JP7324426B2 - Battery unit mounting structure for electric vehicles - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery unit mounting structure for an electric vehicle including battery units that support battery modules and are mounted on a pair of floor frames.

Conventionally, in electric vehicles such as hybrid vehicles and electric vehicles, the battery that is the power source of the electric motor (for example, motor generator or motor) that drives the wheels has a large capacity, so the space below the vehicle body floor is used for the battery unit. are arranged as follows.
Generally, a battery unit is composed of a plurality of battery modules each made up of an assembly of battery cells such as lithium-ion cells, a battery case housing the plurality of battery modules, and a framework frame of the battery case.

The battery mounting structure for an electric vehicle disclosed in Patent Document 1 includes a floor panel, a pair of left and right floor frames below the floor panel that cooperate with the floor panel to form a closed cross section that extends forward and backward, and supports a battery module. and a battery unit attached to a pair of floor frames, the battery unit comprising a lower cover member on which the battery modules are placed, an upper cover member covering the lower cover member, and the lower cover member. and a frame-shaped frame forming a skeleton of the upper cover member, a plurality of battery modules are arranged in the front side region of the frame-shaped frame so that their longitudinal directions extend in the vehicle width direction, and the battery modules are arranged in the rear side region of the frame-shaped frame. A plurality of modules are arranged so that the longitudinal direction extends in the longitudinal direction of the vehicle body.

During steady running of the vehicle, vibration energy generated by the wheels and the road surface is transmitted to the vehicle body strength members via the suspension members, vibrating the panel members such as the floor panel that constitute the vehicle interior. Vibrations of these panel members generate driving noise such as drumming noise and road noise.
The drumming noise is a low frequency sound of 20-50 Hz, and the road noise is a medium frequency sound of 100-400 Hz. It is sometimes called road noise including drumming noise. Driving noise such as drumming noise and road noise is dealt with by adding a damping material or increasing the rigidity of the lower body (for example, Patent Document 2).

JP 2011-251620 A JP-A-10-129369

In the battery mounting structure for an electric vehicle disclosed in Patent Document 1, the longitudinal direction of the plurality of battery modules arranged in the first mounting portion on the front side coincides with the vehicle width direction, and the plurality of battery modules arranged in the second mounting portion on the rear side. Since the battery modules are arranged such that the longitudinal direction thereof coincides with the longitudinal direction of the vehicle body, the size of the battery units increases, and the space required for arranging the battery units increases.
When installing a plurality of battery modules on the vehicle body, especially on the lower side of the floor panel, it is possible to minimize the installation space by arranging them in multiple rows in the same orientation in the vehicle width direction, the front-rear direction, and the height direction. It is possible.

However, when a plurality of battery modules are arranged in the same posture and in a plurality of rows, the vibration of each battery module has substantially the same natural frequency. There is a concern that the vehicle body vibration may be amplified by resonating with the vibration. In the case of resonance with vehicle body vibrations in the middle frequency band equivalent to 100 to 400 Hz, road noise performance may deteriorate.
That is, it is not easy to reduce running noise while ensuring compactness of the battery unit.

SUMMARY OF THE INVENTION An object of the present invention is to provide a battery unit mounting structure and the like for an electric vehicle capable of reducing running noise while ensuring compactness.

A battery unit mounting structure for an electric vehicle according to claim 1 comprises a floor panel, a pair of left and right floor frames forming a closed cross section extending forward and backward in cooperation with the floor panel below the floor panel, and a battery module. A battery unit mounting structure for an electric vehicle comprising a battery unit that supports and is mounted to the pair of floor frames, wherein the battery unit is mounted to the pair of floor frames; a pair of left and right side frames; a cross frame extending in the vehicle width direction and connecting the pair of side frames; a plurality of battery modules each having a horizontal dimension and a height dimension orthogonal to the vertical and horizontal dimensions and having substantially the same height dimension, wherein the plurality of battery modules is supported in the same posture by the side frames and/or cross frames and extends in the vehicle width direction and/or the vehicle width direction so that the direction of the vertical dimension of the rectangular shape is substantially parallel to the vehicle length direction or the vehicle width direction. Adjacent rows are arranged in a plurality of rows, the mounting rigidity of battery modules in some rows is different from the mounting rigidity of battery modules in other rows, and the plurality of battery modules are mounted via mounting brackets. are attached to the side frames and/or the cross frames, and the mounting rigidity of the rear wall portion of the battery module in the front row is greater than the mounting rigidity of the front wall portion of the battery module in the front row. and

