Vehicle underbody structure

Abstract

To provide a lower vehicle body structure of a vehicle which enables an anteroposterior extending part to maintain side sill support effect during a lateral collision.SOLUTION: A lower vehicle body structure 100 of a vehicle includes: a floor panel 2; side sills 50; and frame members 20 each extending in an anteroposterior direction at an inner side as seen in a vehicle width direction of the side sill 50 and having an anteroposterior extending part 22 which contacts with the inner side as seen in the vehicle width direction of the side sill 50 and extends along the side sill 50 in a vehicle anteroposterior direction. The anteroposterior extending part 22 has: a bottom surface part 41 facing the floor panel 2 from below; an inner wall part 42 extending from an inner end part as seen in the vehicle width direction of the bottom surface part 41 to the floor panel 2; and an inner flange 44 extending from a tip of the inner wall part 42 to the inner side as seen in the vehicle width direction and joined to the floor panel 2. The bottom surface part 41 is formed with deformation promotion parts 48, 49 which promote deformation of the bottom surface part 41 in the vehicle width direction when a buffer load acting in the vehicle width direction is input.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] Patent Document 1 discloses a vehicle lower body structure including a frame member that extends in the front-rear direction on the vehicle width inner side of the side sill, is joined to the floor panel from below, and forms a closed cross section together with the floor panel, and has a front-rear extension that abuts against the side sill on the vehicle width inner side and extends in the vehicle front-rear direction along the side sill. The side sill is supported from the vehicle width inner side by the frame member, particularly the front-rear extension, and inward collapse deformation during a side collision is suppressed.

[0003] The front and rear extension portions have a first surface portion that faces the floor panel from below, an inner wall portion that extends from the inner end portion of the first surface portion in the vehicle width direction toward the floor panel, and an inner flange that extends from the tip portion of the inner wall portion inward in the vehicle width direction and is joined to the floor panel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 10,155,542 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the frame member constitutes the framework of the vehicle body, it is generally made of a material (e.g., a thicker plate) that is more rigid than the steel plate that constitutes the floor panel. In other words, in a closed cross section formed by the frame member and the floor panel, the first surface portions of the front and rear extension portions that face each other in the vertical direction and the floor panel have different rigidities. Specifically, the first surface portions have a higher rigidity than the floor panel.

[0006] For this reason, in the vehicle lower body structure of Patent Document 1, when a collision load acting toward the inside of the vehicle width direction through the side sill acts on the front and rear extensions during a side collision, the amount of deformation of the portion of the floor panel facing the first surface portion is likely to be excessively large compared to the amount of deformation of the first surface portion. As a result, excessive shear strain is generated at the joint between the front and rear extensions and the floor panel at the inner flange, causing the joint to break and the front and rear extensions to fall off the floor panel.

[0007] If the front and rear extensions fall off the floor panel, they will no longer support the side sill, reducing the effect of the front and rear extensions in preventing the side sill from collapsing inward in the event of a side collision.

[0008] An object of the present invention is to provide a lower body structure for a vehicle that can maintain the supporting effect of the side sill by the front and rear extension portions even during a side collision. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention is characterized by the following configuration.

[0010] The present invention relates to A floor panel that constitutes a floor surface portion of the vehicle; A side sill extending in a front-rear direction of the vehicle at an end in a vehicle width direction of the vehicle; a frame member extending in a front-rear direction on the vehicle width directional inner side of the side sill and joined to the floor panel in a vertical direction to form a closed cross section together with the floor panel, the frame member having a front-rear extending portion that abuts against the side sill on the vehicle width directional inner side and extends in the vehicle front-rear direction along the side sill; Equipped with The front and rear extension portions are A first surface portion that faces the floor panel in a vertical direction; an inner wall portion extending from an inner end portion of the first surface portion in a vehicle width direction toward the floor panel; an inner flange extending inward in a vehicle width direction from a tip end portion of the inner wall portion and joined to the floor panel; It has The first surface portion is formed with a deformation promoting portion that promotes deformation of the first surface portion in the vehicle width direction when a collision load is input in the vehicle width direction. And, The compressive strength of the portion of the floor panel that forms a closed cross section together with the front and rear extension portions toward the inside in the vehicle width direction is equal to the compressive strength of the first surface portion. The present invention provides an underbody structure for a vehicle.

[0011] According to the present invention, when a collision load in the vehicle width direction is input to the front / rear extension portion through the side sill during a side collision, the deformation of the first surface portion in the vehicle width direction can be promoted through the deformation promoting portion. As a result, the deformation amount of the first surface portion, which generally has a higher rigidity than the floor panel, approaches the deformation amount of the portion of the floor panel facing the first surface portion.

[0012] This reduces shear strain at the joint between the inner flange and the floor panel, making it easier to maintain the joint at the inner flange, and therefore easier to maintain the closed cross section of the front and rear extensions, which makes it easier to maintain support for the side sill from the inside in the vehicle width direction by the front and rear extensions, thereby suppressing inward collapse of the side sill. In addition, the compressive strength of the floor panel in the vehicle width direction of the portion that forms a closed cross section together with the front and rear extensions is equivalent to the compressive strength of the first surface portion, so that when a collision load in the vehicle width direction is input to the front and rear extensions via the side sill during a side collision, the deformation amount of the first surface portion is equivalent to the deformation amount of the portion of the floor panel that faces the first surface portion. As a result, there is no misalignment of the inner flange with the floor panel in the vehicle width direction, so no shear strain is generated at the joint between the inner flange and the floor panel, and the joint at the inner flange can be maintained.

[0013] The deformation promoting portion may be a bead extending in the front-rear direction or a hole penetrating in the vehicle up-down direction.

[0014] According to this configuration, the deformation promoting portion can be easily formed integrally as a bead or a hole on the first surface portion by, for example, press molding the front and rear extension portions. The bead in this configuration may be either a bead that is concave on the inside of the closed cross section (i.e., the floor pan side) or a bead that is convex on the outside of the closed cross section (i.e., the opposite side to the floor pan).

