Lower vehicle body structure for vehicle

Abstract

To provide a lower vehicle body structure for a vehicle that is able to achieve both improvement in an amount of energy absorption by a side sill in the event of vehicle side collision and improvement in side sill rigidity in normal traveling.SOLUTION: A lower vehicle body structure for a vehicle includes an outer side reinforcing member 13 and an inner side reinforcing member 14 inside a side sill 2. Ridge lines 11f, 11g extending in a longitudinal direction are formed between an outer vertical wall portion 11a and an outer top plate portion 11b of the side sill 2 and between the outer vertical wall portion 11a and an outer bottom plate portion 11c of the side sill, respectively. The inner side reinforcing member 14 is fixed to an inner vertical wall portion 12a, and has a to-be-fitted portion 15 that is fitted to the outer side reinforcing member 13 in the event of vehicle side collision. The outer side reinforcing member 13 has: a fitting portion 18 that fits in the to-be-fitted portion 15; and brace portions 17a, 17b that connect at least one of a space between the outer vertical wall portion 11a and the outer top plate portion 11b and a space between the outer vertical wall portion 11a and the outer bottom plate portion 11c, across the ridge lines 11f, 11g.SELECTED DRAWING: Figure 3

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 pole collides with the side of a vehicle, that is, during a side impact of the vehicle, various techniques are known for crushing a side sill that forms the lower part of the vehicle side to absorb the energy during the collision. In particular, in an electric vehicle, since a battery pack is disposed under the vehicle floor, it is particularly important to improve the energy absorption performance of the side sill from the viewpoint of protecting the battery pack.

[0003] In the structure described in Patent Document 1, in order to improve the energy absorption amount of the side sill, an outer side reinforcing member and an inner side reinforcing member are provided inside the closed cross section of the side sill. In this structure, the outer side reinforcing member is fixed to the vertical wall portion of the side sill outer, which is the outer side portion of the side sill. Similarly, the inner side reinforcing member is fixed to the vertical wall portion of the side sill inner, which is the inner side portion of the side sill. The outer side reinforcing member and the inner side reinforcing member are in contact with each other inside the closed cross section of the side sill.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above structure, since the outer side reinforcing member is fixed only to the vertical wall on the passenger compartment side of the side sill, during a side collision of the vehicle, it is impossible to suppress the angular displacement at the ridge line (corner) formed by the vertical wall portion of the outer side of the side sill and the horizontal wall above or below the vertical wall portion (i.e., the top plate portion or the bottom plate portion), and the outer side of the side sill may be deformed such that the angle between the vertical wall portion and the horizontal wall opens or closes.

[0006] Therefore, during a side collision of the vehicle, due to the angular displacement at the ridge line of the outer side of the side sill, the outer side reinforcing member is displaced in the vertical direction, making it difficult to stably fit the outer side reinforcing member to the inner side reinforcing member. As a result, there is a problem that it is difficult to improve the energy absorption amount by the outer side reinforcing member and the inner side reinforcing member.

[0007] Also, in the above structure, even during normal driving, only the outer side reinforcing member fixed to the vertical wall cannot suppress the angular displacement at the ridge line on the passenger compartment side of the side sill, so there is a problem that it is difficult to improve the side sill rigidity.

[0008] Furthermore, since the outer side reinforcing member and the inner side reinforcing member are in contact within the closed cross-section of the side sill, there is also a concern that abnormal noise may be generated due to the vertical movement of the outer side reinforcing member accompanying minute angular displacement of the side sill during normal driving.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a lower vehicle body structure of a vehicle capable of achieving both an improvement in the energy absorption amount by the side sill during a side collision of the vehicle and an improvement in the side sill rigidity during normal driving.

Means for Solving the Problems

[0010] To solve the above problems, the lower body structure of the vehicle according to the present invention has a closed cross-section, and includes side sills extending in the longitudinal direction of the vehicle, outer side reinforcing members disposed inside the side sills and extending in the longitudinal direction, and inner side reinforcing members disposed inside the side sills and closer to the vehicle interior than the outer side reinforcing members and extending in the longitudinal direction. The side sills have an outer vertical wall portion, an inner vertical wall portion located on the vehicle interior side with respect to the outer vertical wall portion, an outer top plate portion connected to the upper end of the outer vertical wall portion, and an outer bottom plate portion connected to the lower end of the outer vertical wall portion. The outer vertical wall portion, the inner vertical wall portion, the outer top plate portion, and the outer bottom plate portion form at least a part of the closed cross-section of the side sills. Ridge lines extending in the longitudinal direction are formed respectively between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion. The inner side reinforcing member is fixed to the inner vertical wall portion and has a fitting portion that is fitted with the outer side reinforcing member when an impact load from the side of the vehicle is input to the side sill. The outer side reinforcing member has a fitting portion that fits with the fitting portion of the inner side reinforcing member when an impact load from the side of the vehicle is input to the side sill, and a brace portion that connects at least one of the spaces between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion across the ridge line.

[0011] In the above configuration, an outer side reinforcing member and an inner side reinforcing member are provided inside the side sill. Moreover, the outer side reinforcing member includes a brace portion together with a fitting portion that fits with the fitting portion of the inner side reinforcing member when the vehicle is side-impacted, that is, when an impact load from the side of the vehicle is input to the side sill. The brace portion connects at least one of the spaces between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion across the ridge line of the side sill.

[0012] In this configuration, since the brace portion suppresses the angular displacement of the ridge line (for example, displacement such as the angle of the corner portion of the closed cross-section opening or closing), when the vehicle is side-collided, the fitting portion of the outer side reinforcing member is less likely to shift in the vertical direction, and the fitting portion of the outer side reinforcing member and the fitted portion of the inner side reinforcing member can be more stably fitted, and the outer side reinforcing member and the inner side reinforcing member can be sufficiently compressed and deformed. As a result, the energy absorption amount is improved.

[0013] Also, during normal driving, since the brace portion can suppress the angular displacement of the ridge line, the vehicle body rigidity is also improved.

