Lower vehicle body structure of vehicle

Abstract

The purpose of the present invention is to provide a lower vehicle-body structure for a vehicle, the lower vehicle-body structure being capable of practically increasing the amount of energy absorbed during a lateral collision. A vehicle body (1) is provided with a first reinforcement (5), a second reinforcement (6), and a third reinforcement (7) disposed inside a closed cross-section (2a) of a side member (2). The first reinforcement (5) has a cap shape and has an upper wall portion (5a), a lower wall portion (5b), and a vertical wall portion (5d) extending in the vertical direction. The second reinforcements (6) cooperate with the upper wall portion (5a) to form a plurality of first closed cross sections (8). The third reinforcing member (7) cooperates with the lower wall part (5b) to form a plurality of second closed cross sections (9).

Description

Technical Field

[0001] The present invention relates to a lower body structure of a vehicle. Background Art

[0002] When an obstacle, such as a ball, collides with a vehicle from the side, known as a side collision, a significant amount of collision energy is input into the side sills, components of the vehicle's side. This energy transfer from the side sills into the vehicle's interior can potentially impact occupants and other components. In electric vehicles (EVs), this can particularly impact the battery pack, which is positioned further inward in the vehicle's width than the side sills. To prevent these impacts, side sills are required to absorb the energy.

[0003] Therefore, various previously proposed structures have employed reinforcement members with a hollow, closed cross-section within the side sills to absorb energy during side collisions. For example, in the vehicle body structure described in Patent Document 1, a reinforcement member formed of sheet metal with a roughly M-shaped cross-section is installed within the side sills. The reinforcement member is positioned so that the two protruding portions of the M-shaped cross-section face outward in the vehicle width direction, forming a hollow, closed cross-section together with the side sills.

[0004] In the above structure, when a side collision occurs, the hollow closed cross section formed by the two convex portions of the reinforcement member having a substantially M-shaped cross section is compressed in the vehicle width direction, thereby absorbing energy.

[0005]

Prior art literature

[0006] [Technical problem to be solved by the invention] However, the M-shaped reinforcement within the side sill can sometimes undergo unexpected deformation depending on the conditions of a side collision. In a side collision, the closed section formed by the convex portion does not compress in the vehicle width direction as expected, but instead compresses vertically while shifting. This can lead to a loss of energy absorption within the reinforcement, sometimes failing to achieve the target energy absorption.

[0007] In view of the above circumstances, an object of the present invention is to provide a vehicle lower body structure that can reliably increase the amount of energy absorbed during a side collision.

[0008]

Technical means to solve technical problems

[0009] In this embodiment, when a side collision occurs, the second and third reinforcements are axially compressed from the outside in the vehicle width direction, thereby absorbing energy. This suppresses out-of-plane deformation of the first reinforcement, specifically, suppresses upward bending of the upper wall and downward deformation of the lower wall. As a result, vertical deformation of the first reinforcement within the side sill is suppressed, effectively increasing energy absorption during a side collision.

[0010] In the above vehicle lower body structure, preferably, the second reinforcement is fixed to an upper side surface of the upper wall portion, and the third reinforcement is fixed to a lower side surface of the lower wall portion.

[0011] In the above embodiment, the second and third reinforcements are vertically separated with the first reinforcement sandwiched therebetween, and can absorb energy outside the first reinforcement. Therefore, out-of-plane deformation of the first reinforcement can be further suppressed.

[0012] In the above-mentioned vehicle lower body structure, the side member preferably includes an outer member and an inner member, the inner member being arranged further inward in the vehicle width direction than the outer member and joined to the outer member, and the longitudinal wall portion is preferably arranged further outward in the vehicle width direction than a joint between the outer member and the inner member.

[0013] The above configuration can quickly and reliably transmit the side collision load from the outer side in the vehicle width direction from the outer side member 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] In the above aspect, the first closed cross section of the polygonal structure has a plurality of ridge lines extending in the vehicle width direction, thereby reliably increasing the amount of energy absorbed during 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] In the above aspect, the second closed cross section of the polygonal structure has a plurality of ridge lines extending in the vehicle width direction, thereby reliably increasing the amount of energy absorbed during a side collision.

[0018] In the above vehicle lower body structure, it is preferred that the second reinforcement and the third reinforcement have different rigidities from each other.

[0019] The above-described configuration can arbitrarily change the distribution of the load transmitted to the interior of the vehicle body via the second reinforcement and the third reinforcement having different rigidities.

[0020] The vehicle lower body structure preferably further comprises a cross member extending in the vehicle width direction and connecting the left and right paired side members, and the first closed cross section is preferably arranged at a position overlapping the cross member when viewed from the side of the vehicle.

[0021] The above configuration can smoothly transmit the collision load input to the first closed cross-section (the first closed cross-section formed by the upper wall portion of the first reinforcement and the second reinforcement) during a side collision to the cross member.

[0022] Effects of the invention As described above, the vehicle underbody structure of the present invention can reliably increase the amount of energy absorbed during a side collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A vehicle body plan view showing the overall structure of a lower vehicle body structure of a vehicle according to an embodiment of the present invention; Figure 2 exhibit Figure 1 A partial cross-sectional enlarged view of the side member, the cross member, and the arrangement of the first reinforcement and the second reinforcement inside the side member; Figure 3 For the Figure 2 A cross-sectional view along line III-III; Figure 4 for Figure 3 An enlarged view of the side member and the first to third reinforcement members inside it; Figure 5 From the outside of the vehicle width direction, that is, from the side of the vehicle Figure 3 Figures of the 1st to 3rd reinforcement members; Figure 6 for Figure 5 An enlarged oblique view of the first to third reinforcement members; Figure 7 (a) to (d) show the side collision Figure 3 Figure 2 shows the deformation behavior of the side member and the first to third reinforcements; Figure 8 This is a top view of a modified example of the present invention, illustrating a structure in which the peak portion of the second reinforcement and the peak portion of the M-shaped cross-member are arranged in the vehicle width direction, and the peak portion of the second reinforcement between the cross-members expands in the front-rear direction toward the inner side in the vehicle width direction; Figure 9 exhibit Figure 8 An enlarged perspective view of a structure in which the peak portion of the second reinforcement member expands in the front-rear direction as it moves inward in the vehicle width direction; Figure 10 This is a side view of another modified example of the present invention, which shows the following structure: on the front side of the vehicle, the peak portion of the second reinforcement and the peak portion of the M-shaped cross-section beam are arranged in the vehicle width direction, while on the rear side of the vehicle, the peak portion of the second reinforcement is low. DETAILED DESCRIPTION

