Lower body structure of vehicle

Abstract

To provide a lower body structure of a vehicle that can surely increase energy absorption amounts at the time of a side collision.SOLUTION: A vehicle body 1 comprises a first reinforcement 5, a second reinforcement 6 and a third reinforcement 7 which are arranged inside a closed cross section 2a of a side sill 2. The first reinforcement 5 is formed in a hat shape having an upper wall part 5a and a lower wall part 5b and a vertical wall part 5c extending in a vertical direction. The second reinforcement part 6 forms a plurality of first closed cross sections 8 in cooperation with the upper wall part 5a. The third reinforcement 7 forms a plurality of second closed cross sections 8 in cooperation with the lower wall part 5b.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an underbody structure of a vehicle. [Background technology]

[0002] In a side collision where a vehicle collides with an obstacle such as a pole from the side, a large amount of collision energy is input into the side sill, which is a component of the side of the vehicle body. The energy transmitted from the side sill to the interior of the vehicle may affect the occupants and on-board components inside the vehicle. In particular, in the case of electric vehicles (EVs), there is a risk of impacting the battery pack, which is located on the inside of the side sill in the vehicle width direction. To avoid these effects, the side sill must absorb the energy.

[0003] Therefore, various structures have been proposed in the past to absorb energy during a side collision by providing a reinforcing member that forms a hollow closed cross section inside the side sill. For example, in the vehicle body structure described in Patent Document 1, a reinforcing member formed of sheet metal with a substantially M-shaped cross section is provided inside the side sill. The reinforcing member is arranged so that two protrusions that form the M-shaped cross section face outward in the vehicle width direction, and together with the side sill, forms a hollow closed cross section.

[0004] In this structure, during a side collision, the hollow closed cross section formed by the two protruding portions of the reinforcing member having a substantially M-shaped cross section is compressed in the vehicle width direction, thereby absorbing energy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2023-522161 Summary of the Invention [Problem to be solved by the invention]

[0006] However, depending on the conditions of a side collision, the reinforcing member with a roughly M-shaped cross section inside the side sill may undergo unintended deformation in which the closed cross section formed by the convex portion is compressed vertically rather than compressed in the vehicle width direction as expected. In this case, the reinforcing member loses its energy absorption capacity, and the targeted energy absorption amount may not be achieved.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a vehicle lower body structure that can reliably increase the amount of energy absorbed in the event of a side collision. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the underbody structure of a vehicle of the present invention comprises a pair of left and right side sills that form a closed cross section extending in the longitudinal direction of the vehicle on the outer sides of the vehicle body in the vehicle width direction, and a first reinforcement, a second reinforcement, and a third reinforcement that are reinforcing members arranged inside the closed cross sections, wherein the first reinforcement is fixed to a wall portion on the inner side of the side sill in the vehicle width direction, and has an upper wall portion and a lower wall portion that extend in the vehicle width direction and the longitudinal direction, and a vertical wall portion that extends in the vertical direction from the outer end of the upper wall portion in the vehicle width direction to the outer end of the lower wall portion, and has a hat shape that protrudes outward in the vehicle width direction and opens inward in the vehicle width direction, and the second reinforcement cooperates with the upper wall portion to form a plurality of first closed cross sections that are lined up in the longitudinal direction of the vehicle in a side view of the vehicle, and the third reinforcement cooperates with the lower wall portion to form a plurality of second closed cross sections that are lined up in the longitudinal direction of the vehicle in a side view of the vehicle.

[0009] With this configuration, during a side collision, the second and third reinforcements are axially compressed from the outside in the vehicle width direction to absorb energy. This suppresses out-of-plane deformation of the first reinforcement, i.e., upward bending of the upper wall portion and downward deformation of the lower wall portion. As a result, vertical deformation of the first reinforcement within the side sill is suppressed, making it possible to reliably increase the amount of energy absorbed during a side collision.

[0010] In the above vehicle underbody structure, it is preferable that the second reinforcement is fixed to an upper surface of the upper wall portion, and the third reinforcement is fixed to a lower surface of the lower wall portion.

[0011] With this configuration, the second reinforcement and the third reinforcement are arranged vertically spaced apart from each other with the first reinforcement in between, allowing energy absorption to occur outside the first reinforcement, thereby further suppressing out-of-plane deformation of the first reinforcement.

[0012] In the lower body structure of the above vehicle, it is preferable that the side sill has a side sill outer and a side sill inner that is positioned inward in the vehicle width direction from the side sill outer and joined to the side sill outer, and that the vertical wall portion is positioned outward in the vehicle width direction from the joint between the side sill outer and the side sill inner.

[0013] With this configuration, a side collision load from the outside in the vehicle width direction can be quickly and reliably transmitted from the side sill outer to the vertical wall portion of the first reinforcement.

[0014] In the above vehicle lower body structure, the first closed cross section preferably has a polygonal structure having a plurality of ridgelines extending in the vehicle width direction.

[0015] According to this configuration, the first closed cross section of the polygonal structure has a plurality of ridgelines extending in the vehicle width direction, which makes it possible to reliably increase the amount of energy absorbed in the event of a side collision.

[0016] In the above vehicle lower body structure, the second closed cross section preferably has a polygonal structure having a plurality of ridgelines extending in the vehicle width direction.

[0017] According to this configuration, the second closed cross section of the polygonal structure has a plurality of ridgelines extending in the vehicle width direction, which makes it possible to reliably increase the amount of energy absorbed in the event of a side collision.

[0018] In the above vehicle underbody structure, the second reinforcement and the third reinforcement preferably have different rigidities.

[0019] With this configuration, it is possible to arbitrarily change the distribution of the load transmitted to the inside of the vehicle body via the second reinforcement and the third reinforcement, which have different rigidities.

[0020] In the lower body structure of the above vehicle, it is preferable that the vehicle further includes a cross member extending in the vehicle width direction and connecting the pair of left and right side sills, and that the first closed cross section is positioned so as to overlap with the cross member when viewed from the side of the vehicle.