In this battery unit mounting structure for an electric vehicle, the battery unit includes a pair of left and right side frames mounted on the pair of floor frames, and a cross frame extending in the vehicle width direction and connecting the pair of side frames. a vertical dimension that is the longitudinal dimension of the rectangular shape, a horizontal dimension that is orthogonal to the longitudinal direction of the rectangular shape, and a vertical dimension that is orthogonal to the vertical dimension and the horizontal dimension, and the vertical dimension of the vehicle body. a plurality of battery modules each having substantially the same height dimension, which is a directional dimension, and the plurality of battery modules are supported in the same posture by the side frame and/or the cross frame; To make the battery unit compact because the battery units are arranged in a plurality of rows adjacent to each other in the vehicle width direction and/or the vehicle width direction so that the direction of the vertical dimension of the rectangular shape is substantially parallel to the vehicle body front-rear direction or the vehicle width direction. can be done. The mounting rigidity of the battery modules in some rows is made different from the mounting rigidity of the battery modules in other rows , and the plurality of battery modules are attached to the side frames and/or cross frames via mounting brackets. Because the mounting rigidity of the rear wall of the battery module in the front row is greater than the mounting rigidity of the front wall of the battery module in the front row, the change in the mounting rigidity has The vibration frequency can be made different from the natural frequency of the battery modules in the other rows, and by reducing the medium-frequency component of the battery unit, resonance with vehicle body vibration in the medium-frequency band can be suppressed. .

According to the invention of claim 2, in the invention of claim 1, the first mounting bracket is connected to the front wall of the battery module in the front row, and the second mounting bracket is connected to the rear wall of the battery module in the front row. and wherein the number of attachment points of the second mounting bracket to the side frame and/or the cross frame is larger than the number of attachment points of the first mounting bracket to the side frame and/or the cross frame. .
According to this configuration, the resonance suppressing effect can be enhanced by changing the mounting rigidity of the battery modules in the row on the one end side, which has a large effect on vehicle body vibration.

The invention of claim 3 is the invention of claim 2, wherein the plurality of battery modules are arranged in three or more rows in the front-rear direction, the battery module in the front row is arranged in a single layer state, and the battery module in the rearmost row is arranged in a single layer. It is characterized in that the battery modules are arranged in two layers below the kick-up portion of the floor panel, and the mounting rigidity of the battery modules in the front row is different from the mounting rigidity of the battery modules in the other rows. there is
According to this configuration, it is possible to improve the road noise performance of the battery unit in which the upper and lower battery modules are mounted with a minimum change in mounting rigidity.

According to the invention of claim 4, in the invention of claim 2, the plurality of battery modules are arranged in three or more rows in the front-rear direction, and the battery module in the front row and the battery module in the second row adjacent to the rear of the front row A row of battery modules in which battery modules are arranged in a single layer and arranged in a two-tiered state of two upper and lower tiers behind the second row of battery modules, and the mounting rigidity of the battery modules in the front row is The feature is that the mounting rigidity of the battery modules in the second row is made different .
According to this configuration, it is possible to improve the road noise performance of the battery unit in which the upper and lower battery modules are mounted with a minimum change in mounting rigidity.

The invention of claim 5 is based on the invention of any one of claims 1 to 4 , wherein the mounting points of the mounting brackets for mounting the battery modules in a part of the rows are larger than the mounting points of the mounting brackets for mounting the battery modules in the other rows. It is characterized by having a lot of
According to this configuration, it is possible to make the natural frequency of the battery modules in some rows different from the natural frequency of the battery modules in other rows while ensuring the mounting rigidity of the battery modules in some rows. .

According to the invention of claim 6, in the invention of any one of claims 1 to 4 , the mounting points of the mounting brackets for mounting the battery modules in some rows are larger than the mounting points of the mounting brackets for mounting the battery modules in the other rows. is characterized by an increase in
According to this configuration, the natural frequency of the battery modules in some columns can be made higher than the natural frequency of the battery modules in the other columns with minimal changes.

According to the battery module mounting structure for an electric vehicle of the present invention, by changing the mounting rigidity of the battery module, it is possible to reduce running noise while ensuring compactness of the battery unit.

2 is a bottom view of the electric vehicle according to the first embodiment; FIG. It is the perspective view which looked at the electric vehicle from the back side downward direction. 3 is an exploded perspective view of the battery unit; FIG. FIG. 4 is a plan view of the battery unit with the cover member and the right battery module omitted; Fig. 2 is a front perspective view of the battery unit with the cover member and the right battery module omitted; FIG. 5 is a perspective cross-sectional view of a main part of FIG. 4; FIG. 5 is a cross-sectional view taken along line VII-VII of FIG. 4; 5 is a cross-sectional view taken along line VIII-VIII of FIG. 4; FIG. FIG. 4 is a perspective view of first to third mounting brackets; It is an analysis result about the noise level of a present Example model and an evaluation standard model. FIG. 5 is an explanatory diagram of vibration behavior of the evaluation reference model corresponding to the cross-sectional view taken along the line XI-XI of FIG. 4;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or uses.