[0015] Moreover, the deformation promoting portion is provided in plurality, The plurality of deformation promoting portions may include at least two of the deformation promoting portions aligned in a vehicle width direction.

[0016] According to this configuration, the first surface portion can be easily deformed so as to be compressed reliably in the vehicle width direction at the position where at least two deformation promoting portions aligned in the vehicle width direction are formed.

[0017] Moreover, the deformation promoting portion is provided in plurality, The plurality of deformation promoting portions may include at least two of the deformation promoting portions aligned in a front-rear direction of the vehicle.

[0018] According to this configuration, the at least two deformation promoting portions aligned in the vehicle longitudinal direction make it easy to deform the first surface portion so as to be compressed stably in the vehicle width direction over a wide range in the longitudinal direction.

[0019] In addition, the front and rear extension portions are joined to the floor panel from below, A lower surface of the front-rear extension portion may be located higher than a lower surface of the side sill.

[0020] According to this configuration, the ridgeline portion formed between the lower surface portion and the outer wall portion of the front and rear extension portion is located above the lower surface of the inner wall portion of the side sill in the vehicle width direction, so that the highly rigid ridgeline portion can easily support the inner wall portion of the side sill. Furthermore, the collision load is reliably transmitted from the side sill to the bottom surface portion, so that the bottom surface portion can easily be deformed so as to be compressed in the vehicle width direction stably. Therefore, when a collision load toward the inside of the vehicle width direction acts on the side sill during a side collision, the front and rear extension portions can easily support the side sill, and it is easy to suppress the inward collapse deformation of the side sill.

[0021] On the other hand, when the lower surfaces of the front and rear extensions are located lower than the lower surface of the side sill, the inner wall of the side sill is not supported by the ridges, and the collision load is not efficiently transmitted from the side sill to the lower surfaces of the front and rear extensions. Also, when the lower surfaces of the front and rear extensions are located at the same height as the lower surface of the side sill, the side sill is likely to collapse inward, starting from the ridges.

[0022] The front-rear extension portion may have an outer wall portion extending from a vehicle width direction outer end portion of the first surface portion toward the floor panel, and may be joined to the side sill at the outer wall portion.

[0023] According to this configuration, since the front and rear extensions are joined to the side sill, when a collision load acts on the side sill toward the inside in the vehicle width direction during a side collision, the front and rear extensions resist the inward collapse deformation of the side sill from the inside in the vehicle width direction. This makes it easier to suppress the inward collapse deformation of the side sill. Effect of the Invention

[0026] According to the present invention, the front and rear extension portions can be easily maintained in contact with the floor panel even during a side collision, thereby maintaining the supporting effect of the side sill provided by the front and rear extension portions. [Brief description of the drawings]

[0027] [Figure 1] 1 is a perspective view showing a lower body structure of a vehicle according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a bottom view of the lower body structure of FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. [Figure 6] Cross-sectional view taken along line VI-VI in Figure 2. [Figure 7] FIG. 3 is a cross-sectional view taken along line VII-VII in FIG. 2 . [Figure 8] FIG. 4 is a bottom view of the lower frame and its surroundings showing the analysis results of a side impact with a pole. [Figure 9] FIG. 9 is a perspective view of the analysis results of FIG. 8 as viewed from the inside in the vehicle width direction. [Figure 10] FIG. 10 is a cross-sectional view taken along line XX in FIG. [Figure 11] 10 is a cross-sectional view taken along line XI-XI in FIG. 9 . [Figure 12] 5A and 5B are diagrams illustrating a deformation state of the lower frame and its periphery during a side collision. [Figure 13] 7 is a cross-sectional view similar to FIG. 6, showing a lower frame according to a modified example. [Figure 14] 10 , showing a modified embodiment of the lower frame according to the comparative example. [Figure 15] 13 is a cross-sectional view similar to FIG. 12, showing a modified aspect of the lower frame according to the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] Fig. 1 is a perspective view showing a vehicle lower body structure 100 according to one embodiment of the present invention. Fig. 2 is a bottom view of the left half of the lower body structure 100. In the following description, the front-rear direction, vehicle width direction (left-right direction), and up-down direction as seen by an occupant in the vehicle are respectively defined as the front-rear direction, vehicle width direction (left-right direction), and up-down direction of the lower body structure 100 and each member.

[0030] As shown in FIG. 1, the lower body structure 100 includes a floor panel 2 that constitutes the floor surface portion of the vehicle interior space, a pair of side sills 50 that extend in the fore-and-aft direction along both ends of the floor panel 2 in the vehicle width direction, and a dash panel 10 disposed in front of the floor panel 2.

[0031] Each side sill 50 includes a side sill inner 51 formed in a hat shape that opens outward in the vehicle width direction in a cross section perpendicular to the front-rear direction, and a side sill outer 52 (see FIG. 2) formed in a hat shape that opens inward in the vehicle width direction. The side sill inner 51 and the side sill outer 52 are joined to each other so as to form a closed cross section that is continuous in the front-rear direction.

[0032] The lower body structure 100 further includes a pair of hinge pillars 11 rising upward from the front ends of the pair of side sills 50. A dash panel 10 is installed between the pair of hinge pillars 11. The dash panel 10 separates the interior space of the vehicle from the engine room in the front-rear direction. A pair of front frames 7 extending in the front-rear direction are disposed on both sides of the engine room in the vehicle width direction (only one of the front frames 7 is shown in FIG. 1).

[0033] A tunnel section 3 that bulges upward from the floor panel 2 and extends in the front-rear direction is provided in the center of the vehicle width direction of the lower body structure 100. The tunnel section 3 is formed in a U-shape that opens downward in a cross section perpendicular to the front-rear direction. Specifically, the tunnel section 3 has a top surface section 3a that extends in the front-rear direction and the vehicle width direction in the center of the vehicle width direction, and a pair of vertical wall sections 3b that extend downward from both sides of the top surface section 3a in the vehicle width direction and are connected to the floor panel 2.

