Vehicle lower part structure

Abstract

To provide a vehicle lower part structure that can stably absorb a collision load during lateral collision.SOLUTION: A vehicle lower part structure has: a first skeleton member which is located at a vehicle width direction end of a vehicle lower part, and comprises a first absorption member with a hat-shaped cross section therein; a second skeleton member which is connected a vehicle width direction inner side of the first skeleton member, and comprises a second absorption member therein; and a cross member which is located a vehicle width direction inner side of the second skeleton member and extends in a vehicle width direction, and is connected to the second skeleton member. The first absorption member, the second absorption member and the cross member are arranged at a position overlapped in a vehicle side view.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage. [Background technology]

[0002] Patent Document 1 discloses a structure in which a first stiffener and a second stiffener are provided inside rockers (side sills) arranged on both sides of the battery case in the vehicle width direction in a vehicle having a battery case mounted under the floor of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-137354 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle described in Patent Document 1, the rocker deforms and the second stiffener with a hat-shaped cross section collapses during a side collision, allowing the vehicle to absorb part of the collision load. However, there is a possibility that the rocker and the second stiffener will not deform into the desired shape, and there is room for improvement in stabilizing the ability to absorb collision loads during side collisions.

[0005] An object of the present invention is to provide a vehicle underbody structure that can stably absorb a collision load during a side collision. [Means for solving the problem]

[0006] The vehicle undercarriage structure of claim 1 comprises a first skeletal member that is arranged at the vehicle width direction end of the vehicle underside and has a first absorption member with a hat-shaped cross section inside, a second skeletal member that is connected to the vehicle width direction inner side of the first skeletal member and has a second absorption member inside, and a cross member that is arranged in the vehicle width direction inner side of the second skeletal member, extends in the vehicle width direction, and is connected to the second skeletal member, and is arranged in a position where the first absorption member, the second absorption member, and the cross member overlap when viewed from the side of the vehicle.

[0007] In the vehicle undercarriage structure according to claim 1, a first skeletal member is disposed at an end of the vehicle underside in the vehicle width direction, and a first absorbing member having a hat-shaped cross section is disposed inside the first skeletal member. A second skeletal member is connected to the inside of the first skeletal member in the vehicle width direction, and a second absorbing member is disposed inside the second skeletal member. A cross member extending in the vehicle width direction is disposed inside the second skeletal member in the vehicle width direction, and one end of the cross member is connected to the second skeletal member. As a result, in the event of a side collision of the vehicle (hereinafter sometimes referred to as a "side collision"), the first absorbing member and the second absorbing member are deformed by the collision load input to the vehicle, thereby absorbing at least a portion of the collision load. Furthermore, the collision load can be transmitted to the side opposite the collision via the first skeletal member, the second skeletal member, and the cross member.

[0008] Furthermore, since the first absorption member, the second absorption member and the cross member are positioned in a position where they overlap when viewed from the side of the vehicle, the first absorption member and the second absorption member are sandwiched between the cross member and the collision body, and the first absorption member and the second absorption member can be deformed more stably compared to a configuration in which no reaction force is input from the cross member.

[0009] The vehicle undercarriage structure of claim 2 is the same as claim 1, wherein the second absorption member includes a pair of upper and lower partition walls that are arranged at intervals in the vertical direction and extend in the vehicle width direction to connect the inner walls of the second framework member, and left and right partition walls that connect the upper and lower partition walls vertically.

[0010] In the vehicle underbody structure according to claim 2, the second absorption member has a structure in which two chambers are provided in the vehicle width direction by a pair of upper and lower partition walls and left and right partition walls, and thereby the chambers collapse sequentially from the outermost chamber in the vehicle width direction, thereby absorbing the collision load more effectively than in a structure without partition walls.

[0011] The vehicle undercarriage structure according to claim 3 is the same as claim 2, wherein at least one of the pair of upper and lower partition walls has a weak portion formed on the outer side of the left and right partition walls in the vehicle width direction that is weaker than other portions.

[0012] In the vehicle underbody structure according to claim 3, by forming the weakened portion, the chamber on the outer side in the vehicle width direction of the second absorption member can be deformed into a desired shape.

[0013] The vehicle undercarriage structure of claim 4 is, in claim 3, wherein the first absorption member includes a pair of upper and lower lateral wall portions extending outward in the vehicle width direction from the first framework member, and a vertical wall portion connecting the lateral wall portions vertically, and the pair of upper and lower lateral wall portions are each positioned so as to overlap the upper and lower partition walls of the second absorption member when viewed from the side of the vehicle.