[0024] Hereinafter, a vehicle underbody structure according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0025] (Overall structure of vehicle body 1) In this embodiment, an example Figure 1 As shown, a vehicle body 1 of an electric vehicle (EV) having a battery pack 4 below a cross member 3 will be described as an application example of the lower vehicle body structure of the present invention. Figures 1 to 3 The vehicle body 1 shown includes: a pair of left and right side members 2 having a closed cross-section 2a extending in the vehicle front-rear direction X on the outside Y1 in the vehicle width direction of the vehicle body 1; a plurality of cross members 3 extending in the vehicle width direction Y; a battery pack 4 arranged below Z2 of the cross member 3; a first reinforcement (hereinafter referred to as the first reinforcement 5), a second reinforcement (hereinafter referred to as the second reinforcement 6), and a third reinforcement 7 (hereinafter referred to as the third reinforcement 7), which are three reinforcement members arranged inside the closed cross-section 2a.

[0026] The side member 2 includes an outer member 21, which is located on the outer side Y1 in the vehicle width direction, and an inner member 22, which is located on the inner side Y2 in the vehicle width direction. The inner member 22 is positioned further inwardly than the outer member 21 in the vehicle width direction Y2, and cooperates with the outer member 21 to form the side member 2 having a closed cross-section 2a.

[0027] like Figure 4As shown, the outer side member 21 and the inner side member 22 respectively have deformation promoting portions 23 and 24 for promoting inward deformation of the side member 2 during a side collision. The deformation promoting portions 23 and 24 will be described in detail in the following paragraphs.

[0028] like Figure 4 As shown, the outer side member 21 includes an upper wall portion 21a, a lower wall portion 21b located below the upper wall portion 21a (Z2), an outer wall portion 21c, an upper flange portion 21d, and a lower flange portion 21e. These are formed from metal plates 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 vertical direction Z. The outer wall portion 21c forms the side wall of the side member 2 on the vehicle width direction outer side Y1. It extends in the vertical direction Z and connects the vehicle width direction 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 vertical direction Z, spaced apart from each other, from the vehicle width direction inner side Y2 ends of the upper wall portion 21a and the lower wall portion 21b.

[0029] The inner side member 22 includes an upper wall portion 22a, a lower wall portion 22b located below the upper wall portion 22a (Z2), an inner wall portion 22c, an upper flange portion 22d, and a lower flange portion 22e. The inner side member 22 is formed from 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, separated from each other in the vertical direction Z. The inner wall portion 22c forms the side wall of the side member 2 on the vehicle width direction inner side Y2. It extends in the vertical direction Z and connects the vehicle width direction 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 from the vehicle width direction outer side Y1 ends of the upper wall portion 22a and the lower wall portion 22b in the vertical direction Z and in directions separated from each other.

[0030] The upper flange portion 22d and the lower flange portion 22e of the inner beam 22 are respectively joined to the upper flange portion 21d and the lower flange portion 21e of the outer beam 21 by welding or the like.

[0031] like Figures 1-2 As shown, a plurality of cross members 3 extend in the vehicle width direction Y and are separated from each other in the front-rear direction X, and connect the inner side members 22 of the left and right paired side members 2 .

[0032] like Figure 3 As shown, the battery pack 4 is positioned below the plurality of cross members 3 and between the paired left and right side members 2. The battery pack 4 comprises a battery housing 4a and at least one battery module 4b housed within the housing 4a. A flange 4a1 protrudes from the side wall of the battery housing 4a toward the vehicle width direction outward Y1.

[0033] The battery pack 4 is fixed to the lower wall portion 22b of the inner side member 22 of the left and right paired side members 2. Specifically, the flange portion 4a1 of the battery case 4a is fixed to the lower wall portion 22b (specifically, the horizontal wall portion 22b1 described below) by bolts 11 and nuts 12.

[0034] (Description of Three Reinforcement Members (First Reinforcement 5, Second Reinforcement 6, Third Reinforcement 7)) like Figure 4 As shown, the first reinforcement 5 includes an upper wall portion 5a, a lower wall portion 5b located below the upper wall portion 5a at a position Z2, a longitudinal 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 separated from each other in the vertical 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 paired flange portions 5c form a hat-shaped first reinforcement member 5 that protrudes toward the vehicle width direction outer side Y1 and opens toward the vehicle width direction inner side Y2.

[0036] In this embodiment, the upper wall portion 5a is formed to be inclined so as to gradually separate 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 that gradually moves upward Z1 as it moves toward the vehicle width direction inner side Y2. The inclination angle θ1 of the upper wall portion 5a relative to the horizontal direction (the vehicle width direction Y) is set so that, in the event of a side collision, the upper wall portion 5a will be oriented horizontally after receiving a compressive load directed toward the vehicle width direction inner side Y2 on the longitudinal wall portion 5d.