[0034] A backbone frame 8 extending in the front-rear direction is joined to both sides in the vehicle width direction of the upper part of the tunnel section 3. The backbone frame 8 is formed in an L-shape so as to be joined along the top surface portion 3a and the vertical wall portion 3b of the tunnel section 3 in a cross section perpendicular to the front-rear direction. The backbone frame 8 reinforces the corner between the top surface portion 3a and the vertical wall portion 3b of the tunnel section 3.

[0035] A pair of cross members 4 extending in the vehicle width direction are joined to the upper surface of the floor panel 2. The pair of cross members 4 are provided on both sides of the tunnel section 3 in the vehicle width direction. The cross members 4 are, for example, press-formed products made of steel plate, and are formed in a hat shape that is open downward in a cross section perpendicular to the vehicle width direction. At the lower end, the cross member 4 has a front flange 4a extending forward and a rear flange 4b ​​extending rearward.

[0036] The cross member 4 is joined to the floor panel 2 from above at a front flange 4a and a rear flange 4b ​​by, for example, spot welding. Therefore, a closed cross section (not shown) that is continuous in the vehicle width direction is formed between the cross member 4 and the floor panel 2.

[0037] An inner seat bracket 5 for supporting the front portion of an inner seat rail (not shown) is joined to the inner end of the cross member 4 in the vehicle width direction, and an outer seat bracket 6 for supporting the front portion of an outer seat rail (not shown) is joined to the outer end of the cross member 4 in the vehicle width direction. The cross member 4 is connected to the vertical wall portion 3b of the tunnel portion 3 via the inner seat bracket 5, and is joined to the side sill inner 51 via the outer seat bracket 6.

[0038] A pair of frame members 20 extending in the front-rear direction between the side sill 50 and the tunnel section 3 are joined to the floor panel 2. The pair of frame members 20 are provided on both sides in the vehicle width direction of the tunnel section 3. The frame members 20 have an inclined portion 21 extending rearwardly and in a direction inclined outwardly in the vehicle width direction, and a front-rear extension portion 22 (see FIG. 2) that is continuous with the rear portion of the inclined portion 21 and extends rearward in parallel in the front-rear direction.

[0039] The inclined portion 21 has a front end portion that is continuous with the rear end portion of the front frame 7, and a rear end portion that terminates at the outer end portion in the vehicle width direction of the cross member 4. The front and rear extension portions 22 abut against the inner side of the side sill inner panel 51 in the vehicle width direction.

[0040] In addition, a pair of connecting members 15 are joined to the upper surface of the floor panel 2, which connect a pair of frame members 20, specifically a pair of inclined portions 21, to a pair of vertical wall portions 3b of the tunnel portion 3 in the vehicle width direction. The pair of connecting members 15 are provided on both sides of the tunnel portion 3 in the vehicle width direction (only one of the connecting members 15 is shown in FIG. 1).

[0041] The connecting member 15 has a horizontal portion 16 extending in the vehicle width direction along the floor panel, a rising portion 17 extending upward along the vertical wall portion 3b of the tunnel portion 3, and a slope portion 18 connecting the horizontal portion 16 and the rising portion 17. The horizontal portion 16 extends in a direction approximately perpendicular to the extending direction of the inclined portion 21 in a top view. The slope portion 18 is spaced apart from the floor panel 2 and the vertical wall portion 3b of the tunnel portion 3 and extends in a direction inclined upward toward the inside in the vehicle width direction.

[0042] The connecting member 15 is, for example, a press-formed product made of a steel plate, and has a cross-sectional shape perpendicular to the extending direction formed into a hat shape that is open downward or toward the inside in the vehicle width direction.

[0043] The horizontal portion 16 of the connecting member 15 is joined to the inclined portion 21 at its outer end in the vehicle width direction, and forms a closed cross section extending in the vehicle width direction between the horizontal portion 16 and the floor panel 2. The rising portion 17 of the connecting member 15 is joined to the vertical wall portion 3b of the tunnel portion 3, and forms a closed cross section extending in the up-down direction together with the vertical wall portion 3b. In addition, the upper end of the rising portion 17 is joined to the backbone frame 8. The slope portion 18 of the connecting member 15 is not joined to either the floor panel 2 or the tunnel portion 3.

[0044] Fig. 3 is a cross-sectional view perpendicular to the front-rear direction at inclined portion 21 of frame member 20 taken along line III-III in Fig. 1. As shown in Fig. 3, frame member 20 has an upper frame 30 joined to the upper surface of floor panel 2, and a lower frame 40 joined to the lower surface of floor panel 2. In inclined portion 21, upper frame 30 and lower frame 40 are arranged to face each other vertically with floor panel 2 in between.

[0045] In this embodiment, the inclined portion 21 is formed by the upper frame 30 and a portion of the lower frame 40 located forward of the cross member 4. The front-rear extension portion 22 is formed by a portion of the lower frame 40 located rearward of the cross member 4, including a portion facing the cross member 4 from below in the front-rear direction. The upper frame 30 and the lower frame 40 are press-formed products made of, for example, steel plate.

[0046] The upper frame 30 is formed in a hat shape that is open downward in the cross section shown in Fig. 3. Specifically, the upper frame 30 has an upper surface portion 31 that extends generally parallel to the floor panel 2 on the upper surface side of the floor panel 2, an inner wall portion 32 that extends downward from an inner end portion in the vehicle width direction of the upper surface portion 31, an outer wall portion 33 that extends downward from an outer end portion in the vehicle width direction of the upper surface portion 31, an inner flange 34 that extends inward in the vehicle width direction from a lower end portion of the inner wall portion 32, and an outer flange 35 that extends outward in the vehicle width direction from a lower end portion of the outer wall portion 33.

