JP7744569B2 - Automobile body structure - Google Patents

Description

This disclosure relates to automobile body structures.

Electric vehicles are equipped with a battery box that houses a battery. As disclosed in Patent Document 1, for example, the battery box is located inside the side sill in the vehicle width direction and below the floor panel. In electric vehicles, it is necessary for the body structure and the battery box itself to absorb the load and energy during a collision, thereby protecting the battery from the collision load.

For example, Patent Document 2 discloses a vehicle body structure including a pair of left and right side sills and a floor cross member connecting the left and right side sills. The vehicle body structure of Patent Document 2 further includes a load absorption member, a load support portion, and multiple battery pack cross members. In the vehicle body structure of Patent Document 2, the load absorption member is disposed within the upper part of the side sill and includes multiple hat-shaped cross-sectional portions and multiple wave-shaped cross-sectional portions. The load support portion is provided in the lower part of the side sill. Each battery pack cross member is disposed between the batteries and extends in the vehicle width direction. Patent Document 2 states that when a side collision load is input to the vehicle body structure, the load absorption member, load support portion, and battery pack cross member transmit the load evenly along the vehicle width direction via three paths, thereby absorbing the impact.

Like Patent Document 2, the vehicle body structures disclosed in Patent Documents 3 and 4 also have components within the side sill to absorb impact during a side collision. In the vehicle body structure of Patent Document 3, the components within the side sill are tubular bodies with polygonal cross sections. In the vehicle body structure of Patent Document 4, the components within the side sill include, for example, a web, which is a corrugated plate, and flanges arranged on both sides of the web and fixed to the side sill. Each flange has a roughly C-shaped cross section and sandwiches the web, which extends in the vehicle longitudinal direction, from above and below.

International Publication No. 2019/198753 Japanese Patent Application Laid-Open No. 2021-88264 Patent No. 6566176 International Publication No. 2021/157651

In the vehicle body structures of Patent Documents 2 to 4, the components arranged within the side sill include corners extending in the vehicle width direction. Such components have high strength against collision loads during a side collision and exhibit excellent energy absorption performance when crushed, but due to their high strength, they are difficult to crush. Therefore, it is preferable to devise a vehicle body structure that makes it easier for the components within the side sill to crush when a collision load is input.

The objective of this disclosure is to provide a vehicle body structure that can effectively absorb collision energy by making it easier to crush the energy absorbing member inside the side sill.

The vehicle body structure of the present disclosure comprises a side sill, an energy absorbing member, multiple floor cross members, a floor panel, an under member, a battery box, multiple battery box brackets, and multiple battery box cross members. The side sill includes an outer wall and an inner wall. The inner wall is disposed inward of the outer wall in the vehicle width direction and faces the outer wall in the vehicle width direction. The side sill has a cylindrical shape extending in the vehicle length direction. The energy absorbing member is disposed within the side sill and fixed to the side sill. The energy absorbing member includes a corner extending in the vehicle width direction. The floor cross member extends in the vehicle width direction. The floor cross member is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction. The floor cross member is disposed on the upper surface of the floor panel. The under member is connected to the lower surface of the floor panel. The under member extends in the vehicle length direction across the multiple floor cross members. The under member is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction. The battery box is located inside the side sill in the vehicle width direction. The battery box is located below the floor panel. The battery box bracket is connected to the battery box and supports the lower part of the side sill. The battery box cross member is housed within the battery box. The battery box cross member extends in the vehicle width direction.

The vehicle body structure disclosed herein makes it easier to crush the energy absorbing member inside the side sill, allowing for better absorption of collision energy.

FIG. 1 is a perspective view of a vehicle body structure according to an embodiment, as viewed from above. FIG. 2 is a perspective view of the vehicle body structure according to the embodiment, as viewed from below. FIG. 3 is another perspective view of the vehicle body structure according to the embodiment, seen from below. FIG. 4 is a cross-sectional view of the vehicle body structure shown in FIG. FIG. 5 is another cross-sectional view of the vehicle body structure shown in FIG. FIG. 6 is a vertical cross-sectional view of an energy absorbing member included in the vehicle body structure shown in FIG. FIG. 7 is a vertical cross-sectional view of an energy absorbing member different from the energy absorbing member shown in FIG. FIG. 8 is a partial cross-sectional view of a vehicle body structure to which an energy absorbing member different from the energy absorbing members shown in FIGS. 6 and 7 is applied. FIG. 9 is a vertical cross-sectional view of an energy absorbing member included in the vehicle body structure shown in FIG. FIG. 10 is a vertical cross-sectional view of an energy absorbing member different from the energy absorbing member shown in FIG. FIG. 11 is a partially enlarged view of FIG. 4 or FIG. FIG. 12 is yet another cross-sectional view of the vehicle body structure shown in FIG. FIG. 13 is a diagram showing a modified example of the battery box bracket included in the vehicle body structure according to the embodiment.

The vehicle body structure of an embodiment includes a side sill, an energy absorbing member, multiple floor cross members, a floor panel, an under member, a battery box, multiple battery box brackets, and multiple battery box cross members. The side sill includes an outer wall and an inner wall. The inner wall is located more inward than the outer wall in the vehicle width direction and faces the outer wall in the vehicle width direction. The side sill has a cylindrical shape extending in the vehicle length direction. The energy absorbing member is located within the side sill and fixed to the side sill. The energy absorbing member includes a corner extending in the vehicle width direction. The floor cross member extends in the vehicle width direction. The floor cross member is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction. The floor cross member is located on the upper surface of the floor panel. The under member is connected to the lower surface of the floor panel. The under member extends in the vehicle length direction across the multiple floor cross members. The under member is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction. The battery box is located inside the side sill in the vehicle width direction. The battery box is located below the floor panel. The battery box bracket is connected to the battery box and supports the lower part of the side sill. The battery box cross member is housed within the battery box. The battery box cross member extends in the vehicle width direction (first configuration).