Embodiment 1 of the present invention will be described below with reference to FIGS. 1 to 11. FIG.
A vehicle V according to the first embodiment is a hybrid vehicle that uses an internal combustion engine (not shown) such as a gasoline engine or a diesel engine and an electric motor (motor generator) (not shown) for driving the vehicle as drive sources.

As shown in FIGS. 1 and 2, a vehicle V includes a pair of left and right side sills 1 extending longitudinally, a floor panel 2, a pair of left and right floor frames 3 extending longitudinally, a battery unit 10, and the like. . Hereinafter, in the drawings, the direction of arrow F is defined as the front in the longitudinal direction of the vehicle body, the direction of arrow L is defined as the left in the vehicle width direction, and the direction of arrow U is defined as the upper direction in the vertical direction of the vehicle. Further, the vehicle V has a substantially bilaterally symmetrical structure.

First, the overall configuration of the vehicle V will be described.
The side sill 1 includes an outer panel having a substantially hat-shaped cross section forming a vehicle width direction outer wall portion, and an inner panel having a substantially hat-shaped cross section forming a vehicle width direction inner wall portion. It forms an elongated substantially rectangular closed cross section. A vertically extending hinge pillar is connected to the front end portion of the side sill 1, and a vertically extending rear pillar is connected to the rear end portion thereof. The vehicle V has a so-called double door structure in which the front door opens and closes around the hinge of a hinge pillar formed at the front end, and the rear door opens and closes around the hinge of the rear pillar formed at the rear end. , the center pillar is omitted.

The floor panel 2 is formed in a full-flat shape so as to span between a pair of side sills 1, and does not have a tunnel portion that bulges into the vehicle interior.
As shown in FIGS. 1, 2, and 8, the floor panel 2 includes a front panel 2a on which a seat for a front passenger (not shown) is mounted, and a front panel 2a which slopes backward upward from the rear end of the front panel 2a. It also has a rear panel 2b on which a rear seat passenger seat (not shown) is mounted.

The pair of floor frames 3 are each formed to have a substantially hat-shaped cross section, and the distance between the pair of floor frames 3 increases toward the rear. Therefore, the distance between the side sill 1 and the adjacent floor frame 3 becomes closer toward the rear. The floor frame 3 cooperates with the lower surface of the front panel 2a to form a closed cross section with a substantially rectangular cross section extending forward and backward. The rear suspension 4 is arranged behind the kick-up panel 2c and below the rear panel 2b. The suspension 4 has a pair of left and right trailing arms 4a that rotatably support wheels (not shown) at its rear end, and a pair of trailing arms 4a at both ends in the vehicle width direction. It is a torsion beam type suspension with an extending torsion beam 4b.

Next, the battery unit 10 will be explained.
As shown in FIGS. 1 and 2, the battery unit 10 is laid out in the space below the floor panel 2 . As shown in FIG. 3 , the battery unit 10 includes a plurality of (for example, 16) battery modules 11 and a battery case 12 that houses the plurality of battery modules 11 . The battery module 11 that supplies electric power to the electric motor for driving the vehicle is formed into a rectangular parallelepiped battery assembly in which a plurality of rectangular parallelepiped battery cells 11a (see FIG. 8) having a standard voltage are arranged in a stack in the front-rear direction. there is This battery module 11 is formed in a rectangular shape in plan view. The battery cell 11a is, for example, a lithium ion battery, which is a type of secondary battery.

The plurality of battery modules 11 has a vertical dimension that is the longitudinal dimension of the rectangular shape in plan view, a horizontal dimension that is orthogonal to the longitudinal direction of the rectangular shape, and a vertical dimension that is orthogonal to the vertical dimension and the horizontal dimension and is vertical. They are set to have the same height specification, that is, the same shape, and are accommodated in the battery case 12 with their longitudinal directions parallel to the front-rear direction.
The weight of this battery module 11 is, for example, approximately 14 kg, and the total weight of the battery unit 10 is, for example, approximately 300 kg.

Since the battery case 12 accommodates a high-voltage battery in which the battery modules 11 are connected in series, it is configured to ensure vibration resistance and water resistance.
As shown in FIG. 3, the battery case 12 includes a pair of left and right side frames 21, a front frame 22 that extends left and right and connects the front ends of the pair of side frames 21, and a pair of side frames that extend left and right. A rear frame 23 that connects the rear end of the frame 21, a tub-shaped battery tray 24 that is supported by each of the frames 21 to 23 and forms the bottom of the battery case 12, and a plurality of A cover member 25 made of synthetic resin and the like is provided to form a sealed space capable of accommodating the battery module 11 .

