Vehicle underbody structure

Abstract

To provide a lower vehicle-body structure of a vehicle which can properly attain sectional-deformation suppression of the cross member in a normal vehicle traveling, vibration suppression of the floor panel by the sectional-deformation suppression, and protection of the battery unit in the vehicle side collision.SOLUTION: A lower vehicle-body structure of a vehicle comprises: a floor tunnel 2 projecting upwardly and extending in a vehicle longitudinal direction at a central position, in a vehicle width direction, of a floor panel 1; a cross member 18 having edge lines x3, x5 extending in the vehicle width direction at a rear end of the floor tunnel 2 and having a closed cross-sectional part 21 interconnecting a pair of right-and-left side sills 5; and a pair of right-and-left battery units 31, 32 positioned below the floor panel 1 and between the side sills 5, and provided on right-and-left sides in the vehicle width direction across the floor tunnel 2, and the cross member 18 has reinforcement parts 41, 42 for reinforcing the edge lines x3, x5 in a range including at least the vehicle width direction position of the battery units 31, 32 and excludes the central position in the vehicle width direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a lower body structure of a vehicle. More specifically, at the center position in the vehicle width direction of a floor panel, there is a floor tunnel that protrudes upward and extends in the vehicle front-rear direction, and a ridge line that extends in the vehicle width direction at the rear end of the floor tunnel. The closing surface portion connects a pair of left and right side sills, and a cross member, and below the floor panel and located between the side sills, a pair of left and right battery units provided on the left and right in the vehicle width direction with the floor tunnel therebetween. The present invention relates to a lower body structure of a vehicle provided with these components.

Background Art

[0002] Generally, when mounting a pair of left and right battery units under the floor, so-called under the floor, separated by a floor tunnel, as in a plug-in hybrid vehicle, in the event of a side impact of the vehicle, it is desired to suppress the behavior in which the body on the side sill side collides with the battery unit by crushing the tunnel area where the battery unit is not arranged.

[0003] Patent Document 1 discloses a structure for increasing the ridge line for the purpose of improving the load transmission of the side impact load by the cross member during a side impact of the vehicle. When applying the structure disclosed in this prior art document to the lower body structure of the vehicle described above, during a side impact of the vehicle, the increased ridge line of the cross member protrudes, causing stress to concentrate at the joint between the cross member and the side sill, making the floor tunnel difficult to collapse, and crushing the floor panel area where the battery unit is arranged, and there is a risk that the body on the side sill side collides with the battery unit or the pair of left and right battery units collide with each other.

[0004] This will be described below with reference to FIG. 15. FIG. 15 is a bottom view showing a conventional lower body structure of a vehicle with an increased ridge line of the cross member 96. As shown in FIG. 15, a floor frame 92 is provided at the front portion inside the vehicle width direction of the side sill 91, and a rear side frame 93 is provided at the rear portion inside the vehicle width direction of the side sill 91.

[0005] A tunnel side member 95 is provided at the lower part of the tunnel section 94, which serves as a floor tunnel. A cross member 96 is provided at the rear end of the tunnel section 94, extending in the vehicle width direction and connecting a pair of left and right side sills 91, 91.

[0006] This cross member 96 has a cross member upper 97 and a cross member lower 98, and has a closed section extending in the vehicle width direction. The vehicle width end of the cross member upper 97 is directly joined to the side sill 91, and the cross member lower 98 is joined to the side sill 91 via the rear side frame 93.

[0007] As described above, increasing the number of ridges on the cross member 96 causes these ridges to brace themselves during a vehicle side impact, concentrating stress at the joint 99 between the cross member 96 and the side sill 91. This allows the side impact input from a collision object such as a pole to directly enter the battery unit (not shown), making the tunnel section 94 less likely to collapse, while the floor panel 100 collapses significantly. This resulted in problems such as the vehicle body on the side sill 91 colliding with the battery unit, or the left and right battery units colliding with each other. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2009-220715 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, the present invention aims to provide a vehicle underbody structure that can achieve the following: suppression of cross-sectional deformation of the cross member during normal driving, suppression of vibration of the floor panel due to said suppression of cross-sectional deformation, and protection of the battery unit in the event of a vehicle side collision. [Means for solving the problem]

[0010] This invention comprises a floor tunnel projecting upward from the center of the floor panel in the vehicle width direction and extending in the vehicle longitudinal direction; a cross member having a ridge extending in the vehicle width direction at the rear end of the floor tunnel, with a closed cross section connecting a pair of left and right side sills; and a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and provided on the left and right sides in the vehicle width direction, wherein the cross member has a reinforcing portion that reinforces the ridge in the vehicle width direction, in a range that includes at least the vehicle width direction position of the battery units and excludes the center of the vehicle width direction. Furthermore, the reinforcing portion is an L-shaped reinforcement provided along the ridge of the cross member, and a bracket is provided at the center of the cross member in the vehicle width direction, and the bracket and the reinforcement are joined together. This is a vehicle lower body structure characterized by the following:

[0011] Furthermore, this invention relates to a lower body structure for a vehicle, comprising: a floor tunnel projecting upward from the center of the floor panel in the vehicle width direction and extending in the vehicle longitudinal direction; a cross member having a ridge extending in the vehicle width direction at the rear end of the floor tunnel, with a closed cross section connecting a pair of left and right side sills; and a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and provided on the left and right sides in the vehicle width direction. The cross member has a reinforcing portion that reinforces the ridge in the vehicle width direction, including at least the vehicle width direction position of the battery units and excluding the center of the vehicle width direction. The reinforcing portion is an L-shaped cross section reinforcement provided along the ridge of the cross member, and the ridge of the cross member comprises an upper ridge and a lower ridge, with the reinforcement reinforcing the upper ridge and the lower ridge.