In the first configuration, multiple floor cross members are connected to the side sill so as to support the inner wall of the side sill from the inside in the vehicle width direction. In addition, the under member is also connected to the side sill so as to support the inner wall of the side sill from the inside in the vehicle width direction. Therefore, when a collision load is applied to the side sill from the outer wall side during a side collision of the vehicle, the collision load is absorbed by the floor cross member and under member, restricting the movement of the side sill. Furthermore, in the first configuration, the lower portion of the side sill, i.e., the portion away from the center of the side sill, is supported by multiple battery box brackets. Therefore, when a collision load is applied to the side sill from the outer wall side, the battery box brackets restrict the rotation of the side sill, suppressing torsional deformation of the side sill. Because the side sill is firmly and stably supported by the floor cross member, under member, and battery box bracket, when a collision load is applied to the side sill from the outside in the vehicle width direction, the energy absorbing member inside the side sill is more likely to be crushed in the vehicle width direction. The crushing of the energy absorbing member allows for effective absorption of collision energy. This protects the battery box located inside the side sill in the vehicle width direction, as well as the battery inside this battery box.

At least one of the battery box brackets may be arranged so as to be aligned with one of the battery box cross members in the vehicle width direction (second configuration).

In the second configuration, at least one battery box bracket is aligned with one of the battery box cross members in the vehicle width direction. This reduces deflection due to the battery box's own weight.

The strength of the portion of the floor panel where the floor cross member is located may be greater than the strength of other portions (third configuration).

In the third configuration, the strength of the portion of the floor panel where the floor cross member is located is relatively high. This allows the floor cross member on the floor panel to more firmly support the side sill. Therefore, when a collision load is input to the side sill from the outside in the vehicle width direction, the energy absorbing member is more likely to be crushed.

The vehicle body structure may further include a connecting member. The connecting member is disposed on the upper surface of the floor panel. The connecting member extends in the vehicle length direction and connects two or more of the floor cross members. The connecting member is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction (fourth configuration).

In the fourth configuration, the connecting member can support the inner wall of the side sill from the inside in the vehicle width direction and connects two or more floor cross members. Therefore, a collision load input to the side sill is distributed to two or more floor cross members via the connecting member. This improves the support strength of the side sill by the floor cross members. Therefore, when a collision load is input to the side sill from the outside in the vehicle width direction, the energy absorbing member is more likely to crush.

The under member may include a plate portion. It is preferable that the portion of this plate portion facing the floor panel be positioned higher than the portion facing the side sill (fifth configuration).

In the fifth configuration, the portion of the plate included in the under member that faces the floor panel is positioned higher. In this case, the collision load input to the side sill crushes the energy absorbing member inside the side sill, and is then transmitted to the floor panel via the plate of the under member, acting to lift the floor panel. This causes the floor panel to deform upward and away from the battery box. This prevents the deformed floor panel from coming into contact with the battery box, protecting the battery inside the battery box.

The vehicle body structure may further include multiple partition members. The partition members are arranged in the vehicle length direction within the space between the side sill, floor panel, and undermember (sixth configuration).

In the sixth configuration, multiple partition members are provided in the space between the side sill, floor panel, and under-member. These partition members can suppress deformation of the under-member due to collision load, thereby improving the support strength of the side sill by the under-member. As a result, when a collision load is input to the side sill from the outside in the vehicle width direction, the energy absorbing member is more likely to be crushed.

In at least one of the floor cross members, the outer end in the vehicle width direction may differ from other portions in at least one of thickness and strength (seventh configuration).

In the seventh configuration, the thickness and/or strength of the outer end of at least one floor cross member in the vehicle width direction is different from that of other portions. For example, if the thickness or strength of the end of the floor cross member is relatively small, the end of the floor cross member will be more likely to deform when the floor cross member is subjected to a collision load. On the other hand, if the thickness or strength of the end of the floor cross member is relatively large, the end of the floor cross member will be less likely to deform when the floor cross member is subjected to a collision load. The deformation mode of the floor cross member affects the deformation mode of the floor panel. Therefore, by adjusting the thickness and/or strength of the end of the floor cross member, the deformation mode of the floor panel can be controlled, for example, to prevent the floor panel from coming into contact with the battery box.

Each of the battery box brackets may have a recess or hole on its upper surface (eighth configuration).

In the eighth configuration, a recess or hole is provided on the upper surface of each battery box bracket. In this case, after the energy absorbing member inside the side sill is crushed by the collision load, the battery box bracket does not resist the collision load and is destroyed starting from the recess or hole. This prevents the battery box bracket from damaging the battery box and protects the battery inside the battery box.

The battery box cross member may be joined to the battery box by at least one of adhesive, welding, and mechanical joining (ninth configuration).

In the ninth configuration, the battery box cross-member is firmly joined to the battery box by at least one of adhesive, welding, and mechanical joining. This makes it easier for the battery box and battery box cross-member to withstand collision loads input through the battery box bracket, improving the load transferability of the battery box and battery box cross-member. Furthermore, by firmly joining the battery box cross-member to the battery box, deflection due to the battery box's own weight can be reduced, protecting the battery inside the battery box. This is also effective in protecting the battery when the battery box comes into contact with the ground.

Embodiments of the present disclosure will be described below with reference to the drawings. In each drawing, identical or equivalent components are designated by the same reference numerals, and the same descriptions will not be repeated.

[Body structure]
Fig. 1 is a perspective view of a vehicle body structure 100 according to this embodiment as seen from above. Figs. 2 and 3 are perspective views of the vehicle body structure 100 as seen from below. The vehicle body structure 100 is applied to a vehicle that runs on a battery as an energy source, such as an electric vehicle.

As shown in Figures 1 to 3, the vehicle body structure 100 includes a side sill 10, an energy absorbing member 20, a floor panel 30, multiple floor cross members 40A, 40B, an under member 50, a battery box 60, multiple battery box cross members 70, and multiple battery box brackets 80. The vehicle body structure 100 further includes a connecting member 90.

