Vehicle underbody structure

Abstract

To provide a vehicle lower part structure which can absorb buffer load at the time of lateral collision of a vehicle without narrowing foot space of a crew member seated on a rear seat.SOLUTION: A vehicle lower part structure 10 comprises: a cross member 20 which is arranged between a floor panel 14 of a vehicle 12 and a battery case 16 and extended in a vehicle width direction in the front side of a rear side part of a support member 18 supporting a front seat; and a connection member 22 with a closed cross-sectional shape which connects an outer end part of the cross member 20 in the vehicle width direction with a rocker 30. A first fragile site 24 and a second fragile site 26 are formed on an upper wall 22U of the connection member 22 from an outermost side thereof in the vehicle width direction to an inner side in order to extend in a longitudinal direction, and a third fragile site 28 is formed on a lower wall 22D of the connection member 22 between the first fragile site 24 and the second fragile site 26 in a front view to extend in the longitudinal direction. An interval D1 between the first fragile site 24 and the third fragile site 28 in the vehicle width direction is shorter than an interval D2 between the second fragile site 26 and the third fragile site 28 in the vehicle width direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a vehicle underbody structure.

Background Art

[0002] In a vehicle in which a battery case with a battery housed therein is mounted below a cross member, in the event of a side collision of the vehicle, a structure is known in which a seat bracket is rotated to deform the outer end portion in the vehicle width direction of the cross member downward to absorb a collision load (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above structure, it is necessary to position the cross member in the vehicle front-rear direction at the same position as the rear side portion of the seat bracket that supports the front seat. That is, it is necessary to arrange the cross member closer to the rear seat. In this case, there is a problem that the toes of the passengers sitting in the rear seat hit the cross member via the floor panel, resulting in a narrow foot space for the passengers sitting in the rear seat.

[0005] Therefore, an object of the present invention is to obtain a vehicle underbody structure that can absorb a collision load during a side collision of the vehicle without narrowing the foot space of the passengers sitting in the rear seat.

Means for Solving the Problems

[0006] In order to achieve the above object, a vehicle underbody structure according to a first aspect of the present invention includes a battery case mounted on the lower side of a vehicle floor panel of a vehicle, a cross member extending in the vehicle width direction on the vehicle front side of a rear side portion of a support member that supports a front seat of the vehicle between the floor panel and the battery case, a rocker extending in the vehicle longitudinal direction on the outer side in the vehicle width direction of the cross member, and a connecting member formed in a closed cross-sectional shape and connecting an outer end portion in the vehicle width direction of the cross member and the rocker. A first weak portion and a second weak portion extending in the vehicle longitudinal direction are formed in order from the outermost side to the inner side in the vehicle width direction on an upper wall of the connecting member, and a third weak portion extending in the vehicle longitudinal direction is formed on a lower wall of the connecting member between the first weak portion and the second weak portion in a front view. A distance along the vehicle width direction between the first weak portion and the third weak portion is shorter than a distance along the vehicle width direction between the second weak portion and the third weak portion.

[0007] According to the invention of the first aspect, at the time of a side collision of the vehicle, a collision load directed inward in the vehicle width direction is input to the connecting member via the rocker. Here, a first weak portion and a second weak portion extending in the vehicle longitudinal direction are formed in order from the outermost side to the inner side in the vehicle width direction on the upper wall of the connecting member, and a third weak portion extending in the vehicle longitudinal direction is formed on the lower wall of the connecting member between the first weak portion and the second weak portion in a front view. And a distance along the vehicle width direction between the first weak portion and the third weak portion is shorter than a distance along the vehicle width direction between the second weak portion and the third weak portion.

[0008] Therefore, when a collision load directed inward in the vehicle width direction is input to the connecting member, the upper wall and the lower wall of the connecting member between the first weak portion and the second weak portion are deformed so as to protrude upward of the vehicle. As a result, it becomes possible to deform an outer end portion in the vehicle width direction of the cross member extending in the vehicle width direction on the vehicle front side of a rear side portion of a support member that supports a front seat of the vehicle downward of the vehicle, and it becomes possible to deform a substantially central portion in the vehicle width direction of the cross member upward of the vehicle. That is, the connecting member and the cross member absorb a collision load at the time of a side collision of the vehicle without narrowing a foot space of an occupant sitting in the rear seat.