[0012] The aforementioned reinforcing portion may be integrated with the cross member or it may be a separate component. According to this invention, since the ridge of the cross member is reinforced by the reinforcing portion, cross-sectional deformation of the cross member can be suppressed during normal driving, thereby improving vehicle rigidity. Furthermore, the improved vehicle rigidity can suppress vibrations of the floor panel.

[0013] Furthermore, since the reinforcing section reinforces the ridge of the cross member except for the central part in the width direction of the vehicle, it does not hinder the bending deformation of the floor tunnel during a side collision. This suppresses stress concentration at the joint between the side sill and the cross member, thereby suppressing collision between the vehicle body on the side sill side and the battery unit. Furthermore, in the event of a vehicle side collision, the inner side of the pair of battery units in the vehicle width direction is displaced upward due to the deformation of the floor tunnel, which can also suppress collisions between the battery units themselves.

[0014] Also , As mentioned above, The above-mentioned reinforcing portion is an L-shaped cross-section reinforcement provided along the ridge of the above-mentioned cross member. ru . child re According to this, by means of a simple configuration in which a reinforcement separate from the cross member is provided along the ridge line of the cross member, the ridge line of the cross member can be reinforced, and the cross-sectional deformation of the cross member during normal driving can be suppressed.

[0015] Also , As mentioned above, A bracket is provided at the center position in the vehicle width direction of the cross member, and the bracket and the reinforcement are joined. ru . Thi re According to this, by providing the bracket, the load transmission of the cross member during normal driving is not inhibited. Specifically, since the bracket acts as a load transmission path, the load transmission of the cross member during normal driving is not inhibited.

[0016] Furthermore, as described above, the ridge of the cross member comprises an upper ridge and a lower ridge, and the reinforcement reinforces the upper ridge and the lower ridge. According to this, since the upper and lower ridges are reinforced with the above-mentioned reinforcement, the deformation of the cross-section of the cross member can be further suppressed.

[0017] As an aspect of this invention, a vulnerable part may be formed at the center position in the vehicle width direction of the bracket. The above-mentioned vulnerable parts include notches, those with reduced plate thickness, those made vulnerable to other parts by heat treatment, those with changed material strength, and the like.

[0018] According to this invention, since the vulnerable part is formed on the bracket, when the vehicle is side-impacted, the bracket is deformed starting from the vulnerable part, so that the deformation of the floor tunnel is not inhibited. As an aspect of this invention, the vulnerable part may be a notch. The above-mentioned notch can be formed by a recess, a notch, a cut, or the like. According to this invention, since the notch is formed on the bracket, when the vehicle is side-impacted, the bracket is deformed starting from the notch, so that the deformation of the floor tunnel is not inhibited.

[0019] As an aspect of this invention, the bracket may be provided with a flexible coupling part having damping performance between the bracket and the cross member. The flexible joint having the damping performance described above may also be a vibration-damping adhesive that has a high Young's modulus (longitudinal elastic modulus) and dampens vibrations by accumulating strain energy and dissipating it as heat. According to this invention, by interposing the flexible joint between the bracket and the cross member, the ride comfort can be improved. 。

[0020] child In one embodiment of the invention, the reinforcement that reinforces the lower ridge may have a tank mounting portion for attaching a fuel tank. According to this invention, since the reinforcement has a tank mounting portion, there is no need to provide a separate tank mounting bracket, and a fuel tank can be mounted. [Effects of the Invention]

[0021] This invention has the effect of suppressing cross-sectional deformation of the cross member during normal driving, suppressing vibration of the floor panel by suppressing this cross-sectional deformation, and protecting the battery unit in the event of a vehicle side collision. [Brief explanation of the drawing]

[0022] [Figure 1] A perspective view showing the lower body structure of the vehicle. [Figure 2] A top perspective view showing the main part of Figure 1 as seen from the front and above. [Figure 3] Figure 2 shows a top perspective view with the cross member upper removed. [Figure 4] (a) is a cross-sectional view of the main part along line AA in Figure 2, and (b) is a cross-sectional view of the main part along line BB in Figure 2. [Figure 5] A perspective view showing the cross member lower, upper and lower reinforcements, and bracket related structure with the cross member upper removed. [Figure 6] A perspective view from Figure 5 showing the upper reinforcement removed. [Figure 7] Front view of the bracket. [Figure 8] A bottom view showing the arrangement of the battery unit. [Figure 9] Cross-sectional view taken along line CC in Figure 8. [Figure 10] A bottom view showing the fuel tank's layout. [Figure 11] This diagram illustrates the behavior of the battery unit during a vehicle side collision, as viewed from the rear of the vehicle. [Figure 12] This diagram illustrates the behavior of the cross member during a vehicle side collision, as viewed from the rear of the vehicle. [Figure 13] This diagram illustrates the behavior of the upper and lower reinforcements and brackets during a vehicle side impact, as viewed from the rear of the vehicle. [Figure 14] A bottom view showing the behavior of the lower body structure of this embodiment during a vehicle side collision. [Figure 15] A bottom view showing the behavior of a conventional lower body structure during a vehicle side collision. [Modes for carrying out the invention]

