Vehicle lower section structure

Abstract

To provide a vehicle lower section structure which can expand a loading space of a battery by effectively utilizing a space beside the battery.SOLUTION: A vehicle lower section structure 1 includes: a floor cross member 4 arranged above a battery (battery pack 2); and an impact absorbing member 5 arranged on a side of the battery (battery pack 2). The impact absorbing member 5 has: an upper side impact absorbing section 51 arranged to face the floor cross member 4; and a lower side impact absorbing section 52 continuously provided on the upper side impact absorbing section 51. The upper side impact absorbing section 51 and the lower side impact absorbing section 52 include vehicle inside regions 51A, 52A and vehicle outside regions 51B, 52B, respectively. In the lower side impact absorbing section 52, a dimension in a vertical direction of the vehicle inside region 52A is larger than a dimension in a vertical direction of the vehicle outside region 52B. Electric wiring 23 or piping (cooling liquid piping 22, hydraulic piping 24) are inserted into the vehicle inside region 52A in the lower side impact absorbing section 52.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A vehicle equipped with a motor as a driving source is equipped with a battery for driving the motor. The battery may be placed on the floor under the feet of the occupants. Therefore, in order to prevent electric shock or fire due to electric leakage caused by damage to the battery in the event of a vehicle collision, a vehicle underbody structure is known that absorbs impacts applied to the vehicle and protects the battery (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a vehicle underbody structure that includes a pair of rockers integrated with shock absorbing members that absorb shocks in the vehicle width direction, a floor cross member provided between the upper parts of the pair of rockers, and a battery cross member provided between multiple battery modules. The shock absorbing members undergo plastic deformation when subjected to an external shock, absorbing the collision energy and making it possible to prevent the rockers from breaking inward. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-188124 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the vehicle underbody structure described in Patent Document 1, the rocker and the shock absorbing member are integrated to prevent the rocker from bending inward, but the shape and size of the shock absorbing member are restricted in order to prevent the rocker from bending inward, which leaves room for improvement in terms of effectively utilizing the space next to the battery.

[0006] Therefore, there is a demand for a vehicle underbody structure that can effectively utilize the space beside the battery. [Means for solving the problem]

[0007] The characteristic configuration of the vehicle underbody structure of the present invention is a vehicle underbody structure comprising a floor cross member arranged above a battery and an impact absorbing member arranged to the side of the battery, wherein the impact absorbing member has an upper impact absorbing portion arranged opposite the floor cross member and a lower impact absorbing portion connected to the upper impact absorbing portion, each of the upper impact absorbing portion and the lower impact absorbing portion includes an interior side region and an exterior side region of the vehicle, the vertical dimension of the interior side region of the lower impact absorbing portion is larger than the vertical dimension of the exterior side region, and electrical wiring or piping is inserted into the interior side region of the lower impact absorbing portion.

[0008] According to this configuration, the external force applied to the impact absorbing member is transmitted to the floor cross member disposed above the battery via the upper impact absorbing portion, so there is no need to place a cross member (strength member) below the battery. This allows the vehicle lower structure to be made smaller, so that the vehicle interior space and the battery loading space can be expanded. In addition, the number of parts in the vehicle lower structure can be reduced, so that the vehicle can be made lighter and the vehicle lower structure can be manufactured efficiently. Furthermore, since the electrical wiring or piping is inserted in the vehicle interior region of the lower impact absorbing portion, it is not necessary to route these above, to the side, or below the battery, so that a space for arranging these is not required, and it is possible to expand the vehicle interior space and the battery loading space. Here, since the vertical dimension of the vehicle interior region is larger than the vertical dimension of the vehicle exterior region, the external force transmitted to the lower impact absorbing portion via the upper impact absorbing portion becomes smaller toward the lower side of the vehicle interior region, and the amount of crushing of the vehicle interior region of the lower impact absorbing portion is smaller. Therefore, by inserting the electrical wiring or the like into the vehicle interior region of the lower impact absorbing portion, it is possible to suppress damage to these and displacement of their arrangement position. In addition, since there is no need for insulating coatings or other components that were previously required when arranging electrical wiring or piping above, below, or beside the battery, it is possible to reduce the manufacturing costs of the vehicle underbody structure. In this way, the vehicle underbody structure makes effective use of the space beside the battery. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view showing the arrangement of a battery unit in a vehicle. [Diagram 2] 1 is a vertical cross-sectional view of a vehicle underbody structure according to a first embodiment. [Diagram 3] 1 is a vertical cross-sectional view of an impact absorbing member according to a first embodiment. [Figure 4] FIG. 11 is a vertical cross-sectional view of a vehicle underbody structure relating to a second embodiment. [Diagram 5] FIG. 11 is a vertical cross-sectional view of a shock absorbing member according to a second embodiment. [Figure 6] FIG. 11 is a vertical cross-sectional view of a vehicle underbody structure relating to a third embodiment. [Figure 7] FIG. 11 is a vertical cross-sectional view of a shock absorbing member according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a vehicle underbody structure according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit and scope of the present invention.

