Vehicle undercarriage
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-01-24
- Publication Date
- 2026-08-05
Smart Images
Figure 2026126671000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vehicle underbody structure.
Background Art
[0002] A vehicle body structure of an electric vehicle in which a plurality of cross members extending in the vehicle width direction are installed between a pair of left and right frames extending in the front-rear direction, and a battery pack is disposed above the plurality of cross members has been conventionally known (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, in a frame vehicle, in order to suppress its torsion, a cross member is installed between a pair of left and right side frames. However, when an energy absorption member is disposed outside the battery pack in the vehicle width direction and below the side frame in the vehicle, in order to allow the outer end portion of the cross member in the vehicle width direction, it is necessary to notch a part of the energy absorption member in a substantially rectangular shape in a bottom view.
[0005] Therefore, when a load is input from the outside in the vehicle width direction to the energy absorption member during a side collision of the vehicle or the like, a tensile stress acting relatively outward in the vehicle width direction is applied to the portion of the energy absorption member that allows the outer end portion of the cross member in the vehicle width direction, and the energy absorption member may break. That is, there is a possibility that the shock absorption performance against a load input from the outside in the vehicle width direction cannot be sufficiently exhibited.
[0006] Therefore, the present invention aims to provide a vehicle understructure that can suppress the reduction in impact absorption performance against loads input from the outside in the vehicle width direction. [Means for solving the problem]
[0007] To achieve the above objective, the vehicle understructure of the first embodiment of the present invention comprises a pair of left and right side frames extending in the longitudinal direction of the vehicle, a battery pack disposed between the side frames, a cross member installed between the side frames on the lower side of the battery pack, and an energy absorbing member disposed on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frames, wherein, in a bottom view, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction starting from the portion that reaches the energy absorbing member and attached to the side frame, and the outer end of the energy absorbing member in the vehicle longitudinal direction is arranged along the surface of the cross member at the outer end in the vehicle width direction that faces inward in the vehicle longitudinal direction, and a reinforcing member having a plane facing the energy absorbing member in the vehicle width direction is provided on the bent portion of the cross member.
[0008] According to the first embodiment of the invention, a battery pack is arranged between a pair of left and right side frames that extend in the longitudinal direction of the vehicle. A cross member is installed between the side frames on the lower side of the battery pack, and an energy absorbing member is arranged on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frames.
[0009] In this view from below, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction, starting from the point where it reaches the energy absorbing member, and attached to the side frame. The outer end of the energy absorbing member in the vehicle longitudinal direction is positioned along the surface of the cross member at its outer end in the vehicle width direction that faces inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the cross member, having a plane that faces the energy absorbing member in the vehicle width direction.
[0010] Therefore, even when a load is applied to the energy-absorbing member from the outside in the vehicle width direction during a side collision, etc., a tensile stress directed relatively outward in the vehicle width direction is less likely to act on the outer end of the energy-absorbing member in the vehicle longitudinal direction due to the outer end of the cross member in the vehicle width direction, making it difficult for the energy-absorbing member to break. As a result, the load applied from the outside in the vehicle width direction is effectively absorbed by the energy-absorbing member and effectively supported by the reinforcing member. In other words, the decrease in impact absorption performance against loads applied from the outside in the vehicle width direction is suppressed.
[0011] Furthermore, the vehicle understructure of the second embodiment of the present invention comprises a vehicle body frame having a pair of left and right side frames extending in the longitudinal direction of the vehicle, a front connecting frame connecting the front vehicle portion of the side frames in the vehicle width direction, and a rear connecting frame connecting the rear vehicle portion of the side frames in the vehicle width direction; a battery pack disposed inside the vehicle body frame; a subframe having a cross member installed between the side frames on the vehicle lower side of the battery pack and supporting the battery pack from the vehicle lower side; and an energy absorbing member disposed on the vehicle width side of the battery pack and on the vehicle lower side of the side frames. In a bottom view, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction starting from the portion that reaches the energy absorbing member and attached to the side frame, and the outer end of the energy absorbing member in the vehicle longitudinal direction is arranged along the surface of the outer end of the cross member in the vehicle width direction that faces inward in the vehicle longitudinal direction, and a reinforcing member having a plane facing the energy absorbing member in the vehicle width direction is provided on the bent portion of the cross member.