[0023] The objective is to suppress cross-sectional deformation of the cross member during normal driving, suppress vibration of the floor panel due to said suppression of cross-sectional deformation, and protect the battery unit in the event of a vehicle side collision. The floor panel comprises a floor tunnel projecting upward from the center in the vehicle width direction and extending in the vehicle longitudinal direction, a cross member having a ridge extending in the vehicle width direction at the rear end of the floor tunnel and a closed cross section connecting a pair of left and right side sills, and a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and provided on the left and right sides in the vehicle width direction. The cross member has a reinforcing portion that reinforces the ridge in the vehicle width direction, in a range that includes at least the vehicle width direction position of the battery unit and excludes the center in the vehicle width direction. Furthermore, the reinforcing portion is an L-shaped reinforcement provided along the ridge of the cross member, and a bracket is provided at the center of the cross member in the vehicle width direction, and the bracket and the reinforcement are joined together. This was achieved with the following configuration. [Examples]

[0024] One embodiment of this invention will be described in detail below with reference to the drawings. The drawings show the lower body structure of the vehicle. Figure 1 is a perspective view showing the lower body structure, Figure 2 is a top perspective view showing the main part of Figure 1 from the front and above, Figure 3 is a top perspective view showing the cross member upper removed from Figure 2, Figure 4(a) is a cross-sectional view of the main part along line AA in Figure 2, and Figure 4(b) is a cross-sectional view of the main part along line BB in Figure 2.

[0025] Figure 5 is a perspective view showing the cross member lower, upper and lower reinforcements, and bracket related structure with the cross member upper removed, and Figure 6 is a perspective view showing the upper reinforcement removed from Figure 5.

[0026] Furthermore, Figure 7 is a front view of the bracket, Figure 8 is a bottom view showing the arrangement structure of the battery unit, Figure 9 is a cross-sectional view taken along the CC line in Figure 8, and Figure 10 is a bottom view showing the arrangement structure of the fuel tank.

[0027] However, Figures 1 to 9 show the underbody structure of a plug-in hybrid electric vehicle (PHEV), and Figure 10 shows the underbody structure of a typical internal combustion engine-driven four-wheel drive (4WD) vehicle or front-engine, rear-wheel drive (FR) vehicle, obtained by removing the battery unit and installing a fuel tank from a vehicle with the same structure as Figures 1 to 9.

[0028] As shown in Figures 1 to 3, 8 and 10, a front floor panel 1 is provided to form the floor surface of the passenger compartment, and a tunnel section 2 is provided at the center of the front floor panel 1 in the vehicle width direction, projecting upward and extending in the longitudinal direction of the vehicle as a floor tunnel.

[0029] As shown in Figures 1 to 3, tunnel reinforcements 3, 3 are provided on the upper left and right corners of the tunnel section 2 that protrudes into the passenger compartment, extending in the longitudinal direction of the vehicle along the tunnel section 2. On the other hand, as shown in Figures 8 and 10, tunnel side members 4, 4 are provided at the lower end of the tunnel section 2, extending in the longitudinal direction of the vehicle along the lower end of the tunnel skirt section and the lower end surface 2a of the tunnel.

[0030] As shown in Figures 2, 3, and 8-10, a pair of left and right side sills 5 are provided at both the left and right ends in the vehicle width direction of the front floor panel 1. As shown in the same figures, the side sills 5 are vehicle body strength members that have a closed side sill section 8 (see Figure 9) extending in the front-rear direction of the vehicle, formed by joining and fixing a side sill inner 6 and a side sill outer 7.

[0031] As shown in Figures 1 to 3, a center pillar 9 is provided in the middle of the vehicle's longitudinal direction, connecting the aforementioned side sill 5 and a roof side rail (not shown) in the vertical direction. The center pillar 9 has a center pillar inner and a center pillar outer 10, and has a center pillar closed cross section extending in the vertical direction of the vehicle, but only the center pillar outer 10 is shown in Figures 1 to 3.

[0032] As shown in Figures 1 to 3, a rear wheel house 13 is provided at the rear end of a pair of left and right side sills 5, and includes a wheel house inner 11 and a wheel house outer 12.

[0033] As shown in the figure, a rear side frame 14 is provided that extends in the longitudinal direction of the vehicle along the wheel house inner 11 of the rear wheel house 13. As shown in Figure 9, the above-mentioned rear side frame 14 is a vehicle body strength member that forms a rear side closed section 17 extending in the longitudinal direction of the vehicle by joining and fixing the rear side frame upper 15 and the rear side frame lower 16.

[0034] As shown in Figures 1 to 3, 8 and 10, the front part of the rear side frame 14 described above is provided to overlap with the rear part of the side sill 5 described above.

[0035] As shown in Figures 1 to 3, a cross member 18 (so-called No. 3 cross member) is provided at the rear end of the tunnel section 2, extending in the vehicle width direction and connecting the left and right pair of side sills 5, 5. As shown in Figure 4, the cross member 18 is provided with a closed section 21 extending in the vehicle width direction, formed by joining and fixing a cross member upper 19, which also serves as a kick-up section, and a cross member lower 20.

[0036] As shown in Figures 1 to 3, a rear seat pan 22 is provided as a rear floor panel that extends from the rear of the cross member 18 toward the rear of the vehicle. This rear seat pan 22 extends in the longitudinal direction of the vehicle from the rear of the cross member 18 to a position corresponding to the middle of the rear wheel house 13 in the longitudinal direction, and both left and right ends of the rear seat pan 22 in the vehicle width direction are connected to the left and right rear side frames 14.