[0014] In the vehicle underbody structure according to claim 4, when a collision load is input, the load can be transmitted from the side wall portion to the cross member through the upper and lower partition walls, thereby enabling at least a portion of the collision load to be transmitted effectively to the anti-collision side before the first absorption member and the second absorption member are crushed.

[0015] The vehicle undercarriage structure of claim 5 is any one of claims 1 to 4, wherein the second skeletal member is a battery frame disposed under the vehicle and to which a battery case that houses a battery is fastened, and the first skeletal member is a rocker extending in the fore-and-aft direction of the vehicle.

[0016] In the vehicle underbody structure according to claim 5, the first absorbing member and the second absorbing member collapse to absorb at least a part of the collision load, thereby making it possible to suppress transmission of the collision load to the battery case. [Effects of the Invention]

[0017] As described above, the vehicle underbody structure according to the present invention can stably absorb a collision load during a side collision. [Brief explanation of the drawings]

[0018] [Figure 1] 2 is an enlarged cross-sectional view showing a main part of the vehicle undercarriage structure according to the embodiment; FIG. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main portion showing a state immediately after a collision load is input during a side collision. [Figure 3] 3 is an enlarged cross-sectional view of a main part showing a state after a certain time has elapsed since the state shown in FIG. 2. FIG. [Figure 4] 4 is an enlarged cross-sectional view of a main part showing a state after a certain time has elapsed since the state of FIG. 3. FIG. [Figure 5] 5 is an enlarged cross-sectional view of a main part showing a state after a certain time has elapsed since the state of FIG. 4. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing a battery frame according to a first modified example. [Figure 7] FIG. 10 is a cross-sectional view showing a battery frame according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0019] A vehicle underbody structure according to an embodiment will be described with reference to the drawings.

[0020] 1 is an enlarged cross-sectional view showing a main part of a vehicle undercarriage according to an embodiment. Note that the arrows UP and RH in the figure respectively indicate the vehicle upward and vehicle rightward directions of a vehicle 10 to which the vehicle undercarriage is applied. In the following description, unless otherwise specified, when the front-rear, up-down, and left-right directions are used, they refer to the front-rear direction of the vehicle, the up-down direction of the vehicle, and the left-right direction (width direction) of the vehicle, respectively.

[0021] 1, the vehicle undercarriage structure of this embodiment includes a battery case 12. The battery case 12 includes an upper case 14 and a lower case 16, and accommodates a battery BT inside the battery case 12.

[0022] The upper case 14 is formed in a generally hat shape with an open lower side in a cross section seen from the vehicle longitudinal direction, and an upper flange 14A is formed at the vehicle right end of the upper case 14. The upper flange 14A is superimposed on the lower surface of the battery frame 30, which will be described later. Note that, since the vehicle undercarriage structure of this embodiment is symmetrical, only the configuration on the right side of the vehicle will be illustrated and described below.

[0023] The lower case 16 is formed in a generally hat shape with an open upper side in a cross section seen from the vehicle front-rear direction, and a lower flange 16A is formed at the vehicle right end of the lower case 16. The upper flange 14A and the lower flange 16A are mechanically fastened to a battery frame 30, which will be described later.

[0024] In this embodiment, as an example, no floor panel is provided, and the upper case 14 of the battery case 12 forms the floor of the vehicle compartment. However, this is not limited to this, and a floor panel may be provided above the upper case 14 of the vehicle.

[0025] A rocker 18 serving as a first framework member is disposed on the outer side in the vehicle width direction of the battery case 12. The rocker 18 is disposed at the end of the vehicle width direction of the lower part of the vehicle, and is a framework member with a closed cross-sectional structure configured to include a rocker outer panel 20, a rocker inner panel 22, and a first absorbing member 24. The rocker 18 also extends in the front-rear direction of the vehicle, and a similar rocker is disposed at the end on the left side of the vehicle.

[0026] The rocker outer panel 20 constitutes the outer side of the rocker 18 in the vehicle width direction, and is formed in a generally hat-shaped cross section with the inner side in the vehicle width direction being open when viewed from the vehicle front-rear direction. Outer flanges 20A extending in the vehicle up-down direction are formed at the upper and lower ends of the rocker outer panel 20.

