Vehicle underbody

Abstract

A vehicle underbody (100) comprising: two longitudinal beams (14) which are arranged separately in a vehicle width direction and extend in a vehicle length direction, a floor cross member (16) which extends in the direction of the vehicle width and is connected to the two longitudinal members (14), where the floor cross member (16) has two low-strength floor cross member areas (16a) on both sides in the vehicle width direction, which are of lower strength than a central area (16b), further with a battery (20) which is arranged between the two longitudinal beams (14), and characterized in that The floor crossbeam (16) overlaps the two longitudinal beams (14) when viewed from the front at the upper and lower sides of the two longitudinal beams (14), wherein at least one of the longitudinal beams (14) comprises two plates, each having a concave section, and the two plates are joined such that the two concave sections face each other.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vehicle undercarriage, and more particularly to handling a side impact. BACKGROUND

[0002] JP 2014-201277-A discloses the design of a battery storage area with a floor upper housing and a floor lower housing forming a vehicle floor, with a battery mounted beneath this floor. The rigidity of the floor upper housing and floor lower housing is then maintained by a side frame, which is a skeletal structure (rigid structure) in the vehicle's longitudinal direction, and a cross member, which is a skeletal structure in the vehicle's width direction. JP 2014-226957-A also discloses such a vehicle substructure. JP 2014-012524-A teaches a construction according to the preamble of claim 1.

[0003] By maintaining rigidity through the use of cross members, it is possible to reduce the deformation of a vehicle's underbody during a side impact and to mitigate the impact on a battery. Although the structure can increase rigidity against a side impact, impact energy absorption is low, and the vehicle's acceleration upon impact becomes relatively large.

[0004] The present disclosure provides a vehicle undercarriage that can more effectively absorb impact energy. SUMMARY

[0005] The present disclosure is a vehicle substructure having the features listed in claim 1. Advantageous further developments are the subject of the subclaims.

[0006] According to the present disclosure, at the time of side impact, the impact energy is absorbed to effectively cushion the shock, and it is possible to protect the battery. BRIEF EXPLANATION OF THE DRAWINGS Fig. 1 is a perspective drawing showing a vehicle understructure of an embodiment. Fig. Figure 2 is a schematic drawing showing the vehicle undercarriage of one embodiment viewed from the rear. Fig. 3 is a perspective drawing showing a state where a seat bracket has been attached to the floor cross member. Fig. 4 is a schematic drawing in which a battery mounting portion of the vehicle undercarriage of an embodiment is viewed from below. EXPLANATION OF THE EMBODIMENTS

[0007] Embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to the embodiments described herein.

[0008] Fig. 1 is a perspective view showing a vehicle underbody structure 100 of one embodiment. A floor tunnel 12 extending in the vehicle longitudinal direction is disposed at a central portion in the vehicle width direction of a floor panel 10. The floor tunnel 12 is formed by raising a portion of the floor panel 10 to protrude upward, and the interior creates a space in which various elements are housed.

[0009] Longitudinal beams 14 extending in the vehicle's longitudinal direction are arranged on both left and right side portions (both sides in the vehicle width direction) of the floor panel 10. These longitudinal beams 14 are tubular members with a square cross section formed by joining two long sheets with a C-shaped cross section so that their concave portions face each other. The longitudinal beams 14 are structural components of the vehicle and have relatively high strength.

[0010] Floor cross members 16 extending in the vehicle width direction are provided on the floor panel 10. These floor cross members 16 are structural components of the vehicle and provide protection against lateral forces. Both left and right ends of the floor cross members 16 are attached to the side walls of the side members 14. In this way, by coupling the side members 14 and the floor cross members 16, it is possible to protect the vehicle interior in both the longitudinal and transverse directions. The floor cross members 16 have a C-shaped cross section and are attached to the floor panel 10 with the concave portions facing downward.

[0011] Furthermore, two longitudinally extending kick elements, steps, or (hereinafter:) profile elements 18 are arranged on the floor panel 10. These profile elements 18 have a C-shaped cross-section and are attached to the floor panel 10 from above with the concave areas facing downward. The profile elements 18 are also arranged within (positioned between) the two side members 14, with inwardly curved front sides positioned centrally and rear sides (both sides in the vehicle width direction) positioned close to the side members 14.

[0012] A battery 20 is arranged between the two profile elements 18 in an area below the floor panel 10. More precisely, the battery 20 is arranged between the two longitudinal members 14 and the two profile elements 18. Furthermore, the floor cross members 16 are arranged above the battery 20. Accordingly, the floor cross members 16 also function as protective elements for the battery 20 in the vehicle width direction.

