Vehicle under structure

Abstract

A vehicle lower structure is provided with: a pair of sills extending in the front-rear direction of a vehicle; a vehicle lower structure includes a pair of sills, and a floor cross member extending in a vehicle width direction and connecting the pair of sills, the floor cross member having low-strength portions having weak strength at both end portions, the vehicle lower structure further including a battery disposed between the pair of sills, the floor cross member being located on an upper side of the battery, and the lower portion of the floor cross member being located on a lower side of the battery. A seat bracket for fixing a seat on which an occupant sits is attached to the floor cross member low-strength portion, the floor cross member low-strength portion being positioned further outward in the vehicle width direction than the battery, and the floor cross member low-strength portion being positioned further outward in the vehicle width direction than the battery.

Description

[0001] This application is a divisional application of the Chinese Patent Application No. 201910004171.4, with the title of "Vehicle lower structure", filed on January 3, 2019. TECHNICAL FIELD

[0002] The present disclosure relates to a vehicle lower structure, and particularly relates to a countermeasure against a collision from a side. BACKGROUND

[0003] A technology of forming a battery housing region by a floor upper shell and a floor lower shell that constitute a floor of a vehicle, and mounting a battery under the floor is shown in Patent Literature 1. And, a rigidity of the floor upper shell and / or the floor lower shell is maintained by a side frame (English: side frame) that is a skeletal structure in a front-rear direction of the vehicle, and / or a cross beam that is a skeletal structure in a vehicle width direction.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2014-201277

[0007] By maintaining the rigidity by the cross beam, it is possible to reduce a deformation of the vehicle lower structure against an impact from a side, and it is possible to reduce an influence on the battery. Here, in this structure, although it is possible to increase the rigidity against the impact from the side of the vehicle, an absorption of collision energy is small, and an acceleration of the vehicle caused by the impact becomes relatively large.

[0008] The present disclosure provides a vehicle lower structure that is able to more effectively absorb collision energy. SUMMARY

[0009] The present disclosure relates to a vehicle lower structure including a pair of rockers configured at intervals in a vehicle width direction and extending in a vehicle front-rear direction, and a floor cross beam extending in the vehicle width direction and connecting the pair of rockers, the floor cross beam having a pair of floor cross beam low strength portions having a strength weaker than a central portion at both end sides in the vehicle width direction.

[0010] Further, it can be that the vehicle lower structure has a battery disposed between the pair of rockers, and the pair of floor cross beam low strength portions are located at positions further outward in the vehicle width direction than the battery.

[0011] In addition, it can be that the floor cross beam is located above the battery and is fixed to the pair of rockers at both sides of the battery.

[0012] Moreover, the vehicle lower structure can include a pair of side frames arranged at intervals in a vehicle width direction and extending in a vehicle front-rear direction, a battery arranged between the pair of side frames, and a cross member extending in the vehicle width direction and connecting the pair of side frames, the cross member having a pair of cross member low-strength portions at both end sides in the vehicle width direction, which are weaker in strength than a central portion.

[0013] In addition, the cross member can be located on a lower side of the battery and fixed to the pair of side frames at both side portions of the battery.

[0014] In addition, the cross member low-strength portions can be located below the floor cross member low-strength portions.

[0015] According to the present disclosure, at the time of a side collision, energy at the time of collision can be absorbed, impact can be effectively mitigated, and a battery and the like can be protected. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a perspective view showing a vehicle lower structure of an embodiment.

[0017] Figure 2 is a schematic view as seen from the rear of the vehicle lower structure of the embodiment.

[0018] Figure 3 is a perspective view showing a state in which a seat bracket is attached to the floor cross member.

[0019] Figure 4 is a schematic view as seen from below of a battery mounting portion of the vehicle lower structure of the embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of the present disclosure will be described based on the drawings. Furthermore, the present disclosure is not limited to the embodiment described here.

[0021] Figure 1 is a perspective view showing a vehicle lower structure 100 of an embodiment. A floor tunnel 12 extending in a vehicle front-rear direction is provided at a central portion in a vehicle width direction of a floor panel 10. The floor tunnel 12 is a space formed by a portion of the floor panel 10 being raised upward and housing various members inside.

[0022] A rocker 14 extending in the vehicle front-rear direction is arranged at both side portions (both sides in the vehicle width direction) of the floor panel 10. The rocker 14 is a tubular member having a quadrangular cross section formed by joining two long plates having a C-shaped cross section with the concave portions facing each other. The rocker 14 is a skeletal member of the vehicle and is relatively strong in strength.