[0021] With this configuration, during a side collision, the collision load input to the first closed cross section formed by the upper wall portion of the first reinforcement and the second reinforcement can be smoothly transmitted to the cross member. [Effects of the Invention]

[0022] As described above, the vehicle lower body structure of the present invention can reliably increase the amount of energy absorbed during a side collision. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a plan view of a vehicle body showing the overall configuration of a vehicle underbody structure according to an embodiment of the present invention; [Figure 2] 2 is a partially cutaway enlarged view showing the arrangement of the side sill, the cross member, and the first reinforcement and the second reinforcement inside the side sill of FIG. 1. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4]FIG. 4 is an enlarged view of the side sill of FIG. 3 and the first to third reinforcements therein. [Figure 5] FIG. 4 is a view of the first to third reinforcements in FIG. 3 as seen from the outside in the vehicle width direction, that is, as seen from the side of the vehicle. [Figure 6] FIG. 6 is an enlarged perspective view of the first to third reinforcements of FIG. 5. [Figure 7] 4(a) to 4(d) are diagrams showing the deformation behavior of the side sill and the first to third reinforcements in FIG. 3 during a side collision. [Figure 8] FIG. 10 is a plan view showing a modified example of the present invention, in which the peaks of the second reinforcement are arranged alongside the peaks of a cross member with an M-shaped cross section in the vehicle width direction, and the peaks of the second reinforcement expand in the fore-and-aft direction between the cross members as they move inward in the vehicle width direction. [Figure 9] 9 is an enlarged perspective view showing a structure in which the peaks of the second reinforcement in FIG. 8 become wider in the front-rear direction as they move inward in the vehicle width direction. FIG. [Figure 10] FIG. 10 is a side view showing another variant of the present invention, in which the peaks of the second reinforcement are arranged side by side in the vehicle width direction with the peaks of the M-shaped cross member at the front of the vehicle, and the peaks of the second reinforcement are lower at the rear of the vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle underbody structure according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0025] (Overall structure of body 1) In this embodiment, as an application example of the underbody structure of the present invention, an electric vehicle (EV) body 1 equipped with a battery pack 4 below a cross member 3 shown in Fig. 1 will be described. The vehicle body 1 shown in Figs. 1 to 3 includes a pair of left and right side sills 2 each having a closed cross section 2a extending in the vehicle longitudinal direction X on the vehicle width outer side Y1 of the vehicle body 1, a plurality of cross members 3 extending in the vehicle width direction Y, a battery pack 4 arranged below the cross members 3 Z2, and three reinforcing members arranged inside the closed cross section 2a: a first reinforcement (hereinafter referred to as first reinforcement 5), a second reinforcement (hereinafter referred to as second reinforcement 6), and a third reinforcement 7 (hereinafter referred to as third reinforcement 7).

[0026] The side sill 2 has a side sill outer 21, which is a portion on the outer side Y1 in the vehicle width direction, and a side sill inner 22, which is a portion on the inner side Y2 in the vehicle width direction. The side sill inner 22 is disposed on the inner side Y2 in the vehicle width direction of the side sill outer 21, and cooperates with the side sill outer 21 to form the side sill 2 having a closed cross section 2a.

[0027] As shown in FIG. 4, the side sill outer 21 and the side sill inner 22 each have deformation promoting portions 23, 24 that promote inward deformation of the side sill 2 during a side collision. The deformation promoting portions 23, 24 will be described in detail later.

[0028] As shown in FIG. 4 , the side sill outer 21 has an upper wall portion 21a, a lower wall portion 21b located below the upper wall portion 21a in the region Z2, an outer wall portion 21c, an upper flange portion 21d, and a lower flange portion 21e, and is formed of a metal plate or the like. The upper wall portion 21a and the lower wall portion 21b extend in the vehicle width direction Y and the front-rear direction X, spaced apart from each other in the up-down direction Z. The outer wall portion 21c constitutes a side wall on the vehicle width outer side Y1 of the side sill 2, and extends in the up-down direction Z to connect the vehicle width outer side Y1 ends of the upper wall portion 21a and the lower wall portion 21b. The upper flange portion 21d and the lower flange portion 21e extend in the up-down direction Z from the vehicle width inner side Y2 ends of the upper wall portion 21a and the lower wall portion 21b in the up-down direction Z and in directions spaced apart from each other.

[0029] The side sill inner 22 has an upper wall portion 22a, a lower wall portion 22b located below the upper wall portion 22a in the region Z2, an inner wall portion 22c, an upper flange portion 22d, and a lower flange portion 22e, and is formed of a metal plate or the like. The upper wall portion 22a and the lower wall portion 22b extend in the vehicle width direction Y and the front-rear direction X, spaced apart from each other in the up-down direction Z. The inner wall portion 22c constitutes a side wall on the vehicle width inner side Y2 of the side sill 2, and extends in the up-down direction Z to connect the vehicle width inner side Y2 ends of the upper wall portion 22a and the lower wall portion 22b. The upper flange portion 22d and the lower flange portion 22e extend in the up-down direction Z from the vehicle width outer side Y1 ends of the upper wall portion 22a and the lower wall portion 22b in directions spaced apart from each other.

[0030] The upper flange portion 22d and the lower flange portion 22e of the side sill inner 22 are joined to the upper flange portion 21d and the lower flange portion 21e of the side sill outer 21 by welding or the like, respectively. In this way, the side sill inner 22 is joined to the side sill outer 21.

[0031] As shown in FIGS. 1 and 2, the multiple cross members 3 each extend in the vehicle width direction Y, are spaced apart from each other in the front-rear direction X, and connect the side sill inners 22 of a pair of left and right side sills 2.

[0032] 3, the battery pack 4 is disposed below the multiple cross members 3 and between a pair of left and right side sills 2. The battery pack 4 includes a battery housing 4a and at least one battery module 4b housed in the battery housing 4a. A flange 4a1 protrudes from the outer surface of the side wall of the battery housing 4a toward the outer side Y1 in the vehicle width direction.