[0037] As shown in Figures 1 to 3, a rear cross member 23 (so-called No. 4 cross member) is provided at the rear end of the rear seat pan 22, connecting a pair of left and right rear side frames 14, 14 that extend in the vehicle width direction. Furthermore, a cargo area floor 24, which serves as a rear floor panel, is provided extending from the rear of the rear cross member 23 toward the rear of the vehicle.

[0038] This cargo floor 24 extends in the longitudinal direction of the vehicle from the rear of the rear cross member 23 to the rear end position, and both left and right ends of the cargo floor 24 in the vehicle width direction are connected to the left and right rear side frames 14.

[0039] On the other hand, as shown in Figures 1 to 3, a left front cross member 25 (so-called No. 2.5 cross member) is provided that extends in the vehicle width direction and connects the left skirt portion of the tunnel portion 2 and the side sill inner 6 of the left side side sill 5 of the vehicle, and a closed cross section 26 extending in the vehicle width direction is formed between this front cross member 25 and the front floor panel 1.

[0040] Similarly, as shown in Figures 2 and 3, a right-side front cross member 27 (so-called No. 2.5 cross member) is provided that extends in the vehicle width direction and connects the right-side skirt portion of the tunnel portion 2 and the side sill inner 6 of the right-side side sill 5 of the vehicle, and a closed cross section 28 extending in the vehicle width direction is formed between this front cross member 27 and the front floor panel 1.

[0041] As shown in Figure 8, an intermediate cross member 29 (so-called No. 3.5 cross member) is provided immediately in front of the rear cross member 23, at a position spaced apart from the rear cross member 23 in the forward direction of the vehicle, extending in the vehicle width direction and connecting a pair of left and right rear side frames 14. A closed cross section 30 extending in the vehicle width direction is formed between this intermediate cross member 29 and the lower surface of the rear seat pan 22.

[0042] As shown in Figures 8 and 9, adjacent to the inner side of the side sill 5 in the vehicle width direction, and below the front floor panel 1 and rear seat pan 22, the left and right battery units 31 and 32, namely the first battery unit 31 and the second battery unit 32, are provided separated by a tunnel section 2 and spaced apart in the vehicle width direction.

[0043] As shown in Figure 9, the first and second battery units 31 and 32 described above each include a battery 34 consisting of a plurality of battery modules 33, a battery tray 35 with a concave cross-section that covers the lower part of the battery 34, and a battery cover 36 with an inverted concave cross-section that covers the upper part of the battery 34.

[0044] In other words, in the first and second battery units 31 and 32 described above, the battery 34 is supported by a battery tray 35, and the battery 34 is located within a battery storage space surrounded by the battery tray 35 and a battery cover 36. Furthermore, the bottom surface of the battery tray 35 in each of the aforementioned battery units 31 and 32 is formed flat to take aerodynamic performance into consideration (see Figure 9).

[0045] As shown in Figure 9, a relay unit RE for switching the vehicle's electrical circuits is fixed to the rear of the first battery unit 31 and the second battery unit 32. As shown in Figures 8 to 10, multiple brackets, for example a total of six, are fixed by welding or the like, spanning the upper lower surface and the side outer wall surface of the tunnel section 2, corresponding to the inner positions of the battery units 31 and 32 in the vehicle width direction.

[0046] Of the six brackets 37 in total, the pair of left and right brackets 37 located at the front of the vehicle and the pair of left and right brackets 37 located at the rear of the vehicle are brackets for supporting the battery units 31 and 32, while the pair of left and right brackets 37 located in the middle of the vehicle in the longitudinal direction are brackets for supporting the propeller shaft 38 (see Figure 11).

[0047] The inner sides of the first and second battery units 31 and 32 in the vehicle width direction are supported by the tunnel section 2 described above by battery unit suspension support members attached to the bracket 37 described above.

[0048] Furthermore, as shown in Figures 8 and 9, the outer sides of the first and second battery units 31 and 32 described above are fixedly supported on the lower rear side frame 16 and the lower side sill inner 6 of the rear side frame 14 using fixing members 39 and fixing brackets 40.

[0049] Incidentally, as shown in Figures 2 and 4, the cross member upper 19 of the cross member 18 is integrally formed with a flange portion 19a located at the front and joined and fixed to the front floor panel 1 and the tunnel portion 2, a vertical wall portion 19b rising upward from the rear end of the flange portion 19a, a steeply inclined portion 19c extending upward and backward at a steep angle from the upper end of the vertical wall portion 19b, a gently inclined portion 19d extending upward and backward at a gentle angle from the upper end of the steeply inclined portion 19c, and an upper surface portion 19e extending rearward from the rear end of the gently inclined portion 19d and joined and fixed to the rear seat pan 22.

[0050] Furthermore, ridges X1, X2, X3, and X4 extending in the vehicle width direction are formed between the flange portion 19a and the vertical wall portion 19b, between the vertical wall portion 19b and the steeply sloping portion 19c, between the steeply sloping portion 19c and the gently sloping portion 19d, and between the gently sloping portion 19d and the upper surface portion 19e, respectively.

[0051] Furthermore, as shown in Figure 4, the lower cross member 20 of the cross member 18 is integrally formed with a lower surface portion 20a located at the front and joined and fixed to the front floor panel 1 and the tunnel portion 2, a vertical wall portion 20b rising upward and rearward from the rear end of the lower surface portion 20a, and an upper surface portion 20c extending rearward from the upper end of the vertical wall portion 20b and joined and fixed to the rear seat pan 22.