[0027] The rocker inner panel 22 constitutes the vehicle width direction inner side of the rocker 18, and is formed in a substantially flat plate shape with its thickness direction being the vehicle width direction. Inner flanges 22A overlapping the outer flanges 20A are formed at the upper and lower ends of the rocker inner panel 22, and the outer flanges 20A and the inner flanges 22A are joined by welding or the like.

[0028] The first absorbing member 24 is disposed within a cross section surrounded by the rocker outer panel 20 and the rocker inner panel 22, and has a generally hat-shaped cross section when viewed from the vehicle longitudinal direction. Specifically, the first absorbing member 24 includes a pair of upper and lower lateral wall portions 24A extending outward in the vehicle width direction from the rocker inner panel 22, and a vertical wall portion 24B connecting these lateral wall portions 24A in the vertical direction. Furthermore, extending portions 24C extending in the vertical direction along the rocker inner panel 22 are formed at the inner ends of the lateral wall portions 24A in the vehicle width direction.

[0029] The upper extending portion 24C extends upward along the rocker inner panel 22 and is joined to the rocker inner panel 22 in a state where it is overlapped thereon. The lower extending portion 24C extends downward along the rocker inner panel 22 and is joined to the rocker inner panel 22 in a state where it is overlapped thereon.

[0030] In the present embodiment, as an example, the vertical wall portion 24B is close to or in contact with the rocker outer panel 20, but is not limited to this. For example, a gap may be provided between the vertical wall portion 24B and the rocker outer panel 20.

[0031] A battery frame 30 serving as a second framework member is disposed on the inner side in the vehicle width direction of the rocker 18. The battery frame 30 is formed in a generally frame-like shape so as to surround the periphery of the battery case 12, and has a closed cross-sectional structure.

[0032] The battery frame 30 includes side frames 32 that extend in the front-to-rear direction of the vehicle along the battery case 12, and the side frames 32 are fixed to the rocker 18. Specifically, the rocker inner panel 22 and the side frames 32 are overlapped and fastened together by fasteners such as bolts (not shown).

[0033] The side frames 32 are formed with a generally rectangular cross section when viewed from the front-to-rear direction of the vehicle, and the battery case 12 is fastened to the lower wall portions of the side frames 32. Specifically, the battery case 12 is placed on the lower surface of the side frame 32, and is fastened to the side frame 32 with bolts 40 and nuts 42.

[0034] A second absorbing member 34 is provided inside the side frame 32. The second absorbing member 34 includes a pair of upper and lower partition walls 34A that are spaced apart in the vertical direction and extend in the vehicle width direction to connect the inner walls of the battery frame 30, and left and right partition walls 34B that connect the upper and lower partition walls 34A vertically. In the present embodiment, as an example, the left and right partition walls 34B are provided at positions that equally divide the upper and lower partition walls 34A in the vehicle width direction, but the present invention is not limited to this.

[0035] The upper and lower partition walls 34A and the left and right partition walls 34B of the second absorption member 34 are formed to be thinner than the battery frame 30 main body, and are configured to be more easily deformed than the battery frame 30 main body.

[0036] A cross member 36 is disposed on the inner side of the battery frame 30 in the vehicle width direction. The cross member 36 extends in the vehicle width direction and connects the left and right battery frames 30 in the vehicle width direction. The cross member 36 includes an upper wall portion 36A extending in the vehicle width direction and the vehicle front-rear direction, and front and rear wall portions 36B extending downward from the front and rear ends of the upper wall portion 36A, respectively.

[0037] A joint 36C is formed at one end of the upper wall 36A of the cross member 36 in the vehicle width direction, and is bent to follow the outline of the battery frame 30. The joint 36C is superimposed on the upper surface of the battery frame 30 and joined to the battery frame 30 by welding or the like. The cross member 36 and the battery frame 30 may also be mechanically fastened together with bolts and nuts.

[0038] Here, the first absorption member 24, the second absorption member 34, and the cross member 36 are arranged in positions where they overlap in a side view of the vehicle. In the present embodiment, as an example, the pair of upper and lower lateral wall portions 24A of the first absorption member 24 are positioned at the same height as the upper and lower partition walls 34A of the second absorption member 34, and the lateral wall portions 24A and the upper and lower partition walls 34A overlap in a side view of the vehicle.