[0033] The battery pack 4 is fixed to the lower wall portions 22b of the side sill inner panels 22 of the pair of left and right side sills 2. Specifically, a flange portion 4a1 of the battery housing 4a is fixed to the lower wall portions 22b (specifically, a horizontal wall portion 22b1, which will be described later) using bolts 11 and nuts 12.

[0034] (Explanation of the three reinforcing members (first rein 5, second rein 6, third rein 7)) 4, the first rein 5 has an upper wall portion 5a, a lower wall portion 5b located below the upper wall portion 5a in the Z2 direction, a vertical wall portion 5d, and a pair of flange portions 5c, and is formed of a metal plate or the like. The upper wall portion 5a and the lower wall portion 5b are spaced apart from each other in the up-down direction Z and extend in the vehicle width direction Y and the front-rear direction X.

[0035] The upper wall portion 5a, the lower wall portion 5b, the vertical wall portion 5d, and the pair of flange portions 5c form a hat-shaped first raincoat 5 that protrudes to the outer side Y1 in the vehicle width direction and opens to the inner side Y2 in the vehicle width direction.

[0036] In this embodiment, the upper wall portion 5a is formed so as to be inclined in a direction gradually separating from the lower wall portion 5b as it moves toward the vehicle width direction inner side Y2. Specifically, the upper wall portion 5a is inclined in a direction toward the upward direction Z1 as it moves toward the vehicle width direction inner side Y2. The inclination angle θ1 of the upper wall portion 5a with respect to the horizontal direction (vehicle width direction Y) is set to an angle such that the vertical wall portion 5d faces the horizontal direction when it receives a compressive load toward the vehicle width direction inner side Y2 during a side collision.

[0037] In this embodiment, the lower wall portion 5b is formed so as to be inclined in a direction away from the upper wall portion 5a as it approaches the vehicle width direction inner side Y2. Specifically, the lower wall portion 5b is inclined in a direction toward the downward Z2 direction as it approaches the vehicle width direction inner side Y2. The inclination angle θ2 of the lower wall portion 5b with respect to the horizontal direction (vehicle width direction Y) is set to an angle such that the vertical wall portion 5d faces the horizontal direction when it receives a compressive load toward the vehicle width direction inner side Y2 during a side collision.

[0038] The vertical wall portion 5d extends in the up-down direction Z and connects the ends of the upper wall portion 5a and the lower wall portion 5b on the outer side Y1 in the vehicle width direction. That is, the vertical wall portion 5d extends in the up-down direction Z from the end of the upper wall portion 5a on the outer side Y1 in the vehicle width direction to the end of the lower wall portion 5b on the outer side Y1 in the vehicle width direction.

[0039] The vertical wall portion 5d is disposed on the outer side Y1 in the vehicle width direction than the upper flange portions 21d, 22d and the lower flange portions 21e, 22e, which are the joints between the side sill outer panel 21 and the side sill inner panel 22.

[0040] 3, the first rain 5 may be disposed in a position overlapping the cross member 3 and the battery pack 4 in the vertical direction Z, or in a range between the cross member 3 and the battery pack 4. This allows the collision load received by the first rain 5 during a side collision to be distributed and transmitted to the cross member 3 and the battery pack 4.

[0041] The pair of flange portions 5c extend in the vertical direction Z from the ends of the upper wall portion 5a and the lower wall portion 5b on the inner side Y2 in the vehicle width direction and in directions away from each other. The upper wall portion 5a and the lower wall portion 5b are fixed to the wall portion on the inner side Y2 in the vehicle width direction of the side sill 2 (i.e., the inner wall portion 22c of the side sill inner panel 22) via the pair of flange portions 5c.

[0042] There are no particular limitations on the manufacturing method of the first rein 5. For example, it is preferable to form a portion divided into two vertically at the vertical wall portion 5d in advance during the intermediate stage of manufacturing the first rein 5, and then join the second rein 6 and the third rein 7 to each of the two divided portions by welding or the like, and then join the two portions by welding or the like. This manufacturing method makes it possible to easily join the second rein 6 and the third rein 7 to the divided first rein 5. Note that the first rein 5 may also be integrally molded from a metal plate or the like.

[0043] The second rein 6 is a reinforcing member that cooperates with the upper wall portion 5a of the first rein 5 to form a plurality of first closed cross sections 8 aligned in the front-rear direction X of the vehicle in the vehicle side view shown in FIG.

[0044] As shown in FIGS. 2 to 6, the second rein 6 of this embodiment is fixed to the upper wall portion 5a of the first rein 5 and is a strip-shaped member extending in the vehicle longitudinal direction X and having continuous concave and convex portions in the up-down direction Z. The second rein 6 has multiple peaks 6a and valleys 6b arranged alternately in the vehicle longitudinal direction X, and is joined to the upper surface 5a1 of the upper wall portion 5a at the valleys 6b by welding or the like. The peaks 6a are approximately trapezoidal in a side view of the vehicle. Therefore, the peaks 6a and the upper wall portion 5a form a trapezoidal first closed cross section 8 extending in the vehicle width direction Y. The first closed cross section 8 has a polygonal structure having multiple ridges 13 (see FIG. 6) extending in the vehicle width direction Y. The first closed cross section 8 is not limited to a trapezoidal shape, and may have another polygonal structure. Alternatively, the first closed cross section 8 may be triangular.

[0045] The first closed cross section 8 is disposed at a position overlapping with the cross member 3 in the side view of the vehicle shown in Fig. 5. That is, as shown in Figs. 2 and 3, the first closed cross section 8 formed at the position of the peak portion 6a of the second rein 6 is disposed within the range in which the cross member 3 exists in the vehicle longitudinal direction X.

[0046] The third reinforcing members 7 are reinforcing members that cooperate with the lower wall portion 5b to form a plurality of second closed cross sections 9 aligned in the front-rear direction X of the vehicle in the vehicle side view shown in FIG.