[0052] Furthermore, ridges X5 and X6 extending in the vehicle width direction are formed between the lower surface portion 20a and the vertical wall portion 20b, and between the vertical wall portion 20b and the upper surface portion 20c, respectively.

[0053] As shown in Figures 3 and 4(b), the cross member 18 includes at least the vehicle width direction positions of the battery units 31 and 32, and has a pair of left and right upper reinforcements 41 and a pair of left and right lower reinforcements 42 as reinforcing parts that reinforce the above-mentioned ridges in the range excluding the vehicle width direction center position, specifically one ridge X3 of the multiple ridges X1 to X4 of the cross member upper 19 and one ridge X5 of the multiple ridges X5 and X6 of the cross member lower 20. In this embodiment, the upper and lower reinforcements 41 and 42 are configured separately from the cross member 18.

[0054] In detail, as shown in Figure 5, the inner end in the vehicle width direction of the upper reinforcement 41 located on the left side of the vehicle and the inner end in the vehicle width direction of the upper reinforcement 41 located on the right side of the vehicle are spaced apart in the vehicle width direction at the center position in the vehicle width direction, corresponding to the tunnel section 2.

[0055] Similarly, as shown in Figures 5 and 6, the inner end in the vehicle width direction of the lower reinforcement 42 located on the left side of the vehicle and the inner end in the vehicle width direction of the lower reinforcement 42 located on the right side of the vehicle are spaced apart in the vehicle width direction at the center position in the vehicle width direction, corresponding to the tunnel section 2.

[0056] In this manner, the ridges X3 and X5 of the cross member 18 are reinforced by the upper and lower reinforcements 41 and 42 described above, thereby suppressing the cross-sectional deformation of the cross member 18 during normal driving and improving vehicle rigidity. This improvement in vehicle rigidity suppresses vibrations of the front floor panel 1.

[0057] Furthermore, the upper and lower reinforcements 41 and 42 described above reinforce the ridges X3 and X5 of the cross member 18, except for the central part in the width direction of the vehicle, so as not to hinder the bending deformation of the tunnel section 2 during a vehicle side impact. This suppresses stress concentration at the joint 43 between the side sill 5 and the cross member 18 (see Figures 2 and 3), thereby suppressing collision between the vehicle body on the side sill 5 side and the battery units 31 and 32.

[0058] Furthermore, in the event of a vehicle side collision, the inner sides of the pair of battery units 31 and 32 in the vehicle width direction are displaced upward due to the deformation of the tunnel section 2, thus suppressing collisions between the battery units 31 and 32.

[0059] As shown in Figure 4(b), the above-mentioned reinforcing portion is an upper reinforcement 41 and a lower reinforcement 42 with an L-shaped cross section, provided along the ridge line X3 of the cross member upper 19 and the ridge line X5 of the cross member lower 20.

[0060] More specifically, the upper reinforcement 41 comprises a front portion 41a that follows the steeply sloping portion 19c of the cross member upper 19, an upper portion 41b that follows the gently sloping portion 19d of the cross member upper 19, and a ridge line X7 that is located between these respective surfaces 41a and 41b and extends in the vehicle width direction.

[0061] Then, the ridge line X7 of the upper reinforcement 41 is aligned with the ridge line X3 of the cross member upper 19, and the upper reinforcement 41 and the cross member upper 19 are fixed to each other by fastening with fastening members or by welding.

[0062] Furthermore, the lower reinforcement 42 includes a lower surface portion 42a that follows the lower surface portion 20a of the cross member lower 20, a rear surface portion 42b that follows the vertical wall portion 20b of the cross member lower 20, and a ridge line X8 located on each of these surfaces 42a, 42b and extending in the vehicle width direction.

[0063] Then, the ridge line X8 of the lower reinforcement 42 is aligned with the ridge line X5 of the cross member lower 20, and the lower reinforcement 42 and the cross member lower 20 are fixed to each other by fastening with fastening members or by welding.

[0064] This configuration allows for a simple setup in which separate reinforcements 41 and 42 are provided along the ridges X3 and X5 of the cross member 18, thereby reinforcing the ridges X3 and X5 of the cross member 18 and suppressing cross-sectional deformation of the cross member 18 during normal driving.

[0065] As shown in Figures 5 and 6, a bracket 50 is provided at the center of the cross member 18 in the vehicle width direction, and the bracket 50 is joined to the lower reinforcement 42.

[0066] As shown in Figures 5, 6, and 7, the bracket 50 described above comprises a front central portion 51, left and right front portions 53 continuously formed on the left and right of the front central portion 51 via stepped portions 52, left and right side portions 54 extending rearward from the outer ends of the left and right front portions 53 in the vehicle width direction, a rear connecting piece 55 extending outward in the vehicle width direction from the rear ends of the left and right side portions 54, and a lower connecting piece 57 extending outward in the vehicle width direction via leg portions 56 on the left and right side portions 54.

[0067] Furthermore, the bracket 50 described above comprises an upper central portion 58, left and right upper surfaces 60 continuously formed on the left and right sides of the upper central portion 58 via stepped portions 59, and bent pieces 61 extending downward from the outer side in the vehicle width direction of the left and right upper surfaces 60. In this embodiment, as shown in Figure 7, the bracket 50 is formed symmetrically.