[0037] In this embodiment, the lower wall portion 5b is formed to be inclined so as to separate from the upper wall portion 5a as it moves toward the vehicle width direction inner side Y2. Specifically, the lower wall portion 5b is inclined so as to move downward toward the vehicle width direction inner side Y2. The inclination angle θ2 of the lower wall portion 5b relative to the horizontal direction (the vehicle width direction Y) is set so that, in the event of a side collision, the vertical wall portion 5d, upon receiving a compressive load directed toward the vehicle width direction inner side Y2, will orient the lower wall portion 5b toward the horizontal direction.

[0038] The vertical wall portion 5d is a portion that extends in the vertical direction Z and connects the end portions of the upper wall portion 5a and the lower wall portion 5b on the vehicle width direction outer side Y1. In other words, the vertical wall portion 5d extends in the vertical direction Z from the end portion of the upper wall portion 5a on the vehicle width direction outer side Y1 to the end portion of the lower wall portion 5b on the vehicle width direction outer side Y1.

[0039] The vertical wall portion 5d is arranged farther outward in the vehicle width direction Y1 than the upper flange portions 21d and 22d and the lower flange portions 21e and 22e which are the joint portions between the outer side member 21 and the inner side member 22.

[0040] like Figure 3As shown, the first reinforcement 5 can be placed at a position overlapping the cross member 3 and the battery pack 4 in the vertical direction Z or in the range between the cross member 3 and the battery pack 4. This allows the collision load applied to the first reinforcement 5 during a side collision to be dispersed and transmitted to the cross member 3 and the battery pack 4.

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

[0042] The manufacturing method of the first reinforcement 5 is not particularly limited. For example, it is preferable to pre-form two vertically divided sections at the longitudinal wall portion 5d during the intermediate stage of manufacturing the first reinforcement 5. The second reinforcement 6 and the third reinforcement 7 are then joined to the two divided sections by welding or other means, and then the two sections are joined together by welding or other means. This manufacturing method allows the second reinforcement 6 and the third reinforcement 7 to be easily joined to the divided first reinforcement 5. Alternatively, the first reinforcement 5 can be integrally formed from a metal plate or the like.

[0043] The second reinforcement 6 is a reinforcement member. Figure 5 In the side view of the vehicle shown, a plurality of first closed cross sections 8 arranged in the vehicle front-rear direction X are formed in cooperation with the upper wall portion 5 a of the first reinforcement 5 .

[0044] like Figures 2 to 6 As shown, the second reinforcement 6 of this embodiment is a strip-shaped plate-like member, which is fixed to the upper wall portion 5a of the first reinforcement 5, extends in the vehicle front-rear direction X, and continuously repeats the convex and concave in the up-down direction Z. The second reinforcement 6 has a plurality of peaks 6a and valleys 6b arranged alternately in the vehicle front-rear direction X, and is joined to the upper side surface 5a1 of the upper wall portion 5a at the valley portion 6b by welding or the like. The peak 6a is roughly trapezoidal in shape when viewed from the side of the vehicle. Therefore, the peak 6a and the upper wall portion 5a form a first closed section 8 of a trapezoidal shape extending in the vehicle width direction Y. The first closed section 8 is a member having a plurality of ridges 13 extending in the vehicle width direction Y (see Figure 6 ) polygonal structure. In addition, the first closed cross section 8 can be not only trapezoidal, but also other polygonal structures. The first closed cross section 8 can also be triangular.

[0045] The first closed section 8 is Figure 5 The side view of the vehicle shown is arranged at a position that overlaps with the crossbeam 3. Figures 2-3 As shown, the first closed cross section 8 formed at the position of the peak portion 6 a of the second reinforcement 6 is arranged in the range where the cross member 3 exists in the vehicle front-rear direction X.

[0046] The third reinforcement member 7 is a reinforcement member. Figure 5 In the side view of the vehicle shown, it cooperates with the lower wall portion 5b to form a plurality of second closed cross sections 9 arranged in the vehicle front-rear direction X.

[0047] The shape of the third reinforcement member 7 of this embodiment is the shape of the second reinforcement member 6 turned upside down. Figures 3 to 6 As shown, the third reinforcement 7 is a strip-shaped plate-like member fixed to the lower wall portion 5b of the first reinforcement 5, which extends in the vehicle front-rear direction X and continuously repeats convex and concave in the up-down direction Z. The third reinforcement 7 has a plurality of peaks 7a and valleys 7b arranged alternately in the vehicle front-rear direction X, and is joined to the lower side surface 5b1 of the lower wall portion 5b at the valley portion 7b by welding or the like. The peak 7a is roughly trapezoidal in shape when viewed from the side of the vehicle. Therefore, the peak 7a and the lower wall portion 5b form a second closed section 9 of a trapezoidal shape extending in the vehicle width direction Y. The second closed section 9 is a section having a plurality of ridges 14 extending in the vehicle width direction Y (refer to Figure 6 The second closed cross section 9 may not only be a trapezoidal shape but also other polygonal structures. Alternatively, the second closed cross section 9 may be a triangular shape.

[0048] The second reinforcement 6 and the third reinforcement 7 are shaped so that they can cooperate with the upper wall portion 5a and the lower wall portion 5b of the first reinforcement 5 to form the first closed cross section 8 and the second closed cross section 9. Therefore, the second reinforcement 6 and the third reinforcement 7 can be made of not only Figure 2 、 Figures 5-6 The structure shown is composed of a series of strip-shaped plate-shaped members, but may also be composed of a plurality of hat-shaped members having at least one peak portion 6a, 7a.

[0049] The second reinforcement 6 and the third reinforcement 7 may have different rigidities. This allows for the distribution of loads transmitted to the vehicle body interior via the second reinforcement 6 and the third reinforcement 7 during a side collision to be arbitrarily varied. The "rigidity" mentioned above refers to bending rigidity against side collision loads.