[0014] Furthermore, even if the outer side reinforcing member and the inner side reinforcing member are set in a contact state within the closed cross-section of the side sill, during normal driving, there is no minute angular displacement of the side sill, and there is no vertical movement of the outer side reinforcing member associated therewith, so no abnormal noise occurs.

[0015] In the lower vehicle body structure of the vehicle described above, it is preferable that one of the fitting portion and the fitted portion has a convex cross-section and extends in the front-rear direction, and the other has a concave cross-section corresponding to the convex cross-section and extends in the front-rear direction.

[0016] In such a configuration, the fitting portion and the fitted portion can be stably fitted by fitting of a concave portion (that is, a groove) and a convex portion (that is, a ridge) that respectively extend in the front-rear direction. Further, by roll-forming a metal plate material, it is possible to continuously form either one of the fitting portion and the fitted portion into a shape having a convex cross-section and extending in the front-rear direction and the other into a shape having a concave cross-section and extending in the front-rear direction, and it is possible to easily form a shape that can realize stable fitting.

[0017] In the lower vehicle body structure of the vehicle described above, it is preferable that the outer side reinforcing member includes a first portion having the fitting portion and a second portion connected to the first portion and having the brace portion.

[0018] With such a configuration, it is possible to continuously form the first part having the fitting portion and the second part having the brace portion into desired cross-sectional shapes by roll-forming of metal plates separately. Then, by connecting the formed first part to the second part, it is possible to easily manufacture the outer side reinforcing member having the fitting portion and the brace portion.

[0019] In the lower body structure of the vehicle described above, it is preferable that the first part is fixed to the side sill via the second part.

[0020] According to such a configuration, it is possible to reliably transmit the collision load input to the side sill during a side impact of the vehicle to the first part via the second part in the outer side reinforcing member. As a result, it is possible to smoothly perform the load transmission from the brace portion of the second part to the fitting portion of the first part.

[0021] In the lower body structure of the vehicle described above, the first part has an upper wall portion that connects the fitting portion to the second part and a lower wall portion that is located below the upper wall portion and connects the fitting portion to the second part, and it is preferable that the upper wall portion and the lower wall portion have deformation promoting portions that promote partial deformation during a side impact of the vehicle.

[0022] According to such a configuration, during a side impact of the vehicle, the first part of the outer side reinforcing member is partially deformed in the deformation promoting portions of the upper wall portion and the lower wall portion while the fitting portion is fitted to the fitted portion of the inner side reinforcing member during a side impact of the vehicle, so that the energy absorption amount in the outer side reinforcing member is further improved.

[0023] In the lower body structure of the vehicle described above, it is preferable that the first part is composed of a plate material, and the deformation promoting portion is composed of a plurality of stepped portions formed by partially bending and deforming the plate material.

[0024] In such a configuration, by forming the deformation promoting portion with a plurality of stepped portions, the deformation promoting portion can be formed with a simple structure on the upper wall portion and the lower wall portion of the first portion of the outer side reinforcing member. During a side impact of the vehicle, by deforming (so-called bellows-like deformation) that is folded at the plurality of stepped portions, the first portion of the outer side reinforcing member can be easily deformed. At the same time, it is possible to easily set or control the amount of energy absorption in the outer side reinforcing member due to the stepped shape of the first portion.

[0025] In the lower vehicle body structure of the vehicle described above, it is preferable that the brace portion connects both between the outer wall portion and the outer top plate portion in the side sill and between the outer vertical wall portion and the outer bottom plate portion across the ridge line.

[0026] In such a configuration, since the brace portion connects between the outer top plate portion, the outer vertical wall portion, and the outer bottom plate portion of the side sill across the two ridge lines formed therebetween, it is possible to further improve the amount of energy absorption by the side sill during a side impact of the vehicle and to further improve the rigidity of the side sill during normal driving.

[0027] In the lower vehicle body structure of the vehicle described above, it is preferable that the outer vertical wall portion has beads extending in the front-rear direction and the brace portion is fixed to the beads.

[0028] According to such a configuration, since the outer vertical wall portion of the side sill has beads extending in the front-rear direction, the rigidity of the outer vertical wall portion is improved. Further, since the brace portion is fixed to the beads in the outer vertical wall portion where the rigidity is high, the impact load during a side impact of the vehicle can be smoothly transmitted from the outer vertical wall portion of the side sill to the brace portion of the outer side reinforcing member, and the amount of energy absorption in the outer side reinforcing member can be further improved.

[0029] In the lower vehicle body structure of the vehicle described above, it is preferable that the inner side reinforcing member and the outer side reinforcing member are formed by roll-forming a metal sheet material.

[0030] According to such a configuration, since the inner side reinforcing member and the outer side reinforcing member are formed by roll-forming a metal plate material, it is possible to continuously form them into a desired cross-sectional shape easily and inexpensively. Further, since the inner side reinforcing member and the outer side reinforcing member are continuously formed by roll-forming, they can be applied to vehicles of various vehicle lengths, that is, they can correspond to vehicle body variations.

[0031] Furthermore, since the inner side reinforcing member and the outer side reinforcing member continuously formed by roll-forming reinforce the side sill in a long section in the front-rear direction, a high energy absorption amount can be obtained even if an obstacle collides with any section of the side sill in the front-rear direction.

[0032] In the lower body structure of the vehicle described above, it further includes a cross member extending in the vehicle width direction, and the cross member is preferably connected to the inner vertical wall portion of the side sill in the vertical direction within a range including the overlapping portion of the inner side reinforcing member and the side sill.

[0033] According to such a configuration, at the time of a side collision of the vehicle, the cross member can effectively receive the collision load while supporting the overlapping portion of the inner side reinforcing member and the side sill from the inside of the vehicle. Thereby, it is possible to further improve the energy absorption amount in the side sill and the inner side reinforcing member.