[0047] The third rein 7 of this embodiment has a shape obtained by inverting the second rein 6. That is, as shown in FIGS. 3 to 6, the third rein 7 is fixed to the lower wall portion 5b of the first rein 5, and is a strip-shaped member extending in the vehicle longitudinal direction X and having a continuous concave and convex shape in the vertical direction Z. The third rein 7 has a plurality of peaks 7a and valleys 7b arranged alternately in the vehicle longitudinal direction X, and is joined to the lower surface 5b1 of the lower wall portion 5b at the valleys 7b by welding or the like. The peaks 7a are substantially trapezoidal in a side view of the vehicle. Therefore, the peaks 7a and the lower wall portion 5b form a trapezoidal second closed cross section 9 extending in the vehicle width direction Y. The second closed cross section 9 has a polygonal structure having a plurality of ridges 14 (see FIG. 6) extending in the vehicle width direction Y. The second closed cross section 9 may also have a polygonal structure other than a trapezoidal shape. Alternatively, the second closed cross section 9 may have a triangular shape.

[0048] The second rein 6 and the third rein 7 may have any shape as long as they can cooperate with the upper wall portion 5a and the lower wall portion 5b of the first rein 5 to form the first closed cross section 8 and the second closed cross section 9. Therefore, the second rein 6 and the third rein 7 may be configured not only by a series of strip-shaped members as shown in Figures 2 and 5-6, but also by a plurality of hat-shaped members having at least one ridge portion 6a, 7a.

[0049] The second rein 6 and the third rein 7 may have different rigidities. In this case, it is possible to arbitrarily change the distribution of the load transmitted to the interior of the vehicle via the second rein 6 and the third rein 7 during a side collision. Note that the "rigidity" mentioned above refers to bending rigidity against a side collision load.

[0050] 3 and 4, in terms of its positional relationship with the second rein 6, the vertical wall portion 5d of the first rein 5 in this embodiment is disposed on the outer side Y1 of the vehicle width direction of the end portion 61 of the second rein 6 on the outer side Y1 of the vehicle width direction. In other words, the end portion 61 of the second rein 6 is located a distance d3 away from the outer surface of the vertical wall portion 5d of the first rein 5 on the inner side Y2 of the vehicle width direction. Similarly, the end portion 71 of the third rein 7 is located a distance d3 away from the outer surface of the vertical wall portion 5d of the first rein 5 on the inner side Y2 of the vehicle width direction.

[0051] Also, as shown in Figure 4, the total length d5 ​​of the region R extending in the vertical direction Z and the vehicle width direction Y including the vertical wall portion 5d of the first rain 5, which is located on the outer side Y1 of the vehicle width direction of the end 61 of the second rain 6 on the outer side Y1 of the vehicle width direction and the end 71 of the third rain 7 on the outer side Y1 of the vehicle width direction, is set to be equal to the distance d4 in the vertical direction Z between the inner side Y2 end of the upper wall portion 5a of the first rain 5 and the inner side Y2 end of the lower wall portion 5b in the vehicle width direction.

[0052] (Regarding the deformation promoting portion 23 of the side sill outer 21) As shown in FIG. 4, the second rain 6 of this embodiment is disposed on the surface of the upper wall portion 5a facing outward from the first rain 5, that is, on the upper surface 5a1 of the upper wall portion 5a.

[0053] The side sill outer 21 of this embodiment has the following corner portion 21a3, which becomes a deformation promoting portion 23 that deforms inward of the side sill 2 so as to abut against the second rain 6 arranged as described above from above Z1 (from the outside in the vertical direction Z) during a side collision of the vehicle.

[0054] The side sill outer 21 extends in the vehicle width direction Y and the vehicle front-rear direction X as described above, and has an upper wall portion 21a which is an opposing wall portion opposing the second rain 6.

[0055] 4, the upper wall portion 21a is bent toward the inside of the side sill 2, and has a corner 21a3 that protrudes in a direction approaching the second rain 6 due to the bend. The deformation promoting portion 23 is constituted by the corner 21a3.

[0056] Specifically, the upper wall portion 21a of this embodiment has a horizontal portion 21a1 extending horizontally (in the vehicle width direction Y) and an inclined portion 21a2 inclined upward in the direction Z1 as it extends toward the vehicle width inner side Y2. The inclined portion 21a2 connects the horizontal portion 21a1 to the upper flange portion 21d. The upper wall portion 21a has a corner portion 21a3 formed by the horizontal portion 21a1 and the inclined portion 21a2 and protruding toward the inside of the side sill 2. In the side sill outer 21, during a side collision, the horizontal portion 21a1 of the upper wall portion 21a receives a compressive load in the horizontal direction (in the vehicle width direction Y) toward the vehicle width inner side Y2, which allows the upper wall portion 21a to bend reliably toward the inside of the side sill 2, starting from the corner portion 21a3, which serves as the deformation promoting portion 23.

[0057] In this embodiment, the deformation promoting portion 23 is composed of the corner portion 21a3 of the upper wall portion 21a, which is the opposing wall portion, but if the entire upper wall portion 21a is curved so as to convex toward the inside of the side sill 2, the entire curved upper wall portion 21a may be used as the deformation promoting portion 23.

[0058] The corner portion 21a3, which becomes the deformation promoting portion 23 shown in FIG. 4, is separated from the second rain 6 by a distance d1 in the normal state before a side collision, but the present invention is not limited to this, and the corner portion 21a3 may be in contact with the second rain 6 in advance.

[0059] (Regarding the deformation promoting portion 24 of the side sill inner 22) As shown in FIG. 4, the third rain 7 of this embodiment is disposed on the surface of the lower wall portion 5b facing outward from the first rain 5, that is, on the lower surface 5b1 of the lower wall portion 5b.

[0060] The side sill inner 22 of this embodiment has the following corner portion 22b3, which becomes a deformation promoting portion 24 that deforms inward of the side sill 2 so as to abut against the third rain 7 arranged as described above from below Z2 (from the outside in the vertical direction Z) during a side collision of the vehicle.