[0013] In this embodiment, cross members 22 extending in the vehicle width direction are arranged below the battery 20, and the cross members 22 support the battery 20 from below. Furthermore, the cross members 22 are long plates and are attached to both ends of the side members 26. The cross members 22 are high-strength members and function as protective members that protect the battery 20 from impacts in the vehicle width direction.

[0014] In this embodiment, low-strength floor cross member regions 16a are provided at the connecting regions of floor cross members 16 and longitudinal members 14. The strength of these low-strength floor cross member regions 16a (e.g., the allowable shear stress) decreases compared to the central region 16b of the floor cross member 16. For example, the strength is preferably approximately half that of the central region 16b.

[0015] In this embodiment, the low-strength floor cross-member portions 16a are formed as separate elements from the central portion 16b. Therefore, it is possible to adjust the strength simply by replacing the material or changing the thickness of the low-strength floor cross-member portions 16a. The low-strength floor cross-member portions 16a do not necessarily have to be formed as separate elements, but can also be formed by changing the thickness, cross-sectional area, or by providing slots. It should be noted that if the low-strength portions 16a are formed as separate elements, the low-strength floor cross-member portions 16a are connected to the central portion 16b by suitable means such as welding.

[0016] It should be noted that the low-strength floor cross member portions 16a are essentially members with a downwardly open C-shaped cross section and portions that extend flange-like to both sides in the longitudinal direction, and are connected at these portions to the top attachment portions 18a of the profile members 18. Furthermore, flange-like edge portions are formed for portions that contact the side surfaces of the side members 14, and the low-strength portions 16a are connected to the side surfaces of the side members 14 at these points. The top surfaces of the low-strength floor cross member portions 16a are laterally extending extension portions, and these portions are then superimposed on the top surfaces of the side member 14. Accordingly, it is possible to attach the extension portions to the top surfaces of the side members 14.At these joints, it is possible to use suitable means such as welding, similar to those described above.

[0017] Furthermore, low-strength cross member portions 22a are provided at connecting portions of both ends of the cross member 22 to the side members 26. These low-strength cross member portions 22a have a lower strength compared to the central portion 22b of the cross member 22. Similar to the low-strength floor cross member portions 16a, the low-strength cross member portions 22a can be constructed as separate elements from the central portion 22b or formed as part of the cross member 22, and it is also possible to perform strength adjustments in the same manner as for the low-strength floor cross member portions 16a.

[0018] The low-strength cross member sections 22a are attached to the side members 26 via a sleeve 24 by screw fastening. Specifically, the side members 26 are positioned behind the profile elements 18, above the low-strength cross member sections 22a, and below the rear side of the profile elements 18, with the floor panel 10 located between them. Accordingly, the side members 26 and the low-strength cross member sections 22a are attached with screws penetrating the sleeve 24.

[0019] The structure of the floor cross members 16, cross members 22, longitudinal members 14 and profile elements 18 is shown in Fig. 2 is schematically illustrated as viewed from the rear. In particular, connecting portions between the low-strength cross member portions 22a and the side members 26 are clearly shown. The low-strength cross member portions 22a are plate-shaped similar to the cross members 22, with one end (inner end) connected (e.g., welded) to an end portion of a cross member 22. The low-strength cross member portions 22a have an inclined portion at a center portion in the vehicle width direction with a high outer side and a low inner side. Inner portions of the low-strength cross member portions 22a are then connected to one end of the cross member 22 from below.

[0020] The side beams 26 are elements with an upwardly open C-shaped cross-section and have flange portions (edge ​​portions) on an upper side that are connected to flange portions of the profile elements 18. A lower surface of a side beam 26 faces a low-strength cross member portion 22a, with a hollow cylindrical sleeve 24 disposed between the two. By passing a bolt 28 through the low-strength cross member portion 22a, the sleeve 24, and the side beam 26, and fastening a nut 30 to an outermost end of this bolt 28, the low-strength cross member portion is fastened to the side beam 26.

[0021] Both ends of the center portion 16b of the floor cross member 16 and the center portion 22b of the cross member 22 protrude beyond the battery 20 in the vehicle width direction. In other words, positions where the strength of the low-strength floor cross member portions 16a and the low-strength cross member portion begins to weaken are located on the outer side of the battery 20 in the vehicle width direction. Accordingly, it is possible to protect the battery 20 by the high-strength center portions 16b of the floor cross members 16 and the center portions 22b of the cross member 22.