[0012] According to the second embodiment of the invention, the vehicle body frame is constructed by connecting the front portion of a pair of left and right side frames extending in the longitudinal direction of the vehicle in the vehicle width direction by a front connecting frame, and connecting the rear portion of the side frames in the vehicle width direction by a rear connecting frame. The battery pack is arranged inside the vehicle body frame. A subframe that supports the battery pack from below the vehicle has a cross member that is installed between the side frames below the battery pack, and an energy absorbing member is arranged on the outside of the battery pack in the vehicle width direction and on the below portion of the side frames.
[0013] In this view from below, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction, starting from the point where it reaches the energy absorbing member, and attached to the side frame. The outer end of the energy absorbing member in the vehicle longitudinal direction is positioned along the surface of the cross member at its outer end in the vehicle width direction that faces inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the cross member, having a plane that faces the energy absorbing member in the vehicle width direction.
[0014] Therefore, even when a load is applied to the energy-absorbing member from the outside in the vehicle width direction during a side collision, etc., a tensile stress directed relatively outward in the vehicle width direction is less likely to act on the outer end of the energy-absorbing member in the vehicle longitudinal direction due to the outer end of the cross member in the vehicle width direction, making it difficult for the energy-absorbing member to break. As a result, the load applied from the outside in the vehicle width direction is effectively absorbed by the energy-absorbing member and effectively supported by the reinforcing member. In other words, the decrease in impact absorption performance against loads applied from the outside in the vehicle width direction is suppressed.
[0015] Furthermore, a third embodiment of the vehicle understructure according to the present invention is a vehicle understructure according to the first or second embodiment, wherein the reinforcing member is formed in a triangular shape when viewed from the bottom, having an inclined wall located between the surface of the cross member facing inward in the vehicle longitudinal direction and the surface of the energy absorbing member facing inward in the vehicle width direction.
[0016] According to the invention of the third aspect, the reinforcing member is formed in a triangular shape in plan view having an inclined wall positioned between the surface of the cross member facing the inner side in the vehicle longitudinal direction and the surface of the energy absorbing member facing the inner side in the vehicle width direction. Therefore, the rigidity of the reinforcing member is improved, and the load input from the outer side in the vehicle width direction is effectively received by the reinforcing member and the cross member.
Advantages of the Invention
[0017] As described above, according to the present invention, it is possible to suppress a decrease in shock absorption performance with respect to a load input from the outer side in the vehicle width direction.
Brief Description of the Drawings
[0018] [Figure 1] It is a schematic plan view showing a vehicle body lower structure according to the present embodiment. [Figure 2] It is a schematic perspective view showing a vehicle body lower structure according to the present embodiment. [Figure 3] It is a schematic exploded perspective view showing a vehicle body lower structure according to the present embodiment. [Figure 4] It is a schematic rear view taken in the direction of the arrow X-X in FIG. 1. [Figure 5] It is a schematic plan view showing an enlarged part of a vehicle body lower structure according to the present embodiment. [Figure 6] It is a schematic plan view showing a state when a load is input to a vehicle body lower structure according to the present embodiment.
Embodiments for Carrying Out the Invention
[0019] Hereinafter, embodiments according to the present invention will be described in detail based on the drawings. For convenience of explanation, in each figure, the arrow UP shown as appropriate is the upward direction of the vehicle, the arrow FR is the forward direction of the vehicle, and the arrow RH is the rightward direction of the vehicle. In the following description, when the directions of up and down, front and back, and left and right are described without particular mention, they indicate up and down, front and back, and left and right in the vehicle. Also, the left and right directions are synonymous with the vehicle width direction.
[0020] As shown in FIG. 1, the frame vehicle 12 as a vehicle equipped with the vehicle lower structure 10 according to the present embodiment is mainly a battery electric vehicle (BEV) or a fuel cell electric vehicle (FCEV). The frame vehicle 12 has a pair of left and right side frames 14 that are arranged on the outer side in the vehicle width direction and extend in the front-rear direction. Each side frame 14 is formed in a rectangular closed cross-sectional shape when viewed in cross-section from the front-rear direction. Note that front wheels 22 and rear wheels 24 are respectively arranged on the outer side in the vehicle width direction at the front side and the rear side of each side frame 14.
[0021] Further, as shown in FIGS. 2 and 3, since a suspension unit (see FIG. 1) or the like is arranged on the lower side at the front side and the rear side of each side frame 14, in a side view seen from the vehicle width direction, they are located above the central part side of each side frame 14. That is, the front side and the rear side of each side frame 14 each have an inclined portion that inclines upward from the front upper side and the rear upper side from the central part side, and extend from each inclined portion toward the front side and the rear side, respectively.