[0068] Then, the aforementioned rear joining piece 55 is joined to the rear surface portion 42b of the lower reinforcement 42 by means of spot welding or the like, and the lower joining piece 57 is joined to the lower surface portion 42a of the lower reinforcement 42 by means of spot welding or the like, thereby joining and fixing the bracket 50 and the lower reinforcement 42.

[0069] By providing the bracket 50 described above, the load transmission of the cross member 18 is not obstructed during normal driving. Specifically, the bracket 50 acts as a transmission path for side impact loads, thereby preventing obstruction of the load transmission of the cross member 18 during normal driving.

[0070] As shown in Figures 5, 6, and 7, notches 62 and 63 are formed at the center of the bracket 50 in the vehicle width direction. Specifically, a notch 62 is formed in the upper central part 58 of the bracket 50, which opens to the rear of the vehicle as a vulnerable point, and a notch 63 is formed in the lower part of the front central part 51 of the bracket 50, which opens to the lower side of the vehicle as a vulnerable point.

[0071] In the drawing, U-shaped notches are shown as notches 62 and 63, but these could also be V-shaped notches or cut sections. In this way, by forming the notches 62 and 63 as weak points in the bracket 50 described above, the bracket 50 deforms starting from the notches 62 and 63 when a vehicle is struck from the side, thereby preventing it from hindering the deformation of the tunnel section 2.

[0072] As shown in Figures 4, 5, 6, and 7, the bracket 50 described above is equipped with a flexible coupling portion 64 that has damping properties between it and the cross member 18.

[0073] In this embodiment, a damping adhesive is used as the flexible joint 64 having the damping performance described above. This adhesive has a high Young's modulus (longitudinal elastic modulus) and dampens vibrations by accumulating strain energy and dissipating it as heat.

[0074] As shown in Figures 4 to 7, the above-mentioned flexible joint portion 64 is provided on the upper part of the upper surface portion 60 of the bracket 50 and abuts against the gently sloping portion 19d of the cross member upper 19 via the upper reinforcement 41.

[0075] In this way, the flexible coupling portion 64 is interposed between the bracket 50 and the cross member upper 19 of the cross member 18 in order to improve ride comfort.

[0076] As shown in Figure 4, among the multiple ridges X1 to X4 of the cross member upper 19 described above, a specific ridge X3 is the upper ridge, and among the multiple ridges X5 and X6 of the cross member lower 20, a specific ridge X5 is the lower ridge.

[0077] In other words, the cross member 18 has an upper ridge X3 and a lower ridge X5. The upper and lower reinforcements 41 and 42 mentioned above reinforce the upper ridge X3 and the lower ridge X5. Specifically, the upper reinforcement 41 reinforces the upper ridge X3, and the lower reinforcement 42 reinforces the lower ridge X5.

[0078] In this way, the upper and lower reinforcements 41 and 42 reinforce the upper ridge line X3 and the lower ridge line X5, thereby further suppressing the cross-sectional deformation of the cross member 18.

[0079] As shown in Figures 3 and 10, the lower reinforcement 42 that reinforces the lower ridge X5 has a pair of left and right tank mounting sections 45 for attaching the fuel tank 70.

[0080] When removing the battery units 31 and 32 from the lower body structure of the plug-in hybrid vehicle shown in Figure 8 and applying the same body structure to the lower body structure of a typical internal combustion engine-driven four-wheel drive vehicle or a front-engine rear-wheel drive vehicle, a fuel tank 70 is required.

[0081] In this case, as shown in Figure 10, the fuel tank 70 is positioned below the rear seat pan 22. The fuel tank 70 is equipped with a pair of tank bands 71, 71 spaced apart in the vehicle width direction. The front end of each tank band 71 is fastened to the lower cross member 20 of the cross member 18 using a fastening member 72, and the rear end of each tank band 71 is fastened to the rear cross member 23 using a fastening member 73. This positions the fuel tank 70 below the rear seat pan 22.

[0082] The fastening member 72 that fastens the front end of the tank band 71 shown in Figure 10 to the cross member lower 20 is fastened and fixed to the tank mounting portion 45 provided on the lower reinforcement 42 shown in Figure 3.

[0083] Thus, since the lower reinforcement 42 has a tank mounting portion 45, there is no need to provide a separate tank mounting bracket, and the fuel tank 70 can be mounted.

[0084] Next, we will explain the behavior of a vehicle during a side collision, referring to Figures 11 to 14. Figure 11 is an explanatory diagram showing the behavior of the battery unit during a vehicle side collision, viewed from the rear of the vehicle. Figure 12 is an explanatory diagram showing the behavior of the cross member during a vehicle side collision, viewed from the rear of the vehicle. Figure 13 is an explanatory diagram showing the behavior of the upper and lower reinforcements and brackets during a vehicle side collision, viewed from the rear of the vehicle. Figure 14 is a bottom view showing the behavior during a vehicle side collision. Note that in Figure 13, the lower cross member 20 is shown removed.

[0085] However, Figures 11 to 14 show the deformation behavior of each part after the same amount of time has elapsed since the side impact load was applied from the left side of the vehicle.

[0086] As shown in Figure 13, the bracket 50 provided at the center of the vehicle width direction of the cross member 18 has notches 62 and 63 formed at the center of the vehicle width direction, so when the vehicle is hit from the side, the bracket 50 deforms starting from these notches 62 and 63.

[0087] Furthermore, the upper and lower reinforcements 41 and 42 reinforce the ridges X3 and X5 of the cross member 18, except for the central part in the vehicle width direction, so they do not hinder the bending deformation of the tunnel section 2 during a side collision with the vehicle. As a result, the tunnel section 2 bends so that the central part in the vehicle width direction moves upward towards the vehicle, as shown in Figure 13.