[0039] In addition, the front and rear wall portions 36B of the cross member 36 are located at the same height as the lateral wall portions 24A of the first absorption member 24 and the upper and lower partition walls 34A of the second absorption member 34, and when viewed from the side of the vehicle, the lateral wall portions 24A and the upper and lower partition walls 34A overlap the front and rear wall portions 36B.

[0040] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0041] In the vehicle undercarriage structure according to this embodiment, a rocker 18 is disposed at an end of the vehicle underside in the vehicle width direction, and a first absorption member 24 with a hat-shaped cross section is disposed inside the rocker 18. A battery frame 30 is connected to the inside of the rocker 18 in the vehicle width direction, and a second absorption member 34 is disposed inside the battery frame 30. A cross member 36 extending in the vehicle width direction is disposed on the inside of the battery frame 30 in the vehicle width direction, and one end of the cross member 36 is connected to the battery frame 30. As a result, in the event of a side collision of the vehicle 10, the first absorption member 24 and the second absorption member 34 are deformed by the collision load input to the vehicle 10, thereby absorbing at least a portion of the collision load. The collision load can also be transmitted to the anti-collision side via the rocker 18, the battery frame 30, and the cross member 36.

[0042] In addition, in this embodiment, the first absorption member 24, the second absorption member 34, and the cross member 36 are arranged in positions that overlap in a side view of the vehicle, so the first absorption member 24 and the second absorption member 36 are sandwiched between the cross member 36 and the colliding body. This allows the first absorption member 24 and the second absorption member 34 to be deformed more stably than in a configuration in which no reaction force is input from the cross member 36, and allows collision load to be absorbed stably during a side collision. This action will be described with reference to FIGS. 2-5.

[0043] Fig. 2 is an enlarged cross-sectional view of a main part showing the state immediately after a collision load is input during a side collision, and Fig. 3 is an enlarged cross-sectional view of a main part showing the state after some time has passed since the state of Fig. 2. Fig. 4 is an enlarged cross-sectional view of a main part showing the state after some time has passed since the state of Fig. 3, and Fig. 5 is an enlarged cross-sectional view of a main part showing the state after some time has passed since the state of Fig. 4. As an example, Figs. 2 to 5 explain the transition of deformation of a vehicle undercarriage when a pole, acting as a collision object, collides from the right side of the vehicle, but for ease of explanation, the pole is not shown.

[0044] 2, immediately after a side collision, the pole collides with the rocker outer panel 20 on the right side of the vehicle, transmitting the collision load to the left side of the vehicle and starting to deform the rocker 18. At this time, the lateral wall portion 24A of the first absorption member 24 arranged inside the rocker 18 is deformed in a bending manner, thereby absorbing part of the collision load.

[0045] As time passes from the state shown in FIG. 2, the rocker 18 and the first absorbing member 24 are pinched between the pole and the battery frame 30 and completely crushed, as shown in FIG.

[0046] Next, as time passes from the state shown in Fig. 3, the battery frame 30 starts to deform as shown in Fig. 4. Specifically, deformation begins from the outer side (collision side) in the vehicle width direction of the second absorbing member 34. The second absorbing member 34 has a shape in which two chambers are arranged side by side on the left and right sides, formed by a pair of upper and lower partition walls 34A and left and right partition walls 34B, and the upper and lower partition walls 34A that form the chambers on the outer sides in the vehicle width direction are deformed so as to be folded.

[0047] Here, the second absorption member 34 is disposed in a position overlapping with the cross member 36 in a side view of the vehicle, and can be stably deformed into a desired shape by being sandwiched between the pole and the cross member 36. Also, part of the collision load is absorbed by the deformation of the chamber on the outer side in the vehicle width direction.

[0048] As time passes from the state shown in Fig. 4, the chambers on the outer side in the vehicle width direction of the second absorption member 34 are completely crushed, and the chambers on the inner side in the vehicle width direction of the battery frame 30 main body and the second absorption member 34 start to deform, as shown in Fig. 5. Even at this time, the second absorption member 34 is sandwiched between the pole and the cross member 36, so it can be deformed into a desired shape and some of the collision load is absorbed. In this way, in this embodiment, the chambers collapse sequentially from the outer side in the vehicle width direction, so that the collision load can be absorbed more effectively than in a structure without a partition wall.

[0049] In addition, the collision load that is not absorbed by the rocker 18, the first absorption member 24, the battery frame 30, and the second absorption member 34 is transmitted to the anti-collision side via the cross member 36, thereby effectively preventing excessive collision load from being input to the battery case 12.