[0047] The lower frame 40 is formed in a hat shape that is open upward in the cross section shown in Fig. 3. Specifically, the lower frame 40 has a bottom surface portion 41 (first surface portion) that extends substantially parallel to the floor panel 2 on the lower surface side of the floor panel 2, an inner wall portion 42 that extends upward from an inner end portion in the vehicle width direction of the bottom surface portion 41, an outer wall portion 43 that extends upward from an outer end portion in the vehicle width direction of the bottom surface portion 41, an inner flange 44 that extends inward in the vehicle width direction from an upper end portion of the inner wall portion 42, and an outer flange 45 that extends outward in the vehicle width direction from a lower end portion of the outer wall portion 43.

[0048] The upper frame 30 and the lower frame 40 have their inner flanges 34, 44 and outer flanges 35, 45 joined by, for example, spot welding in a triple-layer configuration with the floor panel 2 sandwiched therebetween. Therefore, in the inclined portion 21, the upper frame 30 and the lower frame 40 form a substantially rectangular closed cross section extending in the front-to-rear direction, sandwiching the floor panel 2 from above and below.

[0049] 2, a battery 60 and a plurality of pipes 70 are arranged below the floor panel 2 as vehicle components according to the present invention. The battery 60 is arranged between the lower frame 40 and the tunnel section 3 in the vehicle width direction. The outer end of the battery 60 in the vehicle width direction is fixed to the bottom surface section 41 of the lower frame 40 via a battery bracket 61 by fastening, and the inner end of the battery 60 in the vehicle width direction is fixed to a bracket (not shown) provided on the floor panel 2 and / or the tunnel section 3 by fastening.

[0050] The battery bracket 61 is formed in an L-shape having a first surface portion 62 extending in the fore-and-aft direction parallel to the bottom surface portion 41 of the lower frame 40, and a second surface portion 63 extending downward from the inner end portion of the first surface portion 62 in the vehicle width direction.

[0051] The first surface portion 62 is fixed to the bottom surface portion 41 of the lower frame 40 by fastening from below. The outer end portion of the battery 60 in the vehicle width direction is fixed to the second surface portion 63 by fastening from the outside in the vehicle width direction. Therefore, the outer end portion of the battery 60 in the vehicle width direction is fixed to the bottom surface portion 41 of the lower frame 40 via the battery bracket 61.

[0052] The multiple pipes 70 extend in the front-rear direction along the inner wall portion 42 of the lower frame 40. The multiple pipes 70 are arranged above the outer end portion of the battery 60 in the vehicle width direction and adjacent to the inner side of the inner wall portion 42 of the lower frame 40 in the vehicle width direction.

[0053] Fig. 4 is a perspective view showing a cross section perpendicular to the front-rear direction of the front-rear extension portion 22 of the frame member 20 taken along line IV-IV in Fig. 2. The battery 60 and the side sill outer 52 are omitted in Fig. 4. As shown in Fig. 4, the multiple pipes 70 include a first fuel pipe 71, a second fuel pipe 72, a first brake pipe 73, and a second brake pipe 74.

[0054] The first fuel pipe 71 is a pipe for supplying fuel from a fuel tank (not shown) to an engine (not shown). The second fuel pipe 72 is a pipe for introducing evaporated gas generated in the fuel tank into, for example, a canister (not shown). The first and second brake pipes 73 and 74 are pipes for transmitting hydraulic pressure to brake devices (not shown) for the left and right rear wheels, respectively.

[0055] Fig. 5 is a perspective view of the periphery of the lower frame 40 seen from below, omitting the battery 60, and showing a state in which the plurality of pipes 70 are disassembled. As shown in Fig. 5, the plurality of pipes 70 are attached to the inner wall portion 42 of the lower frame 40 via pipe clips 76 at a plurality of locations spaced apart in the front-rear direction. In this embodiment, the plurality of pipes 70 are attached to the lower frame 40 via pipe clips 76 at two locations, one from the front side and one from the rear side of the front-rear extension portion 22.

[0056] 6, the piping clip 76 has a plurality of holding portions 77 that individually hold the plurality of pipes 70, and an attachment portion 78 that is attached to the inner wall portion 42 of the lower frame 40. The plurality of pipes 70 each have a straight pipe portion 70a that is adjacent to the inside of the lower frame 40 in the vehicle width direction and extends linearly in parallel to the front-rear direction, and a held portion 70b that is bent from the straight pipe portion 70a and held by the corresponding holding portions 77 of the piping clip 76.

[0057] 4, floor panel 2 has outer flange 2a extending upward from the outer end in the vehicle width direction. Side sill inner 51 has inner wall portion 53 extending vertically on the inside in the vehicle width direction, upper surface portion 54 extending outward in the vehicle width direction from the upper end of inner wall portion 53, lower surface portion 55 extending outward in the vehicle width direction from the lower end of inner wall portion 53, upper flange 56 extending upward from the outer end in the vehicle width direction of upper surface portion 54, and lower flange 57 extending downward from the outer end in the vehicle width direction of lower surface portion 55.

[0058] The inner wall portion 53 extends in the vertical direction so as to cross the floor panel 2 from the lower surface side to the upper surface side. Specifically, the vertical center position of the inner wall portion 53 is located below the floor panel 2. The side sill inner 51 is joined to the side sill outer 52 (see FIG. 2) by an upper flange 56 and a lower flange 57.

[0059] Similar to the inclined portion 21, the lower frame 40 also has a bottom surface portion 41, an inner wall portion 42, an outer wall portion 43, and an inner flange 44 in the front-rear extension portion 22. The bottom surface portion 41 is located higher than a lower surface portion 55 of the side sill inner panel 51.

[0060] On the other hand, unlike the inclined portion 21, the lower frame 40 does not have an outer flange 45 at the front / rear extending portion 22, and the outer wall portion 43 extends upward beyond the floor panel 2. The outer wall portion 43 is joined to the inner wall portion 53 of the side sill inner panel 51 by spot welding. Specifically, the lower frame 40 is joined to the inner wall portion 53 of the side sill inner panel 51 below the center position of the outer wall portion 43 in the up-down direction.

[0061] The lower frame 40 is joined at the upper end of the outer wall portion 43, in three layers, by, for example, spot welding, to the inner wall portion 53 of the side sill inner panel 51 together with the outer flange 2a of the floor panel 2. That is, the lower frame 40 is joined at the outer wall portion 43 to the inner wall portion 53 of the side sill inner panel 51 at two locations on the upper and lower sides of the floor panel 2 that are spaced apart vertically.