Advantages of the Invention

[0034] As described above, according to the lower body structure of the vehicle of the present invention, it is possible to achieve both an improvement in the energy absorption amount by the side sill at the time of a side collision of the vehicle and an improvement in the side sill rigidity during normal running.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0036] Hereinafter, the lower body structure of a vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0037] As shown in FIGS. 1 to 2, a vehicle body 1 to which the lower vehicle body structure according to an embodiment of the present invention is applied includes side sills 2 that form the lower side portions in the vehicle width direction Y on both sides of the vehicle body 1. In the following drawings, the front-rear direction of the vehicle is indicated by arrow X, the vehicle width direction is indicated by arrow Y, and the vertical direction is indicated by arrow Z.

[0038] Specifically, the vehicle body 1 includes a pair of side sills 2 extending in the front-rear direction X of the vehicle, a front pillar 3 (A pillar) extending upward from the front end of each side sill 2 on the front side of the vehicle, a center pillar 4 (B pillar) extending upward at a position in the middle of the front-rear direction X of each side sill 2, a rear pillar 5 (C pillar) extending upward from near the rear end of each side sill 2 on the rear side of the vehicle, a roof rail 10 extending in the front-rear direction X connecting the upper ends of these three pillars 3 to 5, and four cross members 6 to 9 (first cross member 6, front side intermediate cross member 7, second cross member 8, and third cross member 9) extending in the vehicle width direction Y between the pair of side sills 2 and connected to the side sills 2.

[0039] The side sills 2, the three pillars 3 to 5, and the roof rail 10 constitute the portions on both sides in the vehicle width direction in the vehicle skeleton.

[0040] Further, the four cross members 6 to 9 are arranged at intervals in the front-rear direction X. The four cross members 6 to 9 are connected to the inner vertical wall portion 12a of the side sill inner 12 within a range including the overlapping portion of the inner side reinforcing member 14 and the side sill 2 in the vertical direction Z, like the front side intermediate cross member 7 shown in FIG. 3. Also, the first cross member 6 and the second cross member 8 are connected to the side sill 2 within the range of the portions where the front pillar 3 and the center pillar 4 are connected to the side sill 2 in the front-rear direction X, respectively.

[0041] Also, as shown in FIG. 3, inside the side sill 2, there are two reinforcing members, namely, The outer side reinforcing member 13 and the inner side reinforcing member 14 are fixed to the inner surface of the side sill 2. The outer side reinforcing member 13 and the inner side reinforcing member 14 are each disposed inside the side sill 2 and extend in the longitudinal direction X. The inner side reinforcing member 14 is disposed closer to the vehicle interior, that is, on the inner side Y2 in the vehicle width direction Y, than the outer side reinforcing member 13.

[0042] Hereinafter, the configuration of the side sill 2 and the outer side reinforcing member 13 and the inner side reinforcing member 14 inside thereof will be described in more detail.

[0043] (Description of the side sill 2) As shown in FIG. 3, the side sill 2 is a hollow cylindrical body extending in the longitudinal direction X of the vehicle. The side sill 2 is composed of two hat-shaped cross-section members, that is, the side sill outer 11 and the side sill inner 12. This side sill 2 has a closed cross-section C with a substantially rectangular cross-section. The side sill 2 is manufactured by joining the upper and lower pairs of flange portions 11d, 11e of the side sill outer 11 and the upper and lower pairs of flange portions 12d, 12e of the side sill inner 12 to each other.

[0044] The side sill outer 11 has an outer vertical wall portion 11a, an outer top plate portion 11b, an outer bottom plate portion 11c, an upper flange portion 11d, and a lower flange portion 11e.

[0045] The outer vertical wall portion 11a is a flat plate portion facing the outer side in the vehicle width direction Y and extending in the longitudinal direction X of the vehicle. The outer top plate portion 11b is a flat plate portion whose one end (the end portion in the vehicle width direction outer side Y1) is connected to the upper end of the outer vertical wall portion 11a and faces upward. The outer bottom plate portion 11c is a flat plate portion whose one end (the end portion in the vehicle width direction outer side Y1) is connected to the lower end of the outer vertical wall portion 11a and faces downward. The outer top plate portion 11b and the outer bottom plate portion 11c each extend in a substantially horizontal direction and are slightly inclined in a direction away from each other as they approach the side sill inner 12.

[0046] The upper flange portion 11d is a flat plate-like portion that extends upward from the other end of the outer top plate portion 11b (the end portion on the inner side Y2 in the vehicle width direction). The lower flange portion 11e is a flat plate-like portion that extends downward from the other end of the outer bottom plate portion 11c (the end portion on the inner side Y2 in the vehicle width direction).

[0047] Between the outer vertical wall portion 11a and the outer top plate portion 11b and between the outer vertical wall portion 11a and the outer bottom plate portion 11c, ridge lines 11f, 11g extending in the front-rear direction X (that is, the corners on the outer side Y1 in the vehicle width direction in the closed cross-section C) are formed. That is, the ridge line 11f (in other words, the upper ridge line 11f or the first ridge line 11f) is formed between the outer vertical wall portion 11a and the outer top plate portion 11b. On the other hand, the ridge line 11g (in other words, the lower ridge line 11g or the second ridge line 11g) is formed between the outer vertical wall portion 11a and the outer bottom plate portion 11c and is disposed below the ridge line 11f.

[0048] The outer vertical wall portion 11a has a bead 11h extending in the front-rear direction X (a recessed portion recessed inward in the vehicle width direction Y2 in FIG. 3).

[0049] The side sill inner 12 is disposed on the inner side Y2 in the vehicle width direction of the side sill outer 11. The side sill inner 12 has an inner vertical wall portion 12a, an inner top plate portion 12b, an inner bottom plate portion 12c, an upper flange portion 12d, and a lower flange portion 12e.