[0088] Therefore, stress concentration at the joint 43 between the side sill 5 and the cross member 18 can be suppressed, and collision between the vehicle body on the side sill 5 side and the battery unit 31 can be suppressed.

[0089] As shown in Figures 12 and 13, the cross member 18 and rear seat pan 22 described above deform so that their central portions in the vehicle width direction are displaced upward. In addition, the pair of left and right battery units 31 and 32 deform upward and outward in the vehicle width direction as the tunnel portion 2 collapses, as shown in Figure 11, thereby suppressing collisions between the battery units 31 and 32.

[0090] Furthermore, due to the crushing deformation of the tunnel section 2 described above, the amount of crushing of the front floor panel 1 is reduced compared to the conventional structure shown in Figure 15 (see Figure 14).

[0091] In the above explanation, we described the behavior of each part in response to a side impact load input from the left side outward in the vehicle width direction. However, in this embodiment, even when a side impact load input is received from the right side outward in the vehicle width direction, each part will deform in the same manner as described above.

[0092] In Figure 11, 74 is the exhaust pipe. Also, in Figures 13 and 14, 75 is the underbody floor frame located between the inner side of the side sill inner 6 in the vehicle width direction and the front floor panel 1.

[0093] Furthermore, in the diagram, arrow F indicates the front of the vehicle, arrow R indicates the rear of the vehicle, arrow IN indicates the inward direction in the vehicle width direction, arrow OUT indicates the outward direction in the vehicle width direction, arrow LE indicates the outward left direction in the vehicle width direction, arrow RI indicates the outward right direction in the vehicle width direction, and arrow UP indicates the top of the vehicle.

[0094] As described above, the lower body structure of the vehicle according to this embodiment comprises a floor tunnel (tunnel section 2) that protrudes upward from the center position in the vehicle width direction of the floor panel (front floor panel 1) and extends in the vehicle longitudinal direction, a cross member 18 having ridges X3 and X5 extending in the vehicle width direction at the rear end of the floor tunnel (tunnel section 2) and a closed section 21 connecting a pair of left and right side sills 5, and a pair of left and right battery units 31 and 32 located below the floor panel (front floor panel 1) and between the side sills 5, and provided on the left and right sides in the vehicle width direction separated by the floor tunnel (tunnel section 2), wherein the cross member 18 has reinforcing sections (reinforcements 41 and 42) that reinforce the ridges X3 and X5 in the vehicle width direction, including at least the vehicle width direction position of the battery units 31 and 32 and excluding the center position in the vehicle width direction (see Figures 1, 3, 4, 8 and 9).

[0095] With this type of vehicle lower body structure, the ridges X3 and X5 of the cross member 18 are reinforced by the reinforcement parts (reinforcements 41 and 42), so that the cross-sectional deformation of the cross member 18 can be suppressed during normal driving, thereby improving vehicle rigidity. In addition, the improvement in vehicle body rigidity can suppress vibrations of the floor panel (front floor panel 1).

[0096] Furthermore, since the reinforcement parts (reinforcements 41, 42) reinforce the ridges X3, X5 of the cross member 18 except for the central part in the width direction of the vehicle, they do not hinder the bending deformation of the floor tunnel (tunnel section 2) during a side collision. This suppresses stress concentration at the joint 43 between the side sill 5 and the cross member 18, and can suppress collision between the vehicle body on the side sill 5 side and the battery units 31, 32.

[0097] Furthermore, in the event of a vehicle side collision, the inner sides of the pair of battery units 31 and 32 in the vehicle width direction are displaced upward due to the deformation of the floor tunnel (tunnel section 2), thus suppressing collisions between the battery units 31 and 32 themselves.

[0098] Furthermore, in the lower body structure of such a vehicle, the reinforcing portion is an L-shaped reinforcement 41, 42 provided along the ridges X3, X5 of the cross member 18 (see Figures 3 and 4).

[0099] With such a vehicle lower body structure, a simple configuration is achieved by providing reinforcements 41 and 42, separate from the cross member 18, along the ridges X3 and X5 of the cross member 18. This reinforces the ridges X3 and X5 of the cross member 18 and suppresses cross-sectional deformation of the cross member 18 during normal driving.

[0100] Furthermore, in the lower body structure of such a vehicle, a bracket 50 is provided at the center of the cross member 18 in the vehicle width direction, and the bracket 50 is joined to the reinforcements 41 and 42 (see Figures 5 to 7).

[0101] According to the lower body structure of such a vehicle, the bracket 50 does not obstruct the load transmission of the cross member 18 during normal driving. Specifically, since the bracket 50 acts as a load transmission path, it does not obstruct the load transmission of the cross member 18 during normal driving.

[0102] Furthermore, in the lower body structure of such a vehicle, a weak point (see notches 62 and 63) is formed at the center of the bracket 50 in the vehicle width direction (see Figures 5 to 7). With this type of lower body structure for a vehicle, a weak point (see notches 62 and 63) is formed in the bracket 50. Therefore, when the vehicle is struck from the side, the bracket 50 deforms starting from the weak point (see notches 62 and 63), which does not hinder the deformation of the floor tunnel (tunnel section 2).

[0103] Furthermore, in the lower body structure of such a vehicle, the weak points are characterized by notches 62 and 63. With this type of lower body structure for a vehicle, notches 62 and 63 are formed in the bracket 50, so that when the vehicle is struck from the side, the bracket 50 deforms starting from the notches 62 and 63, and does not hinder the deformation of the floor tunnel (tunnel section 2).