[0050] 1, in this embodiment, the side wall portions 24A of the first absorption member 24 are disposed at positions that overlap the upper and lower partition walls 34A of the second absorption member 34 in a side view of the vehicle. As a result, during a side collision, the collision load can be transmitted in a substantially linear manner from the side wall portions 24A to the cross member 36 through the upper and lower partition walls 34A, and at least a portion of the collision load can be transmitted satisfactorily to the anti-collision side before the first absorption member 24 and the second absorption member 34 are crushed.

[0051] In this embodiment, the battery frame 30 has the shape shown in Fig. 1, but is not limited to this and may have other shapes. For example, the shapes shown in Fig. 6 and Fig. 7 may be adopted.

[0052] (First Modification) 6 is a cross-sectional view showing a battery frame 50 according to a first modified example. In this modified example, the battery frame 50 has a second absorbing member 52 provided inside a frame main body having a substantially rectangular cross section.

[0053] The second absorption member 52 is composed of a pair of upper and lower partition walls 52A that are arranged at intervals in the vertical direction and extend in the vehicle width direction to connect the inner walls of the battery frame 50, and left and right partition walls 52B that connect the upper and lower partition walls 52A vertically.

[0054] In this modification, the upper and lower partition walls 52A are formed with weakened portions 52C on the outer side in the vehicle width direction than the left and right partition walls 52B. The weakened portions 52C are formed thinner than other portions of the upper and lower partition walls 52A, and the weakened portions 52C of the upper upper partition wall 52A have a notched shape on the lower surface. The weakened portions 52C of the lower upper partition wall 52A have a notched shape on the upper surface.

[0055] According to this modification, when a side collision load is input to the battery frame 50, the upper partition wall 52A is deformed by being bent upward due to the fragile portion 52C, and the lower partition wall 52A is deformed by being bent downward due to the fragile portion 52C. This allows the second absorption member 52 to be deformed into a desired shape.

[0056] (Second Modification) 7 is a cross-sectional view showing a battery frame 60 according to a second modified example. In this modified example, the battery frame 60 has a second absorbing member 62 provided inside a frame main body having a substantially rectangular cross section.

[0057] The second absorption member 62 is composed of a pair of upper and lower partition walls 62A that are arranged at intervals in the vertical direction and extend in the vehicle width direction to connect the inner walls of the battery frame 60, and two left and right partition walls 62B that connect the upper and lower partition walls 62A vertically.

[0058] In this modified example, the two left and right partition walls 62B are arranged at equal intervals, so the space surrounded by the main body of the battery frame 60 and the upper and lower partition walls 62A is divided into three equal parts by the left and right partition walls 62B. Therefore, the second absorption member 62 in this modified example has a shape in which three chambers are arranged side by side in the vehicle width direction.

[0059] According to this modification, the three compartments deform with different times, absorbing the collision load and preventing excessive collision load from being input to the vehicle body. While the above-described embodiment and modification have been described with the vertically extending upper and lower partition walls, this is not limiting. For example, the upper and lower partition walls may be inclined, and may extend obliquely from the corner between the right inner wall of the battery frame and the lower vertical partition wall toward the corner between the left inner wall of the battery frame and the upper vertical partition wall. Conversely, the upper and lower partition walls may be provided so as to extend obliquely from the corner between the right inner wall of the battery frame and the upper vertical partition wall toward the corner between the left inner wall of the battery frame and the lower vertical partition wall.

[0060] Although the vehicle underbody structure according to the embodiment has been described above, it is needless to say that it can be embodied in various forms without departing from the spirit and scope of the present invention. For example, in the above embodiment, as shown in FIG. 1, the side wall portion 24A of the first absorption member 24 and the upper and lower partition walls 34A of the second absorption member 34 are disposed at the same height, but this is not limiting. A structure in which one side wall portion 24A and the upper and lower partition walls 34A are disposed at the same height may also be employed, or a structure in which the side wall portion 24A and the upper and lower partition walls 34A are offset in the height direction may also be employed. Even in this case, the same effect can be achieved as long as the first absorption member 24, the second absorption member 34, and the cross member 36 are disposed in positions where they overlap in a side view of the vehicle.

[0061] In the above embodiment, the first absorption member 24 is formed to have a generally hat-shaped cross section with an open inner side in the vehicle width direction, but is not limited to this. For example, a first absorption member having a generally hat-shaped cross section with an open outer side in the vehicle width direction may be used.

