Battery mounting structure of electric vehicles

Abstract

An object of the present invention is to provide a battery mounting structure for an electric vehicle capable of improving NVH performance. 【Solution means】The battery module 10 mounted on the vehicle body 1 includes a battery housing 21, a plurality of cells 22 arranged in series in the vehicle front-rear direction, a support portion 23 that supports each of the plurality of cells 22, and a partition portion 24 disposed between adjacent cells 22. Taking the support rigidity of the support portion 23 as y [N / m], the mass of the cell 22 as m [kg], and the value of tanδ, which is the loss coefficient of the support portion 23, as x, and the minimum value y min of y, min y 9 = 5.184×10 2 (1 / x) 3 (1 / m) and the maximum value y max of y, max y 2 = 482.2531x 5 m When y min < y max is set such that y satisfies y min ≦ y ≦ y max is within the range.

Description

Technical Field

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

Background Art

[0002] Conventionally, in an electric vehicle in which a battery module having a plurality of cells housed inside a battery case is mounted on a vehicle body, due to vibrations input to the vehicle body from a suspension or the like that supports wheels during vehicle travel, the plurality of cells inside the battery case vibrate individually in the vertical direction, and the vibrations are transmitted to the cabin. As a result, noise, vibration, and harshness (roughness and discomfort) that affect the ride comfort inside the cabin occur. Therefore, in an electric vehicle, improving the NVH performance, which is the performance of reducing these noise, vibration, and harshness, has become an issue.

[0003] Therefore, in order to improve the NVH performance, in the structure described in Patent Document 1, the battery case includes a pair of side plates having a C-shaped cross section so that the plurality of cells of the battery module do not vibrate in the vertical direction. Each of the pair of side plates has an upper flange portion and a lower flange portion that support the cell from above and below. By collectively restraining the left and right sides of the plurality of cells with the pair of side plates having a C-shaped cross section, the flange portions on the upper and lower sides suppress the vertical vibration of each cell, thereby improving the NVH performance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above structure, a pair of side plates with a C-shaped cross-section collectively restrain the left and right sides of a plurality of cells, so that the flange portions on the upper and lower sides suppress the vibration of each cell in the vertical direction. However, the influence on the vibration caused by the resonance of each cell during vehicle running is not considered, and there is room for improvement in NVH performance.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery mounting structure for an electric vehicle capable of improving NVH performance.

Means for Solving the Problems

[0007] In order to solve the above problems, the battery mounting structure of the electric vehicle of the present invention includes, in the battery mounting structure of the electric vehicle, a vehicle body, at least one battery module fixed to the vehicle body, and a pair of left and right front wheels rotatably attached to the left and right sides of the front part of the vehicle body. The battery module includes a battery housing, a plurality of cells housed in the battery housing and arranged in series in a predetermined direction, a support portion arranged in the battery housing for supporting each of the plurality of cells, and a partition portion arranged between adjacent cells and supported by the battery housing. Taking the support rigidity of the support portion as y [N / m], the mass of the cell as m [kg], and the value of tanδ, which is the loss coefficient of the support portion, as x, and the minimum value y of y 2 , max ,

[0008] , , min , min , 5 , max , , , <0000,013>, max as y min = 5.184×10 9 (1 / x) 2 (1 / m) 3 , the maximum value y of y max as y max = 482.2531x 2 m 5 , y min < y max When this is the case, y is set in the range of y min ≦ y ≦ y max It is characterized by being set.

[0008] In this configuration, vibration waves input to the vehicle body from the left and right front wheels during electric vehicle operation are transmitted to a battery module fixed to the vehicle body. At that time, in the battery module, elastic waves are sequentially transmitted to multiple cells arranged in a predetermined direction via the support. In the above configuration, as the support stiffness y of the support satisfies the above conditions, the multiple cells resonate with each other, interfering with the elastic waves and reducing them.

[0009] In other words, in the frequency range of vibrations input to the vehicle body during vehicle operation, vibration energy dissipation and interference occur for vibrations transmitted sequentially in each series-connected cell in a predetermined direction. That is, a vibration damping effect by so-called meta-damping is obtained, which utilizes the mass of two or more series-connected cells and the loss coefficient or damping characteristics of the support part to perform continuous vibration damping along the direction of vibration transmission.