[0050] The inner vertical wall portion 12a is a flat plate-like portion that is located on the vehicle interior side with respect to the above-mentioned outer vertical wall portion 11a and faces the inner side in the vehicle width direction Y, and extends in the vehicle front-rear direction X. One end (the end portion on the inner side Y2 in the vehicle width direction) of the inner top plate portion 12b is connected to the upper end of the inner vertical wall portion 12a, and it is a flat plate-like portion facing upward. One end (the end portion on the inner side Y2 in the vehicle width direction) of the inner bottom plate portion 12c is connected to the lower end of the inner vertical wall portion 12a, and it is a flat plate-like portion facing downward. The inner top plate portion 12b and the inner bottom plate portion 12c each extend in a substantially horizontal direction and are slightly inclined in a direction away from each other as they approach the side sill outer 11.

[0051] The upper flange portion 12d is a flat plate-like portion that extends upward from the other end of the inner top plate portion 12b (the end on the outer side Y1 in the vehicle width direction). The lower flange portion 12e is a flat plate-like portion that extends downward from the other end of the inner bottom plate portion 12c (the end on the outer side Y1 in the vehicle width direction).

[0052] Between the inner vertical wall portion 12a and the inner top plate portion 12b and between the inner vertical wall portion 12a and the inner bottom plate portion 12c, ridge lines 12f, 12g extending in the front-rear direction X (that is, the corners on the inner side Y2 in the vehicle width direction in the closed cross-section C) are formed.

[0053] The closed cross-section C of the side sill 2 is formed in a substantially rectangular shape by the above six flat plate-like portions, that is, the outer vertical wall portion 11a, the inner vertical wall portion 12a, the outer top plate portion 11b, the outer bottom plate portion 11c, the inner top plate portion 12b, and the inner bottom plate portion 12c. Therefore, the outer vertical wall portion 11a, the inner vertical wall portion 12a, the outer top plate portion 11b, and the outer bottom plate portion 11c form a part of the closed cross-section C. In the case where the inner vertical wall portion 12a of the side sill inner 12 is curved and has a semi-circular cross-section, the inner top plate portion 12b and the inner bottom plate portion 12c may not be provided.

[0054] (Description of the outer side reinforcing member 13 and the inner side reinforcing member 14) The inner side reinforcing member 14 and the outer side reinforcing member 13 shown in FIG. 3 are formed by roll-forming a metal plate material. Roll-forming is a forming method in which a plate material is continuously formed into a desired cross-sectional shape by feeding the plate material between a pair or a plurality of pairs of rolls and compressing the plate material from both sides.

[0055] The inner side reinforcing member 14 shown in FIG. 3 is fixed to the inner vertical wall portion 12a and has a fitting portion 15 that is fitted with the fitting portion 18 of the outer side reinforcing member 13 when an impact load from the side of the vehicle is input to the side sill 2. The details of the fitting portion 15 will be described later.

[0056] The inner side reinforcing member 14 has a hat cross-sectional shape. Specifically, it has a main body portion 14a with a substantially U-shaped cross-section having a fitted portion 15, an upper flange portion 14b extending upward from the end of the upper wall portion of the main body portion 14a and joined to the inner vertical wall portion 12a and the inner top plate portion 12b of the side sill inner 12, and a lower flange portion 14c extending downward from the end of the lower wall portion of the main body portion 14a and joined to the inner vertical wall portion 12a and the inner bottom plate portion 12c of the side sill inner 12.

[0057] The upper flange portion 14b and the lower flange portion 14c of the inner side reinforcing member 14 are joined to the inner vertical wall portion 12a, the inner top plate portion 12b, and the inner bottom plate portion 12c of the side sill inner 12 by spot welding or the like, respectively, whereby it is possible to suppress angular displacement of the ridge lines 12f, 12g (corners) of the side sill inner 12.

[0058] The outer side reinforcing member 13 may have a configuration having a fitting portion 18 that fits with the fitted portion 15 of the inner side reinforcing member 14, and brace portions 17a, 17b.

[0059] The outer side reinforcing member 13 shown in FIG. 3 specifically includes a first portion 16 having a fitting portion 18, and a second portion 17 that is connected to the first portion 16 and has brace portions 17a, 17b. The first portion 16 and the second portion 17 are each separately formed by roll forming of a metal plate material, and are joined to each other by welding or the like after forming. The first portion 16 is fixed to the side sill outer 11 via the second portion 17.

[0060] Specifically, the first portion 16 has a front end surface 16a extending in the vertical direction Z that is the main part of the fitting portion 18, an upper wall portion 16b connecting the upper end of the front end surface 16a to the brace portions 17a, 17b of the second portion 17, and a lower wall portion 16c located below the upper wall portion 16b and connecting the lower end of the front end surface 16a to the brace portions 17a, 17b of the second portion 17.

[0061] The upper wall portion 16b and the lower wall portion 16c have stepped portions 16f, 16g as deformation promoting portions that partially promote deformation during a vehicle side impact.

[0062] Since the first portion 16 shown in FIG. 3 is composed of a plate material. In the example of FIG. 3, the deformation promoting portion is composed of a plurality of stepped portions 16f, 16g formed by partially bending and deforming (buckling or curving) the plate material. The stepped portions 16f, 16g shown in FIG. 3 are bead or uneven portions extending in the front-rear direction X.

[0063] Hereinafter, the fitting portion 18 and the fitted portion 15 will be described in detail.

[0064] (Description of the fitting portion 18 and the fitted portion 15) The fitting portion 18 is configured to fit with the fitted portion 15 of the inner reinforcing member 14 when an impact load from the side of the vehicle is input to the side sill 2. Note that the fitting portion 18 shown in FIG. 3 is separated from the fitted portion 15 before the input of the collision load at the time of a side collision of the vehicle, but may be in contact with the fitted portion 15.

[0065] The fitting portion 18 and the fitted portion 15 may be such that one of them has a convex cross-section and extends in the front-rear direction X, and the other has a concave cross-section corresponding to the convex cross-section and extends in the front-rear direction X.