(Side sill)
1 and 2, a side sill 10 is provided on each of the left and right sides of an automobile. Each side sill 10 extends in the vehicle length direction. Each side sill 10 has a substantially cylindrical shape. Each side sill 10 includes an outer member 11 and an inner member 12.

Figure 4 is a cross-sectional view (transverse cross-section) of the vehicle body structure 100 taken perpendicular to the vehicle length direction at the position of floor cross-member 40A. Figure 5 is a cross-sectional view (transverse cross-section) of the vehicle body structure 100 taken perpendicular to the vehicle length direction at the position of floor cross-member 40B. Referring to Figures 4 and 5, the outer member 11 and inner member 12 of the side sill 10 each have a generally hat-shaped cross-section. The outer member 11 includes an outer wall 111, an upper wall 112, a lower wall 113, and flanges 114 and 115. The inner member 12 includes an inner wall 121, an upper wall 122, a lower wall 123, and flanges 124 and 125.

In the outer member 11, the upper wall 112 is provided continuous with the upper end of the outer wall 111. The lower wall 113 is provided continuous with the lower end of the outer wall 111. In a cross-sectional view of the vehicle body structure 100, the upper wall 112 and the lower wall 113 extend inward from the outer wall 111 in the vehicle width direction. The flange 114 is continuous with the upper wall 112 and protrudes upward from the upper wall 112. The flange 115 is continuous with the lower wall 113 and protrudes downward from the lower wall 113.

The inner wall 121 of the inner member 12 is positioned more inward than the outer wall 111 of the outer member 11 in the vehicle width direction. The inner wall 121 faces the outer wall 111 in the vehicle width direction. The upper wall 122 is provided continuous with the upper end of the inner wall 121. The lower wall 123 is provided continuous with the lower end of the inner wall 121. In a cross-sectional view of the vehicle body structure 100, the upper wall 122 and the lower wall 123 extend from the inner wall 121 outward in the vehicle width direction. The flange 124 is continuous with the upper wall 122 and protrudes upward from the upper wall 122. The flange 125 is continuous with the lower wall 123 and protrudes downward from the lower wall 123.

The flanges 124, 125 of the inner member 12 are joined to the flanges 114, 115 of the outer member 11, respectively. The flanges 124, 125 of the inner member 12 are joined to the flanges 114, 115 of the outer member 11, for example, by welding or mechanical joining using bolts or rivets. In this embodiment, the side sill 10 is formed by the outer member 11 and the inner member 12. However, the side sill 10 does not have to be formed from multiple members.

The side sill 10 is typically made of a metal plate. Preferably, the side sill 10 is made of a steel plate. For example, the side sill 10 can be made of a steel plate having a tensile strength of 980 MPa or more.

(Energy absorbing member)
1 , the energy absorbing member 20 is a member that absorbs collision energy by being crushed in the vehicle width direction when, for example, a vehicle experiences a side collision. The energy absorbing member 20 is disposed within the side sill 10. The energy absorbing member 20 is fixed to the side sill 10. The energy absorbing member 20 extends in the vehicle length direction.

Referring to Figures 4 and 5, the energy absorbing member 20 includes a main body portion 21 and flange portions 22, 23. The main body portion 21 and the flange portions 22, 23 each extend in the vehicle length direction. The flange portions 22, 23 are roughly C-shaped in a cross-sectional view of the vehicle body structure 100. The flange portion 22 is arranged to sandwich the outer end of the main body portion 21 in the vehicle width direction from above and below. The flange portion 23 is arranged to sandwich the inner end of the main body portion 21 in the vehicle width direction from above and below. The flange portions 22, 23 may be joined to the main body portion 21 by, for example, welding or mechanical joining.

The flange portions 22, 23 are joined to the outer wall 111 and inner wall 121 of the side sill 10, for example, by welding or mechanical joining. This secures the energy absorbing member 20 to the outer wall 111 and inner wall 121 of the side sill 10. However, the energy absorbing member 20 may be secured to only one of the outer wall 111 and inner wall 121 of the side sill 10.

Figure 6 is a cross-sectional view (longitudinal cross-sectional view) of the energy absorbing member 20 taken substantially perpendicular to the vehicle width direction. As shown in Figure 6, the main body 21 of the energy absorbing member 20 is, for example, a corrugated plate that repeatedly bends or curves up and down in the longitudinal cross-sectional view of the energy absorbing member 20. This main body 21 includes a plurality of corners 211. Each of the corners 211 extends in the vehicle width direction.

The energy absorbing member 20 may include at least one corner 211 extending in the vehicle width direction. However, it is preferable that the energy absorbing member 20 include multiple corners 211. The configuration of the energy absorbing member 20 is not limited to the example shown in Figure 6 and can be modified as appropriate.

Figure 7 is a longitudinal cross-sectional view of another energy absorbing member 20 that can be applied to the vehicle body structure 100. In the energy absorbing member 20 shown in Figure 7, the main body 21 includes multiple cylindrical bodies 212 lined up in the vehicle length direction. Each of the cylindrical bodies 212 extends in the vehicle width direction. Each cylindrical body 212 has a polygonal shape in a longitudinal cross-sectional view of the energy absorbing member 20. Each cylindrical body 212 has, for example, a rectangular shape in a longitudinal cross-sectional view of the energy absorbing member 20. Each cylindrical body 212 includes multiple corners 211 extending in the vehicle width direction.

Figure 8 is a partial cross-sectional view of a vehicle body structure 100 to which yet another energy absorbing member 20 is applied. Figure 9 is a longitudinal cross-sectional view of this energy absorbing member 20. In the energy absorbing member 20 shown in Figures 8 and 9, the main body 21 is a cylindrical body having a polygonal shape in longitudinal cross-section. As shown in Figure 8, this energy absorbing member 20 includes a cover 24. The cover 24 seals one end of the main body 21 in the vehicle width direction. The main body 21 is fixed to the inner wall 121 of the side sill 10 via the cover 24. Although not shown, the energy absorbing member 20 may further include a cover that seals the other end of the main body 21 in the vehicle width direction. The main body 21 may be fixed to the outer wall 111 of the side sill 10 via this cover.