[0022] In addition, a front connecting frame 16 that extends along the vehicle width direction is installed at the front part (front side portion) of each side frame 14, and a rear connecting frame 18 that extends along the vehicle width direction is installed at the rear part (rear side portion) of each side frame 14. That is, the front end portion of the side frame 14 is connected in the vehicle width direction by the front connecting frame 16, and the rear end portion of the side frame 14 is connected in the vehicle width direction by the rear connecting frame 18. Thereby, a vehicle body frame 20 having a substantially rectangular frame shape in plan view is formed.
[0023] Further, as shown in FIGS. 2 and 3, a battery pack 26 is arranged inside the vehicle body frame 20 (between the side frames 14). The battery pack 26 has a substantially rectangular box-shaped case 26A that houses a plurality of battery cells (not shown), and is configured to be supported from below by a sub-frame 30 arranged inside the vehicle body frame 20. That is, the sub-frame 30 is arranged below the battery pack 26.
[0024] The subframe 30 is made of, for example, high-tensile steel, and has a first frame 32 with a rectangular closed cross-section that extends in the front-rear direction at the center of the vehicle width direction of the vehicle body frame 20, and a second frame 34 with a rectangular closed cross-section that extends in the vehicle width direction at approximately the center of the vehicle width direction of the vehicle body frame 20.
[0025] In other words, the subframe 30 is configured in a roughly "+" shape in plan view with the first frame 32 and the second frame 34. The central part of the second frame 34 in the vehicle width direction is fitted into a rectangular notch 32A formed in the roughly central part of the first frame 32 in the front-rear direction and assembled, and the two parts are integrally joined by welding or the like.
[0026] Furthermore, the outer end of the second frame 34 in the vehicle width direction is formed to be wide so as to be approximately elliptical in plan view, and is fastened and attached to the lower surface of each side frame 14. In other words, the second frame 34 is installed between a pair of side frames 14. The first frame 32 is configured to have higher rigidity than the second frame 34. Specifically, the first frame 32 is formed to be thicker than the second frame 34, for example.
[0027] Furthermore, the subframe 30 has a third frame 36 that extends in the vehicle width direction at the rear of the vehicle body frame 20, and the rear end of the first frame 32 is integrally joined to the center of the third frame 36 in the vehicle width direction by welding or the like. In addition, when viewed from the rear in the front-rear direction, the third frame 36 is formed in a roughly "U" shape with both ends in the left-right direction bent so as to extend upward.
[0028] Furthermore, the subframe 30 is formed in a rectangular closed cross-sectional shape and extends in the vehicle width direction, and has multiple cross members that are installed between a pair of side frames 14 in order to suppress twisting of the vehicle body frame 20 (to improve durability and strength performance). Specifically, the subframe 30 has three cross members 38, 40, and 42 at equal intervals in the longitudinal direction on the front side of the second frame 34, and two cross members 44 and 46 at equal intervals in the longitudinal direction between the second frame 34 and the third frame 36.
[0029] The first frame 32, located forward of the second frame 34, has three rectangular notches 32A formed at equal intervals in the front-to-back direction. The central portions of each cross member 38, 40, and 42 in the vehicle width direction are fitted into each notch 32A and assembled, and are integrally joined by welding or the like. The outer ends of each cross member 38, 40, and 42 in the vehicle width direction are attached to each side frame 14.
[0030] Similarly, the first frame 32 located behind the second frame 34 has two rectangular notches 32A formed at equal intervals in the front-rear direction. The central portions of each cross member 44 and 46 in the vehicle width direction are fitted into each notch 32A and assembled, and are integrally joined by welding or the like. The outer ends of each cross member 44 and 46 in the vehicle width direction are then attached to each side frame 14.
[0031] Furthermore, as shown in Figures 1 to 4, energy absorbing members 28, which are formed in a grid pattern in a cross-sectional view from the front-rear direction, are arranged on the outer side of the battery pack 26 in the vehicle width direction and on the lower side of each side frame 14. A notch 28C, which is roughly "U" shaped in plan view, is formed on the inner side in the vehicle width direction at approximately the center of the energy absorbing member 28 in the front-rear direction, allowing the outer end of the second frame 34 in the vehicle width direction to be accommodated.
[0032] Furthermore, as shown in Figure 1, the rear end (outer end in the front-rear direction) 28B of the energy absorbing member 28 extends to a position close to the rearmost cross member 46, and the front end (outer end in the front-rear direction) 28A of the energy absorbing member 28 extends to a position not exceeding the second cross member 40 from the front. Now, the positional relationship between the outer end in the vehicle width direction of the cross member 40 and the front end 28A of the energy absorbing member 28 will be explained.