[0061] The side sill inner 22 extends in the vehicle width direction Y and the vehicle front-rear direction X as described above, and has a lower wall portion 22b which is an opposing wall portion opposing the third rain 7.

[0062] 4, the lower wall portion 22b is bent toward the inside of the side sill 2, and has a corner 22b3 that protrudes toward the inside of the side sill 2 due to the bending. The deformation promoting portion 24 is constituted by the corner 22b3.

[0063] The lower wall portion 22b of this embodiment has a horizontal wall portion 22b1 that extends in the horizontal direction (vehicle width direction Y) and faces the third rain 7, and a lower wall portion 22b2 that extends downward Z2 as a distant wall portion that extends from the outer vehicle width direction Y1 end of the horizontal wall portion 22b1 in a direction away from the third rain 7. The corner portion 22b3 is formed by the horizontal wall portion 22b1 and the lower wall portion 22b2.

[0064] A distance d2 between the lower end of the third rain 7 and the corner portion 22b3 in the vertical direction Z is set to be smaller than a length d6 in the vehicle width direction Y of the horizontal wall portion 22b1.

[0065] In this embodiment, the deformation promoting portion 24 is formed by the corner portion 22b3 of the lower wall portion 22b, which is the opposing wall portion. However, if the entire lower wall portion 22b is curved so as to convex toward the inside of the side sill 2, the entire curved lower wall portion 22b may be used as the deformation promoting portion 24.

[0066] The corner portion 22b3, which becomes the deformation promoting portion 24 shown in Figure 4, is separated from the third rain 7 by a distance d2 in the normal state before a side collision, but the present invention is not limited to this and the corner portion 22b3 may be in contact with the third rain 7 in advance.

[0067] (Deformation behavior of side sill 2 and first rain 5 to third rain 7 during a side impact) In the vehicle body 1 configured as described above, as shown in Figures 7(a) to (d), when an obstacle such as a pole P collides from the outer side Y1 of the vehicle width direction toward the inner side Y2 of the vehicle width direction (side collision), the side sill outer 21 is compressed and the three reinforcing members inside the side sill 2, the first rein 5, the second rein 6 and the third rein 7, deform to absorb energy, thereby increasing energy absorption.

[0068] 7(a), the outer wall portion 21c of the side sill outer panel 21 is pushed by the pole P and moves toward the vehicle width direction inward Y2, and the corner portion 21a3 of the upper wall portion 21a, which is the deformation promoting portion 23 of the side sill outer panel 21, enters the inside of the side sill 2, promoting the bending deformation of the upper wall portion 21a. At the same time, the corner portion 21a3 pinches the second rein 6 from above Z1.

[0069] Furthermore, the vertical wall portion 5d of the first rein 5 is pushed toward the vehicle width direction inward Y2 by the outer wall portion 21c, causing the vertical wall portion 5d of the first rein 5 and its surrounding area to be elongated in the up-down direction Z. As a result, the upper wall portion 5a and the lower wall portion 5b of the first rein 5 change from the inclined state shown in Fig. 4 to face horizontally (the vehicle width direction Y) as shown in Fig. 7(a). Therefore, the second rein 6 and the third rein 7 and the first closed cross section 8 and the second closed cross section 9 formed by them face horizontally and are axially compressed in a horizontal state.

[0070] 7(b), the collision load is transmitted to the lower wall portion 22b of the side sill inner 22 via the lower wall portion 21b of the side sill outer panel 21, and the corner portion 22b3 of the lower wall portion 22b, which is the deformation promoting portion 24 of the side sill inner 22, enters the inside of the side sill 2, promoting the bending deformation of the lower wall portion 22b. At the same time, the corner portion 22b3 pinches the third rein 7 from below Z2.

[0071] As described above, the second and third reins 6 and 7, which cooperate with the upper and lower wall portions 5a and 5b of the first rein 5 to form the first and second closed cross sections 8 and 9, are axially compressed in the horizontal direction, thereby suppressing out-of-plane deformation in which the upper and lower wall portions 5a and 5b of the first rein 5 open in the vertical direction Z. At the same time, it is also possible to suppress unintended deformation of the first rein 5, i.e., deformation in which the first rein 5 is compressed while shifting in the vertical direction Z.

[0072] As described above, by suppressing the out-of-plane deformation of the first rein 5 and axially compressing the second rein 6 and the third rein 7 in a horizontal state, the first rein 5, the second rein 6, and the third rein 7 can achieve ideal compressive deformation without unintended displacement in the vertical direction Z, as shown in Figures 7(a) to (d), making it possible to significantly increase the amount of energy absorption.

[0073] (Main features of this embodiment) (1) In the vehicle lower body structure of this embodiment, three reinforcing members, a first rein 5, a second rein 6, and a third rein 7, are arranged inside the closed cross section 2a of the side sill 2.

[0074] In the vehicle side view shown in Figure 5, the second rein 6 cooperates with the upper wall portion 5a of the first rein 5 to form a plurality of first closed cross sections 8 aligned in the vehicle longitudinal direction X. The third rein 7 cooperates with the lower wall portion 5b to form a plurality of second closed cross sections 9 aligned in the vehicle longitudinal direction X.

[0075] With the above-described structure, the second rein 6 and the third rein 7 are axially compressed from the outer side Y1 in the vehicle width direction during a side collision, absorbing energy. This suppresses out-of-plane deformation of the first rein 5, i.e., bending of the upper wall portion 5a upward Z1 and deformation of the lower wall portion 5b downward Z2. As a result, deformation of the first rein 5 in the side sill 2 in the up-down direction Z is suppressed, making it possible to reliably increase the amount of energy absorbed during a side collision.

[0076] (2) In the vehicle lower body structure of this embodiment, as shown in Fig. 4, the second rein 6 is fixed to the upper surface 5a1 of the upper wall portion 5a, and the third rein 7 is fixed to the lower surface 5b1 of the lower wall portion 5b.