As shown in FIG. 9, the main body 21 includes plate-like members 213 and 214. The plate-like members 213 and 214 are each formed in a wave-like shape that repeatedly bends or curves up and down. The plate-like member 214 is disposed below the plate-like member 213 and has a shape that is, for example, an upside-down version of the plate-like member 213. In the example shown in FIG. 9, the cylindrical main body 21 is formed by joining both ends of the plate-like member 213 in the vehicle length direction to both ends of the plate-like member 214 in the vehicle length direction. This main body 21 includes multiple corners 211 extending in the vehicle width direction.

When the main body 21 is cylindrical, it does not necessarily have to be made up of multiple plate-like members. For example, as shown in Figure 10, the main body 21 may be made up of a single member. Furthermore, the longitudinal cross-sectional shape of the main body 21 is not limited to the polygonal shape shown in Figures 9 and 10. The shape of the energy absorbing member 20 is not particularly limited as long as it includes corners 211 extending in the vehicle width direction.

The energy absorbing member 20 is typically made of a metal plate. Preferably, the energy absorbing member 20 is made of a steel plate. When the energy absorbing member 20 is made of a steel plate, the tensile strength of the steel plate is, for example, 590 MPa or more, preferably 780 MPa or more, and more preferably 980 MPa or more. The plate thickness of the energy absorbing member 20 may be greater than the plate thickness of the side sill 10.

(Floor panel)
1 and 2, the floor panel 30 is disposed between the left and right side sills 10. The floor panel 30 is joined to the side sills 10 by, for example, welding or mechanical joining. As shown in FIG. 1, a plurality of floor cross members 40A, 40B are disposed on the upper surface of the floor panel 30. For convenience of explanation, two floor cross members 40A, 40B are shown in FIG. 1, but the vehicle body structure 100 may also be provided with three or more floor cross members. The floor cross members 40A, 40B are aligned in the vehicle length direction on the floor panel 30.

The floor panel 30 is typically made of metal plate. Preferably, the floor panel 30 is made of steel plate. As indicated by hatching in FIG. 2, the strength of the portion 31 of the floor panel 30 where the floor cross members 40A, 40B are arranged may be greater than the strength of the other portion 32. When the floor panel 30 is made of steel plate, the tensile strength of the high-strength portion 31 may be, for example, 780 MPa or more. The tensile strength of the other portion 32 may be less than the tensile strength of the high-strength portion 31, for example, 270 MPa or more. The plate thickness of the high-strength portion 31 may be greater than the plate thickness of the other portion 32.

(Floor cross member)
1, floor cross members 40A and 40B each extend in the vehicle width direction. Floor cross member 40A is disposed forward of floor cross member 40B in the vehicle length direction.

The front floor cross member 40A includes a main body 41 and an end portion 42. The main body 41 has a roughly hat-shaped cross section perpendicular to the vehicle width direction. The main body 41 includes a top plate 411, vertical walls 412, and flanges 413. Each flange 413 is joined to the upper surface of the floor panel 30 by, for example, welding or mechanical joining. Each vertical wall 412 is continuous with the flange 413 and rises upward from the flange 413 in the vehicle height direction. The top plate 411 connects the upper ends of the two vertical walls 412.

In this embodiment, the end portion 42 is a separate member from the main body portion 41. The end portion 42 is disposed outward in the vehicle width direction relative to the main body portion 41. The end portion 42 is connected to the main body portion 41 so as to extend the main body portion 41 outward in the vehicle width direction. The end portion 42 includes a top plate 421, a vertical wall 422, and a flange 423. The top plate 421 is disposed on the top plate 411 of the main body portion 41, for example, so as to partially overlap the top plate 411. The vertical walls 422 rise in the vehicle height direction from the floor panel 30 side to the top plate 421 side and are connected to each other by the top plate 421. The flange 423 is continuous with the lower ends of the vertical walls 422. The flange 423 is also continuous with the outer ends of the top plate 421 and each vertical wall 422 in the vehicle width direction. The flanges 423 extend continuously from the lower ends of the vertical walls 422 to the outer ends of the top plate 421 and the vertical walls 422 in the vehicle width direction. The flanges 423 are joined to the floor panel 30 and the side sill 10 by, for example, welding or mechanical joining.

Referring to Figure 4, the floor cross member 40A is connected to the side sill 10 so as to support the inner wall 121 from the inside in the vehicle width direction. More specifically, of the flanges 423 at the end 42 of the floor cross member 40A, the portions that continue to each vertical wall 422 (Figure 1) are joined to the inner wall 121 of the side sill 10 from the inside in the vehicle width direction. Of the flanges 423, the portions that continue to the top plate 421 are joined to the upper wall 122 of the side sill 10 from above. The end of the floor panel 30 in the vehicle width direction is also joined to the inner wall 121 of the side sill 10.

In this embodiment, the floor cross member 40A is directly connected to the side sill 10. However, the floor cross member 40A may also be indirectly connected to the side sill 10 via another member. The floor cross member 40A is only required to be positioned so as to support the inner wall 121 from the inside in the vehicle width direction when a collision load is input to the side sill 10 from the outer wall 111 side. Similarly, the floor panel 30 may be directly or indirectly connected to the side sill 10.

The floor cross member 40A is typically made of metal plate. Preferably, the floor cross member 40A is made of steel plate. The end portion 42 of the floor cross member 40A may differ from the main body portion 41 in at least one of the plate thickness and strength. That is, in the floor cross member 40A, the plate thickness of the end portion 42 may be greater or less than the plate thickness of the main body portion 41. The plate thickness of the main body portion 41 and the end portion 42 can be set, for example, in the range of 1.0 mm or more and 3.0 mm or less. In the floor cross member 40A, the strength of the end portion 42 may be greater or less than the strength of the main body portion 41. If the floor cross member 40A is made of steel plate, the tensile strength of the main body portion 41 and the end portion 42 can be, for example, 980 MPa or more.