[0023] A floor cross member 16 extending in the vehicle width direction is provided on the floor panel 10. This floor cross member 16 is a skeletal member of the vehicle, and resists a force from the side. The left and right end portions of the floor cross member 16 are fixed to the side walls of the rocker 14. Thus, the pair of rockers 14 and the floor cross member 16 can protect the passenger room from the front and rear directions and the left and right directions. The floor cross member 16 has a C-shaped cross section, and is fixed to the floor panel 10 with the concave portion facing downward.

[0024] In addition, a pair of kick panels 18 extending in the front and rear directions are provided on the floor panel 10. The kick panels 18 have a C-shaped cross section, and are fixed to the floor panel 10 from above with the concave portion facing downward. In addition, the kick panels 18 are provided inside the pair of rockers 14, and the front sides of the kick panels 18 are curved toward the inside and are located on the center side, and the rear sides of the kick panels 18 are located near the rockers 14 (both sides in the vehicle width direction).

[0025] A battery 20 is provided in a region inside the kick panels 18 and on the lower side of the floor panel 10. That is, the battery 20 is provided between the pair of rockers 14, and is provided between the pair of kick panels 18. In addition, the floor cross member 16 is located above the battery 20. Thus, the floor cross member 16 also functions as a vehicle width direction protection member for the battery 20.

[0026] A cross member 22 extending in the vehicle width direction is provided on the lower side of the battery 20, and supports the battery 20 from below. In addition, the cross member 22 is long plate-shaped, and both ends of the cross member 22 are fixed to the longitudinal members 26. The cross member 22 is a member having high strength, and functions as a protection member for protecting the battery 20 from an impact in the vehicle width direction.

[0027] In this embodiment, a floor cross member low-strength portion 16a is provided at a joint portion of the floor cross member 16 that is joined to the rocker 14. The floor cross member low-strength portion 16a has a smaller strength (for example, a shear allowable stress strength) than a central portion 16b of the floor cross member 16. For example, the strength is preferably about half the strength of the central portion 16b.

[0028] In this embodiment, the floor cross member low-strength portion 16a is formed by a separate member from the central portion 16b. Thus, the strength can be easily adjusted by changing the material or the thickness. Alternatively, the floor cross member low-strength portion 16a can be formed by changing the thickness, or changing the cross-sectional area, or forming a notch, instead of being formed by a separate member. Further, in the case of being formed as a separate member, the floor cross member low-strength portion 16a and the central portion 16b are joined by welding or the like.

[0029] Further, the floor cross member low strength portion 16a is a substantially lower open C-shaped member, and has flange-like portions at both sides in the front-rear direction, at which portions the upper surface of the step portion 18 is joined to the joining portion 18a. Also, the portions that abut against the side surfaces of the rocker 14 are formed with flange-like portions, at which portions the side surfaces of the rocker 14 are joined. Also, the upper surface of the floor cross member low strength portion 16a has an extended portion that extends to the side, and this portion overlaps the upper surface of the rocker 14. Therefore, this extended portion can be fixed to the upper surface of the rocker 14. For these joints, a suitable method such as welding can be used as well.

[0030] Further, a cross member low strength portion 22a is provided at the connecting portions of the cross member 22 at both ends thereof to the longitudinal members 26. This cross member low strength portion 22a is lower in strength than the central portion 22b of the cross member 22. As with the floor cross member low strength portion 16a, this cross member low strength portion 22a can be formed as a separate member from the central portion 22b, but can also be formed as a portion of the cross member 22, and the adjustment of the strength can be performed as with the floor cross member low strength portion 16a.

[0031] The cross member low strength portion 22a is fixed to the longitudinal member 26 via the collar 24 and by bolt fastening. That is, the longitudinal member 26 is located behind the step portion 18 and above the cross member low strength portion 22a and below the joining portion 18a with the floor panel 10 interposed. Therefore, the longitudinal member 26 and the cross member low strength portion 22a are joined by bolt fastening through the collar 24.

[0032] Figure 2 Fig. 6 schematically shows the structure as viewed from the rear of the floor cross member 16, the cross member 22, the rocker 14, and the step portion 18. In particular, the joining portion of the cross member low strength portion 22a to the longitudinal member 26 is clearly shown. The cross member low strength portion 22a is also plate-like as with the cross member 22, and one end (the inner end) is joined (e.g., welded) to the end portion of the cross member 22. The cross member low strength portion 22a has an inclined portion at the middle in the vehicle width direction, with the outer side being at a high position and the inner side being at a low position. Also, the inner side portion of the cross member low strength portion 22a is joined from the lower side to the end portion of the cross member 22.

