and lower surfaces of each of the plurality of battery cells. ​

Images