[0009] Moreover, the vehicle lower structure according to the second aspect of the present invention is the vehicle lower structure of the first aspect, wherein the third weak part is formed to be weaker than the first weak part and the second weak part.

[0010] According to the invention of the second aspect, the third weak part is formed to be weaker than the first weak part and the second weak part. Therefore, when a collision load directed inward in the vehicle width direction is input to the connecting member during a side collision of the vehicle, the upper wall and the lower wall of the connecting member between the first weak part and the second weak part are likely to be deformed so as to protrude upward of the vehicle.

[0011] Moreover, the vehicle lower structure according to the third aspect of the present invention is the vehicle lower structure of the first aspect, wherein the first weak part, the second weak part, and the third weak part are the first bead part, the second bead part, and the third bead part, respectively, and the depth of the third bead part is made deeper than the depths of the first bead part and the second bead part.

[0012] According to the invention of the third aspect, the first weak part, the second weak part, and the third weak part are the first bead part, the second bead part, and the third bead part, respectively, and the depth of the third bead part is made deeper than the depths of the first bead part and the second bead part. Therefore, when a collision load directed inward in the vehicle width direction is input to the connecting member during a side collision of the vehicle, the upper wall and the lower wall of the connecting member between the first weak part (the first bead part) and the second weak part (the second bead part) are likely to be deformed so as to protrude upward of the vehicle.

[0013] Moreover, the vehicle lower structure according to the fourth aspect of the present invention is the vehicle lower structure of any one of the first to third aspects, wherein the connecting member is made less rigid than the cross member.

[0014] According to the invention of the fourth aspect, the connecting member is made less rigid than the cross member. Therefore, when a collision load directed inward in the vehicle width direction is input to the connecting member, the upper wall and the lower wall of the connecting member between the first weak part and the second weak part are even more likely to be deformed so as to protrude upward of the vehicle. [Effect of the Invention]

[0015] As described above, according to the present invention, it is possible to absorb the collision load during a side collision of a vehicle without narrowing the foot space of the occupant sitting in the rear seat. [Brief Description of the Drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0017] Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. For convenience of explanation, in each figure, the arrow UP appropriately shown is the upward direction of the vehicle, the arrow FR is the front direction of the vehicle, the arrow LH is the left direction of the vehicle, and the arrow RH is the right direction of the vehicle. Also, in the following description, when the directions of up and down, front and back, and left and right are described without special mention, they indicate up and down, front and back, and left and right in the vehicle. Also, the left and right directions are synonymous with the vehicle width direction.

[0018] As shown in FIGS. 1 and 2, a vehicle 12 to which a vehicle lower structure 10 according to this embodiment is applied includes a substantially rectangular frame member 15 disposed between the axles (not shown) of the front wheels Fw and the axles (not shown) of the rear wheels Rw in a plan view. Above the frame member 15, a floor panel 14 constituting the floor of the vehicle 12 is disposed, and below the frame member 15, a battery case 16 is mounted.

[0019] That is, the frame member 15 is disposed between the floor panel 14 and the battery case 16 in a front view. In FIG. 2, the floor panel 14 and the battery case 16 are not shown, but the battery case 16 is supported by the frame member 15 and the like. Further, as shown in FIG. 1, a battery stack 17 in which a plurality of battery cells 17A stacked in the front-rear direction are provided in a plurality of columns in the vehicle width direction is accommodated inside the battery case 16. That is, this vehicle 12 is an electric vehicle or a plug-in hybrid vehicle.

[0020] The frame member 15 has a metal cross member 20 extending in the vehicle width direction and a pair of left and right rocker members 30 made of metal and extending in the front-rear direction outside the vehicle width direction of the cross member 20. The cross member 20 is formed in a substantially hat-shaped cross section and is provided at a substantially central portion in the front-rear direction of the frame member 15 (see FIG. 2). Note that the frame member 15 is also provided with cross members (not shown) similar to the cross member 20 on the front side and the rear side of the cross member 20.