[0050] like Figures 3-4 As shown, in terms of positional relationship with the second reinforcement 6, the vertical wall portion 5d of the first reinforcement 5 in this embodiment is positioned further outward in the vehicle width direction Y1 than the end portion 61 of the second reinforcement 6 on the vehicle width direction outward Y1. In other words, the end portion 61 of the second reinforcement 6 is positioned a distance d3 from the outer surface of the vertical wall portion 5d of the first reinforcement 5 toward the inner side Y2 in the vehicle width direction. Furthermore, the end portion 71 of the third reinforcement 7 is also positioned a distance d3 from the outer surface of the vertical wall portion 5d of the first reinforcement 5 toward the inner side Y2 in the vehicle width direction.

[0051] In addition, if Figure 4As shown, the total length d5 ​​of the region R of the first reinforcement 5 including the longitudinal wall portion 5d extending in the up-down direction Z and the vehicle width direction Y, that is, the total length d5 ​​of the region R which is closer to the vehicle width direction outer side Y1 than the vehicle width direction outer side Y1 end 61 of the second reinforcement 6 and the vehicle width direction outer side Y1 end 71 of the third reinforcement 7, is set to be equal to the distance d4 in the up-down direction Z between the vehicle width direction inner side Y2 end of the upper wall portion 5a of the first reinforcement 5 and the vehicle width direction inner side Y2 end of the lower wall portion 5b.

[0052] (Regarding the Deformation Accelerating Portion 23 of the Outer Beam 21) like Figure 4 As shown, the second reinforcement 6 of the present embodiment is arranged on the surface of the upper wall portion 5 a facing outward from the first reinforcement 5 , that is, on the upper side surface 5 a 1 of the upper wall portion 5 a .

[0053] The outer side member 21 of this embodiment has a corner portion 21a3 described later. This corner portion 21a3 serves as a deformation promoting portion 23. When the vehicle is involved in a side collision, it contacts the second reinforcement 6 arranged as described above from the upper side Z1 (from the outer side in the vertical direction Z) and deforms toward the inside of the side member 2.

[0054] As described above, the outer side member 21 includes the upper wall portion 21 a which is an opposing wall portion extending in the vehicle width direction Y and the vehicle front-rear direction X and facing the second reinforcement 6 .

[0055] exist Figure 4 The upper wall portion 21a is bent inwardly of the side member 2 in the vehicle front view, and has a corner portion 21a3 protruding toward the second reinforcement 6. The deformation promoting portion 23 is formed by the corner portion 21a3.

[0056] Specifically, the upper wall portion 21a of this embodiment includes a horizontal portion 21a1 extending in the horizontal direction (the vehicle width direction Y), and an inclined portion 21a2 that slopes upward (Z1) toward the vehicle width direction inner side Y2. The inclined portion 21a2 connects the horizontal portion 21a1 and the upper flange portion 21d. The upper wall portion 21a includes a corner portion 21a3 formed by the horizontal portion 21a1 and the inclined portion 21a2, which protrudes inwardly toward the side sill 2. In the event of a side collision, the horizontal portion 21a1 of the upper wall portion 21a of the outer side sill 21 is subjected to a compressive load in the horizontal direction (the vehicle width direction Y) toward the vehicle width direction inner side Y2. This allows the upper wall portion 21a to reliably bend inwardly toward the side sill 2, starting from the deformation promoting portion 23, i.e., the corner portion 21a3.

[0057] The deformation promoting portion 23 of this embodiment is composed of the corner portion 21a3 of the upper wall portion 21a, which is the opposite wall portion. However, when the upper wall portion 21a is bent as a whole and protrudes toward the inner side of the side member 2, the entire bent upper wall portion 21a can serve as the deformation promoting portion 23.

[0058] Figure 4 The illustrated deformation promoting portion 23 , namely the corner portion 21 a 3 , is spaced apart from the second reinforcement 6 by a distance d1 in a normal state before a side collision. However, the present invention is not limited thereto, and the corner portion 21 a 3 may be in contact with the second reinforcement 6 in advance.

[0059] (Regarding the Deformation Accelerating Portion 24 of the Inner Sill 22) like Figure 4 As shown, the third reinforcement 7 of this embodiment is arranged on the surface of the lower wall portion 5b facing the outside of the first reinforcement 5, that is, on the lower side surface 5b1 of the lower wall portion 5b.

[0060] The inner side member 22 of this embodiment has a corner portion 22b3 described later as a deformation promoting portion 24. When the vehicle is involved in a side collision, the deformation promoting portion 24 contacts the third reinforcement 7 arranged as described above from the lower side Z2 (from the outer side in the vertical direction Z) and deforms toward the inner side of the side member 2.

[0061] As described above, the inner side member 22 includes the lower wall portion 22 b which is an opposing wall portion extending in the vehicle width direction Y and the vehicle front-rear direction X and which faces the third reinforcement 7 .

[0062] exist Figure 4 The lower wall portion 22b is bent inwardly of the side member 2 in the vehicle front view, and the bending provides a corner portion 22b3 that protrudes inwardly of the side member 2. The deformation promoting portion 24 is formed by the corner portion 22b3.

[0063] The lower wall portion 22b of this embodiment includes a horizontal wall portion 22b1 extending horizontally (in the vehicle width direction Y) and facing the third reinforcement member 7; and a lower wall portion 22b2 extending downwardly (Z2) as a distance wall portion extending from the vehicle width direction outer side (Y1) end of the horizontal wall portion 22b1 in a direction away from the third reinforcement member 7. A 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 reinforcement 7 and the corner portion 22b3 in the up-down direction Z is set to be smaller than a length d6 of the horizontal wall portion 22b1 in the vehicle width direction Y.