In each of the frames 21 to 23, a substantially L-shaped lower panel and a substantially L-shaped upper panel cooperate to form a substantially rectangular closed cross section (see FIG. 7). The closed cross-sections formed by the frames 21 to 23 are connected in a ring to form a substantially square-shaped closed cross-section structure.
Each frame 21-23 is attached to the vehicle body by attachment portions 26-29.
The four pairs of left and right mounting portions 26 and the one pair of left and right mounting portions 27 extend outward in the vehicle width direction from the lower panels of the pair of side frames 21 . These mounting portions 26 and 27 are fastened and fixed to the lower wall portion of the floor frame 3 via bolts b. A pair of left and right mounting portions 28 extend forward from the lower panel of the front frame 22 . These mounting portions 28 are fastened and fixed to the lower surface of the front portion of the front panel 2a via bolts b. The mounting portion 29 extends upward from the center portion of the lower panel of the rear frame 23, and its upper end portion is fastened and fixed to a cross member (not shown) that cooperates with the rear panel 2b to form a closed cross-section that extends left and right via bolts b. It is

As shown in FIGS. 3 to 5, the battery tray 24 is firmly welded while being placed on the upper walls of the frames 21 to 23 . A plate-shaped rubber member (not shown) is arranged between the battery tray 24 and the battery module 11 with a cooling pipe (not shown) interposed therebetween. Thereby, the gap between the battery tray 24 and the battery module 11 is configured to be relatively displaceable.

The battery tray 24 is divided into first to third housing areas (battery housing areas) S1 to S3 for housing the battery modules 11 by first to third cross frames 31 to 33 having substantially hat-shaped cross sections. The third and first cross frames 33, 31 define the front and rear range of the first accommodation area S1 corresponding to the lower front portion (front passenger seat) of the front panel 2a. 32 defines the front and rear range of the second accommodation area S2 corresponding to the lower rear portion of the front panel 2a, and the second cross frame 32 and the rear frame 23 form the third accommodation area corresponding to the lower portions of the kick-up panel 2c and the rear panel 2b. It divides the range before and after the region S3. The first and second housing areas S1 and S2 house four battery modules 11 in each row in a single-layer state after aligning them laterally adjacent to each other.

The third accommodation area S3 has a two-stage support mechanism 40, in which the four battery modules 11 are arranged side by side in the lower row and the four battery modules 11 are horizontally arranged in the upper row. It accommodates eight battery modules 11 in two layers aligned adjacently.
As shown in FIGS. 4 to 6, the two-stage support mechanism 40 includes a substantially .pi. The upper four battery modules 11 are provided with a pair of left and right substantially T-shaped side support portions 43 that connect the left and right ends of the battery modules 11, respectively, and a bottom plate member 44 that spans the respective support portions 41 to 43. support. A pair of left and right legs of the front support part 41 are fastened and fixed to the upper wall of the second cross frame 32 , and a pair of left and right legs of the rear support part 42 are fastened and fixed to the upper wall of the rear frame 23 . It is Leg portions of the pair of side support portions 43 are fastened and fixed onto the battery tray 24 .

The first to third cross frames 31 to 33 cooperate with the battery tray 24 on the upper side of the battery tray 24 to form closed cross sections extending left and right.
As shown in FIGS. 4 to 6, the first cross frame 31 includes upper wall connecting portions 31a extending outward in the vehicle width direction from both left and right ends of the upper wall portion, and left and right ends of the front wall portion and the rear wall portion. A pair of front and rear side wall connecting portions 31b extending forward and rearward from each other are formed. The upper wall connecting portion 31a is connected to the upper wall portion of the side frame 21, and the pair of side wall connecting portions 31b are connected to the inner side wall portions of the side frame 21, respectively. The upper wall connecting portion 31a and the pair of side wall connecting portions 31b are continuously formed so as to be integrally connected. The third cross frame 33 includes an upper wall connection portion 33a extending outward in the vehicle width direction from both left and right ends of the upper wall portion, and a front and rear pair of front and rear wall portions extending forward and rearward from both left and right ends of the front wall portion and the rear wall portion, respectively. side wall connecting portion 33b is formed. The upper wall connecting portion 33a is connected to the upper wall portion of the side frame 21, and the pair of side wall connecting portions 33b are connected to the inner side wall portions of the side frame 21, respectively. The upper wall connecting portion 33a and the pair of side wall connecting portions 33b are formed independently.