[0021] Further, as shown in FIG. 2, the vehicle 12 (cross members, side members, etc. not shown) is provided with a pair of front and rear support members as seat brackets 18 to which the front lower portion and the rear lower portion of a seat rail (not shown) that slidably supports the front seat (not shown) are attached (in FIG. 2, only the seat bracket 18 on the outer side in the vehicle width direction is shown). And the cross member 20 is disposed in a plan view on the front side of the rear side portion 18B of the seat bracket 18 and on the rear side of the front side portion 18F of the seat bracket 18.

[0022] Further, the frame member 15 has a metal extension 22 as a connecting member that connects the outer end portion in the vehicle width direction of the cross member 20 and the rocker 30. The extension 22 has a lower rigidity than the cross member 20. That is, the plate thickness of the extension 22 is formed thinner than the plate thickness of the cross member 20. Other configurations of the extension 22 will be described in detail later.

[0023] As shown in FIGS. 1 and 2, the rocker 30 has a rocker outer panel 32 formed in a substantially hat-shaped cross section and extending in the front-rear direction, and a rocker inner panel 34 formed in a substantially hat-shaped cross section and extending in the front-rear direction. The rocker 30 is formed in a closed cross-sectional shape by welding or the like the upper and lower flange portions 32A of the rocker outer panel 32 and the upper and lower flange portions 34A of the rocker inner panel 34 to each other.

[0024] The extension 22 is formed in a closed cross-sectional shape (a rectangular tube shape having a substantially rectangular cross section) in a side view, and the inner end portion in the vehicle width direction thereof is inserted into the outer end portion in the vehicle width direction of the cross member 20 and integrally joined by welding or the like. A flange portion (not shown) is integrally formed at the outer end portion in the vehicle width direction of the extension 22 (at least the outer end portion in the vehicle width direction of the upper wall 22U), and the flange portion is joined to the rocker 30 (the rocker inner panel 34) by welding or the like.

[0025] As shown in FIG. 3, a first bead portion 24 as a first vulnerable portion that is recessed downward in a substantially arc-shaped cross section and extends in the front-rear direction, and a second bead portion 26 as a second vulnerable portion that is recessed downward in a substantially arc-shaped cross section and extends in the front-rear direction are formed in order from the outermost side to the inner side in the vehicle width direction on the upper wall 22U of the extension 22.

[0026] That is, on the upper wall 22U of the extension 22, the first bead portion 24 is formed at the outermost side in the vehicle width direction, and the second bead portion 26 is formed at a predetermined interval inward in the vehicle width direction of the first bead portion 24. And on the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 in the front view shown in FIG. 3, a third bead portion 28 is formed as a third fragile portion that is recessed upward in a substantially arc-shaped cross section and extends in the front-rear direction.

[0027] As shown in FIG. 3, the interval D1 along the vehicle width direction between the first bead portion 24 and the third bead portion 28 is shorter than the interval D2 along the vehicle width direction between the second bead portion 26 and the third bead portion 28. Further, the third bead portion 28 is formed to be more fragile than the first bead portion 24 and the second bead portion 26. That is, the depth (amount of indentation) of the third bead portion 28 is made deeper (larger) than the depth (amount of indentation) of the first bead portion 24 and the second bead portion 26.

[0028] Next, the operation of the vehicle lower structure 10 according to the present embodiment configured as described above will be described.

[0029] When the vehicle 12 collides with a barrier W such as a pole (see FIG. 5) on the side, a collision load directed inward in the vehicle width direction is input from the outside in the vehicle width direction to the extension 22 via the rocker 30. Here, as shown in FIG. 3, on the upper wall 22U of the extension 22, the first bead portion 24 and the second bead portion 26 extending in the front-rear direction are formed in order from the outermost side to the inside in the vehicle width direction, and on the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 in the front view, a third bead portion 28 extending in the front-rear direction is formed.