[0065] The deformation promoting portion 24 of this embodiment is formed by the corner portion 22b3 of the opposing wall portion, namely the lower wall portion 22b. However, when the lower wall portion 22b is bent as a whole and protrudes toward the inside of the side member 2, the entire bent lower wall portion 22b can serve as the deformation promoting portion 24.

[0066] Figure 4The corner portion 22b3 serving as the deformation promoting portion 24 is shown as being spaced apart from the third reinforcement 7 by a distance d2 in a normal state before a side collision. However, the present invention is not limited thereto, and the corner portion 22b3 may be in contact with the third reinforcement 7 in advance.

[0067] (Deformation Behavior of the Side Sill 2 and the First to Third Reinforcements 5 to 7 During a Side Collision) According to the above scheme, if Figure 7 As shown in (a) to (d), when an obstacle such as a ball P collides with the vehicle body 1 from the outer side Y1 in the vehicle width direction toward the inner side Y2 in the vehicle width direction (in the case of a side collision), the outer side member 21 is compressed and the three reinforcing members inside the side member 2, namely the first reinforcement 5, the second reinforcement 6, and the third reinforcement 7, are deformed and absorb energy at the same time, thereby achieving increased energy absorption.

[0068] Specifically, in Figure 7 In the initial stage of a side collision (shown in (a), the outer wall portion 21c of the outer sill 21 is squeezed by the ball P, causing the outer sill 21 to move inward in the vehicle width direction Y2. The deformation promoting portion 23 of the outer sill 21, namely the corner 21a3 of the upper wall portion 21a, enters the inner side of the side sill 2, thereby promoting the bending deformation of the upper wall portion 21a. Furthermore, the corner 21a3 sandwiches the second reinforcement 6 from above Z1.

[0069] Furthermore, the vertical wall portion 5d of the first reinforcement 5 is pressed toward the vehicle width direction inner side Y2 by the outer wall portion 21c, thereby causing the vertical wall portion 5d of the first reinforcement 5 and its surrounding portion to extend in the vertical direction Z. As a result, the upper wall portion 5a and the lower wall portion 5b of the first reinforcement 5 are extended from Figure 4 The tilted state shown becomes similar to Figure 7 (a) is oriented in the horizontal direction (vehicle width direction Y). Therefore, the second reinforcement 6, the third reinforcement 7, and the first closed cross section 8 and the second closed cross section 9 formed therefrom are oriented in the horizontal direction and are axially compressed in a horizontal state.

[0070] In addition, Figure 7 During the initial to mid-stage of a side collision (shown in (b)), the collision load is transmitted to the lower wall 22b of the inner sill 22 via the lower wall 21b of the outer sill 21. Consequently, the deformation promoting portion 24 of the inner sill 22, namely the corner 22b3 of the lower wall 22b, intrudes into the inner side sill 2 and promotes bending deformation of the lower wall 22b. Furthermore, the corner 22b3 sandwiches the third reinforcement 7 from below (Z2).

[0071] As described above, the second reinforcement 6 and the third reinforcement 7, which form the first closed cross-section 8 and the second closed cross-section 9 in cooperation with the upper wall portion 5 a and the lower wall portion 5 b of the first reinforcement 5 , are axially compressed in the horizontal direction, thereby suppressing the upper wall portion 5 a and the lower wall portion 5 b of the first reinforcement 5 from deforming out of plane, that is, from opening in the vertical direction Z. Furthermore, the first reinforcement 5 can be suppressed from unexpected deformation, that is, from deformation such as the first reinforcement 5 being compressed while being displaced in the vertical direction Z.

[0072] As described above, by suppressing the out-of-plane deformation of the first reinforcement 5 and compressing the second reinforcement 6 and the third reinforcement 7 in the horizontal state, the first reinforcement 5, the second reinforcement 6, and the third reinforcement 7 can be like Figure 7 By achieving ideal compression deformation as in (a) to (d) without unexpected deviation in the vertical direction Z, the energy absorption amount can be greatly increased.

[0073] (Main Features of This Embodiment) (1) In the vehicle lower body structure of the present embodiment, three reinforcement members, namely, the first reinforcement 5 , the second reinforcement 6 , and the third reinforcement 7 , are arranged inside the closed cross section 2 a of the side member 2 .

[0074] exist Figure 5 In the side view of the vehicle shown, the second reinforcement 6 cooperates with the upper wall portion 5a of the first reinforcement 5 to form a plurality of first closed cross-sections 8 arranged in the vehicle front-rear direction X. Furthermore, the third reinforcement 7 cooperates with the lower wall portion 5b to form a plurality of second closed cross-sections 9 arranged in the vehicle front-rear direction X.

[0075] With this structure, in the event of a side collision, the second and third reinforcements 6 and 7 are axially compressed from the vehicle widthwise outer side Y1, thereby absorbing energy. This suppresses out-of-plane deformation of the first reinforcement 5, specifically, suppresses bending of the upper wall portion 5a upward Z1 and deformation of the lower wall portion 5b downward Z2. As a result, vertical Z-direction deformation of the first reinforcement 5 within the side member 2 is suppressed, effectively increasing the amount of energy absorbed during a side collision. (2) In the vehicle lower body structure of this embodiment, as Figure 4 As shown, the second reinforcement 6 is fixed to the upper side surface 5a1 of the upper wall portion 5a, and the third reinforcement 7 is fixed to the lower side surface 5b1 of the lower wall portion 5b.