[0010] In this way, by effectively blocking vibrations input to the vehicle body from the front wheels using multiple cells and support parts, and suppressing their transmission into the passenger compartment, it is possible to improve 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 while driving.

[0011] In the battery mounting structure of the electric vehicle described above, when the value of tanδ is x=2, The minimum value of y min to, y min = 1.296 × 10 9 (1 / m) 3 , Maximum value of y max to, y max = 1.929 × 10 3 m 5 , y min <y max When that happens, y, y min ≦y≦y max It is preferable that the setting be within the range.

[0012] According to this configuration, when x=2, the value of tanδ, which is the loss coefficient of the support part, is within the range of the support stiffness y of the support part, i.e., y min and y max This allows for the widest possible range, enabling the selection of support stiffness y from a broader range to suppress vibrations in the road noise range. As a result, the design freedom of the battery mounting structure is expanded.

[0013] In the above-described battery mounting structure for an electric vehicle, it is preferable that the support portion collectively supports the plurality of cells, which are joined to each other by a joint having a rigidity higher than that of the support portion.

[0014] In this configuration, multiple cells, which are joined to each other by joints with a stiffness higher than that of the support, are supported collectively by the support, making it possible to reliably achieve a damping effect even when there are many cells.

[0015] In the above-described battery mounting structure for electric vehicles, it is preferable that the support portion supports the cell while being sandwiched between the cell and the partition portion.

[0016] In this configuration, the support section can stably support the cell while being sandwiched between the cell and the partition section. This makes it possible to reliably resonate each cell with elastic waves and exert a stable vibration suppression effect.

[0017] In the above-described battery mounting structure for an electric vehicle, it is preferable that the support portion supports the cell while being sandwiched between at least one of the upper and lower surfaces of the cell and the top or bottom wall of the battery housing.

[0018] In this configuration, the support unit can stably support the cell while sandwiched between the cell and the top or bottom wall of the battery housing. This makes it possible to reliably resonate each cell with elastic waves and exert a stable vibration suppression effect.

[0019] In the above-described battery mounting structure for an electric vehicle, it is preferable that the cell and the partition are connected so as to be an integral part, and that the support portion supports the cell and the partition while being sandwiched between the left and right ends of the partition and the side wall of the battery housing.

[0020] With this configuration, the support portion is sandwiched between the left and right ends of the partition portion and the side wall of the battery housing, allowing for stable support of the cells and the partition portion. This makes it possible to reliably resonate the individual cells connected to the partition portion with elastic waves, thereby achieving a stable vibration suppression effect. [Effects of the Invention]

[0021] As described above, the battery mounting structure for electric vehicles of the present invention can improve NVH performance. [Brief explanation of the drawing]

[0022] [Figure 1] This is a plan view showing the overall configuration of the underside of an electric vehicle to which the battery mounting structure of an electric vehicle according to an embodiment of the present invention is applied. [Figure 2] Figure 1 is a cross-sectional view showing the internal configuration of the battery module. [Figure 3] Figure 2 is a three-dimensional graph showing the range of maximum value ymax and minimum value ymin of the support stiffness y in relation to the cell mass m of the battery module, the support stiffness y of the support part, and the loss coefficient tanδ of the support part. [Figure 4] Figure 2 is a graph showing the range of maximum value ymax and minimum value ymin for the support part when the loss coefficient tanδ = 0.4, representing the cell mass m and the support stiffness y of the support part. The graph shows the distribution of the combinations of support stiffness and cell mass included in the present invention (·) and the combinations of comparative examples (×). [Figure 5] Figure 4 is a graph showing the relationship between support stiffness / cell mass and transfer function (FRF OA), illustrating the decrease in the transfer function due to the vibration damping effect in the support stiffness and cell mass combination (·) included in the present invention. [Figure 6] Figure 2 is a graph showing the range of maximum value ymax and minimum value ymin for the support part when the loss coefficient tanδ = 1.0, representing the cell mass m and the support stiffness y of the support part. The graph shows the distribution of the combinations of support stiffness and cell mass included in the present invention (·) and the combinations of comparative examples (×). [Figure 7] Figure 6 is a graph showing the relationship between support stiffness / cell mass and transfer function (FRF OA), illustrating the decrease in the transfer function due to the vibration damping effect in the support stiffness and cell mass combination (·) included in the present invention. [Figure 8] Figure 2 is a schematic cross-sectional diagram illustrating the arrangement of support components in the battery module. [Figure 9] Figure 8 is a cross-sectional diagram illustrating an example of a modified version of the present invention in which the support portion is reduced. [Figure 10] This is a cross-sectional diagram illustrating another variation of the present invention, in which two integrated cells are supported by support parts at the front and rear. [Figure 11] This is a cross-sectional diagram illustrating yet another variation of the present invention, in which a large number of cylindrical cells are bonded together with a high-rigidity adhesive (joint) and integrated, and then connected to a partition via a support. [Figure 12] This is a cross-sectional diagram illustrating yet another variation of the present invention, in which both the upper and lower surfaces of the cell are connected to the top and bottom walls of the battery module via support members. [Figure 13] This is a cross-sectional diagram illustrating yet another variation of the present invention, in which the cells are integrated into a partition and connected to the left and right side walls of the battery module via support parts at both left and right ends of the partition. [Figure 14] 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 15] This is a schematic diagram illustrating the resonance phenomenon, which is a comparative example with metadamping. [Figure 16] 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 17] 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 18] 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]