[0062] As shown in Fig. 5, a plurality of horizontal holes 46 penetrating in the vehicle width direction are formed in the inner wall portion 42 of the lower frame 40. The multiple horizontal holes 46 are used for inserting a jig for spot welding when joining the outer wall portion 43 (see Fig. 4) of the lower frame 40 to the inner wall portion 53 (see Fig. 4) of the side sill inner panel 51 by spot welding inside the closed cross section. The multiple horizontal holes 46 are formed in correspondence with positions where the lower frame 40 is joined to the side sill inner panel 51 by spot welding.

[0063] In this embodiment, the horizontal hole 46 is configured as a round hole, but various other hole shapes such as a rectangular shape can also be used.

[0064] Further, a high-rigidity portion is formed in the inner wall portion 42 of the lower frame 40 to increase the rigidity so as to suppress out-of-plane deformation of the inner wall portion 42. In this embodiment, the high-rigidity portion is constituted by a plurality of ribs 47 extending in the up-down direction.

[0065] The multiple ribs 47 are formed so as to protrude inward in the vehicle width direction from the inner wall portion 42. The multiple ribs 47 extend in the vertical direction over approximately the range in which the horizontal holes 46 are formed, with their upper ends reaching the inner flange 44. The multiple ribs 47 are positioned adjacent to each of the multiple horizontal holes 46 in the front-rear direction. For example, the distance between the horizontal holes 46 and the ribs 47 in the front-rear direction is set to 10 mm or less.

[0066] In addition, the rib 47 is formed at a position in the front-rear direction different from the position at which the piping clip 76 is attached. In this embodiment, the rib 47 is formed between a pair of piping clips 76 attached to the front and rear of the front-rear extension portion 22, and behind the piping clip 76 provided at the rear.

[0067] The surface rigidity of the inner wall portion 42 is easily reduced due to the formation of the multiple horizontal holes 46. However, according to this embodiment, the surface rigidity around the horizontal holes 47 is increased by the ribs 47. In particular, since the ribs 47 extend in the up-down direction, they act to preferably resist out-of-plane deformation of the inner wall portion 42, particularly out-of-plane deformation along the fold lines extending in the front-rear direction.

[0068] 5, the horizontal hole portion 46 and the rib 47 are positioned to face the straight pipe portions 70a of the multiple pipes 70 in the vehicle width direction. In this embodiment, the rib 47 faces all of the multiple pipes 70 in the vehicle width direction, but it is sufficient that the rib 47 faces at least partially to some of the pipes 70.

[0069] 2, the bottom surface portion 41 of the lower frame 40 has a plurality of vertical holes 48 penetrating in the up-down direction and a recess 49 (bead) recessed upward at positions offset in the front-rear direction with respect to the battery bracket 61. In this embodiment, in the front-rear extension portion 22, a first vertical hole 48a and a second vertical hole 48b are formed on the front side of the bottom surface portion 41 in front of the battery bracket 61 so as to be aligned in the front-rear direction, and a recess 49 and a third vertical hole 48c are formed on the rear side of the battery bracket 61 so as to be aligned in the front-rear direction. Furthermore, a fourth vertical hole 48d is formed adjacent to the recess 49 on the outer side in the vehicle width direction.

[0070] Fig. 6 is a cross-sectional view perpendicular to the front-rear direction of the periphery of the lower frame 40 taken along line VI-VI in Fig. 2, specifically, a cross-sectional view passing through the center of the third vertical hole 48c. As shown in Fig. 6, the third vertical hole 48c penetrates the bottom surface portion 41 in the up-down direction.

[0071] Fig. 7 is a cross-sectional view of the periphery of the lower frame 40 taken along line VII-VII in Fig. 2 and perpendicular to the front-rear direction, specifically a cross-sectional view passing through the center of the recess 49 and the fourth hole 49d. As shown in Fig. 7, the recess 49 is recessed upward from the bottom surface portion 41 and protrudes inward of the closed cross section. With reference to Fig. 2 as well, the recess 49 extends in the front-rear direction. The fourth vertical hole 48d penetrates the bottom surface portion 41 in the up-down direction and has a smaller diameter than the first to third vertical holes 41a to 41c.

[0072] Here, in this embodiment, floor panel 2 is made of a steel plate with a tensile strength of 590 MPa and a plate thickness of 0.8 mm, while lower frame 40 is made of a steel plate with a tensile strength of 780 MPa and a plate thickness of 1.4 mm. That is, in a closed cross section formed by floor panel 2 and lower frame 40, bottom surface portion 41 of lower frame 40 has a higher tensile strength and a thicker plate thickness than opposing surface portion 2b of floor panel 2 that faces bottom surface portion 41, so that according to this configuration, bottom surface portion 41 is likely to have a higher compression rigidity than opposing surface portion 2b.

[0073] However, in this embodiment, the bottom surface portion 41 of the lower frame 40 has a reduced compressive rigidity in the vehicle width direction because the multiple vertical holes 48 and recesses 49 are formed in the bottom surface portion 41. That is, the multiple vertical holes 48 reduce the surface rigidity of the bottom surface portion 41, and the recesses 49 act as starting points for folding extending in the front-rear direction when a load is applied in the vehicle width direction, thereby reducing the compressive rigidity of the bottom surface portion 41. That is, the vertical holes 48 and the recesses 49 constitute a deformation promoting portion according to the present invention.

[0074] As a result, the compressive rigidity in the vehicle width direction at bottom surface portion 41 of lower frame 40 is close to the compressive rigidity in the vehicle width direction at opposing surface portion 2b of floor panel 2.

[0075] Next, with reference to Figs. 8 to 12, a description will be given of a deformation mode of the vehicle lower body structure 100 when a side impact load due to a pole side impact is input to the side sill 50.