[0033] The longitudinal member 26 is a C-shaped member that is open at the upper side, and the flange portion (the rim portion) of the upper surface is joined to the flange portion of the step portion 18. The lower surface of the longitudinal member 26 opposes the cross member low strength portion 22a, and the collar 24 that is hollow and cylindrical is disposed thereat. The cross member low strength portion 22a, the collar 24, and the longitudinal member 26 are fastened by the bolt 28 that penetrates therethrough, and the nut 30 is screwed to the top end of the bolt 28, whereby the cross member low strength portion 22a is fixed to the longitudinal member 26.

[0034] Here, both ends of the center portion 16b of the floor cross member 16 and the center portion 22b of the cross member 22 extend outward from the battery 20 in the vehicle width direction. In other words, the strength of the low-strength floor cross member 16a and the low-strength cross member 22a begins to weaken outward from the battery 20 in the vehicle width direction. Therefore, the strong center portion 16b of the floor cross member 16 and the center portion 22b of the cross member 22 can protect the battery 20.

[0035] Figure 3 The structure of the floor cross member 16 is shown in Figure 2. A seat bracket 32, which secures the seat in which the occupant sits, is fixed to the floor cross member 16. The seat bracket 32 ​​is a box-shaped member with a quadrangular pyramidal shape. The flange (edge) at the bottom is fixed to the top and side surfaces of the floor cross member 16 by welding or other means. Furthermore, the seat (seat rails) are fixed to the top surface of the seat bracket 32. The strength of the seat bracket 32 ​​is designed to be lower than that of the center portion 16b of the floor cross member 16.

[0036] In this embodiment, the seat bracket 32 ​​on the vehicle width direction outer side, indicated by the two-dot chain line, is attached to the floor cross member low-strength portion 16a. Therefore, when a force is applied to the floor cross member low-strength portion 16a, the force is also transmitted to the seat bracket 32, squashing the box-shaped seat bracket 32, and effectively absorbing the impact even in this portion.

[0037] As described above, in the vehicle lower structure of this embodiment, the floor cross member 16 and the rocker 14 are connected by a low-strength floor cross member portion 16a. Furthermore, the cross member 22 and the footrest portion 18 are connected by a low-strength cross member portion 22a. Therefore, in the event of a side collision with the vehicle, when a strong force is applied inward from the side of the vehicle, the low-strength floor cross member portion 16a and the low-strength cross member portion 22a deform to absorb the impact force. This reduces the acceleration of the battery 20 caused by the impact of the collision, effectively protecting the battery 20. Furthermore, the acceleration of the vehicle interior is reduced, thereby improving the protection of the occupants and / or other equipment within the vehicle interior.

[0038] In addition, if Figure 3 As shown, by providing the seat bracket 32 ​​at the low-strength portion 16a of the floor cross member, energy absorption due to deformation of the seat bracket 32 ​​is also generated, thereby increasing the total energy absorption amount.

[0039] Figure 4is a view of the battery 20 mounting portion of the vehicle lower structure as viewed from below. In this example, the battery 20 is disposed on the cross members 16 disposed in multiple rows in the vehicle front-rear direction, occupying a large area. Four cross members 22 are disposed at intervals in the vehicle front-rear direction. Further, cross member low-strength portions 22a are provided at both ends of each cross member 22, and the floor cross member low-strength portions 16a are fixed to the side members 26.

[0040] In addition, reinforcing members 34 connecting the plurality of cross members 22 are provided in the vehicle front-rear direction. In this example, two reinforcing members 34 connecting three cross members 22 are provided, and one reinforcing member 34 connecting four cross members 22 is provided midway between the two reinforcing members 34. With this structure, the battery 20 can be effectively protected.

[0041] Furthermore, vehicle frame members for ensuring the rigidity of the vehicle need to withstand large impacts, and are typically made of steel. In addition, metal materials are also suitable for members that are intended to deform and absorb energy.

Claims

1. A vehicle lower structure comprising: a pair of side sills extending in a vehicle front-rear direction; and a floor cross member extending in a vehicle width direction and connecting the pair of side sills, the floor cross member having weak portions at both ends thereof. The vehicle lower structure further includes a battery disposed between the pair of door sills. The floor beam is located on the upper side of the battery, A seat bracket for fixing a seat on which an occupant sits is mounted on the low-strength portion of the floor cross member and has a lower strength than that of the central portion of the floor cross member. The low-strength portion of the floor cross member is located outwardly of the battery in a vehicle width direction.

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