[0030] And the distance D1 along the vehicle width direction between the first bead portion 24 and the third bead portion 28 is made shorter than the distance D2 along the vehicle width direction between the second bead portion 26 and the third bead portion 28. Therefore, when a collision load directed inward in the vehicle width direction is input to the extension 22, as shown in FIG. 4, the upper wall 22U and the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 are plastically deformed so as to bulge upward.

[0031] More specifically, as shown in FIG. 5(A), when the vehicle 12 side-collides with the barrier W, a collision load is relatively input to the rocker 30 from the barrier W. When a collision load is input to the rocker 30 from the outside in the vehicle width direction, as shown in FIG. 5(B), while the rocker 30 collapses inward in the vehicle width direction, a part of the collision load is absorbed, and a part of the remaining collision load is transmitted to the extension 22.

[0032] And when a collision load is input to the extension 22 from the outside in the vehicle width direction, as shown in FIG. 5(C), the extension 22 is plastically deformed so as to bend with the first bead portion 24, the third bead portion 28, and the second bead portion 26 as the reference points, and the collision load is absorbed. That is, the upper wall 22U and the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 are plastically deformed so as to bulge upward, and the collision load is absorbed.

[0033] And thereby, the outer end portion in the vehicle width direction of the cross member 20 (the boundary portion between the cross member 20 and the extension 22) can be deformed downward (so as to be convex downward), and the substantially central portion in the vehicle width direction of the cross member 20 can be deformed upward (so as to be convex upward) (see FIG. 5(C)).

[0034] Here, the cross member 20 extends in the vehicle width direction in front of the rear side portion 18B of the seat bracket 18 that supports the front seat of the vehicle 12 (specifically, the lower rear side of the seat rail that slidably supports the front seat), so that the toes of the passengers sitting in the rear seat do not hit the cross member 20 through the floor panel 14.

[0035] Therefore, the extension 22 and the cross member 20 can efficiently absorb the collision load during a side collision of the vehicle 12 without narrowing the foot space of the passengers sitting in the rear seat. And thereby, it is possible to suppress or prevent the cross member 20 and the barrier W from hitting the battery case 16, so that it is possible to effectively suppress or prevent the collision load from being input to the battery stack 17 through the battery case 16.

[0036] Further, the third bead portion 28 formed on the lower wall 22D of the extension 22 is formed more weakly than the first bead portion 24 and the second bead portion 26 formed on the upper wall 22U of the extension 22. Specifically, as shown in FIG. 3, the depth (amount of indentation) of the third bead portion 28 is made deeper (larger) than the depth (amount of indentation) of the first bead portion 24 and the second bead portion 26.

[0037] Therefore, when a collision load directed inward in the vehicle width direction is input to the extension 22 during a side collision of the vehicle 12, the upper wall 22U and the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 can be easily deformed so as to be convex upward. In other words, it is possible to effectively induce (control) the upper wall 22U and the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 to deform convexly upward.

[0038] As described above, since the flange portion integrally formed at least at the outer end in the vehicle width direction of the upper wall 22U of the extension 22 is joined to the rocker 30, when a collision load is input to the extension 22 via the rocker 30, the collision load is mainly easily transmitted upward from the substantially central portion in the height direction of the extension 22. Therefore, even if a third bead portion 28 with a large depth (a large amount of indentation) is formed on the lower wall 22D of the extension 22, it is possible to suppress a decrease in the strength of the extension 22 against the collision load, and it is possible to suppress a decrease in the energy absorption efficiency by the extension 22.

[0039] Furthermore, this extension 22 is made to have a lower rigidity than the cross member 20. Specifically, the plate thickness of the extension 22 is formed thinner than the plate thickness of the cross member 20. Therefore, when a collision load directed inward in the vehicle width direction is input to the extension 22, the upper wall 22U and the lower wall 22D of the extension 22 between the first bead portion 24 and the second bead portion 26 can be deformed more easily so as to bulge upward.