[0077] In the above embodiment, the second reinforcement 6 and the third reinforcement 7 are spaced apart in the vertical direction Z with the first reinforcement 5 interposed therebetween, and can absorb energy outside the first reinforcement 5. Therefore, out-of-plane deformation of the first reinforcement 5 can be further suppressed. (3) In the vehicle lower body structure of this embodiment, the longitudinal wall portion 5d of the first reinforcement 5 is positioned further outward in the vehicle width direction Y1 than the upper flange portions 21d, 22d and the lower flange portions 21e, 22e, which are the joints between the outer side member 21 and the inner side member 22. This configuration allows a side collision load from the outer side in the vehicle width direction Y1 to be quickly and reliably transmitted from the outer side member 21 to the longitudinal wall portion 5d of the first reinforcement 5. (4) In the vehicle lower body structure of this embodiment, as Figure 5 As shown, the first closed cross section 8 formed by the second reinforcement 6 and the upper wall portion 5a has a polygonal structure having a plurality of ridges 13 extending in the vehicle width direction Y. In the above embodiment, the polygonal first closed cross section 8 having the plurality of ridges 13 extending in the vehicle width direction Y can reliably increase the amount of energy absorbed during a side collision. (5) In the vehicle lower body structure of this embodiment, the second closed cross-section 9 formed by the third reinforcement 7 and the lower wall portion 5b has a polygonal structure having a plurality of ridges 14 extending in the vehicle width direction Y. In this embodiment, the polygonal second closed cross-section 9 having the plurality of ridges 14 extending in the vehicle width direction Y reliably increases the amount of energy absorbed during a side collision. (6) In the vehicle lower body structure of this embodiment, the second reinforcement 6 and the third reinforcement 7 have different rigidities. This configuration can arbitrarily change the distribution of the load transmitted to the vehicle body through the second reinforcement 6 and the third reinforcement 7 having different rigidities. (7) In the vehicle lower body structure of the present embodiment, the first closed cross section 8 formed by the second reinforcement 6 and the upper wall portion 5a is arranged at Figure 5 The position shown is coincident with the crossbeam 3 from the side perspective of the vehicle.

[0083] In the above embodiment, when a side collision occurs, the collision load input to the first closed section 8 (the first closed section 8 formed by the upper wall portion 5a of the first reinforcement 5 and the second reinforcement 6) can be smoothly transmitted to the cross member 3 located on the vehicle width direction inner side Y2 of the first closed section 8 (see Figures 2-3 ). This can further improve the impact resistance against side collisions.

[0084] In addition, as a modification of the present invention, Figure 8 and Figure 10As shown, when the cross member 3 has a peak 3a protruding upward and the cross section of the cross member 3 is M-shaped, as long as the peak 6a of the second reinforcement 6 is positioned so as to overlap with the peak 3a of the cross member 3 when viewed from the side of the vehicle, the collision load input to the first closed section 8 formed by the peak 6a can be smoothly transmitted to the closed section formed by the peak 3a of the cross member 3, which can further improve the impact resistance against side collisions. In addition, the area inside the vehicle where the battery pack 4 is not located does not require high rigidity, so Figure 10 Among the peak portions 6 a of the second reinforcement 6 shown, the height of the peak portion 6 a located on the vehicle rear side X2 can be set low.

[0085] In addition, as other variations of the present invention, Figures 8-9 As shown, the peak portion 6a of the second reinforcement 6 located between two cross members 3 spaced apart in the vehicle longitudinal direction X can be shaped so as to expand in the longitudinal direction X as it moves toward the vehicle width direction inner side Y2. This shape allows the ridgeline 15 of the first closed cross section 8 formed by the peak portion 6a to face the cross member 3. Therefore, even if the cross member 3 is positioned in the longitudinal direction X offset from the peak portion 6a, the collision load can be smoothly transmitted to the cross member 3 via the ridgeline 15.

[0086] (Other Features of This Embodiment) In addition, other features of this embodiment are the following (8) to (19). (8) like Figure 4 As shown, in the lower vehicle body structure of the vehicle of this embodiment, the upper wall portion 5a is formed to be inclined in the upward direction Z1 so as to gradually separate from the lower wall portion 5b as it moves toward the vehicle width direction inner side Y2. Figure 5 In the side view of the vehicle shown, a plurality of first closed cross sections 8 arranged in the vehicle front-rear direction X are formed in cooperation with the upper wall portion 5 a.

[0088] In the above embodiment, during a side collision, the collision load is transferred from the longitudinal wall portion 5d to the first reinforcement 5, causing the first reinforcement 5 to deform out of plane in the vertical direction Z. At this point, the inclined upper wall portion 5a rotates about its end on the inner side Y2 in the vehicle width direction and faces horizontally (in the vehicle width direction Y). This causes the first closed cross-section 8 formed by the upper wall portion 5a and the second reinforcement 6 to be axially compressed while in a horizontal position. As a result, the amount of energy absorbed during a side collision can be further reliably increased. (9) like Figure 4 As shown, in the vehicle lower body structure of this embodiment, the lower wall portion 5b is formed to be inclined in the downward direction Z2 as it moves away from the upper wall portion 5a toward the vehicle width direction inner side Y2. Figure 5In the side view of the vehicle shown, a plurality of second closed cross sections 9 arranged in the vehicle front-rear direction X are formed in cooperation with the lower wall portion 5 b.

[0090] In the above embodiment, during a side collision, the first reinforcement 5 undergoes out-of-plane deformation in the vertical direction Z. This out-of-plane deformation causes the tilted lower wall portion 5b to rotate with its end portion on the inner side Y2 in the vehicle width direction as the center of rotation, oriented horizontally (in the vehicle width direction Y). Consequently, the second closed cross-section 9 formed by the lower wall portion 5b and the third reinforcement 7 is axially compressed while in a horizontal position. This results in a further reliable increase in energy absorption during a side collision. (10) In the vehicle lower body structure of the present embodiment, the vertical wall portion 5 d is arranged further outward in the vehicle width direction Y1 than the end portion 61 of the second reinforcement 6 on the vehicle width direction outer side Y1 .