Returning to Figure 1, the rear floor cross member 40B has a roughly hat-like shape when viewed in a cross section perpendicular to the vehicle width direction. Similar to the main body 41 of floor cross member 40A, floor cross member 40B includes a top plate 411, a vertical wall 412, and a flange 413. Referring to Figure 5, floor cross member 40B is connected to the side sill 10 via the floor panel 30. Floor cross member 40B is positioned adjacent to the inner wall 121 of the side sill 10. Therefore, when a collision load is input to the side sill 10 from the outer wall 111 side, floor cross member 40B can support the inner wall 121 from the inside in the vehicle width direction.

Like floor cross member 40A, floor cross member 40B is typically made of metal plate. Floor cross member 40B is preferably made of steel plate. The material of floor cross member 40B may be the same as that of main body portion 41 or end portion 42 of floor cross member 40A, or may be different from that of main body portion 41 and end portion 42. Furthermore, the strength or plate thickness of floor cross member 40B may be the same as that of main body portion 41 or end portion 42 of floor cross member 40A, or may be different from that of main body portion 41 and end portion 42.

(Under-member)
Figure 2 shows the vehicle body structure 100 with the battery box 60, battery box cross member 70, and battery box bracket 80 omitted. Referring to Figure 2, the under member 50 is disposed below the floor panel 30. The under member 50 is disposed inside the side sill 10 in the vehicle width direction. The under member 50 extends in the vehicle length direction. The under member 50 extends in the vehicle length direction across at least the floor cross members 40A, 40B (Figure 1). The length of the under member 50 in the vehicle length direction may be approximately the same as the length of the side sill 10 in the vehicle length direction.

Referring to Figures 4 and 5, the under member 50 is connected to the underside of the floor panel 30. The under member 50 is also connected to the side sill 10. The under member 50 is connected to the side sill 10 so as to be able to support the inner wall 121 from the inside in the vehicle width direction. The under member 50 is joined to the underside of the floor panel 30 and the inner wall 121 of the side sill 10 by, for example, welding or mechanical joining.

Figure 11 is a partially enlarged view of Figure 4 or Figure 5. As shown in Figure 11, in this embodiment, the entire under member 50 is a plate portion 51. In a cross-sectional view of the vehicle body structure 100, the plate portion 51 extends diagonally upward from the side sill 10 toward the floor panel 30. The distance in the vehicle height direction from the plate portion 51 to the floor panel 30 gradually decreases toward the inside in the vehicle width direction. In other words, the portion of the plate portion 51 facing the floor panel 30 is located higher than the portion facing the side sill 10.

Of the plate portion 51, the connection portion 52 to the side sill 10 is located lower than the connection portion 53 to the floor panel 30. The connection portion 52 is located, for example, lower than the center of the side sill 10 in the vehicle height direction. In this embodiment, the connection portion 52 is located lower than the energy absorbing member 20. On the other hand, the connection portion 53 to the floor panel 30 is located so as to be aligned with the energy absorbing member 20 in the vehicle width direction.

In this embodiment, the under member 50 is directly connected to the underside of the floor panel 30 and the inner wall 121 of the side sill 10. However, the under member 50 may also be indirectly connected to the underside of the floor panel 30 or the inner wall 121 of the side sill 10. The under member 50 may, for example, be spaced apart from the side sill 10. In this case, the under member 50 only needs to be adjacent to the inner wall 121 so as to be able to substantially support the inner wall 121 of the side sill 10 from the inside in the vehicle width direction.

A space S exists between the side sill 10, floor panel 30, and under-member 50. Space S has, for example, a substantially triangular shape in a cross-sectional view of the vehicle body structure 100. Multiple partition members 54 are arranged within space S. The multiple partition members 54 are aligned in the vehicle length direction within space S. For example, partition members 54 may be arranged to correspond to the vertical walls 412, 422 (Figure 1) of floor cross-members 40A, 40B.

Each partition member 54 is, for example, a plate-shaped member. The partition members 54 are arranged in the space S so as to intersect with the vehicle length direction. The partition members 54 may also be arranged substantially perpendicular to the vehicle length direction. The partition members 54 are joined to the under member 50 by, for example, welding or mechanical joining. The partition members 54 may also be joined to the side sill 10 and the floor panel 30.

The under member 50 and the partition wall member 54 are typically made of metal plate. The under member 50 and the partition wall member 54 are preferably made of steel plate. The under member 50 and the partition wall member 54 can be made of steel plate having a tensile strength of, for example, 980 MPa or more. The tensile strength of the under member 50 may be the same as or different from the tensile strength of the partition wall member 54. The plate thickness of the under member 50 may be the same as or different from the plate thickness of the partition wall member 54. For example, the plate thickness of the partition wall member 54 can be greater than the plate thickness of the under member 50.

(battery box)
3, the battery box 60 is disposed inside the side sills 10 in the vehicle width direction. The battery box 60 is positioned between the left and right side sills 10. The battery box 60 is also disposed below the floor panel 30 (FIG. 1).

Referring to Figures 3 to 5, the battery box 60 includes side frames 61, an undercover 62, and multiple battery modules 63. The side frames 61 are provided on each of the left and right sides of the vehicle. The undercover 62 connects the left and right side frames 61 and forms the bottom of the battery box 60.

The undercover 62 may be joined to each side frame 61 using an adhesive, or by welding such as spot welding or arc welding, or by mechanical joining using bolts, rivets, etc. It is preferable that the undercover 62 be joined to the side frame 61 by weld bonding, which combines spot welding and adhesive, or by a method that combines mechanical joining such as bolts or rivets with adhesive. The undercover 62 is joined to the side frame 61 along the entire length in the vehicle length direction.

In the battery box 60, the side frames 61 and undercover 62 are typically made of metal plates. The side frames 61 and undercover 62 are preferably made of steel plates. The side frames 61 and undercover 62 can be made of steel plates with a tensile strength of, for example, 590 MPa or more. The tensile strength of the side frames 61 may be the same as or different from the tensile strength of the undercover 62. Furthermore, the plate thickness of the side frames 61 may be the same as or different from the plate thickness of the undercover 62.