[0066] For example, in the fitting portion 18 and the fitted portion 15 of FIG. 3, a large convex-shaped fitting portion 18 is formed by the tip surface 16a of the first portion 16 of the outer reinforcing member 13 and the portions connecting to the tip surface 16a on the upper wall portion 16b and the lower wall portion 16c. Corresponding to this fitting portion 18, a large concave-shaped fitted portion 15 is formed by the tip surface 15a of the inner reinforcing member 14 and a pair of protrusions 15b protruding outward in the vehicle width direction Y from both the upper and lower ends thereof.

[0067] As shown in FIGS. 6(a) to 6(d), in the event of a side impact of the vehicle, while the large convex fitting portion 18 and the large concave fitting portion 15 are fitted during the side impact of the vehicle, the side sill 2 and the outer side reinforcing member 13 and the inner side reinforcing member 14 inside thereof are crushed, so that the fitting portion 18 does not shift downward and can stably receive loads in all directions (such as the vehicle width direction Y, the longitudinal direction X, the vertical direction Z, and the torsional direction around the X-axis extending in the longitudinal direction X) by the outer side reinforcing member 13 and the inner side reinforcing member 14. Thereby, it is possible to suppress the bending deformation of the side sill 2 inward in the vehicle width direction Y during a side impact of the vehicle. Thereby, in a configuration in which a battery is mounted inside the side sill 2 in the vehicle width direction Y, such as a battery electric vehicle, it is possible to reliably protect the battery.

[0068] On the other hand, as a comparative example, as shown in FIGS. 7(a) to 7(d), in a configuration in which the outer side reinforcing member 13 and the inner side reinforcing member 14 do not have a fitting portion and a fitted portion, the first portion 16 of the outer side reinforcing member 13 shifts downward, so that it is understood that the outer side reinforcing member 13 and the inner side reinforcing member 14 cannot stably receive the load.

[0069] In addition, as another example of the concavo-convex shapes of the fitting portion and the fitted portion, a combination of a fitting portion 28 having a small convex portion 28a as shown in FIG. 4 and a fitted portion 25 having a small concave portion 25a can also prevent the displacement between the outer side reinforcing member 13 and the inner side reinforcing member 14 by the concavo-convex fitting. Or, as shown in FIG. 5, a combination of a fitting portion 38 having a small concave portion 38a and a fitted portion 35 having a small convex portion 35a that can be fitted into the concave portion 38a and a downward convex portion 35b that receives the lower corner portion of the fitting portion 38 can also prevent the displacement between the outer side reinforcing member 13 and the inner side reinforcing member 14 by the concavo-convex fitting. Further, even in the case of the fitting portions 28 and 38 and the fitted portions 25 and 35 which are combinations of small concavo-convex shapes as shown in FIGS. 4 to 5, since the outer side reinforcing member 13 has the brace portions 17a and 17b as shown in FIG. 3, more stable fitting is possible.

[0070] The fitting portions 18, 28, 38 and the fitted portions 15, 25, 35 having the concavo-convex cross-sectional shapes shown in FIGS. 3 to 5 and extending in the front-rear direction X can be easily and continuously formed by roll forming of a metal plate material.

[0071] Next, the second portion 17 having the brace portions 17a and 17b will be described in detail.

[0072] (Description of the second portion 17 having the brace portions 17a and 17b) As shown in FIG. 3, the second portion 17 is formed by continuously roll-forming a metal plate material and has an overall bent inverted V-shape or an obtuse V-shape. Specifically, the second portion 17 includes a pair of upper and lower brace portions 17a and 17b, and three fixing plate portions 17c, 17d, 17e (upper fixing plate portion 17c, middle fixing plate portion 17d, lower fixing plate portion 17e) spaced apart from each other in the vertical direction Z.

[0073] The brace portions 17a and 17b are configured to connect at least one of the spaces between the outer top plate portion 11b and the outer top plate portion 11b and between the outer vertical wall portion 11a and the outer bottom plate portion 11c of the side sill outer 11 across the ridge lines 11f and 11g (preferably, linearly connected by welding). Note that either one of the brace portions 17a and 17b may be omitted.

[0074] In the present embodiment, the brace portions 17a and 17b connect both the spaces between the outer top plate portion 11b and the outer top plate portion 11b and between the outer vertical wall portion 11a and the outer bottom plate portion 11c of the side sill 2 across the ridge lines 11f and 11g. By these brace portions 17a and 17b, it is possible to suppress the angular displacement at the ridge lines 11f and 11g of the side sill outer 11 during a side impact of the vehicle.

[0075] The angular displacement is a displacement in which the angles at the positions of the ridge lines 11f and 11g in the closed cross-section C of FIG. 3 open or close, and in some cases, is a displacement that causes torsion about the X-axis extending in the front-rear direction X of the side sill outer 11.

[0076] Specifically, the upper brace portion 17a extends obliquely inward in the vehicle width direction Y2 upward so as to straddle the upper ridge line 11f in order to connect between the outer top plate portion 11b and the outer vertical wall portion 11a of the side sill outer 11. The upper end of the upper brace portion 17a is connected to the upper fixing plate portion 17c. The upper fixing plate portion 17c is joined to the outer top plate portion 11b by welding or the like. The lower end of the upper brace portion 17a is connected to the intermediate fixing plate portion 17d. The intermediate fixing plate portion 17d is joined to the bead 11h extending in the front-rear direction X of the outer vertical wall portion 11a by welding or the like.

[0077] Also, the lower brace portion 17b extends obliquely inward in the vehicle width direction Y2 downward so as to straddle the lower ridge line 11g in order to connect between the outer bottom plate portion 11c and the outer vertical wall portion 11a of the side sill outer 11. The lower end of the lower brace portion 17b is connected to the lower fixing plate portion 17e. The lower fixing plate portion 17e is joined to the outer bottom plate portion 11c by welding or the like. The upper end of the lower brace portion 17b is connected to the above intermediate fixing plate portion 17d joined to the bead 11h.