The second cross frame 32 includes an upper wall connecting portion 32a extending outward in the vehicle width direction from both left and right ends of the upper wall portion, and a front and rear pair extending forward and rearward from both left and right ends of the front wall portion and the rear wall portion, respectively. side wall connecting portion 32b is formed. The upper wall connecting portion 32a is connected to the upper wall portion of the side frame 21, and the pair of side wall connecting portions 32b are connected to the inner side wall portions of the side frame 21, respectively. The upper wall connecting portion 33a and the pair of side wall connecting portions 33b are continuously formed so as to be integrally connected. As shown in FIGS. 1 and 6 to 8, a lower cross frame 34 extending laterally is provided on the lower surface of the battery tray 24. As shown in FIG. The lower cross frame 34 cooperates with the battery tray 24 below the battery tray 24 to form closed cross sections that extend left and right. The closed cross section formed by the lower cross frame 34 is vertically adjacent to the closed cross section formed by the second cross frame 32 with the battery tray 24 interposed therebetween.

Each battery module 11 is attached to the first to third cross frames 31 to 33 and the rear frame 23 via a pair of front and rear attachment brackets 51 to 53 made of sheet metal.
As shown in FIG. 9, the mounting brackets 51 to 53 include connecting wall portions 51a to 53a that extend vertically and are connected to the battery module 11, and fixed wall portions 51b to 51b that extend forward and backward and are fastened via fastening members. 53b, and has a substantially L-shaped cross section. The connecting wall portions 51a and 53a of the mounting bracket attached to the front side are connected to the front wall portions of the two battery modules 11 adjacent to each other on the left and right sides via four bolts, respectively, and the connecting wall portion of the mounting bracket attached to the rear side. The portions 52a and 53a are respectively connected to the rear wall portions of the two battery modules 11 that are adjacent to each other on the left and right via four bolts. Further, as shown in FIG. 8, the connecting wall portions 51a to 53a of the mounting bracket are arranged such that the height position of the center of gravity of the battery module 11 is the height of the upper wall portions of the first to third cross frames 31 to 33 and the rear frame 23. It is connected to the battery module 11 so as to be at a height position substantially the same as the height position.

A pair of left and right first mounting brackets 51 fixed to the third cross frame 33 and a pair of left and right second mounting brackets 52 fixed to the first cross frame 31 are arranged in the first accommodation area S1. ing. As shown in FIG. 9A, the first mounting bracket 51 is formed by pressing a 1.6 mm steel plate, for example, and includes a connecting wall portion 51a and a fixed wall portion 51b. The fixed wall portion 51b has a fastening portion 51s extending forward (in the direction opposite to the bent portion) at the left end portion, and is slightly closer to the center portion than the middle portion between the center portion and the left end portion of the fixed wall portion 51b. A positioning portion 51p extending forward is formed, and a fastening portion 51t extending forward is formed in a portion symmetrical to the positioning portion 51p with respect to the central portion of the fixed wall portion 51b. The fixed wall portion 51b extends forward from the fixed wall portion 51b, and the fastening portion 51s and the fastening portion 51t are fixed to the upper wall portion of the third cross frame 33 via bolts. In addition, in the left first mounting bracket 51, positioning is performed by the fastening portion 51s on the outer side in the vehicle width direction, and fastening and fixing is performed by the positioning portion 51p on the inner side in the vehicle width direction (see FIG. 4).

As shown in FIG. 9B, the second mounting bracket 52 is formed by pressing a 1.6 mm steel plate, for example, and includes a connecting wall portion 52a and a fixed wall portion 52b. The fixed wall portion 52b has a rearwardly extending fastening portion 52s formed at its right end, a rearwardly extending fastening portion 52t formed at its left end, and a rearwardly extending fastening portion 52u formed at the central portion of the fixed wall portion 52b. A positioning portion 52p extending rearward is formed in the central portion between the fastening portion 52s and the fastening portion 52u. The distance from the left end to the fastening portion 51s is substantially the same as the distance from the right end to the fastening portion 52s and the distance from the left end to the fastening portion 52t, and the distance from the left end to the fastening portion 51p is It is set larger than the distance to the fastening portion 52p. The fixed wall portion 52b extends rearward from the bent portion, and the fastening portion 52s, the fastening portion 52t, and the fastening portion 52u are fixed to the upper wall portion of the first cross frame 31 via bolts.

A pair of left and right third mounting brackets 53 fixed to the first cross frame 31 and a pair of left and right third mounting brackets 53 fixed to the second cross frame 32 are arranged in the second accommodation area S2. ing. As shown in FIG. 9C, the right third mounting bracket 53 fixed to the first cross frame 31 is formed by pressing a steel plate of 2.0 mm, for example, and is formed by connecting the wall portion 53a and the fixing bracket 53a. and a wall portion 53b. The fixed wall portion 53b has a positioning portion 53p extending forward at the left end, a fastening portion 53s extending forward at the center portion between the center portion and the left end of the fixed wall portion 53b, and a fastening portion 53s extending forward at the left end. A fastening portion 53t extending forward is formed. The fixed wall portion 53b extends forward from the bent portion. The distance from the right end to the fastening portion 52s is substantially the same as the distance from the left end to the positioning portion 53p, and the distance from the right end to the fastening portion 52p is substantially the same as the distance from the left end to the fastening portion 53s. be. A left third mounting bracket 53 fixed to the first cross frame 31 and a pair of left and right third mounting brackets 53 fixed to the second cross frame 32 are also configured in the same manner except for the arrangement positions.