(Battery box cross member)
Referring to Figure 3, multiple battery box cross members 70 are housed within the battery box 60. These battery box cross members 70 are arranged in the vehicle length direction. Each battery box cross member 70 extends in the vehicle width direction. A battery module 63 is disposed on top of the battery box cross members 70 via a battery box bottom plate (not shown).

Each battery box cross member 70 has a generally hat-shaped cross section perpendicular to the vehicle width direction. Each battery box cross member 70 is disposed on the upper surface of the undercover 62. Each battery box cross member 70, which has a generally hat-shaped cross section, is joined to the undercover 62 at a flange (not shown) at its lower end.

Each battery box cross-member 70 is joined to the undercover 62, for example, by adhesive. Each battery box cross-member 70 may also be joined to the undercover 62 by welding, such as spot welding or arc welding, or by mechanical joining, such as bolts or rivets. Each battery box cross-member 70 may also be joined to the undercover 62 by weld bonding, which combines spot welding and adhesive, or by a method that combines mechanical joining, such as bolts or rivets, with adhesive. Each battery box cross-member 70 is joined to the undercover 62 along its entire length in the vehicle width direction.

The battery box cross member 70 is typically made of a metal plate. Preferably, the battery box cross member 70 is made of a steel plate. For example, the battery box cross member 70 can be made of a steel plate having a tensile strength of 590 MPa or more.

(Battery box bracket)
Continuing to refer to Figure 3, the battery box bracket 80 is a member for attaching the battery box 60 to the side sill 10. Multiple battery box brackets 80 are arranged on both sides of the battery box 60 in the vehicle width direction and are aligned in the vehicle length direction. It is preferable that at least one of the battery box brackets 80 aligned in the vehicle length direction is aligned with one of the battery box cross members 70 in the vehicle width direction. More preferably, two or more battery box brackets 80 are aligned with the battery box cross member 70 in the vehicle width direction.

Referring to Figures 4 and 5, the battery box bracket 80 is connected to the battery box 60. The battery box bracket 80 is joined to the side frame 61 of the battery box 60 by, for example, welding or mechanical joining. In this embodiment, the battery box bracket 80 is directly connected to the side frame 61. However, the battery box bracket 80 may also be indirectly connected to the side frame 61.

The battery box bracket 80 supports the lower part of the side sill 10. The battery box bracket 80 is connected, for example, to the bottom wall 123 of the side sill 10. The battery box bracket 80 is detachably joined to the bottom wall 123 of the side sill 10 by mechanical joining, for example, with rivets or bolts.

The battery box bracket 80 may have an open cross section that opens downward, or it may have a closed cross section. For example, the battery box bracket 80 has a roughly hat shape when viewed in a cross section that intersects with the vehicle width direction. The battery box bracket 80 may also have a roughly U-shape when viewed in a cross section that intersects with the vehicle width direction. The battery box bracket 80 may also have a rectangular shape, etc. when viewed in a cross section that intersects with the vehicle width direction.

Referring to FIG. 11 , the battery box bracket 80 has a recess 81 on its upper surface. The recess 81 is a portion of the upper surface of the battery box bracket 80 that is recessed downward. For example, the recess 81 can be formed on the upper surface of the battery box bracket 80 by bending the upper surface of the battery box bracket 80 downward. The recess 81 may also be a bead having a downwardly recessed shape. For example, the recess 81 extends substantially or generally in the vehicle length direction.

The battery box bracket 80 is typically made of a metal plate. Preferably, the battery box bracket 80 is made of a steel plate. The battery box bracket 80 can be made of a steel plate having a tensile strength of, for example, 590 MPa or more. The plate thickness of the battery box bracket 80 can be the same as the plate thickness of the battery box cross-member 70, for example. The plate thickness of the battery box bracket 80 may also be different from the plate thickness of the battery box cross-member 70.

(Connection member)
Returning to FIG. 1 , the connecting member 90 is disposed on the upper surface of the floor panel 30. The connecting member 90 is disposed so as to span the two floor cross members 40A, 40B. The connecting member 90 extends in the vehicle length direction to connect the two floor cross members 40A, 40B. The connecting member 90 is connected to the outer ends of the floor cross members 40A, 40B in the vehicle width direction.

In this embodiment, one end of the connecting member 90 in the vehicle length direction abuts against the vertical wall 422 of the end 42 of the front floor cross member 40A and is connected to the vertical wall 422. The other end of the connecting member 90 in the vehicle length direction is placed on top of the rear floor cross member 40B and connected to the top plate 411 of the floor cross member 40B. However, the connection between the connecting member 90 and the floor cross members 40A, 40B is not limited to this. The connecting member 90 may be placed on each of the floor cross members 40A, 40B from above, or may extend between the floor cross members 40A, 40B so as to connect the vertical walls of the floor cross members 40A, 40B.

Figure 12 is a cross-sectional view (horizontal cross-section) of the vehicle body structure 100 taken perpendicular to the vehicle length direction at the position of the connecting member 90. Referring to Figure 12, the connecting member 90 includes a top plate 91, a vertical wall 92, and flanges 93 and 94. The flange 93 is joined to the upper surface of the floor panel 30, for example, by welding or mechanical joining. The vertical wall 92 is continuous with the flange 93 and extends upward from the flange 93 in the vehicle height direction. The top plate 91 is continuous with the vertical wall 92 and extends from the vertical wall 92 side toward the side sill 10 side in a horizontal cross-sectional view of the vehicle body structure 100. The flange 94 is continuous with the top plate 91.

The connecting member 90 is connected to the side sill 10 so as to support the inner wall 121 from the inside in the vehicle width direction. More specifically, the flange 94 of the connecting member 90 is connected to the inner wall 121 of the side sill 10 from the inside in the vehicle width direction. The flange 94 is also connected to the upper wall 122 of the side sill 10. The flange 94 is joined to the side sill 10 by, for example, welding or mechanical joining.