[0040] As described above, the vehicle lower structure 10 according to the present embodiment has been described with reference to the drawings. However, the vehicle lower structure 10 according to the present embodiment is not limited to that shown in the drawings, and can be appropriately designed and changed within a range not departing from the gist of the present invention. For example, the bead portions as the weak portions formed on the extension 22 are not limited to the three shown in the drawings.

[0041] Bead portions may be added to the extension 22 according to the length along the vehicle width direction thereof. That is, on the upper wall 22U of the extension 22, one or more bead portions similar to the first bead portion 24 or the second bead portion 26 are formed on the inner side in the vehicle width direction than the second bead portion 26, and on the lower wall 22D of the extension 22, one or more bead portions similar to the third bead portion 28 are formed on the inner side in the vehicle width direction than the second bead portion 26.

[0042] In addition, when the length along the vehicle width direction of the extension 22 is increased and bead portions are added to the upper wall 22U and the lower wall 22D, the upper and lower bead portions to be added do not have to be formed at the same position in the vehicle width direction. That is, the added bead portions do not have to have a relationship such as the distance D1 between the first bead portion 24 and the third bead portion 28 and the distance D2 between the second bead portion 26 and the third bead portion 28. Therefore, the added bead portions may be formed at equal intervals in the vehicle width direction, for example, alternately up and down.

[0043] Further, the first weak portion, the second weak portion, and the third weak portion are not limited to the first bead portion 24, the second bead portion 26, and the third bead portion 28 shown in the figure. For example, although not shown in the figure, they may be the first long hole portion, the second long hole portion, and the third long hole portion having a long slit shape in the front-rear direction. In this case, if the opening area of the third long hole portion is made larger than the opening areas of the first long hole portion and the second long hole portion, the third long hole portion can be made more fragile than the first long hole portion and the second long hole portion.

[0044] Also, the configuration in which the rigidity of the extension 22 is lower than the rigidity of the cross member 20 is not limited to the one due to the difference in plate thickness. For example, the metal material forming the extension 22 may be a metal material having a lower rigidity than the metal material forming the cross member 20 so that the rigidity of the extension 22 becomes lower than the rigidity of the cross member 20.

Explanation of Reference Numerals

[0045] 10 Vehicle lower structure 12 Vehicle 14 Floor panel 16 Battery case 18 Seat bracket (support member) 20 Cross member 22 Extension (connecting member) 22U Upper wall 22D Lower wall 24 First bead portion (first weak portion) 26 Second bead portion (second weak portion) 28 Third bead part (third weak part) 30 Rocker D1 Interval D2 Interval

Claims

1. A battery case mounted on the lower side of a vehicle floor panel of a vehicle, A cross member extending in the vehicle width direction on the front side of the vehicle in front of the rear side portion of a support member that supports the front seat of the vehicle between the floor panel and the battery case, A rocker extending in the vehicle longitudinal direction outside the vehicle width direction of the cross member, A connecting member formed in a closed cross-sectional shape and connecting the outer end portion in the vehicle width direction of the cross member and the rocker, Comprising: A first weak portion and a second weak portion extending in the vehicle longitudinal direction are formed in order from the outermost side to the inner side in the vehicle width direction on the upper wall of the connecting member, and a third weak portion extending in the vehicle longitudinal direction is formed on the lower wall of the connecting member between the first weak portion and the second weak portion in a front view, A vehicle lower structure in which the interval in the vehicle width direction between the first weak portion and the third weak portion is shorter than the interval in the vehicle width direction between the second weak portion and the third weak portion.

2. The vehicle lower structure according to claim 1, wherein the third weak portion is formed to be more fragile than the first weak portion and the second weak portion.

3. The vehicle lower structure according to claim 1, wherein the first weak portion, the second weak portion, and the third weak portion are respectively a first bead portion, a second bead portion, and a third bead portion, and the depth of the third bead portion is deeper than the depths of the first bead portion and the second bead portion.

4. The vehicle lower structure according to any one of claims 1 to 3, wherein the connecting member has a lower rigidity than the cross member.

Images