A pair of left and right third mounting brackets 53 fixed to the second cross frame 32 and a pair of left and right third mounting brackets 53 fixed to the rear frame 23 are located in the lower stage of the third accommodation area S3. It is arranged similarly to the accommodation area S2. Furthermore, a pair of left and right third mounting brackets 53 fixed to the front support portion 41 and a pair of left and right third mounting brackets 53 fixed to the rear support portion 42 are provided in the upper stage of the third housing area S3. It is arranged in the same way as the bottom row.
The first to third mounting brackets 51 to 53 have substantially the same specifications except for plate thickness, positions of fastening portions, and positions of positioning portions.

The 12 battery modules 11 housed in the second and third housing areas S2 and S3 are attached to the cross frames 31 and 32 and the rear frame 23 by six pairs of front and rear third mounting brackets 53. , all have the same mounting stiffness.
On the other hand, the four battery modules 11 accommodated in the first accommodation area S1 are attached to the cross frames 33, 31 by two pairs of front and rear first and second attachment brackets 51, 52. As shown in FIG. Since the first and second mounting brackets 51 and 52 are different from the third mounting bracket 53 in board thickness and fastening portion position (fixing form), the battery module 11 housed in the first housing area S1 has a unique shape. The frequency differs from the natural frequency of the battery modules 11 housed in the second and third housing areas S2, S3. As a result, even when all the battery modules 11 are accommodated in the battery case 12 in the same posture in the vehicle width direction, the front-rear direction, and the height direction, the resonance between the battery unit 10 and the vibration of the vehicle body in the intermediate frequency band is suppressed. is suppressed.

Next, the operation and effects of the battery unit mounting structure will be described.
A simulation analysis by CAE (Computer Aided Engineering) was performed to explain the action and effect. A vehicle model A (evaluation reference model) in which all the battery modules 11 housed in the first to third housing areas S1 to S3 are attached using the third mounting brackets 53, and a vehicle model B of the present embodiment are created. Then, the noise level (noise) in the passenger compartment in the frequency band of 125 Hz was measured. For simplification of verification, the vehicle model B has the battery module 11 housed in the first housing area S1 attached using the second mounting bracket 52 and housed in the second and third housing areas S2 and S3. A model in which the battery module 11 is mounted using the third mounting bracket 53 is used. Moreover, the vehicle model A and the vehicle model B have the same configuration except for the mounting bracket.

FIG. 10 shows the analysis results.
As shown in FIG. 10, vehicle model A generated road noise in the frequency band of 125 Hz. Since the vehicle model A has the battery modules 11 accommodated in the first to third accommodation areas S1 to S3, the total weight of the battery units (battery modules 11) acts on the vehicle body, which is effective in suppressing road noise. . However, since the mounting rigidity of the battery modules 11 is the same, the battery modules 11 in the first accommodation area S1 and the battery modules 11 in the second accommodation area S2 exhibit the same behavior at the same frequency. motion is amplified. Therefore, as indicated by arrows in FIG. 11, the lateral rocking of the vehicle body with a time difference between the front and rear sides of the vehicle body induces a vertical displacement of the front panel 2a of the vehicle model A, thereby deteriorating the road noise performance. Note that FIG. 11 omits the battery module 11 for the sake of convenience.

On the other hand, in the vehicle model B, since the mounting rigidity (the number of fastening parts) of the battery modules 11 in the first housing area S1 and the battery modules 11 in the second housing area S2 are different, the natural frequencies of both are different. Therefore, the resonance of the battery modules 11 in the first accommodation area S1 and the battery modules 11 in the second accommodation area S2 can be avoided, and the lateral rocking of the vehicle body in the frequency band corresponding to the road noise can be suppressed. In addition, the vertical displacement of the front panel 2a is suppressed to reduce vehicle body vibration in the middle frequency band.
As shown in FIG. 10, it was confirmed that the noise level in the frequency band corresponding to the road noise of the vehicle model B is lower than the noise level in the frequency band corresponding to the road noise of the vehicle model A by 0.3 dB. The natural frequency of the battery module 11 attached using the third mounting bracket 53 was approximately 125 Hz, and the natural frequency of the battery module 11 mounted using the second mounting bracket 52 was approximately 160 Hz. .