In this embodiment, the connecting member 90 is directly connected to the upper surface of the floor panel 30 and the inner wall 121 of the side sill 10. However, the connecting member 90 may also be indirectly connected to the upper surface of the floor panel 30 or the inner wall 121 of the side sill 10. The connecting member 90 only needs to be positioned so as to support the inner wall 121 from the inside in the vehicle width direction when a collision load is input to the side sill 10 from the outer wall 111 side. Furthermore, the connecting member 90 may be directly or indirectly connected to the floor cross members 40A, 40B, for example, by welding or mechanical joining.

The connecting member 90 is typically made of a metal plate. Preferably, the connecting member 90 is made of a steel plate. The connecting member 90 can be made of a steel plate having a tensile strength of, for example, 980 MPa or more. The tensile strength of the connecting member 90 may be the same as the tensile strength of the floor cross member 40A or 40B, for example. The plate thickness of the connecting member 90 may be the same as the main body portion 41 of the floor cross member 40A or the floor cross member 40B, for example.

[effect]
The vehicle body structure 100 according to this embodiment includes multiple floor cross members 40A, 40B and an under member 50. The floor cross members 40A, 40B and the under member 50 are capable of supporting the inner wall 121 of the side sill 10 from the inside in the vehicle width direction. Therefore, when a collision load is applied to the side sill 10 from the outer wall 111 side due to a side collision of the vehicle, the floor cross members 40A, 40B and the under member 50 can absorb the collision load and restrict movement of the side sill 10. The vehicle body structure 100 also includes multiple battery box brackets 80. Each battery box bracket 80 supports a lower portion of the side sill 10. That is, portions of the side sill 10 away from its center are supported by the multiple battery box brackets 80. Therefore, when a collision load is applied to the side sill 10 from the outer wall 111 side, the battery box brackets 80 restrict rotation of the side sill 10, thereby suppressing torsional deformation of the side sill 10.

In this way, in the vehicle body structure 100, the side sill 10 is firmly and stably supported by the floor cross members 40A, 40B, under member 50, and battery box bracket 80. As a result, when a collision load is input to the side sill 10 from the outside in the vehicle width direction, the energy absorbing member 20 inside the side sill 10 is more easily crushed in the vehicle width direction, allowing the energy absorbing member 20 to effectively absorb the collision energy. This makes it possible to protect the battery box 60 and battery module 63 located inside the side sill 10 in the vehicle width direction.

In this embodiment, it is preferable that at least some of the battery box brackets 80 are arranged so that they are aligned with one of the battery box cross members 70 in the vehicle width direction. For example, it is preferable that the battery box brackets 80 located on the left and right sides of the battery box 60 and the battery box cross member 70 are aligned in the vehicle width direction. This reduces deflection due to the weight of the battery box 60 compared to when all battery box brackets 80 are arranged away from the battery box cross member 70.

In this embodiment, the portion 31 of the floor panel 30 where the floor cross members 40A, 40B are arranged is preferably a high-strength portion. This allows the floor cross members 40A, 40B on the floor panel 30 to more firmly support the side sill 10. Therefore, when a collision load is input to the side sill 10 from the outside in the vehicle width direction, the energy absorbing member 20 is more likely to be crushed. However, the floor panel 30 may have substantially the same strength throughout its entirety.

The vehicle body structure 100 according to this embodiment includes a connecting member 90 spanning two floor cross members 40A, 40B. Similar to floor cross members 40A, 40B, the connecting member 90 is capable of supporting the inner wall 121 of the side sill 10 from the inside in the vehicle width direction. Therefore, when a collision load is applied to the side sill 10 from the outside in the vehicle width direction, the collision load is distributed to the floor cross members 40A, 40B via the connecting member 90. This improves the support strength of the side sill 10 provided by the floor cross members 40A, 40B. Therefore, when a collision load is applied to the side sill 10 from the outside in the vehicle width direction, the energy absorbing member 20 is more likely to be crushed.

If the vehicle body structure 100 has three or more floor cross members, the three or more floor cross members can be connected by the connecting member 90. On the other hand, the connecting member 90 can also be omitted from the vehicle body structure 100.

In this embodiment, the portion of the plate portion 51 of the under member 50 facing the floor panel 30 is positioned higher than the portion facing the side sill 10. In this case, the collision load input to the side sill 10 crushes the energy absorbing member 20 and is then transmitted to the floor panel 30 via the under member 50, acting to lift the floor panel 30. This causes the floor panel 30 to deform upward and away from the battery box 60. This prevents the deformed floor panel 30 from coming into contact with the battery box 60, protecting the battery module 63.

In this embodiment, multiple partition members 54 are provided in the space S between the side sill 10, floor panel 30, and under member 50. The partition members 54 can suppress deformation of the under member 50 due to a collision load. This improves the support strength of the side sill 10 provided by the under member 50. Therefore, when a collision load is input to the side sill 10 from the outside in the vehicle width direction, the energy absorbing member 20 is more likely to be crushed.

In this embodiment, the thickness of both end portions 42 of the floor cross member 40A may be different from the thickness of the main body portion 41. The strength of both end portions 42 of the floor cross member 40A may be different from the strength of the main body portion 41. For example, if the thickness or strength of the end portions 42 of the floor cross member 40A is relatively small, the end portions 42 are more likely to deform due to collision loads. On the other hand, if the thickness or strength of the end portions 42 of the floor cross member 40A is relatively large, the end portions 42 are less likely to deform due to collision loads. The deformation of the floor cross member 40A also affects the deformation of the floor panel 30. Therefore, by adjusting the thickness and/or strength of the end portions 42 of the floor cross member 40A, it is possible to control the deformation of the floor panel 30, for example, so that the floor panel 30 does not come into contact with the battery box 60.