[0076] FIG. 8 is a bottom view showing the deformation of vehicle lower body structure 100 in a pole side collision, calculated by CAE analysis, and FIG. 9 is a perspective view of the deformed portion in FIG. 8, as viewed from the inside in the vehicle width direction.

[0077] 8 and 9, the CAE analysis calculates the deformation state of the lower body structure 100 when the pole 90 collides from the outside in the vehicle width direction against the front / rear extension portion 22 of the frame member 20. As shown in Fig. 8, the pole 90 penetrates to the inside in the vehicle width direction, and as a result, both the side sill 50 and the frame member 20 are locally pressed inward in the vehicle width direction.

[0078] Fig. 10 is a cross-sectional view perpendicular to the front-rear direction along line XX in Fig. 9, specifically, a cross-sectional view in the vicinity of the horizontal hole 46. As shown in Fig. 10, the lower frame 40 is deformed by the pole side impact so that the inner wall portion 42 protrudes inward in the vehicle width direction, but the rib 47 suppresses the amount of protrusion due to out-of-plane deformation of the inner wall portion 42 inward in the vehicle width direction. As a result, the edge portion 46a of the horizontal hole 46 is suppressed from protruding toward the edge side in the vehicle width direction, and contact between the edge portion 46a and the multiple pipes 70 is avoided. Therefore, damage to the pipes 70 by the edge portion 46a of the horizontal hole 46 during the pole side impact is suppressed.

[0079] Fig. 11 is a cross-sectional view perpendicular to the front-rear direction along line XI-XI in Fig. 9, specifically, a cross-sectional view in the vicinity of rib 47. As shown in Fig. 11, in the event of a pole side collision, the multiple pipes 70 come into contact with rib 47 before coming into contact with inner wall portion 42, which also prevents the pipes 70 from coming into contact with edge portion 46a of horizontal hole portion 46.

[0080] Fig. 14 shows the CAE analysis results at the same cross-sectional position as Fig. 10 for a comparative example in which the rib 47 is not formed on the inner wall portion 42. As shown in Fig. 14, in the comparative example, the out-of-plane deformation of the inner wall portion 42 toward the inside in the vehicle width direction is large compared to this embodiment. Furthermore, in the comparative example, since the rib 47 is not formed on the inner wall portion 42, the rib 47 cannot be brought into contact with the pipe 70 prior to the edge portion 46a of the horizontal hole portion 46. As a result, the edge portion 46a of the horizontal hole portion 46 comes into contact with the multiple pipes 70 during a pole side collision.

[0081] Figures 12 are diagrams that show schematic deformation of the periphery of lower frame 40 during a side collision with a pole. As shown in Figure 12(a), a recess 49 is formed in bottom surface portion 41 of lower frame 40. For this reason, as shown in Figure 12(b), when a pole side collision occurs, bottom surface portion 41 of lower frame 40 is likely to bend upward starting from recess 49.

[0082] Although not shown in the figure, the vertical hole portion 48 reduces the rigidity of the bottom surface portion 41, and thus, like the recess 49, the vertical hole portion 48 also acts to reduce the compressive strength of the bottom surface portion 41 in the vehicle width direction.

[0083] As a result, the amount of deformation (compression) in the vehicle width direction of bottom surface portion 41 of lower frame 40 approaches the amount of deformation (compression) in the vehicle width direction of opposing surface portion 2b of floor panel 2, reducing shear strain in the vehicle width direction at joint portion Z between inner flange 44 and floor panel 2. This makes it easier to maintain the joint at joint portion Z even in a pole collision, and as a result, disengagement at joint portion Z is avoided, making it easier to maintain support by lower frame 40 for side sill 50 from the inside in the vehicle width direction.

[0084] Fig. 15 is a diagram similar to Fig. 12, which shows a schematic view of deformation around the lower frame 40 during a pole side collision in a further comparative example in which neither the vertical hole 48 nor the recess 49 is formed in the bottom surface portion 41. As shown in Fig. 15(a), neither the vertical hole 48 nor the recess 49 is formed in the bottom surface portion 41 of the lower frame 40. For this reason, as shown in Fig. 15(b), during a pole side collision, the lower frame 40 is less likely to deform so that the bottom surface portion 41 is compressed in the vehicle width direction.

[0085] In this case, the amount of deformation (compression) in the vehicle width direction of bottom surface portion 41 of lower frame 40 does not approach the amount of deformation (compression) in the vehicle width direction of opposing surface portion 2b of floor panel 2, and shear strain increases at joint portion Z between inner flange 44 and floor panel 2. As a result, joint portion Z is likely to come loose, and support of side sill 50 by lower frame 40 from the inside in the vehicle width direction is difficult to maintain.

[0086] The vehicle underbody structure 100 according to the embodiment described above provides the following advantages.

[0087] (1) When a collision load in the vehicle width direction is input to the front-rear extension portion 22 of the lower frame 40 via the side sill 50 during a side collision, the deformation of the bottom surface portion 41 in the vehicle width direction can be promoted via the vertical hole portion 48 and the recessed portion 49 serving as deformation promoting portions. As a result, the amount of deformation of the bottom surface portion 41, which has a higher rigidity than the floor panel 2, approaches the amount of deformation of the opposing surface portion 2b of the floor panel 2.

[0088] This reduces shear strain at joint Z between the inner flange 44 and the floor panel 2, making it easier to maintain the joint at the inner flange 44. Therefore, it is easier to maintain the closed cross section of the front and rear extension portions 22 in the lower frame 40 and to maintain support of the side sill 50 from the inside in the vehicle width direction by the front and rear extension portions 22, thereby suppressing inward collapse deformation of the side sill 50.

[0089] (2) When the lower frame 40 is formed by, for example, press molding, the deformation promoting portion can be easily formed integrally as the vertical hole portion 48 and / or the recessed portion 49 on the bottom surface portion 41 .