[0011] [First embodiment] As shown in Fig. 1, the vehicle underbody structure 1 forms a battery unit for a vehicle C mounted at the center in the vehicle width direction and below the floor between the front and rear wheels. The vehicle C is an automobile equipped with a rotary electric motor M (one example of a drive source) such as a motor as a drive source for traveling, and examples thereof include a hybrid vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a battery vehicle (BEV: Battery Electric Vehicle), and a fuel cell electric vehicle (FCEV: Fuel Cell Electric Vehicle). The vehicle C includes the rotary electric motor M that is driven by power supplied from the battery unit, and wheels T to which the power from the rotary electric motor M is transmitted via a reduction mechanism (not shown) or the like. The vehicle C travels when power is supplied to the rotary electric motor M and the wheels T rotate.

[0012] 1 and 2, a vehicle underbody structure 1 (battery unit) includes a battery pack 2 (an example of a battery), an upper cover 3, a floor cross member 4, an impact absorbing member 5, and a lower case 6. In the following, the vehicle width direction of a vehicle C is defined as the X direction, the vehicle length direction as the Y direction, and the vehicle height direction (vertical direction) as the Z direction.

[0013] The battery pack 2 is configured with a plurality of battery modules arranged in parallel along the X direction with a plurality of battery cells connected in series and electrically connected along the Y direction. The battery pack 2 is a rechargeable battery (secondary battery) such as a nickel-metal hydride battery or a lithium-ion battery. The battery pack 2 is housed in a space surrounded by an upper cover 3, an impact absorbing member 5, and a lower case 6 in a plan view (Z direction view).

[0014] The upper cover 3 is made of a metal such as iron or aluminum, and is disposed above the battery pack 2 in a plan view. The upper cover 3 has a pair of protrusions 31 that protrude upward in the Z direction from an end in the X direction. The protrusions 31 are connected to an impact absorbing member 5, which will be described later.

[0015] On the upper surface of the upper cover 3, multiple (two in this embodiment) floor cross members 4 are arranged between a pair of protrusions 31 so as to be in contact with the upper cover 3. The floor cross member 4 is a hollow rectangular tubular member extending in the X direction, and is made of a metal such as iron or aluminum. The hollow portion of the floor cross member 4 may be divided into multiple sections. The length of the floor cross member 4 in the X direction is approximately the same as the length of the upper cover 3 in the X direction. The floor cross member 4 is adjacent to the impact absorbing member 5 so as to face each other via the protrusions 31.

[0016] The lower case 6 is made of a metal such as iron or aluminum, and is disposed below the battery pack 2 in a plan view. A heat sink or the like may be disposed on the upper surface of the lower case 6. In addition, an undercover (not shown) or the like may be disposed below the lower case 6. The lower case 6 is connected to an impact absorbing member 5, which will be described later, via fastening members 12.

[0017] Impact absorbing members 5 are disposed on the sides of the battery pack 2 as viewed in the Y direction, i.e., on the right and left sides of the vehicle C. The impact absorbing members 5 are hollow, rectangular tubular members made of metal such as iron or aluminum, and absorb the component of the external force acting in the X direction by crushing the hollow portion. The impact absorbing members 5 are connected to a rocker (not shown) disposed above the impact absorbing members 5 and a chassis (not shown) disposed on the outside in the X direction by a fastening mechanism (not shown).

[0018] The hollow portion of the impact absorbing member 5 is divided into two along the Z direction by the dividing member 63. Therefore, the impact absorbing member 5 is divided into an upper impact absorbing section 51 located above in the Z direction, and a lower impact absorbing section 52 connected to the upper impact absorbing section 51. The dividing member 63 is a flat plate having a surface perpendicular to the Z direction (XY plane), and has approximately the same thickness as the upper plate 61 that forms the upper surface of the impact absorbing member 5.

[0019] The upper impact absorbing portion 51 is disposed facing the floor cross member 4 in the X direction, and is connected to the protruding portion 31 of the upper cover 3. The dimension in the Z direction of the upper impact absorbing portion 51 is approximately the same as the dimension in the Z direction of the protruding portion 31 of the upper cover 3 and the dimension in the Z direction of the floor cross member 4. Therefore, an external force F (arrow in FIG. 2) applied from the side of the vehicle C is absorbed by the impact absorbing member 5 and then transmitted to the floor cross member 4 via the upper cover 3. This makes it possible to suppress the transmission of the external force F to the battery pack 2.