[0077] In this configuration, the second rain 6 and the third rain 7 are arranged spaced apart in the vertical direction Z with the first rain 5 in between, and energy absorption can be performed outside the first rain 5. Therefore, it is possible to further suppress out-of-plane deformation of the first rain 5.

[0078] (3) In the vehicle underbody structure of this embodiment, the vertical wall portion 5d of the first rein 5 is disposed on the outer side Y1 in the vehicle width direction of the upper flange portions 21d, 22d and the lower flange portions 21e, 22e, which are joints between the side sill outer panel 21 and the side sill inner panel 22. With this configuration, it is possible to quickly and reliably transmit a side collision load from the outer side Y1 in the vehicle width direction from the side sill outer panel 21 to the vertical wall portion 5d of the first rein 5.

[0079] (4) 5, in the vehicle lower body structure of this embodiment, the first closed cross section 8 formed by the second rein 6 and the upper wall portion 5a has a polygonal structure having a plurality of ridgelines 13 extending in the vehicle width direction Y. In this configuration, the polygonal first closed cross section 8 has a plurality of ridgelines 13 extending in the vehicle width direction Y, which makes it possible to reliably increase the amount of energy absorption during a side collision.

[0080] (5) In the vehicle lower body structure of this embodiment, the second closed cross section 9 formed by the third rain 7 and the lower wall portion 5b has a polygonal structure having a plurality of ridgelines 14 extending in the vehicle width direction Y. In this configuration, the polygonal second closed cross section 9 has a plurality of ridgelines 14 extending in the vehicle width direction Y, which makes it possible to reliably increase the amount of energy absorption during a side collision.

[0081] (6) In the vehicle lower body structure of this embodiment, the second rein 6 and the third rein 7 have different rigidities. With this configuration, it is possible to arbitrarily change the distribution of the load transmitted to the inside of the vehicle body via the second rein 6 and the third rein 7, which have different rigidities.

[0082] (7) In the vehicle lower body structure of this embodiment, the first closed cross section 8 formed by the second rein 6 and the upper wall portion 5a is disposed at a position overlapping with the cross member 3 in the vehicle side view shown in FIG.

[0083] With this configuration, during a side collision, the collision load input to the first closed cross section 8 formed by the upper wall portion 5a of the first reinforcing element 5 and the second reinforcing element 6 can be smoothly transmitted to the cross member 3 (see FIGS. 2 and 3) located on the inner side Y2 in the vehicle width direction of the first closed cross section 8. This makes it possible to further improve impact resistance performance in a side collision.

[0084] 8 and 10, in a modified example of the present invention, when the cross member 3 has an M-shaped cross section with upwardly protruding peaks 3a, arranging the peaks 6a of the second rein 6 so that they overlap the peaks 3a of the cross member 3 in a side view of the vehicle allows the collision load input to the first closed cross section 8 formed by the peaks 6a to be smoothly transmitted to the closed cross section formed by the peaks 3a of the cross member 3, further improving impact resistance against side collisions. Note that the height of the peaks 6a of the second rein 6 on the vehicle rear side X2 shown in FIG. 10 may be lowered because high rigidity is not required as long as the battery pack 4 is not located inside the vehicle.

[0085] 8 and 9, in another modification of the present invention, the peaks 6a of the second rein 6 between two cross members 3 spaced apart in the vehicle longitudinal direction X may be shaped to expand in the longitudinal direction X as they move toward the vehicle widthwise inner side Y2. With this shape, the ridges 15 of the first closed cross section 8 formed by the peaks 6a face the cross members 3, so that the collision load can be smoothly transmitted via the ridges 15 to the cross members 3 even when the cross members 3 are positioned offset in the longitudinal direction X from the peaks 6a.

[0086] (Other features of this embodiment) Other features of this embodiment are as follows (8) to (19).

[0087] (8) 4, in the vehicle lower body structure of this embodiment, the upper wall portion 5a is formed to incline in the upward direction Z1 so as to gradually move away from the lower wall portion 5b toward the inner side Y2 in the vehicle width direction. The second reinforcing bars 6 cooperate with the upper wall portion 5a to form a plurality of first closed cross sections 8 aligned in the vehicle fore-and-aft direction X in the vehicle side view shown in FIG.

[0088] In this configuration, when a collision load is input from the vertical wall portion 5d during a side collision, the first rein 5 undergoes out-of-plane deformation in the vertical direction Z. At this time, the inclined upper wall portion 5a rotates around the end portion on the inner side Y2 in the vehicle width direction as the rotation center and faces the horizontal direction (vehicle width direction Y). As a result, the first closed cross section 8 formed by the upper wall portion 5a and the second rein 6 is axially compressed in a horizontal state. As a result, it is possible to further reliably increase the amount of energy absorption during a side collision.

[0089] (9) 4, in the vehicle lower body structure of this embodiment, the lower wall portion 5b is formed to incline in the downward direction Z2 away from the upper wall portion 5a toward the inner side Y2 in the vehicle width direction. The third rein 7 cooperates with the lower wall portion 5b to form a plurality of second closed cross sections 9 aligned in the vehicle fore-and-aft direction X in the vehicle side view shown in FIG.

[0090] In this configuration, during a side collision, the first rein 5 undergoes out-of-plane deformation in the vertical direction Z, causing the inclined lower wall portion 5b to rotate around the end portion on the inner side Y2 in the vehicle width direction as the rotation center and face the horizontal direction (vehicle width direction Y). As a result, the second closed cross section 9 formed by the lower wall portion 5b and the third rein 7 is axially compressed in a horizontal state. As a result, it is possible to further reliably increase the amount of energy absorbed during a side collision.

[0091] (10) In the vehicle lower body structure of the present embodiment, the vertical wall portion 5d is disposed on the outer side Y1 in the vehicle width direction than the end portion 61 of the second rein 6 on the outer side Y1 in the vehicle width direction.