[0078] Therefore, the brace portions 17a and 17b shown in FIG. 3 are fixed to the bead 11h of the outer vertical wall portion 11a of the side sill outer 11 via the intermediate fixing plate portion 17d.

[0079] (Verification of the effects of the brace portions 17a and 17b) Next, the effect of improving the torsional rigidity by the above brace portions 17a and 17b will be verified.

[0080] To verify the effects of the brace portions 17a and 17b, consider a test model having a pair of upper and lower brace portions 17a and 17b shown in FIG. 8. Similar to the comparative example of FIG. 7, the model of FIG. 8 has a configuration in which the outer side reinforcing member 13 and the inner side reinforcing member 14 do not have a fitting portion and a fitted portion, and the second portion 17 of the outer side reinforcing member 13 has a configuration having a pair of upper and lower brace portions 17a and 17b. Regarding other configurations, they are the same as the structure of FIG. 3. The reference numeral 2SW shown in FIG. 8 indicates a location where two spot welds are made.

[0081] On the other hand, as a comparative example for the test model of FIG. 8, consider the conventional structure shown in FIG. 9. The conventional structure shown in FIG. 9 has a configuration without a brace portion and corresponds to the structure described in Patent Document 1. In the structure shown in FIG. 9, an outer side reinforcing member 53, an inner side reinforcing member 54, and a partition member 55 are arranged inside the side sill 50. The side sill outer 51 and the side sill inner 52 of the side sill 50 are joined at the site 3SW by three spot welds together with the partition member 55 at the site of the upper and lower flange portions. At other sites, two spot welds are made at the site 2SW. That is, the outer side reinforcing member 53 is welded to the vertical wall portion 51a of the side sill outer 51, while the inner side reinforcing member 54 is welded to the partition member 55 without being welded to the side sill inner 52.

[0082] In the configuration having the brace portions 17a and 17b shown in FIG. 8, even when receiving the load input during a vehicle collision, it is possible to suppress the angular displacement at the ridge lines 11f and 11g of the side sill outer 11 by the brace portions 17a and 17b. Therefore, in the evaluation test in which a torsional moment about the X-axis extending in the front-rear direction X is applied to the test model shown in FIG. 8, a torsional rigidity of about 110,000 N / rad was measured, and it was found that the mass efficiency was about 40,000 N / rad·kg.

[0083] On the other hand, in the conventional structure shown in FIG. 9, since it does not have a brace portion, the angular displacement of the ridge line of the side sill 50 cannot be suppressed. Therefore, in the evaluation test in which a torsional moment about the X axis is applied to the conventional structure shown in FIG. 9, only a torsional rigidity of about 92,000 N / rad can be obtained, and the mass efficiency is about 30,800 N / rad·kg, which is about 77% of the mass efficiency compared to the structure having the brace portions 17a and 17b shown in FIG. 8. It was found that only the mass efficiency can be obtained. From these test results, it can be seen that the brace portions 17a and 17b greatly contribute to the improvement of the torsional rigidity.

[0084] (Features of this embodiment) (1) In the lower body structure of the vehicle according to this embodiment, an outer side reinforcing member 13 and an inner side reinforcing member 14 are provided inside the side sill 2. Moreover, the outer side reinforcing member 13 includes brace portions 17a and 17b together with a fitting portion 18 that fits with the fitted portion 15 of the inner side reinforcing portion when the vehicle is side-impacted, that is, when an impact load from the side of the vehicle is input to the side sill 2. The brace portions 17a and 17b connect at least one of the spaces between the outer top plate portion 11b of the side sill outer 11 that constitutes the outer portion in the vehicle width direction of the side sill 2 and the outer top plate portion 11b and between the outer vertical wall portion 11a and the outer bottom plate portion 11c (in this embodiment, between these two) across the ridge lines 11f and 11g of the side sill 2.

[0085] Note that either one of the brace portions 17a and 17b may be omitted.

[0086] In this configuration, since the angular displacement of the ridge lines 11f and 11g (for example, displacement such as the corner portion of the closed cross-section C opening or closing) is suppressed by the brace portions 17a and 17b, when the vehicle is side-impacted, the fitting portion 18 of the outer side reinforcing member 13 is less likely to shift in the vertical direction Z, and the fitting portion 18 of the outer side reinforcing member 13 and the fitted portion 15 of the inner side reinforcing member 14 can be fitted more stably. That is, a more stable crushing behavior of the outer side reinforcing member 13 and the inner side reinforcing member 14 can be realized. As a result, since the outer side reinforcing member 13 and the inner side reinforcing member 14 can be sufficiently compressed and deformed, the energy absorption amount is improved.

[0087] Therefore, if the configuration of the present embodiment is applied to an electric vehicle in which a battery pack extends under the vehicle floor, the energy absorption of the side sill 2 is improved, and the battery pack can be protected.

[0088] In addition, during normal driving, the brace portions 17a and 17b can suppress the angular displacement of the ridge lines 11f and 11g, so that the vehicle body rigidity (especially torsional rigidity) is also improved. Thereby, it is possible to suppress the torsional deformation of the side sill 2.

[0089] Furthermore, even if the outer side reinforcing member 13 and the inner side reinforcing member 14 are set in a contact state within the closed cross-section C of the side sill 2, during normal driving, there is no minute angular displacement of the side sill 2, and accordingly, there is no vertical movement of the outer side reinforcing member 13, so that no abnormal noise is generated.

[0090] (2) In the lower vehicle body structure of the vehicle according to the present embodiment, one of the fitting portion 18 and the fitted portion 15 has a convex cross-section and extends in the front-rear direction X, and the other has a concave cross-section corresponding to the convex cross-section and extends in the front-rear direction X.

[0091] In such a configuration, the fitting portion 18 and the fitted portion 15 can be stably fitted by fitting a concave portion (i.e., a groove) and a convex portion (i.e., a ridge) that respectively extend in the front-rear direction X. Further, by roll-forming a metal plate material, one of the fitting portion 18 and the fitted portion 15 can be continuously formed into a shape having a convex cross-section and extending in the front-rear direction X, and the other can be continuously formed into a shape having a concave cross-section and extending in the front-rear direction X, and it is possible to easily form a shape capable of realizing stable fitting.