[0022] The structure of a floor cross member 16 is shown in Fig. 3. A seat bracket 32 ​​for securing seats on which occupants will sit is attached to a floor cross member 16. The seat bracket 32 ​​is a box-shaped member with a square truncated pyramid outer shape, with flange portions (edge ​​portions) of a lower part being fixed to a top surface and side surfaces of the floor cross member 16 by welding, etc. A seat (a seat rail) is then attached to a top surface of this seat bracket 32. The seat bracket 32 ​​has a lower strength than the central portion 16b of the floor cross member 16.

[0023] With this embodiment, a seat bracket 32 ​​is attached to a low-strength floor cross member portion 16a on an outer side in the vehicle width direction, as shown by a two-dot chain line. As a result, when a force acts on the low-strength floor cross member portion 16a, even if this force is transmitted to the seat bracket 32, the box-shaped seat bracket 32 ​​collapses, and the impact is effectively absorbed at this portion as well.

[0024] In this way, with the vehicle underbody structure of this embodiment, the low-strength floor cross member portions 16a are provided at connecting portions between the floor cross members 16 and the side members 14. Likewise, the low-strength cross member portion 22 is provided at connecting portions between the cross member 22 and the profile members 18. This means that at the time of impact on a vehicle side portion, when a large force is received in a direction from the vehicle side surface inward, the low-strength floor cross member portions 16a and the low-strength cross member portion 22a deform to absorb the impact energy. Accordingly, it is possible to reduce the acceleration acting on a battery 20 caused by the impact of an impact and effectively protect the battery 20.Furthermore, it is possible to reduce the acceleration acting on the vehicle interior and improve the protection of the occupants in the vehicle interior and other devices.

[0025] By providing the seat bracket 32 ​​on the low-strength floor cross member area 16a, as in Fig. 3, energy absorption can also be achieved by deforming the seat bracket 32, and it is possible to increase the total amount of energy absorption.

[0026] Fig.Figure 4 is a bottom view of a mounting area for a battery 20 of the vehicle's underbody. In this example, the battery 20 is arranged on several cross members 22 in the vehicle's longitudinal direction and occupies a comparatively large area. Four cross members 22 are arranged at intervals in the vehicle's longitudinal direction. Low-strength cross member sections 22a are then provided at both ends of each cross member 22, and low-strength floor cross member sections 16a are respectively adapted to the side members 26.

[0027] Furthermore, stiffening members 34 connecting a plurality of cross members 22 are provided in the vehicle's longitudinal direction. In this example, two stiffening members 34 are provided connecting three cross members 22, and a single stiffening member 34 connecting four cross members 22 is provided between them. With this type of structure, it is possible to effectively protect the battery 20.

[0028] It should be noted that vehicle structural components must withstand high loads to ensure vehicle rigidity, and steel materials are commonly used. Other metallic materials are also suitable for elements that absorb energy through deformation.

Claims

[1] A vehicle substructure (100) with: two longitudinal members (14) arranged separately in a vehicle width direction and extending in a vehicle longitudinal direction, a floor cross member (16) which extends in the vehicle width direction and is connected to the two longitudinal members (14), where the floor cross member (16) has two low-strength floor cross member regions (16a) on both sides in the vehicle width direction, which are of lower strength than a central region (16b), further comprising a battery (20) arranged between the two longitudinal beams (14), and characterized by , that the floor cross member (16) overlaps the two longitudinal members (14) at the upper and lower sides of the two longitudinal members (14) when viewed from the front, wherein at least one of the longitudinal members (14) comprises two plates, each having a concave section, and the two plates are joined such that the two concave sections face each other. [2] Vehicle substructure (100) according to claim 1, wherein the two low-strength floor cross member portions (16a) are positioned on the outside of the battery (20) in the vehicle width direction. [3] Vehicle substructure (100) according to claim 1, wherein the floor cross member (16) is arranged above the battery (20) and both ends of the floor cross member (16) are connected to the two longitudinal members (14) fastened at positions on the outside of the battery (20). [4] Vehicle substructure according to claim 1, wherein the two low-strength floor cross member portions (16a) are positioned on the outside of the battery (20) in the vehicle width direction. [5] Vehicle substructure (100) according to claim 1, further comprising: two side supports (26) which are arranged separately from one another in the vehicle width direction and extend in the vehicle longitudinal direction, the battery (20) arranged between the two side supports (26), and a cross member (22) extending in the vehicle width direction and connecting the two side members (26), where the cross member (22) has two low-strength cross member regions (22a) on both sides in the vehicle width direction, which are of lower strength than a central region (22b). [6] Vehicle substructure (100) according to claim 5, wherein: the cross member (22) is arranged below the battery (20), and both side supports (26) are fastened at positions on the outside of the battery (20). [7] Vehicle substructure (100) according to claim 6, wherein: the low-strength cross member areas (22a) are positioned below the low-strength floor cross member areas (16a).

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