[0092] According to the above scheme, during the process of the first reinforcement 5 undergoing out-of-plane deformation in the upward and downward directions Z during a side collision, the inclined upper wall portion 5a can be effectively oriented toward the horizontal direction while the longitudinal wall portion 5d of the first reinforcement 5 moves toward the inner side Y2 in the vehicle width direction and reaches the outer side Y1 end portion 61 in the vehicle width direction of the second reinforcement 6. (11) In the lower body structure of the vehicle in this embodiment, the total length d5 ​​of the area R of the first reinforcement 5 including the longitudinal wall portion 5d - that is, the area R which is closer to the outside in the vehicle width direction Y1 than the end 61 of the second reinforcement 6 and the end 71 of the third reinforcement 7 in the vehicle width direction outer side Y1 - is set to be equal to the distance d4 in the up-down direction Z between the end portion in the vehicle width direction inner side Y2 of the upper wall portion 5a of the first reinforcement 5 and the end portion in the vehicle width direction inner side Y2 of the lower wall portion 5b.

[0094] According to the above embodiment, during a side collision, when the first reinforcement 5 deforms out-of-plane in the vertical direction Z, a region R of the first reinforcement 5 located further outward in the vehicle width direction Y1 than the end portion 61 of the second reinforcement 6 and the end portion 71 of the third reinforcement 7 in the vehicle width direction Y1 is compressed inward in the vehicle width direction Y2 while simultaneously extending in the vertical direction Z. While this region R is extending in the vertical direction Z, a length d5 ​​of this region R in the vertical direction Z is equal to a distance d4 in the vertical direction Z between the end portion 5a inward in the vehicle width direction Y2 of the upper wall portion 5a and the end portion 5b inward in the vehicle width direction Y2. The region R formed by the upper wall portion 5a, the lower wall portion 5b, and the longitudinal wall portion 5d forms a rectangular cross-section when viewed from the front of the vehicle. As a result, during a side collision, the inclined upper wall portion 5a and the lower wall portion 5b can be reliably oriented in the horizontal direction while the longitudinal wall portion 5d of the first reinforcement 5 advances toward the inner side Y2 in the vehicle width direction and reaches the end portions 61 and 71 of the second reinforcement 6 and the third reinforcement 7 at the outer side Y1 in the vehicle width direction. (12) In the vehicle lower body structure of this embodiment, the second reinforcement 6 is disposed on an upper side surface 5a1 of the upper wall portion 5a, facing outward from the first reinforcement 5. The outer side member 21 has a deformation promoting portion 23 (corner portion 21a3 in this embodiment) that contacts the second reinforcement 6 from above Z1 (outward in the vertical direction Z) during a side collision of the vehicle, thereby deforming inward of the side member 2.

[0096] According to the above arrangement, during a side collision, the deformation promoting portion 23 of the outer side member 21 deforms inwardly of the side member 2 and abuts against the second reinforcement 6. Consequently, the second reinforcement 6 is sandwiched between the deformation promoting portion 23 and the upper wall portion 5a of the first reinforcement 5, restricting deformation of the second reinforcement 6 in the vertical direction Z. This ensures that the first closed cross-section 8 formed by the upper wall portion 5a and the second reinforcement 6 is axially compressed. As a result, the amount of energy absorbed during a side collision can be further reliably increased. (13) In the lower vehicle body structure of the vehicle of this embodiment, the outer side member 21 has an upper wall portion 21a which is an opposing wall portion extending in the vehicle width direction Y and the vehicle front-rear direction X and facing the second reinforcement 6. The upper wall portion 21a has a corner portion 21a3. Figure 4 The side member 2 is bent inwardly of the side member 2 in the front view of the vehicle shown, and projects toward the second reinforcement 6. The deformation promoting portion 23 is constituted by a corner portion 21a3.

[0098] In this embodiment, during a side collision, the upper wall portion 21a of the outer side member 21 bends and deforms inward, starting from the deformation-promoting portion 23, or corner portion 21a3. Consequently, the deformation-promoting portion 23, or corner portion 21a3, intrudes into the inner side member 2 and deforms, coming into contact with the second reinforcement 6. Consequently, the second reinforcement 6 is sandwiched between the corner portion 21a3 and the upper wall portion 5a of the first reinforcement 5, limiting deformation of the second reinforcement 6 in the vertical direction Z. This ensures that the first closed cross-section 8 formed by the upper wall portion 5a and the second reinforcement 6 is axially compressed. (14) In the vehicle lower body structure of this embodiment, the upper wall portion 5a of the first reinforcement 5 is formed to be inclined in the upward direction Z1, gradually separating from the lower wall portion 5b as it moves toward the vehicle width direction inner side Y2. In this embodiment, during a side collision, the first reinforcement 5 undergoes out-of-plane deformation. The tilted upper wall portion 5a, resulting from this out-of-plane deformation, rotates toward the deformation promoting portion 23 of the outer side member 21, using its end portion on the vehicle width direction inner side Y2 as a fulcrum. Consequently, the second reinforcement 6 is pressed toward the deformation promoting portion 23 by the rotating upper wall portion 5a. As a result, the deformation promoting portion 23, i.e., the corner portion 21a3, can clamp the second reinforcement 6 between itself and the upper wall portion 5a with minimal force. (15) In the vehicle lower body structure of this embodiment, the upper wall portion 5a is positioned above the lower wall portion 5b. The deformation promoting portion 23 is formed on the upper portion of the outer side member 21. In this embodiment, the deformation promoting portion 23 formed on the upper portion of the outer side member 21 can press the second reinforcement member 6 from above. This allows the second reinforcement member 6 to be securely clamped between the deformation promoting portion 23 and the upper wall portion 5a. (16) In the vehicle lower body structure of the present embodiment, the third reinforcement 7 is disposed on a lower side surface 5b1 of the lower wall portion 5b of the first reinforcement 5, which faces outward of the first reinforcement 5. The inner side member 22 has a deformation promoting portion 24 (corner portion 22b3 in the present embodiment) that, in the event of a side collision of the vehicle, contacts the third reinforcement 7 from below Z2 (from the outside in the vertical direction Z) and deforms inward of the side member 2.