[0092] (3) In the lower vehicle body structure of the vehicle according to the present embodiment, the outer side reinforcing member 13 has a first portion 16 having a fitting portion 18 and a second portion 17 that is connected to the first portion 16 and has brace portions 17a and 17b.

[0093] With such a configuration, it is possible to continuously form the first part 16 having the fitting part 18 and the second part 17 having the brace parts 17a and 17b into desired cross-sectional shapes by roll forming of a metal plate material separately. Then, by connecting the formed first part 16 to the second part 17, it is possible to easily manufacture the outer side reinforcing member 13 having the fitting part 18 and the brace parts 17a and 17b.

[0094] (4) In the lower body structure of the vehicle of the present embodiment, the first part 16 is fixed to the side sill 2 via the second part 17.

[0095] According to such a configuration, it is possible to reliably transmit the collision load input to the side sill 2 during a side collision of the vehicle to the first part 16 via the second part 17 in the outer side reinforcing member 13. As a result, it becomes possible to smoothly perform the load transmission from the brace parts 17a and 17b of the second part 17 to the fitting part 18 of the first part 16.

[0096] (5) In the lower body structure of the vehicle of the present embodiment, the first part 16 has an upper wall part 16b that connects the tip surface 16a, which is the main part of the fitting part 18, to the brace parts 17a and 17b of the second part 17, and a lower wall part 16c located below the upper wall part 16b. The upper wall part 16b and the lower wall part 16c have stepped parts 16f and 16g (that is, beads or uneven parts extending in the front-rear direction X) as deformation promoting parts that partially promote deformation during a side collision of the vehicle.

[0097] With such a configuration, during a side collision of the vehicle, the first part 16 of the outer side reinforcing member 13 is partially deformed at the stepped parts 16f and 16g as deformation promoting parts of the upper wall part 16b and the lower wall part 16c while the fitting part 18 fits into the fitted part 15 of the inner side reinforcing member 14, so that the energy absorption amount in the outer side reinforcing member 13 is further improved.

[0098] (6) In the lower body structure of the vehicle according to this embodiment, the first portion 16 is composed of a plate material. The deformation promoting portion is composed of a plurality of stepped portions 16f, 16g formed by partially bending and deforming (buckling or curving) the plate material.

[0099] With such a configuration, by forming the deformation promoting portion with a plurality of stepped portions 16f, 16g, the deformation promoting portion can be formed in a simple structure (in other words, by simple shape change) on the upper wall portion 16b and the lower wall portion 16c of the first portion 16 of the outer side reinforcing member 13. During a side impact of the vehicle, by deforming (so-called bellows-like deformation) and folding at the plurality of stepped portions 16f, 16g, the first portion 16 of the outer side reinforcing member 13 can be easily deformed. At the same time, it is possible to easily set or control the amount of energy absorption in the outer side reinforcing member 13 due to the stepped shape of the first portion 16.

[0100] (7) In the lower body structure of the vehicle according to this embodiment, the brace portions 17a, 17b connect both between the outer top plate portion 11b and the outer top plate portion 11b and between the outer vertical wall portion 11a and the outer bottom plate portion 11c in the side sill 2 across the ridge lines 11f, 11g.

[0101] With such a configuration, since the brace portions 17a, 17b connect between the outer top plate portion 11b, the outer vertical wall portion 11a, and the outer bottom plate portion 11c of the side sill 2 across the two ridge lines 11f, 11g formed therebetween, it is possible to further improve the amount of energy absorption by the side sill 2 during a side impact of the vehicle and further improve the rigidity of the side sill 2 during normal driving.

[0102] (8) In the lower body structure of the vehicle according to this embodiment, the outer vertical wall portion 11a has beads 11h extending in the front-rear direction X (recessed portions recessed inward in the vehicle width direction Y in FIG. 3). The brace portions 17a, 17b are fixed to the beads 11h.

[0103] According to such a configuration, since the outer vertical wall portion 11a of the side sill 2 has the bead 11h extending in the front-rear direction X, the rigidity of the outer vertical wall portion 11a (particularly the bending rigidity in the vehicle width direction Y) is improved. Further, since the brace portions 17a and 17b are fixed to the bead 11h having high rigidity in the outer vertical wall portion 11a, the impact load at the time of a side collision of the vehicle can be smoothly transmitted from the outer vertical wall portion 11a of the side sill outer 11 to the brace portions 17a and 17b of the outer side reinforcing member 13, and the energy absorption amount in the outer side reinforcing member 13 can be further improved.

[0104] (9) In the lower vehicle body structure of the vehicle of the present embodiment, the inner side reinforcing member 14 and the outer side reinforcing member 13 are formed by roll-forming a metal plate material.

[0105] According to such a configuration, since the inner side reinforcing member 14 and the outer side reinforcing member 13 are formed by roll-forming a metal plate material, it is possible to continuously form them easily and inexpensively into a desired cross-sectional shape. Further, since the inner side reinforcing member 14 and the outer side reinforcing member 13 are continuously formed by roll-forming, they can correspond to vehicles of various vehicle lengths, that is, they can correspond to vehicle grid variations.

[0106] Furthermore, since the inner side reinforcing member 14 and the outer side reinforcing member 13 continuously formed by roll-forming reinforce the side sill 2 in a long section in the front-rear direction X, a high energy absorption amount can be obtained even if an obstacle collides with any section of the side sill 2 in the front-rear direction X. Therefore, in a battery electric vehicle, reliable protection of the battery can be achieved.

[0107] (10) In the underbody structure of the vehicle according to this embodiment, the four cross members 6 to 9 (first cross member 6, front side intermediate cross member 7, second cross member 8, and third cross member 9) extending in the vehicle width direction Y are connected to the inner vertical wall portion 12a of the side sill inner 12 within a range including the overlapping portion of the inner side reinforcing member 14 and the side sill 2 in the vertical direction Z, like the front side intermediate cross member 7 in FIG. 3.