[0090] (3) The bottom surface portion 41 of the front-rear extension portion 22 of the lower frame 40 has the fourth vertical hole portion 48d and the recess 49, which serve as deformation-promoting portions, positioned side by side in the vehicle width direction, so that the bottom surface portion 41 can be easily deformed so as to be compressed reliably in the vehicle width direction at the position in the front-rear direction where the fourth vertical hole portion 48d and the recess 49 are formed.

[0091] (4) The first and second vertical holes 48a, 48b are positioned adjacent to each other in the vehicle front-rear direction on the bottom surface portion 41 of the front-rear extension portion 22 of the lower frame 40, and the recess 49 and the third vertical hole 49c are positioned adjacent to each other in the vehicle front-rear direction. As a result, the bottom surface portion 41 can be easily deformed so as to be compressed in the vehicle width direction stably over a wide range in the front-rear direction by at least two deformation promoting portions aligned in the vehicle front-rear direction.

[0092] (5) Since the bottom surface 41 of the lower frame 40 is located higher than the lower surface 55 of the side sill inner 51, the ridge portion formed between the bottom surface 41 and the outer wall portion 43 of the front / rear extension portion 22 of the lower frame 40 is located higher than the lower surface 55 of the side sill inner 51, making it easier for the highly rigid ridge portion to support the inner wall portion 53 of the side sill inner 51.

[0093] Furthermore, since the collision load is reliably transmitted from the side sill inner 51 to the bottom surface portion 41 of the lower frame 40, the bottom surface portion 41 is easily deformed so as to be compressed stably in the vehicle width direction. Therefore, when a collision load toward the inside in the vehicle width direction acts on the side sill inner 51 during a side collision, the side sill 50 is easily supported by the front and rear extension portions 22 of the lower frame 40, and inward collapse deformation of the side sill 50 is easily suppressed.

[0094] In contrast, when the bottom surface portions 41 of the front-rear extension portions 22 of the lower frame 40 are positioned lower than the lower surface portion 55 of the side sill inner panel 51, the inner wall portion 53 of the side sill inner panel 51 is not supported by the ridge portion, and the collision load is not efficiently transmitted from the side sill 50 to the lower surface portion 1 of the lower frame 40. In addition, when the bottom surface portions 41 of the front-rear extension portions 22 are positioned at the same height as the lower surface portion 55 of the side sill inner panel 51, the side sill 50 is likely to be deformed inwardly, starting from the ridge portion.

[0095] (6) In the lower frame 40, the outer wall portion 43 is joined to the inner wall portion 53 of the side sill inner panel 51 at the front-rear extending portions 22. Therefore, when a collision load toward the inside in the vehicle width direction acts on the side sill 50 during a side collision, the front-rear extending portions 22 resist the inward collapse deformation of the side sill 50 from the inside in the vehicle width direction. This makes it easier to suppress the inward collapse deformation of the side sill 50.

[0096] (7) When a collision load in the vehicle width direction acts on the front-rear extension portions 22 of the frame member 20 through the side sill 50 during a side collision, the ribs 47 as high rigidity portions suppress out-of-plane deformation of the inner wall portions 42 of the front-rear extension portions 22 inward in the vehicle width direction. As a result, the edges 46a of the horizontal holes 46 formed in the inner wall portions 42 are prevented from protruding inward in the vehicle width direction in an edge-like shape, suppressing damage to the multiple pipes 70 caused by the edges 46a.

[0097] Furthermore, the above-mentioned effect is particularly effective in the event of a pole side collision in which the collision load is concentrated locally, when the collision load is input locally to the front / rear extension portions 22, causing the inner wall portion 42 of the lower frame 40 to easily deform locally.

[0098] (8) The battery 60 is attached to the bottom surface 41 of the lower frame 40, which is located above the lower surface 55 of the side sill inner panel 51. This makes it easier to arrange the battery 60 higher than when the battery 60 is attached to the underside of the side sill 50, and reduces the deterioration of ground clearance due to the battery 60.

[0099] (9) When a collision load in the vehicle width direction is input to the front-rear extension portion 22 of the lower frame 40 through the side sill 50 during a side collision, the front-rear extension portion 22 promotes deformation of the bottom surface portion 41 in the vehicle width direction through the vertical hole portion 48 and the recessed portion 49 serving as deformation promoting portions, thereby absorbing the collision energy transmitted to the inner wall portion 42. As a result, in the front-rear extension portion 22, out-of-plane deformation of the inner wall portion 42 is further suppressed.

[0100] (10) The ribs 47 are formed as high-rigidity portions in the inner wall portions 42 of the front-rear extension portions 22 of the lower frame 40, in portions that are likely to come into contact with the pipes 70 during a side collision because no pipe clips 76 are provided. Therefore, the ribs 47 suppress out-of-plane deformation of the portions of the inner wall portions 42 that are likely to come into contact with the pipes 70, thereby further suppressing the edge portions 46a of the horizontal hole portions 46 from coming into contact with the pipes 70.

[0101] (11) When the lower frame 40 is formed by, for example, press molding, the high rigidity portion can be easily formed integrally as a rib on the inner wall portion 42 .

[0102] (12) Since the rib 47 protrudes inward in the vehicle width direction from the inner wall portion 42, when a collision load in the vehicle width direction is input to the front / rear extension portion 22 of the lower frame 40 via the side sill 50 during a side collision, the rib 47 is likely to come into contact with the pipe 70 before the inner wall portion 42. This further prevents the edge portion 46a of the horizontal hole portion 46 from contacting the pipe 70.

[0103] (13) Since the rib 47 at least partially overlaps with the pipe 70 in the up-down direction, the rib 47 can reliably suppress out-of-plane deformation of the portion of the inner wall portion 42 in the front-rear extension portion 22 of the lower frame 40 that faces the pipe 70. Furthermore, the rib 47 of the inner wall portion 42 can be more reliably brought into contact with the pipe 70.

[0104] The present invention is not limited to the configurations described in the above embodiments, and various modifications are possible.

[0105] In the above embodiment, the high rigidity portion formed on the inner wall portion 42 of the lower frame 40 is configured by the rib 47 that protrudes inward in the vehicle width direction from the inner wall portion 42, but this is not limiting. The rib 47 may be formed so as to be recessed outward in the vehicle width direction with respect to the inner wall portion 42.