According to the battery unit mounting structure according to the first embodiment, the battery unit 10 connects the pair of left and right side frames 21 mounted to the pair of floor frames 3 and the pair of side frames 21 extending in the vehicle width direction. and a plurality of battery modules 11 having substantially the same vertical dimension, horizontal dimension, and height dimension orthogonal to the vertical dimension and horizontal dimension. , are supported in the same posture by the cross frames 31 to 33, and are arranged in a plurality of rows adjacent to each other in the vehicle width direction so that the vertical dimension is substantially parallel to the front-rear direction, thereby making the battery unit compact. be able to.
Since the mounting rigidity of the battery modules 11 in the first housing area S1 is different from the mounting rigidity of the battery modules 11 in the second and third housing areas S2 and S3, the mounting rigidity of the first housing area S1 is changed by changing the mounting rigidity. The natural frequency of the battery module 11 can be made different from the natural frequency of the battery modules 11 in the second and third accommodation areas S2 and S3. Resonance with vehicle body vibration in the frequency band can be suppressed.

The plurality of battery modules 11 are arranged in three or more rows extending in the vehicle width direction, and the mounting rigidity of the battery module 11 in the first accommodation area S1 on the front end side is set to the same as that of the battery modules in the second and third accommodation areas S2 and S3. Since the mounting rigidity of the battery modules 11 is made different, the resonance suppression effect can be enhanced by changing the mounting rigidity of the battery modules 11 in the row on the one end side, which has a large effect on vehicle vibration.

The plurality of battery modules are arranged in three rows in the front-rear direction. Under the kick-up portion 2c of the floor panel 2, the mounting rigidity of the battery modules 11 in the first accommodation area S1 is adjusted to the mounting rigidity of the battery modules 11 in the second and third accommodation areas S2 and S3. The mounting rigidity has been changed.
As a result, it is possible to improve the road noise performance of the battery unit 10 in which the upper and lower battery modules are mounted with a minimum change in mounting rigidity.

The plurality of battery modules are arranged in three or more rows in the front-rear direction, and the battery modules 11 of the first storage area S1, which is the front row, and the second storage area S2, which is the second row adjacent to the rear side of the front row, are arranged. The battery modules 11 in the third accommodation area S3 are arranged in a single-layer state and arranged in a two-layer state of two upper and lower tiers on the rear side of the battery modules 11 in the second row, and the battery in the first accommodation area S1. The mounting rigidity of the module 11 is changed with respect to the mounting rigidity of the battery module 11 in the second accommodation area S2.
As a result, it is possible to improve the road noise performance of the battery unit 10 in which the upper and lower battery modules are mounted with a minimum change in mounting rigidity.

Since the plurality of battery modules 11 are attached to the cross frames 31 to 33 via the mounting brackets 51 to 53, the mounting brackets 51 to 53 can be changed regardless of the characteristics of the side frame 21 and the cross frames 31 to 33. The mounting rigidity of the battery module 11 can be changed.

Since the mounting rigidity of the battery modules 11 in the first housing area S1 is made higher than the mounting rigidity of the battery modules 11 in the second and third housing areas S2 and S3, the mounting rigidity of the battery modules 11 in the first housing area S1 is ensured. At the same time, the natural frequency of the battery module 11 in the first accommodation area S1 can be made different from the natural frequency of the battery modules 11 in the second and third accommodation areas S2 and S3.

The number of fastening portions 52s to 52u of the second mounting bracket 52 to which the battery module 11 of the first housing area S1 is attached is determined by the number of fastening portions 53s of the third mounting bracket 53 to which the battery modules 53 of the second, third housing areas S2 and S3 are attached. , 53t, the natural frequency of the battery module 11 in the first accommodation area S1 is made higher than the natural frequency of the battery modules 11 in the second and third accommodation areas S2 and S3 with a minimum change. be able to.

Next, a modified example in which the above embodiment is partially changed will be described.
1) In the above-described embodiment, an example in which the plurality of battery modules 11 are supported by the cross frames 31 to 33 and the rear frame 23 in a posture in which the longitudinal direction of the plurality of battery modules 11 is parallel to the front-rear direction has been described. It may be supported by the side frames 21 in a posture in which the longitudinal direction is parallel to the vehicle width direction. In this case, mounting brackets 51 to 53 for mounting battery module 11 are fixed to side frame 21 . Also, although an example in which the front and rear walls of the battery module 11 in the longitudinal direction are sandwiched between the mounting brackets 51 to 53 has been described, the side walls of the battery module 11 in the orthogonal direction to the longitudinal direction may be sandwiched by the mounting brackets 51 to 53 .

2) In the above embodiment, an example in which the first to third accommodation areas S1 to S3 are formed has been described, but two accommodation areas may be formed, or four or more may be formed. In addition, although an example in which the two-stage support mechanism 40 is provided in the third accommodation area S3 at the rear end has been described, three or more stages of support mechanisms may be provided, and the second accommodation area S2 may also be provided with a two-stage support mechanism or Three or more stages of support mechanisms may be provided.