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 predetermined direction in the vehicle's longitudinal direction X, a plurality of support parts 23 that support each of the plurality of cells 22, and a plurality of partition parts 24 that separate adjacent cells 22. Note that the plurality of cells 22 only need to be arranged in a predetermined direction and are not limited to the vehicle's longitudinal direction.

[0031] The battery housing 21 is a hollow, roughly rectangular housing, and specifically has 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, a pair of left and right side walls 21c connecting the left and right ends of the front wall 21a and the rear wall 21b and extending in the vehicle longitudinal direction X, and a top wall 21d and a bottom wall 21e spaced apart in the vertical direction Z as shown in Figure 12.

[0032] Cell 22 consists of a secondary battery such as a lithium-ion battery and has a plate-like or thin pouch-like shape, but it may also be cylindrical as shown in Figure 11 below. Multiple plate-like cells 22 are arranged in the vehicle's longitudinal direction X so that they are parallel to each other, that is, each extends in the vehicle width direction Y.

[0033] The partition portion 24 is a plate-like portion extending in the vehicle width direction Y, positioned between two adjacent cells 22, and both left and right ends are fixed to the side walls 21c of the battery housing 21, respectively.

[0034] The support section 23 is located inside the battery housing 21 and individually supports the cells 22. As shown in Figure 2, the support section 23 individually supports the cells 22 while being sandwiched between the cells 22 and the partition section 24.

[0035] As the support portion 23, a damping adhesive made of polymer material is used. For example, a sealer or rubber-based adhesive is used, which is a polymer adhesive having vibration damping characteristics such as 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. In this embodiment, the cell 22 is bonded to the partition portion 24 by the support portion 23 made of polymer adhesive or the like.

[0036] As shown in Figures 2 and 8, in this embodiment, the support portion 23, made of a polymer adhesive or the like, adheres both the front and rear surfaces of each cell 22 to the adjacent partition portion 24. Alternatively, the support portion 23 may be arranged on both sides of the frontmost and rearmost partition portions 24 in the vehicle's longitudinal direction X, as shown in Figure 2.

[0037] In this embodiment, the support portion 23 supports the cell 22 while being sandwiched between the cell 22 and the partition portion 24. This allows the support portion 23 to stably support the cell 22. Therefore, it is possible to reliably resonate each cell 22 with elastic waves and exhibit a stable vibration suppression effect.

[0038] (Explanation regarding the setting of support stiffness y) In the battery mounting structure of this embodiment, as shown in Figures 1 and 2, the battery module 10 has a configuration in which a plurality of cells 22 and a plurality of support parts 23 that individually support the plurality of cells 22, and the support rigidity y of the support part 23 is set as follows.

[0039] First, let y [N / m] be the support stiffness of the support section 23, m [kg] be the mass of each cell 22, and x be the value of tanδ, which is the loss coefficient of the support section 23. Minimum value of y min to, y min = 5.184 × 10 9 (1 / x) 2 (1 / m) 3 , Maximum value of y max to, y max =482.2531x 2 m 5 , y min <y max When that happens, y, y min ≦y≦y max It is set to the range.