[0092] In this configuration, during a side collision, when the first rein 5 undergoes out-of-plane deformation in the vertical direction Z, the vertical wall portion 5d of the first rein 5 moves toward the inner side Y2 of the vehicle width direction and reaches the end 61 of the second rein 6 on the outer side Y1 of the vehicle width direction, allowing the inclined upper wall portion 5a to reliably face horizontally.

[0093] (11) In the lower body structure of the vehicle of this embodiment, the total length d5 ​​of the region R including the vertical wall portion 5d of the first rain 5, which is located on the outer side Y1 of the vehicle width direction of the end 61 of the second rain 6 on the outer side Y1 of the vehicle width direction and the end 71 of the third rain 7 on the outer side Y1 of the vehicle width direction, is equal to the distance d4 in the vertical direction Z between the inner side Y2 end of the upper wall portion 5a of the first rain 5 and the inner side Y2 end of the lower wall portion 5b in the vehicle width direction.

[0094] In this configuration, during a side collision, the first rein 5 undergoes out-of-plane deformation in the vertical direction Z, and the region R of the first rein 5 on the outer side Y1 of the vehicle width direction relative to the end 61 of the second rein 6 on the outer side Y1 of the vehicle width direction and the end 71 of the third rein 7 on the outer side Y1 of the vehicle width direction is compressed toward the inner side Y2 of the vehicle width direction while being extended in the vertical direction Z. When the region R is extended in the vertical direction Z, the length d5 ​​of the region R in the vertical direction Z becomes equal to the distance d4 in the vertical direction Z between the inner side Y2 end of the upper wall portion 5a in the vehicle width direction and the inner side Y2 end of the lower wall portion 5b in the vehicle width direction, and the region R formed by the upper wall portion 5a, the lower wall portion 5b, and the vertical wall portion 5d forms a rectangular cross section in a front view of the vehicle. This ensures that in the event of a side collision, the inclined upper wall portion 5a and lower wall portion 5b are reliably oriented horizontally while the vertical wall portion 5d of the first rein 5 advances toward the inner side Y2 of the vehicle width direction and reaches the ends 61, 71 of the second rein 6 and the third rein 7 on the outer side Y1 of the vehicle width direction.

[0095] (12) In the vehicle lower body structure of this embodiment, the second rein 6 is disposed on an upper surface 5a1 of the upper wall portion 5a facing outward from the first rein 5. The side sill outer 21 has a deformation promoting portion 23 (a corner portion 21a3 in this embodiment) that deforms toward the inside of the side sill 2 so as to abut against the second rein 6 from above Z1 (from the outside in the vertical direction Z) during a side collision of the vehicle.

[0096] With this configuration, during a side collision, the deformation promoting portion 23 of the side sill outer panel 21 deforms toward the inside of the side sill 2 and comes into contact with the second rein 6. As a result, the second rein 6 is sandwiched between the deformation promoting portion 23 and the upper wall portion 5a of the first rein 5, thereby restricting deformation in the up-down direction Z, thereby ensuring the progression of axial compression of the first closed cross section 8 formed by the upper wall portion 5a and the second rein 6. As a result, it is possible to further reliably increase the amount of energy absorbed during a side collision.

[0097] (13) In the vehicle lower body structure of this embodiment, the side sill outer 21 has an upper wall portion 21a that extends in the vehicle width direction Y and the vehicle front-rear direction X and is an opposing wall portion that faces the second rein 6. In the front view of the vehicle shown in FIG. 4, the upper wall portion 21a has a corner portion 21a3 that bends toward the inside of the side sill 2 and protrudes in a direction toward the second rein 6. The deformation promoting portion 23 is constituted by the corner portion 21a3.

[0098] With this configuration, during a side collision, the upper wall portion 21a of the side sill outer panel 21 is bent inward starting from the corner 21a3, which becomes the deformation promoting portion 23. As a result, the corner 21a3, which becomes the deformation promoting portion 23, deforms while entering the inside of the side sill 2 and comes into contact with the second rein 6. As a result, the second rein 6 is sandwiched between the corner 21a3 and the upper wall portion 5a of the first rein 5, thereby restricting deformation in the up-down direction Z. This makes it possible to reliably progress axial compression of the first closed cross section 8 formed by the upper wall portion 5a and the second rein 6.

[0099] (14) In the vehicle lower body structure of this embodiment, the upper wall portion 5a of the first rein 5 is formed to be inclined in the upward direction Z1 so as to gradually move away from the lower wall portion 5b toward the vehicle width direction inner side Y2. In this configuration, due to out-of-plane deformation of the first rein 5 during a side collision, the inclined upper wall portion 5a rotates toward the deformation promoting portion 23 of the side sill outer panel 21, with the end portion on the vehicle width direction inner side Y2 as a fulcrum. Therefore, the second rein 6 is pressed by the rotating upper wall portion 5a in the direction toward the deformation promoting portion 23. As a result, the corner portion 21a3, which becomes the deformation promoting portion 23, can sandwich the second rein 6 between itself and the upper wall portion 5a with a small force.

[0100] (15) In the vehicle lower body structure of this embodiment, the upper wall portion 5a is disposed higher than the lower wall portion 5b. The deformation promoting portion 23 is formed on the upper portion of the side sill outer 21. In this configuration, the deformation promoting portion 23 formed on the upper portion of the side sill outer 21 can press the second rein 6 from above. This allows the second rein 6 to be securely sandwiched between the deformation promoting portion 23 and the upper wall portion 5a.

[0101] (16) In the vehicle lower body structure of this embodiment, the third rain 7 is disposed on the lower surface 5b1 of the lower wall portion 5b of the first rain 5, facing outward from the first rain 5. The side sill inner 22 has a deformation promoting portion 24 (in this embodiment, a corner portion 22b3) that deforms inward of the side sill 2 so as to abut against the third rain 7 from below Z2 (from the outside in the vertical direction Z) during a side collision of the vehicle.