[0033] As shown in Figures 1 and 5, in a bottom view, the outer end of the cross member 40 in the vehicle width direction is bent forward (outward in the longitudinal direction) starting from the point where it reaches the energy absorbing member 28 and is attached to the lower surface of the side frame 14. Furthermore, in a bottom view, the inner portion in the vehicle width direction of the front end 28A of the energy absorbing member 28 is positioned along the rear surface (surface facing inward in the longitudinal direction) 40B of the outer end of the cross member 40 in the vehicle width direction. In other words, in a bottom view, the inner portion in the vehicle width direction of the front end 28A of the energy absorbing member 28 is cut to a shape that follows the rear surface 40B of the outer end of the cross member 40 in the vehicle width direction.
[0034] Furthermore, a gusset 48 is provided as a reinforcing member at the bent portion (hereinafter referred to as the "bent portion") 40A of the cross member 40, having a flat surface 48A that faces the energy absorbing member 28 in the vehicle width direction. The gusset 48 is formed in a roughly triangular shape when viewed from the bottom, and its front portion is integrally joined to the lower and rear surfaces of the bent portion 40A of the cross member 40 by welding or the like.
[0035] As a result, the outer end of the gusset 48 in the vehicle width direction is a flat surface 48A, which is in close proximity to or in contact with the energy absorbing member 28 and faces it. The rear part of the gusset 48 is an inclined wall 48B located between the rear surface (the surface facing inward in the vehicle's longitudinal direction) which is inward in the vehicle width direction from the bent portion 40A of the cross member 40 and the inner surface (the surface facing inward in the vehicle width direction) of the energy absorbing member 28 when viewed from below.
[0036] The operation of the vehicle understructure 10 according to this embodiment, which has the configuration described above, will now be explained.
[0037] As described above, the front portions of a pair of left and right side frames 14, which extend in the front-rear direction, are connected in the vehicle width direction by a front connecting frame 16, and the rear portions of the side frames 14 are connected in the vehicle width direction by a rear connecting frame 18 to form the vehicle body frame 20. The battery pack 26 is positioned inside the vehicle body frame 20 (between the side frames 14). In other words, the battery pack 26 is supported from below by a subframe 30.
[0038] Here, the first frame 32 of the subframe 30, which is made highly rigid, extends in the longitudinal direction at the center of the vehicle body frame 20 in the vehicle width direction below the battery pack 26, and the second frame 34 of the subframe 30 is mounted on the side frame 14 at approximately the center of the vehicle body frame 20 in the longitudinal direction. Therefore, the heavy battery pack 26 can be stably supported.
[0039] Furthermore, as shown in Figure 4, in a side view, the subframe 30 is located below the vehicle body frame 20 (side frame 14), so the battery pack 26 is enclosed by the vehicle body frame 20. More specifically, in a side view, at least a portion of the battery pack 26 in the height direction overlaps with the vehicle body frame 20, and at least a portion of the battery pack 26 in the height direction is enclosed by the vehicle body frame 20.
[0040] Therefore, the mounting stability of the battery pack 26 can be improved, and the protective performance of the battery pack 26 during a collision with the frame vehicle 12 can be improved. In other words, even if a collision load is applied to the frame vehicle 12 from the longitudinal direction or the width direction, the battery pack 26 can be effectively protected from that collision load.
[0041] Furthermore, an energy absorbing member 28 is positioned on the outer side of the battery pack 26 in the vehicle width direction and below the side frame 14, and the subframe 30 has a cross member 40 that extends in the vehicle width direction. In a bottom view, the outer end of the cross member 40 in the vehicle width direction is bent forward from the point where it reaches the energy absorbing member 28 and attached to the side frame 14, and the front end 28A of the energy absorbing member 28 is positioned along the rear surface 40B of the outer end of the cross member 40 in the vehicle width direction. Moreover, a gusset 48 having a flat surface 48A that faces the energy absorbing member 28 in the vehicle width direction is provided at the bent portion 40A of the cross member 40.
[0042] Therefore, in the event of a side collision of the frame vehicle 12, even if a load is applied to the energy absorbing member 28 from the outside in the vehicle width direction, the front end portion 28A of the energy absorbing member 28 is less likely to be subjected to a relative tensile stress directed outward in the vehicle width direction by the outer end portion of the cross member 40 in the vehicle width direction, making it difficult for the energy absorbing member 28 to break. In addition, the inner portion of the front end portion 28A of the energy absorbing member 28 in the vehicle width direction is effectively supported from the inside in the vehicle width direction by the flat surface 48A of the gusset 48.