[0040] In this embodiment, the conditions for the loss coefficient tanδ and support stiffness y are those for 10-60°C and 100Hz.

[0041] Figure 3 shows the mass m of the cell 22 of the battery module 10 in Figure 2, the support stiffness y of the support part 23, and the maximum value y of the support stiffness y in the loss coefficient tanδ of the support part 23. max and minimum value y min This is a 3D graph showing the range in which this occurs.

[0042] According to the graph in Figure 3, the minimum value y min and maximum value y max These correspond to the ranges represented by roughly conical surfaces. The minimum value y above min and maximum value y max By setting the cell mass m, support stiffness y, and loss coefficient tanδ so that they fall within a certain range, 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.

[0043] For example, Figure 4 shows the maximum value y in the graph of Figure 2 when the loss coefficient of the support part tanδ = 0.4. max and minimum value y min Looking at the graph of the cell mass m and the support stiffness y of the support part, which shows the range, the combination of support stiffness y and cell mass m included in the present invention (·) is the minimum value y in Figure 4. min The curve and maximum value y max The distribution falls within the range enclosed by the curve, and the comparative example combination (×) is distributed outside that range. Furthermore, looking at the graph in Figure 5 showing the relationship between support stiffness / cell mass and the transfer function (FRF OA) at road noise of 100-400 Hz, it can be seen that in the combination of support stiffness y and cell mass m included in the present invention in Figure 4 (·), the transfer function is reduced to a level lower than the level of transfer function A at which vehicle occupants can feel the vibration damping effect due to the vibration damping effect. On the other hand, in the comparative example combination (×), the level is higher than the above level of transfer function A, and it can be seen that no vibration damping effect is obtained.

[0044] Furthermore, if the loss coefficient tanδ = 0.4 or greater, and the cell mass m is 23 kg or greater, then the support stiffness / cell mass [N / (m·kg)] is 3.0 × 10 5 ~1.0×10 7 Within this range, the combination of support stiffness y and cell mass m (·) is the minimum value y in Figure 4. min The curve and maximum value y maxComputer analysis by the inventors has confirmed that vibration damping effect is obtained when the range enclosed by the curve is within the specified range. Furthermore, when the loss coefficient tanδ = 0.4 or higher, and the cell mass m is 47 kg or higher, the support stiffness / cell mass [N / (m·kg)] is 1.0 × 10 4 ~8.0×10 7 Within this range, the combination of support stiffness y and cell mass m (·) is the minimum value y in Figure 4. min The curve and maximum value y max Computer analysis by the inventors has confirmed that the vibration damping effect is obtained when the area falls within the range enclosed by the curve.

[0045] Similarly, the graph in Figure 6 (the maximum value y when the loss coefficient of the support part in the graph in Figure 2 is tanδ = 1.0) max and minimum value y min Looking at the graphs of cell mass m and support stiffness y of the support part (showing the range) and the graph in Figure 5 (a graph showing the relationship between support stiffness / cell mass and transfer function (FRF OA)), it can be seen that in the combination of support stiffness y and cell mass m included in the present invention in Figure 6 (·), the transfer function is reduced to a level lower than the level of transfer function A at which vehicle occupants can feel the vibration damping due to the vibration damping effect.

[0046] Furthermore, if the loss coefficient tanδ = 1.0 or greater, and the cell mass m is 12 kg or greater, then the support stiffness / cell mass [N / (m·kg)] is 2.5 × 10⁻⁶. 5 ~1.0×10 7 Within this range, the combination of support stiffness y and cell mass m (·) is the minimum value y in Figure 6. min The curve and maximum value y max Computer analysis by the inventors has confirmed that the vibration damping effect is obtained when the area falls within the range enclosed by the curve.

[0047] Furthermore, in the case of a low loss coefficient, for example, when the loss coefficient tanδ = 0.1 or higher, if the cell mass m is 47 kg or higher, the support stiffness / cell mass [N / (m·kg)] is 4.0 × 10 4 ~7.0×10 6Within the range, the combination of support stiffness y, cell mass m, and loss coefficient tanδ value x is the minimum value y in Figure 2. min The curve and maximum value y max Computer analysis by the inventors has confirmed that the vibration damping effect is obtained when the area falls within the range enclosed by the curve.