[0102] With this configuration, during a side collision, the deformation promoting portion 24 of the side sill inner panel 22 deforms inwardly of the side sill 2 and comes into contact with the third rein 7. As a result, the third rein 7 is sandwiched between the deformation promoting portion 24 and the lower wall portion 5b of the first rein 5, thereby restricting deformation in the up-down direction Z, thereby ensuring the progression of axial compression of the second closed cross section 9 formed by the lower wall portion 5b and the third rein 7. As a result, it is possible to further reliably increase the amount of energy absorbed during a side collision.

[0103] (17) In the vehicle lower body structure of this embodiment, the side sill inner 22 has a lower wall portion 22b that extends in the vehicle width direction Y and the vehicle front-rear direction X and is an opposing wall portion that faces the third rain 7. In the vehicle front view shown in Figures 3 and 4, the lower wall portion 22b has a corner portion 22b3 that bends inward of the side sill 2 and protrudes inward of the side sill 2. The deformation promoting portion 24 is constituted by the corner portion 22b3.

[0104] With this configuration, during a side collision, the opposing wall portion of the side sill inner 22 is bent inward starting from the corner 22b3, which becomes the deformation promoting portion 24. As a result, the corner 22b3, which becomes the deformation promoting portion 24, deforms while entering the inside of the side sill 2 and comes into contact with the third rein 7. As a result, the third rein 7 is sandwiched between the corner 22b3 and the lower wall portion 5b of the first rein 5, thereby restricting deformation in the up-down direction Z. This makes it possible to reliably progress axial compression of the second closed cross section 9 formed by the lower wall portion 5b and the third rein 7.

[0105] (18) In the lower body structure of the vehicle of this embodiment, the lower wall portion 22b of the side sill inner 22 has a horizontal wall portion 22b1 extending in the vehicle width direction Y and facing the third rain 7, and a lower wall portion 22b2 extending downward Z2 as a distal wall portion extending from the vehicle width direction outer Y1 end of the horizontal wall portion 22b1 in a direction away from the third rain 7.

[0106] The corner 22b3 is formed by the horizontal wall portion 22b1 and the lower wall portion 22b2.

[0107] A distance d2 between the lower end of the third rein 7 and the corner 22b3 in the vertical direction Z is set to be smaller than a length d6 of the horizontal wall portion 22b1 in the vehicle width direction Y. As a result, during a side collision, the third rein 7 is securely sandwiched between the corner 22b3 and the lower wall 5b of the first rein 5, thereby more reliably promoting axial compression of the second closed cross section 9 formed by the lower wall 5b and the third rein 7.

[0108] (19) The vehicle lower body structure of this embodiment includes a battery pack 4 disposed between a pair of left and right side sills 2. The battery pack 4 is fixed to a horizontal wall portion 22b1 of the lower wall portion 22b, which is the opposing wall portion of the side sill inner panel 22. In this configuration, the corner portion 22b3, which is the deformation promoting portion 24, cooperates with the battery pack 4 fixed to the lower wall portion 22b to reliably sandwich the third rein 7 between the lower wall portion 22b and the corner portion 22b in the event of a side collision.

[0109] (Scope of the present invention) In the above embodiment, the body 1 of an electric vehicle (EV) shown in Figure 1 is used as an example of application of the lower body structure of the present invention, but the present invention can be widely applied to all automobiles other than EVs as long as they have side sills. [Explanation of symbols]

[0110] 1. Body 2 Side sill 2a Closed section 3 Cross members 4 Battery Pack 5 First Reinforcement (First Rein) 5a Upper wall 5b Lower wall part 5d Vertical wall section 6 Second Reinforcement (Second Rein) 7 Third Reinforcement (Third Rein) 8 1st closed section 9 Second closed section 21 Side sill outer 21a Upper wall part 21b Lower wall part 21b3 Corner 22 Side sill inner 22a Upper wall part 22b Lower wall part 22b3 Corner 23, 24 Deformation promotion section

Claims

1. a pair of left and right side sills that define a closed cross section extending in the vehicle front-rear direction on the outer sides of the vehicle body in the vehicle width direction; a first reinforcement, a second reinforcement, and a third reinforcement, which are reinforcing members arranged inside the closed cross section; Equipped with the first reinforcement is fixed to a wall portion of the side sill on the inner side in the vehicle width direction, and has an upper wall portion and a lower wall portion extending in the vehicle width direction and the front-rear direction, and a vertical wall portion extending in the up-down direction from the outer end portion of the upper wall portion in the vehicle width direction to the outer end portion of the lower wall portion in the vehicle width direction, and has a hat shape that protrudes outward in the vehicle width direction and opens inward in the vehicle width direction, the second reinforcement cooperates with the upper wall portion to form a plurality of first closed cross sections aligned in the front-rear direction of the vehicle in a side view of the vehicle, the third reinforcement cooperates with the lower wall portion to form a plurality of second closed cross sections aligned in the front-rear direction of the vehicle in a vehicle side view; A vehicle underbody structure characterized by:

2. 2. The vehicle underbody structure according to claim 1, the second reinforcement is fixed to an upper surface of the upper wall portion, The third reinforcement is fixed to the lower surface of the lower wall portion. The vehicle's underbody structure.

3. 3. The vehicle underbody structure according to claim 1, The side sill includes a side sill outer and a side sill inner that is disposed inward of the side sill outer in the vehicle width direction and joined to the side sill outer, The vertical wall portion is disposed outward in the vehicle width direction from a joint portion between the side sill outer and the side sill inner. The vehicle's underbody structure.

4. 3. The vehicle underbody structure according to claim 1, The first closed cross section is a polygonal structure having a plurality of ridgelines extending in a vehicle width direction.

5. 3. The vehicle underbody structure according to claim 1, The second closed cross section is a polygonal structure having a plurality of ridgelines extending in the vehicle width direction.

6. 3. The vehicle underbody structure according to claim 1, The second reinforcement and the third reinforcement have different rigidities.

7. 3. The vehicle underbody structure according to claim 1, a cross member extending in the vehicle width direction and connecting the pair of left and right side sills; The first closed cross section is positioned so as to overlap with the cross member in a side view of the vehicle.

Images