[0108] According to such a configuration, at the time of a side collision of the vehicle, the cross members 6 to 9 can effectively receive the collision load while supporting the overlapping portion of the inner side reinforcing member 14 and the side sill 2 from the inner side of the vehicle. Thereby, it is possible to further improve the amount of energy absorption in the side sill 2 and the inner side reinforcing member 14. Therefore, in an electric vehicle in which a battery pack extends under the floor of the vehicle, reliable protection of the battery pack can be achieved.

[0109] (Modification) In the above embodiment, as an example of the deformation promoting portions on the upper wall portions 16b and 16c of the first portion 16 of the outer side reinforcing member 13, the stepped portions 16f and 16g obtained by bending the plate material, that is, the beads or concavo-convex portions extending in the front-rear direction X, were taken as examples for explanation. However, the present invention is not limited to this, and any configuration that promotes the deformation of the upper wall portion 16b and the lower wall portion 16c is included in the present invention as a deformation promoting portion having various shapes and structures. For example, as the deformation promoting portion, notches may be formed in the upper wall portion 16b and the lower wall portion 16c, or a partially thin-walled portion may be formed.

Industrial Applicability

[0110] The present invention can be applied to a vehicle having side sills. In particular, applying the present invention to an electric vehicle in which a battery pack extends under the floor of the vehicle is preferable in that the energy absorption of the side sill is improved and the battery pack can be protected.

Explanation of Reference Numerals

[0111] 1 Vehicle body 2 Side sill 6 First cross member 7 Front intermediate cross member 8 Second cross member 9 Third cross member 11 Side sill outer 11a Outer vertical wall portion 11b Outer top plate portion 11c Outer bottom plate portion 11f, 11g Ridge line 12 Side sill inner 13 Outer side reinforcement member 14 Inner side reinforcement member 15, 25, 35 Fitted portion 16 First part 16b Upper wall portion 16c Lower wall portion 16f, 16g Step portion (deformation promoting portion) 17 Second part 17a, 17b Brace portion 18, 28, 38 Fitting portion

Claims

1. A side sill having a closed cross-section and extending in the longitudinal direction of the vehicle, An outer side reinforcing member disposed inside the side sill and extending in the longitudinal direction, An inner side reinforcing member disposed inside the side sill closer to the vehicle interior than the outer side reinforcing member and extending in the longitudinal direction And comprising The side sill is An outer vertical wall portion, An inner vertical wall portion located on the vehicle interior side with respect to the outer vertical wall portion, An outer top plate portion connected to the upper end of the outer vertical wall portion, And an outer bottom plate portion connected to the lower end of the outer vertical wall portion, The outer vertical wall portion, the inner vertical wall portion, the outer top plate portion, and the outer bottom plate portion form at least a part of the closed cross-section of the side sill, A ridge line extending in the longitudinal direction is formed between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion, respectively, The inner side reinforcing member is fixed to the inner vertical wall portion and has a fitting portion that is fitted to the outer side reinforcing member when an impact load from the side of the vehicle is input to the side sill, The outer side reinforcing member is A fitting portion that fits with the fitting portion of the inner side reinforcing member when an impact load from the side of the vehicle is input to the side sill, And a brace portion that connects at least one of the spaces between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion across the ridge line A lower vehicle body structure of a vehicle, characterized by the above.

2. In the lower vehicle body structure of the vehicle according to Claim 1, One of the fitting portion and the fitted portion has a convex cross-section extending in the longitudinal direction, and the other has a concave cross-section corresponding to the convex cross-section and extending in the longitudinal direction. A lower vehicle body structure of a vehicle, characterized by the above.

3. In the lower vehicle body structure of the vehicle according to Claim 1 or 2, The outer side reinforcing member includes a first portion having the fitting portion and a second portion connected to the first portion and having the brace portion. A lower vehicle body structure of a vehicle, characterized by the above.

4. In the lower vehicle body structure of the vehicle according to Claim 3, The first portion is fixed to the side sill via the second portion. A lower vehicle body structure of a vehicle, characterized by the above.

5. In the lower vehicle body structure of the vehicle according to Claim 3, The first portion has an upper wall portion that connects the fitting portion to the second portion and a lower wall portion that is located below the upper wall portion and connects the fitting portion to the second portion. The upper wall portion and the lower wall portion have a deformation promoting portion that promotes partial deformation during a side impact of the vehicle. The lower vehicle body structure of a vehicle, characterized in that.

6. In the lower vehicle body structure of the vehicle according to claim 5, The first portion is composed of a plate material, The deformation promoting portion is composed of a plurality of stepped portions formed by partially bending and deforming the plate material. The lower vehicle body structure of a vehicle, characterized in that.

7. In the lower vehicle body structure of the vehicle according to claim 1 or 2, The brace portion connects both between the outer vertical wall portion and the outer top plate portion and between the outer vertical wall portion and the outer bottom plate portion in the side sill across the ridge line. The lower vehicle body structure of a vehicle, characterized in that.

8. In the lower vehicle body structure of the vehicle according to claim 1 or 2, The outer vertical wall portion has beads extending in the front-rear direction, The brace portion is fixed to the beads. The lower vehicle body structure of a vehicle, characterized in that.

9. In the lower vehicle body structure of the vehicle according to claim 1 or 2, The inner side reinforcing member and the outer side reinforcing member are formed by roll-forming a metal plate material. The lower vehicle body structure of a vehicle, characterized in that.

10. In the lower vehicle body structure of the vehicle according to claim 1 or 2, Further provided with a cross member extending in the vehicle width direction, The cross member is connected to the inner vertical wall portion of the side sill in the vertical direction within a range including the overlapping portion of the inner side reinforcing member and the side sill. The lower vehicle body structure of a vehicle, characterized in that.

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