[0020] The lower impact absorbing portion 52 is connected to the upper impact absorbing portion 51 and has a surface (YZ plane) facing the battery pack 2 in the X direction. The lower impact absorbing portion 52 is disposed at a position spaced a predetermined distance from the battery pack 2 in the X direction and is connected to the lower case 6 by a fastening member 12. The predetermined distance is a distance greater than the dimension of the lower impact absorbing portion 52 displaced toward the inside of the vehicle when a predetermined external force is applied to the impact absorbing member 5. The predetermined external force may be adjusted according to an external force expected at the time of a collision of the vehicle C. As a result, even if an external force F is applied from the side of the vehicle C to deform the lower impact absorbing portion 52 and displace it toward the battery pack 2, the lower impact absorbing portion 52 and the battery pack 2 do not come into contact with each other, so that it is possible to suppress the external force from being transmitted to the battery pack 2.

[0021] The upper impact absorbing portion 51 and the lower impact absorbing portion 52 each have a hollow portion divided into two along the X direction by the partition member 64. Therefore, the upper impact absorbing portion 51 is divided into an interior region 51A adjacent to the battery pack 2 and an exterior region 51B formed on the exterior side of the vehicle from the interior region 51A. Similarly, the lower impact absorbing portion 52 is divided into an interior region 52A adjacent to the battery pack 2 and an exterior region 52B formed on the exterior side of the vehicle from the interior region 52A. The partition member 64 is a flat plate having a surface perpendicular to the X direction (YZ plane) and extends downward in the Z direction from approximately the center of the upper plate 61 in the X direction. That is, the dimensions in the X direction of the interior regions 51A, 52A and the exterior regions 51B, 52B are approximately the same. The thickness of the partition member 64 may be the same as the thickness of the upper plate 61 and the partition member 63, but is preferably larger than these thicknesses. As a result, the upper plate 61 or the partition member 63 is more likely to bend than the partition member 64, and therefore the shock absorbing member 5 is more likely to absorb the component of the external force acting in the X direction.

[0022] The Z-direction dimensions of the interior region 52A and the exterior region 52B of the lower impact absorbing portion 52 are larger than the Z-direction dimension of the upper impact absorbing portion 51. The Z-direction dimension of the interior region 52A of the lower impact absorbing portion 52 is larger than the Z-direction dimension of the exterior region 52B and larger than the Z-direction dimension of the battery pack 2. Therefore, the interior region 52A covers the battery pack 2 when viewed in the X direction. On the other hand, the Z-direction dimension of the exterior region 52B is smaller than the Z-direction dimension of the interior region 52A, so that the bottom plate 62B forming the bottom surface of the exterior region 52B is not on the same plane as the bottom plate 62A forming the bottom surface of the interior region 52A, and the bottom plate 62B is separated by a predetermined distance from the plane on which the lower case 6 is provided. Therefore, the external force F is unlikely to be transmitted to a portion of the interior region 52A that is lower than the lowest end of the exterior region 52B. As a result, the external force F can be transmitted mainly to the floor cross member 4, eliminating the need to place a cross member (strength member) below the battery pack 2 to transmit the external force F from the vehicle interior area 52A to the cross member. This makes it possible to reduce the number of parts in the vehicle underbody structure 1 and make the vehicle underbody structure 1 more compact.

[0023] Furthermore, if the Z-direction dimension of the exterior region 52B is too large relative to the Z-direction dimension of the interior region 52A, the external force transmitted to the interior region 52A will be large, and if the Z-direction dimension is too small, the magnitude of the external force that can be absorbed by the impact absorbing member 5 will be small, so it is preferable that the Z-direction dimension of the exterior region 52B be approximately 1 / 3 to 2 / 3 of the Z-direction dimension of the interior region 52A.

[0024] The thickness of the bottom plate 62A forming the bottom surface of the interior region 52A of the lower impact absorbing portion 52 is formed to be larger than the thickness of the vertical plate 65 forming the side surface of the interior regions 51A, 52A facing the battery pack 2. The thickness of the bottom plate 62A may be uniform, but is preferably formed so that the thickness changes toward the exterior side of the vehicle. The bottom plate 62A in this embodiment has a thin portion 62A1 having a smaller thickness than the vertical plate 65 and a thick portion 62A2 having a larger thickness than the vertical plate 65. The thin portion 62A1 is preferably provided on the interior side of the vehicle. The thin portion 62A1 is not in contact with the lower case 6, and the thick portion 62A2 is connected to the lower case 6 by the fastening member 12 and is in contact with the lower case 6.