[0048] From the above results, it can be seen that the vehicle battery mounting structure of this embodiment provides the following effects and advantages.

[0049] 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 the support portion 23. In the above battery mounting structure, the support rigidity y of the support portion is such that the above condition y min ≦y≦y max By satisfying the specified range, multiple cells 22 resonate with each other, interfering with the elastic wave and reducing its elasticity.

[0050] 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 support part 23 to perform continuous vibration damping along the vibration transmission direction.

[0051] In this way, vibrations input from the front wheels 3 to the vehicle body 1 are effectively blocked using multiple cells 22 and support parts 23, 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.

[0052] Here, in the case where x = 2, which is the value of the loss coefficient tanδ of the support part 23, The minimum value of the support stiffness y mentioned above min to, y min = 1.296 × 10 9 (1 / m) 3 , Maximum value of y max to, y max = 1.929 × 10 3 m 5 , y min <y max When that happens, y, y min ≦y≦y max It is preferable to set it within the range of [this range].

[0053] In this configuration, the value of tanδ, which is the loss coefficient of the support part 23, is set to the range of the support stiffness y of the support part 23 when x=2, i.e., y min and y max This allows for the widest possible range, enabling the selection of support stiffness y from a broader range to suppress vibrations in the road noise range. As a result, the design freedom of the battery mounting structure is expanded.

[0054] (Explanation of meta-damping) The inventors have devised a configuration that induces meta-damping (meta-resonance) within each battery module 10 by carefully adjusting the support stiffness y of the support portion 23 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 with multiple cells 22 inside the battery module 10 shown in Figures 1 and 2 above.

[0055] Here, meta-damping, as shown in Figure 14, 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).

[0056] For example, in a typical resonance phenomenon, as shown in Figure 15, 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.

[0057] However, in the meta-damping shown in Figure 14, even when the input wave is continuously excited at the same frequency, the input wave interferes with each set of cells 22 and support parts 23 (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 support parts 23 supporting them (see Figure 2) interfere with the vibrations and dissipate vibration energy, so the vibrations gradually decrease as they move towards the rear X2 of the vehicle.

[0058] In order to generate the damping caused by meta-damping as described above in each battery module 10, the support stiffness y of the support portion 23 is set as described above.

[0059] 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 local resonant elements and damping elements (specifically, the structure of the battery module 10 composed of multiple cells 22 and multiple support parts 23). 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.

[0060] (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.

[0061] In meta-damping, as shown by curve C1 in the graph of Figure 16, 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 and the meta-resonator (the multi-mass point dispersion vibration model in Figure 14 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.

[0062] In a dynamic vibration absorber, the vibration of the main vibration system is damped by adding an auxiliary mass and transferring energy to the auxiliary vibration system. Specifically, in a dynamic vibration absorber, as shown by curve C2 in the graph of Figure 17, the vibration is 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 16) like that of metadamping does not occur.

[0063] 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 18, 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.

[0064] (modified version)

[0065] (A) In the embodiments described above, as shown in Figures 2 and 8, the support portion 23, made of a polymer adhesive or the like, adheres both the front and rear surfaces of each cell 22 to the adjacent partition portion 24, but the present invention is not limited thereto.

[0066] The support portion 23 of the present invention is disposed within the battery housing 21 and only needs to be configured to support the cells 22. As a modification of the present invention, as shown in Figure 9, the support portion 23 made of a polymer adhesive or the like may be bonded to one of the front and rear surfaces of each cell 22, for example, the front surface, to an adjacent partition portion 24.

[0067] (B) Furthermore, as another variation of the present invention, as shown in Figure 10, in a configuration in which two adjacent cells 22 in the vehicle longitudinal direction X are integrally connected by welding or bolting, the two integrated cells 22 may be treated as one large cell and its front and rear surfaces may be bonded to adjacent partitions 24 by support parts 23. In such a configuration, the total mass of the two integrated cells 22 is the cell mass m, and the minimum value of the support stiffness y is y min and maximum value y max You just need to calculate this.

[0068] (C) In the above embodiment, the cell 22 was described using a plate-shaped or pouch-shaped cell as an example, but as a modified example of the present invention, a plurality of cylindrical cells 22 may be applied as shown in Figure 11.