[0102] In this embodiment, during a side collision, the deformation promoting portion 24 of the inner side member 22 deforms inwardly of the side member 2 and abuts against the third reinforcement 7. Consequently, the third reinforcement 7 is sandwiched between the deformation promoting portion 24 and the lower wall portion 5b of the first reinforcement 5, restricting deformation of the third reinforcement 7 in the vertical direction Z. This ensures that the second closed cross-section 9 formed by the lower wall portion 5b and the third reinforcement 7 is axially compressed. Consequently, the amount of energy absorbed during a side collision can be further reliably increased. (17) In the vehicle lower body structure of the present embodiment, the inner side member 22 includes a lower wall portion 22b extending in the vehicle width direction Y and the vehicle front-rear direction X and facing the third reinforcement 7. The lower wall portion 22b has a corner portion 22b3. Figures 3-4 The side member 2 is bent inwardly of the side member 2 in the front view of the vehicle shown, thereby projecting inwardly of the side member 2. The deformation promoting portion 24 is constituted by the corner portion 22b3.

[0104] In this embodiment, during a side collision, the opposing wall portion of the inner side member 22 bends and deforms inward, starting from the deformation-promoting portion 24, i.e., the corner portion 22b3. As a result, the deformation-promoting portion 24, i.e., the corner portion 22b3, enters the inner side of the side member 2 and deforms, coming into contact with the third reinforcement 7. This sandwiches the third reinforcement 7 between the corner portion 22b3 and the lower wall portion 5b of the first reinforcement 5, limiting its deformation in the vertical direction Z. This ensures that the second closed cross-section 9 formed by the lower wall portion 5b and the third reinforcement 7 is reliably compressed in the axial direction. (18) In the lower body structure of the vehicle of this embodiment, the lower wall portion 22b of the inner side member 22 includes: a horizontal wall portion 22b1 extending in the vehicle width direction Y and opposite to the third reinforcement 7; and a lower wall portion 22b2 extending downward Z2, which serves as a distance wall portion and extends from the vehicle width direction outer side Y1 end portion of the above-mentioned horizontal wall portion 22b1 in a direction away from the above-mentioned third reinforcement 7.

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

[0107] The distance d2 between the lower end of the third reinforcement 7 and the corner portion 22b3 in the vertical direction Z is set to be smaller than the length d6 of the horizontal wall portion 22b1 in the vehicle width direction Y. Therefore, in the event of a side collision, the third reinforcement 7 is reliably sandwiched between the corner portion 22b3 and the lower wall portion 5b of the first reinforcement 5, thereby enabling the second closed cross-section 9 formed by the lower wall portion 5b and the third reinforcement 7 to be more reliably compressed in the axial direction. (19) The vehicle lower body structure of this embodiment includes a battery pack 4 positioned between a pair of left and right side members 2. The battery pack 4 is secured to a horizontal wall portion 22b1 of the lower wall portion 22b, which serves as an opposing wall portion of the inner side member 22. In this embodiment, the deformation-promoting portion 24, or corner portion 22b3, cooperates with the battery pack 4 secured to the lower wall portion 22b to reliably sandwich the third reinforcement 7 between it and the lower wall portion 5b during a side collision.

[0109] (Scope of application of the present invention) As an example of application of the lower vehicle body structure of the present invention, the above embodiment lists Figure 1While the vehicle body 1 of the electric vehicle (EV) shown in the figure will be described, the present invention is widely applicable to vehicles other than EVs as long as they have side members.

[0110]

Number Description

Claims

1. A lower body structure of a vehicle, characterized in that have: The paired left and right side members form 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 reinforcement members disposed inside the closed cross section; The first reinforcement comprises: an upper wall portion and a lower wall portion, which are fixed to the wall portion of the side member on the inner side in the vehicle width direction and extend in the vehicle width direction and the front-rear direction; and a longitudinal wall portion, which extends in the vertical 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; the first reinforcement is in 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 arranged in the front-rear direction of the vehicle when viewed from the side of the vehicle; The third reinforcement cooperates with the lower wall portion to form a plurality of second closed cross sections arranged in the vehicle front-rear direction when viewed from the side of the vehicle.

2. The vehicle lower body structure according to claim 1, wherein: The second reinforcement is fixed to the upper side surface of the upper wall portion; The third reinforcement is fixed to the lower side surface of the lower wall portion.

3. The vehicle lower body structure according to claim 1 or 2, characterized in that: The side member includes an outer member and an inner member, wherein the inner member is arranged at a position further inward in the vehicle width direction than the outer member and is joined to the outer member; The vertical wall portion is arranged on the vehicle width direction outer side relative to a joint portion between the outer side member and the inner side member.

4. The vehicle lower body structure according to claim 1 or 2, characterized in that: The first closed cross section has a polygonal structure having a plurality of ridge lines extending in the vehicle width direction.

5. The vehicle lower body structure according to claim 1 or 2, characterized in that: The second closed cross section has a polygonal structure having a plurality of ridge lines extending in the vehicle width direction.

6. The vehicle lower body structure according to claim 1 or 2, characterized in that: The second reinforcement and the third reinforcement have different rigidities.

7. The vehicle lower body structure according to claim 1 or 2, characterized in that Also features: a cross member extending in the vehicle width direction and connecting the left and right paired side members; The first closed cross section is arranged at a position overlapping with the cross member when viewed from the side of the vehicle.

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