In this embodiment, floor cross member 40A contacts the inner wall 121 of the side sill 10, while floor cross member 40B does not contact the inner wall 121 of the side sill 10. The length of floor cross member 40B in the vehicle width direction is smaller than the length of floor cross member 40A in the vehicle width direction. In this case, when a collision load is input to the side sill 10 from the outside in the vehicle width direction, the floor panel 30 is deformed at the gap between floor cross member 40B and the side sill 10, while deformation is suppressed in the center of the floor panel 30. However, floor cross member 40B may also contact the inner wall 121 of the side sill 10, like floor cross member 40A.

In this embodiment, a recess 81 is provided on the upper surface of each battery box bracket 80. In this case, after the energy absorbing member 20 inside the side sill 10 is crushed by the collision load, each battery box bracket 80 does not resist the collision load and is destroyed starting from the recess 81. This allows each battery box bracket 80 to absorb the collision energy. This prevents the battery box bracket 80 from damaging the battery box 60 and protects the battery module 63.

In this embodiment, each battery box cross-member 70 is firmly joined to the undercover 62 of the battery box 60 by, for example, at least one of adhesive, welding, and mechanical joining. This makes it easier for the battery box 60 and battery box cross-member 70 to withstand collision loads input through the battery box bracket 80, improving the load transferability of the battery box 60 and battery box cross-member 70. Furthermore, by firmly joining each battery box cross-member 70 to the undercover 62, deflection due to the battery box 60's own weight can be reduced, protecting the battery module 63. Furthermore, this is also effective in protecting the battery module 63 when the battery box 60 comes into contact with the ground.

It is preferable that each battery box cross-member 70 be joined to the undercover 62 of the battery box 60 by at least one of adhesive and welding. It is particularly preferable that each battery box cross-member 70 be joined to the undercover 62 by at least adhesive. Each battery box cross-member 70 may be joined to the undercover 62 by adhesive alone, or by a combination of adhesive and welding, or a combination of adhesive and mechanical joining. Using adhesive or welding increases the bonding area of each battery box cross-member 70 to the undercover 62 relatively. Using adhesive can further increase the bonding area of each battery box cross-member 70 to the undercover 62. This allows each battery box cross-member 70 to be more firmly bonded to the undercover 62. As a result, the load transferability of the battery box 60 and battery box cross-member 70 can be further improved, and the battery module 63 can be more effectively protected.

The above describes an embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present disclosure.

For example, in the above embodiment, the entire under member 50 is a plate portion 51. However, the under member 50 may be a cylindrical body extending in the vehicle length direction, and a portion of the under member 50 may be a plate portion 51 in which the portion on the floor panel 30 side is positioned higher than the portion on the side sill 10 side. The under member 50 may be, for example, a cylindrical body that has a substantially triangular or rectangular shape in a cross-sectional view of the vehicle body structure 100. If the under member 50 is a cylindrical body, a partition member 54 may be disposed within the under member 50.

In the above embodiment, the battery box bracket 80 has a recess 81 on its upper surface. However, as shown in FIG. 13, the battery box bracket 80 may also have a hole 82 on its upper surface. In this case, too, after the energy absorbing member 20 inside the side sill 10 is crushed by the collision load, the battery box bracket 80 can be destroyed starting from the hole 82.

100: Vehicle body structure 10: Side sill 111: Outer wall 121: Inner wall 20: Energy absorbing member 211: Corner portion 30: Floor panel 40A, 40B: Floor cross member 42: End portion 50: Under member 51: Plate portion 54: Partition member 60: Battery box 70: Battery box cross member 80: Battery box bracket 81: Recess 82: Hole portion 90: Connecting member

Claims (8)

A body structure of an automobile,
a cylindrical side sill extending in a vehicle length direction, the side sill including an outer wall and an inner wall disposed inward of the outer wall in a vehicle width direction and facing the outer wall in the vehicle width direction;
an energy absorbing member disposed within the side sill and fixed to the side sill, the energy absorbing member including a corner portion extending in the vehicle width direction;
a plurality of floor cross members extending in the vehicle width direction and connected to the side sills so as to be able to support the inner wall from the inside in the vehicle width direction;
a floor panel having the plurality of floor cross members disposed on an upper surface thereof;
an under member connected to a lower surface of the floor panel, extending in the vehicle length direction across the plurality of floor cross members, and connected to the side sill so as to be able to support the inner wall from an inner side in the vehicle width direction;
a battery box disposed inside the side sill in the vehicle width direction and below the floor panel;
a plurality of battery box brackets connected to the battery box and supporting the lower portion of the side sill;
a plurality of battery box cross members housed in the battery box and extending in the vehicle width direction;
Equipped with
A vehicle body structure in which the strength of the portion of the floor panel where the floor cross member is located is greater than the strength of other portions . The vehicle body structure according to claim 1,
At least one of the battery box brackets is arranged to be aligned with one of the battery box cross members in the vehicle width direction. The vehicle body structure according to claim 1 or 2 , further comprising:
a connecting member that is disposed on the upper surface of the floor panel, extends in the vehicle length direction, connects two or more of the floor cross members, and is connected to the side sill so as to be able to support the inner wall from the inside in the vehicle width direction;
A vehicle body structure comprising: The vehicle body structure according to any one of claims 1 to 3 ,
The under member includes a plate portion whose portion on the floor panel side is positioned higher than the portion on the side sill side. The vehicle body structure according to any one of claims 1 to 4 , further comprising:
a plurality of partition members arranged in the vehicle length direction within a space between the side sill, the floor panel, and the under member;
A vehicle body structure comprising: The vehicle body structure according to any one of claims 1 to 5 ,
A vehicle body structure in which the outer end of at least one of the floor cross members in the vehicle width direction differs from other portions in at least one of thickness and strength. The vehicle body structure according to any one of claims 1 to 6 ,
A vehicle body structure, wherein each of the battery box brackets has a recess or a hole on its upper surface. The vehicle body structure according to any one of claims 1 to 7 ,
The vehicle body structure, wherein the battery box cross member is joined to the battery box by at least one of an adhesive, a weld, and a mechanical joint.