[0069] In the configuration shown in Figure 11, numerous cylindrical cells 22 are joined to each other by joints 25 having a rigidity higher than that of the support portion 23, forming one large cell. The joint 25 only needs to have a rigidity higher than that of the support portion 23, and can be made of, for example, a polymer adhesive with a higher rigidity than the support portion 23, fastening members such as bolts, or metal solder for brazing.

[0070] In the configuration shown in Figure 11, multiple cylindrical cells 22, joined to each other by a high-rigidity joint 25, are bonded to a partition 24 by a support 23. In this configuration, the support 23 collectively supports multiple cells 22, which are joined to each other by a joint 25 with a rigidity higher than that of the support 23. This makes it possible to reliably achieve a damping effect even when there are a large number of cells 22.

[0071] (D) Furthermore, in yet another variation of the present invention, as shown in Figure 12, the support portion 23 may support the cell 22 by being sandwiched between at least one of the upper surface 22a and lower surface 22b of the cell 22 (both surfaces in Figure 12) and the top wall 21d or bottom wall 21e of the battery housing 21. In Figure 12, both the upper and lower surfaces of the cell 22 are bonded to the battery housing 21 by the support portion 23 made of polymer adhesive.

[0072] In the configuration shown in Figure 12, the support portion 23 can stably support the cell 22 while sandwiched between the cell 22 and the top wall 21d and bottom wall 22e of the battery housing 21. This makes it possible to reliably resonate each cell 22 with elastic waves and exert a stable vibration suppression effect.

[0073] (E) As yet another variation of the present invention, the support portion 23 may support the integrated cell 22 and partition portion 24 from both the left and right ends, as shown in Figure 13.

[0074] In this configuration, the cell 22 and the partition 24 are connected together by welding or adhesive. The support portion 23 is sandwiched between the left and right ends of the partition 24 and the side wall 21c of the battery housing 21, supporting the integrated cell 22 and partition 24, thus enabling stable support. This makes it possible to reliably resonate the individual cells 22 connected to the partition 24 with elastic waves and exert a stable vibration suppression effect. [Explanation of Symbols]

[0075] 1. Vehicle body 3 Front wheels 10 Battery Modules 21 Battery enclosure 22 cells 23 Support part 24 Partition section 25 Joint

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 a predetermined direction, A support portion is disposed within the battery housing and supports each of the multiple cells, A partition portion is disposed between adjacent cells and is supported by the battery housing. Equipped with, Let y [N / m] be the support stiffness of the support portion, m [kg] be the mass of the cell, and x be the value of tanδ, which is the loss coefficient of the support portion, and Minimum value of y ｍｉｎ to, y ｍｉｎ = 5.184 × 10 ９ (1 / x) ２ (1 / m) ３ , The maximum value of y, y ｍａｘ is given by y ｍａｘ = 482.2531x ２ m ５ , y ｍｉｎ <y ｍａｘ When that happens, y, y ｍｉｎ ≦y≦y ｍａｘ Set to the range 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, The minimum value of y ｍｉｎ to, y ｍｉｎ = 1.296 × 10 ９ (1 / m) ３ , Maximum value of y ｍａｘ to, y ｍａｘ = 1.929 × 10 ３ I understand ５ , y ｍｉｎ <y ｍａｘ When that happens, y, y ｍｉｎ ≦y≦y ｍａｘ Set to the range 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 support portion supports the plurality of cells, which are joined to each other by a joint having a stiffness higher than that of the support portion, as a whole. A battery mounting structure for an electric vehicle characterized by the following features.

4. In the battery mounting structure for an electric vehicle according to claim 1 or 2, The support portion supports the cell while being sandwiched between the cell and the partition portion. A battery mounting structure for an electric vehicle characterized by the following features.

5. In the battery mounting structure for an electric vehicle according to claim 1 or 2, The support portion supports the cell while being sandwiched between at least one of the upper and lower surfaces of the cell and the top or bottom wall of the battery housing. A battery mounting structure for an electric vehicle characterized by the following features.

6. In the battery mounting structure for an electric vehicle according to claim 1 or 2, The cell and the partition are connected so as to be an integrated unit. The support portion is sandwiched between the left and right ends of the partition portion and the side wall of the battery housing, and supports the cell and the partition portion. A battery mounting structure for an electric vehicle characterized by the following features.

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