[0106] 13, the high rigidity portion may be configured as a burring portion 80 that protrudes cylindrically from the edge portion 46a of the horizontal hole portion 46 toward the inside of the closed cross section, instead of the rib 47. The burring portion 80 can increase the rigidity of the edge portion 46a of the horizontal hole portion 46. This can suppress out-of-plane deformation of the inner wall portion 42 around the horizontal hole portion 46 when a collision load in the vehicle width direction is input to the front / rear extension portion 22 of the lower frame 40 via the side sill 50 during a side collision.

[0107] Furthermore, since the burring portion 80 extends outward in the vehicle width direction from the inner wall portion 42, even if the burring portion 80 is deformed inward in the vehicle width direction during a side collision, the end of the edge portion 46a of the horizontal hole portion 46 is unlikely to come into contact with the piping 70. This further reduces the contact of the edge portion 46a of the horizontal hole portion 46 with the piping 70.

[0108] In the above embodiment, the vertical hole 48 and the recess 49 are described as examples of deformation promoting portions formed in the bottom surface portion 41 of the lower frame 40, but the present invention is not limited to this. The deformation promoting portions may be configured as protrusions that protrude downward from the bottom surface portion 41 and extend in the front-rear direction. The protrusions also provide a breaking trigger when the bottom surface portion 41 deforms so as to be compressed in the vehicle width direction when a collision load acts toward the inside in the vehicle width direction during a side collision.

[0109] In the above embodiment, a deformation promoting portion is formed on the bottom surface portion 41 of the lower frame 40 so that the amount of deformation of the bottom surface portion 41 in the vehicle width direction during a side collision is made to be close to the amount of deformation of the opposing surface portion 2b of the floor panel 2 in the vehicle width direction that faces it, but it is preferable to configure the deformation promoting portion so that the deformation amounts of both are equal, and it is even more preferable to configure the deformation promoting portion so that the deformation speeds of both are also equal. Here, in this specification, "the deformation amounts of both are equal" and "the deformation speeds of both are equal" mean that the value of one is within a range of ±10% of the value of the other.

[0110] In this case, there is almost no misalignment of the inner flange 44 relative to the floor panel 2 in the vehicle width direction, so that the shear strain at the joint Z between the inner flange 44 and the floor panel 2 is approximately zero, and the joint of the inner flange 44 to the floor panel 2 is further maintained.

[0111] In addition, in the above embodiment, the front-rear extension portion 22 is configured by the lower frame 40, but the present invention can also be suitably applied to the case where the front-rear extension portion 22 is configured by the upper frame 30. That is, for the upper frame 30 and / or the lower frame 40 that configure the front-rear extension portion 22, a high rigidity portion may be formed in the portion of the front-rear extension portion 22 that faces the piping 70, and a deformation promoting portion may be formed in the portion that faces the floor panel 2.

[0112] In addition, in the above embodiment, an example was described in which both a deformation-promoting portion and a high-rigidity portion are provided. However, from the viewpoint of promoting compressive deformation of the bottom surface portion 41 of the lower frame 40 toward the inside in the vehicle width direction during a side collision, a high-rigidity portion is not necessarily required. [Industrial Applicability]

[0113] As described above, according to the vehicle lower body structure of the present invention, the support effect of the side sill provided by the front and rear extension portions can be maintained even in the event of a side collision, and therefore it may be suitably used in this type of manufacturing technology field. [Explanation of symbols]

[0114] 2 Floor Panel 20 Frame members 21 Slope 22 Front and rear extensions 30 Upper Frame 40 Lower frame 46 Side hole 47 Ribs 48 Vertical hole 49 Recess 50 Side sill 51 Side sill inner 60 Battery 61 Battery bracket 70 Piping 76 Plumbing Clip 100 Lower body structure

Claims

1. A floor panel that constitutes a floor surface portion of the vehicle; A side sill extending in a front-rear direction of the vehicle at an end in a vehicle width direction of the vehicle; a frame member extending in a front-rear direction on the vehicle width directional inner side of the side sill and joined to the floor panel in a vertical direction to form a closed cross section together with the floor panel, the frame member having a front-rear extending portion that abuts against the side sill on the vehicle width directional inner side and extends in the vehicle front-rear direction along the side sill; Equipped with The front and rear extension portions are A first surface portion that faces the floor panel in a vertical direction; an inner wall portion extending from an inner end portion of the first surface portion in a vehicle width direction toward the floor panel; an inner flange extending inward in a vehicle width direction from a tip end portion of the inner wall portion and joined to the floor panel; It has a deformation promoting portion that promotes deformation of the first surface portion in a vehicle width direction when a collision load in a vehicle width direction is input to the first surface portion, A vehicle underbody structure, wherein the compressive strength of a portion of the floor panel which, together with the front and rear extension portions, forms a closed cross section toward the inside in the vehicle width direction is equal to the compressive strength of the first surface portion.

2. The deformation promoting portion is a bead extending in the front-rear direction or a hole penetrating in the vehicle up-down direction. The vehicle underbody structure according to claim 1 .

3. The deformation promoting portion is provided in plurality, The plurality of deformation promoting portions include at least two of the deformation promoting portions arranged in a vehicle width direction.

3. The vehicle underbody structure according to claim 1 or 2.

4. The deformation promoting portion is provided in plurality, The plurality of deformation promoting portions include at least two of the deformation promoting portions arranged in the vehicle front-rear direction. The vehicle underbody structure according to any one of claims 1 to 3.

5. The front and rear extension portions are joined to the floor panel from below, The lower surface of the front / rear extension portion is located higher than the lower surface of the side sill. The vehicle underbody structure according to any one of claims 1 to 4.

6. The front-rear extension portion has an outer wall portion extending from an outer end portion of the first surface portion in the vehicle width direction toward the floor panel, and is joined to the side sill at the outer wall portion. The vehicle underbody structure according to any one of claims 1 to 5.

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