[0062] Furthermore, in the above embodiment, the battery frame 30 to which the battery case 12 is fastened is used as the second framework member, but this is not limiting. For example, the present invention may be applied to a structure in which a battery case is not provided under the floor of the vehicle. In this case, the second framework member may be an impact absorbing member that extends in the fore-and-aft direction of the vehicle along the rocker. It may also be a member that functions as part of the rocker.

[0063] The following notes are provided regarding the above embodiment.

[0064] (Appendix 1) a first framework member disposed at an end of the vehicle lower portion in the vehicle width direction and including a first absorption member having a hat-shaped cross section therein; a second frame member connected to the inside of the first frame member in the vehicle width direction and including a second absorption member therein; a cross member disposed inside the second frame member in the vehicle width direction, extending in the vehicle width direction, and having one end connected to the second frame member; and The first absorbing member, the second absorbing member, and the cross member are arranged in overlapping positions in a vehicle side view. Vehicle undercarriage. (Appendix 2) The vehicle undercarriage structure described in Appendix 1, wherein the second absorption member includes a pair of upper and lower partition walls that are arranged at intervals in the vertical direction and extend in the vehicle width direction to connect the inner walls of the second framework member, and left and right partition walls that connect the upper and lower partition walls vertically. (Appendix 3) A vehicle undercarriage structure as described in Appendix 2, wherein at least one of the pair of upper and lower partition walls has a weak portion formed on the outer side of the left and right partition walls in the vehicle width direction that is weaker than other portions. (Appendix 4) The first absorbing member includes a pair of upper and lower lateral wall portions extending outward in the vehicle width direction from the first framework member, and a vertical wall portion connecting the lateral wall portions in the upper and lower directions, 4. The vehicle underbody structure according to claim 3, wherein the pair of upper and lower lateral wall portions are each positioned so as to overlap the upper and lower partition walls of the second absorbing member in a side view of the vehicle. (Appendix 5) the second framework member is a battery frame disposed under a vehicle and to which a battery case for accommodating a battery is fastened, 5. The vehicle underbody structure according to any one of claims 1 to 4, wherein the first framework member is a rocker extending in the vehicle longitudinal direction. (Appendix 6) A vehicle equipped with the vehicle undercarriage structure according to any one of appendices 1 to 4. [Explanation of symbols]

[0065] 12 Battery case 18 Rocker (first frame member) 24 First absorption member 24A Side wall part 24B Vertical wall section 30 Battery frame (second frame member) 34 Second absorption member 34A Upper and lower partition wall 34B Left and right partition wall 36 Cross member 50, 60 Battery frame (second frame member) 52, 62 Second absorption member 52A, 62A upper and lower partition walls 52B, 62B left and right partition walls 52C Weak part

Claims

1. a first framework member disposed at an end of the vehicle lower portion in the vehicle width direction and including a first absorption member having a hat-shaped cross section therein; a second frame member connected to the inside of the first frame member in the vehicle width direction and including a second absorption member therein; a cross member disposed on an inner side of the second frame member in the vehicle width direction, extending in the vehicle width direction, and connected to the second frame member; and The first absorbing member, the second absorbing member, and the cross member are arranged in overlapping positions in a vehicle side view. Vehicle undercarriage.

2. 2. The vehicle undercarriage structure according to claim 1, wherein the second absorption member includes a pair of upper and lower partition walls that are arranged at intervals in the vertical direction and extend in the vehicle width direction to connect the inner walls of the second framework member, and left and right partition walls that connect the upper and lower partition walls vertically.

3. 3. The vehicle underbody structure according to claim 2, wherein at least one of the pair of upper and lower partition walls has a weak portion formed on an outer side of the left and right partition walls in the vehicle width direction that is weaker than other portions.

4. The first absorbing member includes a pair of upper and lower lateral wall portions extending outward in the vehicle width direction from the first framework member, and a vertical wall portion connecting the lateral wall portions in the upper and lower directions, The vehicle underbody structure according to claim 3 , wherein the pair of upper and lower lateral wall portions are respectively arranged at positions overlapping the upper and lower partition walls of the second absorbing member in a side view of the vehicle.

5. the second framework member is a battery frame disposed under a vehicle and to which a battery case for accommodating a battery is fastened, 5. The vehicle underbody structure according to claim 1, wherein the first framework member is a rocker extending in the longitudinal direction of the vehicle.

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