[0043] As a result, as shown in Figure 6, loads input from the outside in the vehicle width direction by obstacles W, etc., are effectively absorbed by the energy absorbing member 28 and also effectively received by the plane 48A of the gusset 48 (the energy absorbing member 28 supported by the plane 48A). Therefore, in the event of a side collision of the frame vehicle 12, etc., a decrease in impact absorption performance against loads input from the outside in the vehicle width direction can be suppressed.
[0044] Furthermore, the gusset 48 is formed in a roughly triangular shape when viewed from the base, having an inclined wall 48B located between the rear surface of the cross member 40 and the inner surface of the energy absorbing member 28. Therefore, compared to the case of a gusset that is not formed in such a roughly triangular shape when viewed from the base (not shown), the rigidity of the gusset 48 can be improved, and the load applied from the outside in the vehicle width direction can be effectively absorbed by the gusset 48 and the cross member 40.
[0045] More specifically, the load applied to the plane 48A of the gusset 48 from the outside in the vehicle width direction can be efficiently transmitted to the cross member 40 via the front and rear (inclined wall 48B) of the gusset 48, and can then be effectively supported by the cross member 40 and further by the side frame 14 (vehicle frame 20).
[0046] The vehicle understructure 10 according to this embodiment has been described above based on the drawings. However, the vehicle understructure 10 according to this embodiment is not limited to the illustrated version, and can be modified as appropriate without departing from the spirit of the present invention. For example, the vehicle according to this embodiment is not limited to a frame vehicle 12. Also, each cross member 38, 40, 42, 44, and 46 is not limited to being formed in a rectangular closed cross-sectional shape, but may be formed in a substantially "U" shape in cross-section.
[0047] Furthermore, although the above embodiment described the cross member 40 located at the front end 28A of the energy absorbing member 28, the cross member 46 located (proximally adjacent) to the rear end 28B of the energy absorbing member 28 may be configured similarly. Also, the gusset 48 only needs to be shaped to effectively receive loads input from the outside in the vehicle width direction, and is not limited to being formed in a roughly triangular shape when viewed from the bottom. [Explanation of Symbols]
[0048] 10. Vehicle understructure 14 Side Frames 16 Front connecting frame 18 Rear connecting frame 20 Body frame 26 Battery Packs 28 Energy absorbing member 30 Subframes 40 Crossmember 48. Gusset (reinforcement member) 48B Slanted wall
Claims
1. A pair of left and right side frames extending in the front-to-rear direction of the vehicle, A battery pack positioned between the side frames, A cross member is installed between the side frames on the lower side of the vehicle of the aforementioned battery pack, An energy absorbing member is positioned on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frame of the vehicle, Equipped with, In a bottom view, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction starting from the portion that reaches the energy absorbing member and attached to the side frame, and the outer end of the energy absorbing member in the vehicle longitudinal direction is positioned along the surface of the cross member at the outer end in the vehicle width direction that faces inward in the vehicle longitudinal direction. A vehicle understructure in which a reinforcing member having a plane facing the energy absorbing member in the vehicle width direction is provided at the bent portion of the cross member.
2. A vehicle body frame having a pair of left and right side frames extending in the longitudinal direction of the vehicle, a front connecting frame connecting the front portion of the side frames in the vehicle width direction, and a rear connecting frame connecting the rear portion of the side frames in the vehicle width direction. A battery pack is positioned inside the vehicle frame, The battery pack has a cross member that is installed between the side frames on the lower side of the vehicle, and a subframe that supports the battery pack from the lower side of the vehicle, An energy absorbing member is positioned on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frame of the vehicle, Equipped with, In a bottom view, the outer end of the cross member in the vehicle width direction is bent outward in the vehicle longitudinal direction starting from the portion that reaches the energy absorbing member and attached to the side frame, and the outer end of the energy absorbing member in the vehicle longitudinal direction is positioned along the surface of the cross member at the outer end in the vehicle width direction that faces inward in the vehicle longitudinal direction. A vehicle understructure in which a reinforcing member having a plane facing the energy absorbing member in the vehicle width direction is provided at the bent portion of the cross member.
3. The vehicle understructure according to claim 1 or claim 2, wherein the reinforcing member is formed in a triangular shape when viewed from below, having an inclined wall located between the surface of the cross member facing inward in the vehicle longitudinal direction and the surface of the energy absorbing member facing inward in the vehicle width direction.