3) In the above embodiment, the first mounting bracket 51 is provided on the front side and the second mounting bracket 52 is provided on the rear side in the first housing area S1. Both may be the second mounting bracket 52 . Also, an example has been described in which the mounting rigidity of the battery modules 11 housed in the first housing area S1 is higher than the mounting rigidity of the battery modules 11 housed in the second and third housing areas S2 and S3. The mounting rigidity of the battery modules 11 housed in the housing area S1 may be lower than the mounting rigidity of the battery modules 11 housed in the second and third housing areas S2 and S3. In this case, the number of fastening portions is reduced, or the plate thickness is reduced.

4) In the above embodiment, the battery modules 11 whose longitudinal direction is parallel to the front-rear direction are arranged in a plurality of rows in the same direction and adjacent to each other in the vehicle width direction. The battery modules 11 may be arranged in a plurality of rows in the same direction and adjacent to each other in the front-rear direction.
In this case, the battery modules 11 may be supported by the cross frames 31 to 33 and the rear frame 23 or may be supported by the side frames 21 .

5) In the above-described embodiment, an example of the rectangular parallelepiped battery module 11 was explained, but a plurality of columnar battery modules may be used as long as they have a rectangular shape at least when viewed from above. Even if the battery units are arranged in the width direction, the same effect can be obtained.

6) In addition, those skilled in the art can implement various modifications to the above-described embodiment or combinations of the embodiments without departing from the scope of the present invention. Any modifications are also included.

2 floor panel 3 floor frame 10 battery unit 11 battery module 21 side frame 31 first cross frame 32 second cross frame 33 third cross frame 51 first mounting brackets 51s, 51t fastening portion 52 second mounting brackets 52s, 52t, 52u Fastening portion 53 Third mounting brackets 53s, 53t Fastening portion V Vehicle

Claims (6)

A floor panel, a pair of left and right floor frames forming a closed cross section extending forward and backward in cooperation with the floor panel under the floor panel, and a battery module supported and attached to the pair of floor frames. In a battery unit mounting structure for an electric vehicle comprising a battery unit,
The battery unit includes a pair of left and right side frames attached to the pair of floor frames, a cross frame extending in the vehicle width direction and connecting the pair of side frames, and a rectangular shape in a plan view. The vertical dimension that is the longitudinal dimension of the rectangular shape, the horizontal dimension that is orthogonal to the longitudinal direction of the rectangular shape, and the height dimension that is orthogonal to the vertical and horizontal dimensions and is the vertical dimension of the vehicle body. a plurality of battery modules each having approximately the same size,
The plurality of battery modules are supported in the same posture by the side frames and/or cross frames, and the longitudinal direction of the rectangular shape is substantially parallel to the vehicle front-rear direction or the vehicle width direction. / or arranged in multiple rows adjacent in the front-rear direction,
making the mounting rigidity of the battery modules in some rows different from the mounting rigidity of the battery modules in other rows ,
The plurality of battery modules are attached to the side frame and/or the cross frame via mounting brackets,
A battery unit mounting structure for an electric vehicle, wherein the mounting rigidity of the rear wall portion of the battery module in the front row is greater than the mounting rigidity of the front wall portion of the battery module in the front row. a first mounting bracket connected to the front wall of the battery module in the front row; and a second mounting bracket connected to the rear wall of the battery module in the front row,
2. The method according to claim 1, wherein the number of attachment points of said second attachment bracket to said side frame and/or cross frame is larger than the number of attachment points of said first attachment bracket to said side frame and/or cross frame. A battery unit mounting structure for the electric vehicle described . The plurality of battery modules are arranged in three or more rows in the front-rear direction. Arranged in two layers,
3. The battery unit mounting structure for an electric vehicle according to claim 2, wherein the mounting rigidity of the battery module in the front row is different from the mounting rigidity of the battery modules in the other rows. The plurality of battery modules are arranged in three or more rows in the front-rear direction, and the battery module in the front row and the battery module in the second row adjacent to the rear side of the front row are arranged in a single layer. has a battery module row arranged in two layers of two upper and lower stages on the rear side of the battery module of
3. The battery unit mounting structure for an electric vehicle according to claim 2, wherein the mounting rigidity of the battery module in the front row is different from the mounting rigidity of the battery module in the second row. The battery unit mounting structure for an electric vehicle according to any one of claims 1 to 4 , wherein the mounting rigidity of the battery modules in some rows is higher than the mounting rigidity of the battery modules in other rows. . 5. The method according to any one of claims 1 to 4, wherein the number of attachment points of the attachment brackets for attaching the battery modules in some rows is larger than the number of attachment points of the attachment brackets for attaching the battery modules in the other rows. Battery unit mounting structure for electric vehicles.