[0104] In addition, in the lower body structure of such a vehicle, the bracket 50 is provided with a flexible coupling portion 64 having damping performance between it and the cross member 18 (see Figures 5 to 7). With such a vehicle lower body structure, the ride comfort can be improved by interposing the flexible coupling portion 64 between the bracket 50 and the cross member 18.

[0105] Furthermore, in the lower body structure of such a vehicle, the ridges X3 and X5 of the cross member 18 include an upper ridge X3 and a lower ridge X5, and the reinforcements 41 and 42 reinforce the upper ridge X3 and the lower ridge X5 (see Figure 4). With this type of vehicle lower body structure, the upper ridge line X3 and the lower ridge line X5 are reinforced by the reinforcements 41 and 42, so that the cross-sectional deformation of the cross member 18 can be further suppressed.

[0106] Furthermore, in the lower body structure of such a vehicle, the reinforcement 42 that reinforces the lower ridge line X5 has a tank mounting portion 45 for attaching the fuel tank 70 (see Figures 3 and 10).

[0107] With this type of vehicle lower body structure, since the reinforcement 42 has a tank mounting portion 45, there is no need to provide a separate tank mounting bracket, and the fuel tank 70 can be mounted.

[0108] In the correspondence between the structure of this invention and the above-described embodiments, The floor panel of this invention corresponds to the front floor panel 1 of the embodiment, The same applies to the following: The floor tunnel corresponds to tunnel section 2, The side sill corresponds to side sill 5. The cross member corresponds to cross member 18. The closed section corresponds to the closed section 21, The battery unit corresponds to the first battery unit 31 and the second battery unit 32. The reinforcing section corresponds to the upper reinforcement 41 and the lower reinforcement 42. The tank mounting section corresponds to the tank mounting section 45. The bracket is compatible with bracket 50. The vulnerable areas correspond to notches 62 and 63. The flexible joint corresponds to the flexible joint 64, The fuel tank is compatible with fuel tank 70. The ridges correspond to the upper ridge x3 and the lower ridge x5, This invention is not limited to the configuration of the above-described embodiment, and many other embodiments can be obtained. [Industrial applicability]

[0109] As described above, the present invention is useful for a lower body structure of a vehicle, comprising: a floor tunnel projecting upward from the center of the floor panel in the vehicle width direction and extending in the vehicle longitudinal direction; a cross member having a ridge extending in the vehicle width direction at the rear end of the floor tunnel, with a closed cross section connecting a pair of left and right side sills; and a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and provided on the left and right sides in the vehicle width direction. [Explanation of Symbols]

[0110] 1…Front floor panel (floor panel) 2…Tunnel section (floor tunnel) 5... Side sill 18…Crossmember 21...Closed section 31…First battery unit (battery unit) 32…Second battery unit (battery unit) 41…Upper reinforcement (reinforcement section) 42…Lower reinforcement (reinforcement section) 45... Tank mounting section 50…Bracket 62, 63... Notches (weak points) 64…Flexible joint 70…Fuel tank X3... Upper ridge (ridge) X5…Lower ridgeline (ridgeline)

Claims

1. At the center of the floor panel in the vehicle width direction, there is a floor tunnel that protrudes upward and extends in the vehicle longitudinal direction, and a cross member that has a ridge extending in the vehicle width direction at the rear end of the floor tunnel and whose closed cross section connects a pair of left and right side sills, It comprises a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and positioned on the left and right sides in the vehicle width direction, The above cross member includes at least the vehicle width direction position of the battery unit, and It has a reinforcing section that reinforces the above-mentioned ridge line in a range excluding the center position in the width direction of the vehicle, The above-mentioned reinforcing portion is an L-shaped cross-section reinforcement provided along the ridge of the above-mentioned cross member, A bracket is provided at the center of the cross member in the vehicle width direction, and the bracket and the reinforcement are joined together. The lower body structure of the vehicle.

2. At the center of the floor panel in the vehicle width direction, there is a floor tunnel that protrudes upward and extends in the vehicle longitudinal direction, and a cross member that has a ridge extending in the vehicle width direction at the rear end of the floor tunnel and whose closed cross section connects a pair of left and right side sills, It comprises a pair of left and right battery units located below the floor panel and between the side sills, separated by the floor tunnel and positioned on the left and right sides in the vehicle width direction, The above cross member includes at least the vehicle width direction position of the battery unit, and It has a reinforcing section that reinforces the above-mentioned ridge line in a range excluding the center position in the width direction of the vehicle, The above-mentioned reinforcing portion is an L-shaped cross-section reinforcement provided along the ridge of the above-mentioned cross member, The above-mentioned ridge of the cross member comprises an upper ridge and a lower ridge. The above reinforcement is characterized by reinforcing the above-mentioned upper ridge and the above-mentioned lower ridge. The lower body structure of the vehicle.

3. A weak point is formed at the center of the bracket in the vehicle width direction. The lower body structure of the vehicle according to claim 1.

4. The vulnerable area mentioned above is a notch. The lower body structure of the vehicle according to claim 3.

5. The bracket described above is equipped with a flexible joint having damping properties between it and the cross member described above. The lower body structure of a vehicle according to claim 1 or 3.

6. The reinforcement that reinforces the lower ridge has a tank mounting portion for attaching a fuel tank. The lower body structure of the vehicle according to claim 2.

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