[0025] Since the bottom plate 62A has the thick portion 62A2 that is thicker than the vertical plate 65, when an external force F is applied to the impact absorbing member 5, the vertical plate 65 is more likely to bend than the bottom plate 62A. This makes it possible to reduce the deformation and displacement of the vehicle interior region 52A. Furthermore, since the bottom plate 62A has the thick portion 62A2, the contact area between the bottom plate 62A and the lower case 6 can be reduced, so that the external force F applied to the impact absorbing member 5 is less likely to be transmitted to the lower case 6. This eliminates the need to improve the impact absorption resistance of the lower case 6, and eliminates the need to arrange a strength member such as a cross member below the battery pack 2, making it possible to simplify the vehicle lower structure 1. The thickness of the vertical plate 65 may be smaller than or equal to the thickness of the upper plate 61 and the partition member 63. The thickness of the bottom plate 62B may also be smaller than or equal to the thickness of the upper plate 61 and the partition member 63.

[0026] 1 and 2, a coolant pipe 22, an electric wiring 23, and a hydraulic pipe 24 are inserted in the vehicle interior area 52A of the impact absorbing member 5. The coolant pipe 22 is a pipe that supplies a coolant that cools the rotating motor M and a power conversion module 26 (an example of a heating element) including an inverter that drives the rotating motor M. The electric wiring 23 is a wire that supplies power to a rotating motor (not shown) at the front of the vehicle C when power stored in the battery is taken from the rear of the vehicle C, or supplies power to the rotating motor M (see FIG. 1) at the rear of the vehicle C when power stored in the battery is taken from the front of the vehicle C. The hydraulic pipe 24 is a pipe that supplies brake oil to a reduction mechanism that reduces the speed of the wheels T, which are the rear wheels of the vehicle C.

[0027] In this embodiment, the coolant pipe 22 is inserted into the vehicle interior area 52A of the impact absorbing member 5 arranged on the right side of the vehicle C, and the electric wiring 23 and the hydraulic pipe 24 are inserted into the vehicle interior area 52A of the impact absorbing member 5 arranged on the left side of the vehicle C. As a result, it is no longer necessary to route the coolant pipe 22, the electric wiring 23, and the hydraulic pipe 24 above, to the sides, or below the battery pack 2, and space for arranging them is no longer required. This makes it possible to expand the vehicle interior space and the battery loading space. In addition, since the impact absorbing member 5 is made of metal and has an electromagnetic wave shielding effect, by inserting the electric wiring 23 into the vehicle interior area 52A, an electromagnetic noise absorbing material that was required when arranging it above, to the sides, or below the battery pack 2 is no longer required. As a result, it is possible to reduce the number of parts of the electric wiring 23 and reduce the manufacturing cost of the vehicle undercarriage 1. Note that the arrangement positions of these are not limited to this embodiment, and the coolant pipe 22 may be inserted into the vehicle interior area 52A of the impact absorbing member 5 arranged on the left side of the vehicle C.

[0028] The coolant pipe 22 and the hydraulic pipe 24 are fixed at a position separated from the vertical plate 65 in the vehicle interior area 52A. That is, the coolant pipe 22 and the hydraulic pipe 24 are not in contact with the vertical plate 65. The impact absorbing member 5 is made of metal such as iron or aluminum and has a high thermal conductivity. When the impact absorbing member 5 comes in contact with the coolant pipe 22 and the hydraulic pipe 24, heat transfer occurs between them, resulting in heat loss. Therefore, by fixing the coolant pipe 22 and the hydraulic pipe 24 at a position separated from the vertical plate 65 as in this embodiment, it is possible to improve the insulation of the coolant pipe 22 and the hydraulic pipe 24.

[0029] The electrical wiring 23 is fixed so as to be in contact with the vertical plate 65. By bringing the electrical wiring 23 into contact with the vertical plate 65, it is possible to transfer heat generated in the electrical wiring 23 to the shock absorbing member 5. As a result, it is possible to reduce the heat resistance of the electrical wiring 23, so that it is possible to reduce the cross-sectional area of ​​the electrical wiring 23 and reduce the manufacturing cost.

[0030] 2, the hollow portions of the vehicle interior regions 51A, 52A are filled with foamed resin 7. Therefore, in this embodiment, the coolant pipes 22, the electrical wiring 23, and the hydraulic pipes 24 are fixed by the foamed resin 7. The foamed resin 7 may be made of a material having adhesiveness and insulating properties, such as urethane foam. This eliminates the need for adhesives for fixing the coolant pipes 22 and the like, fixing parts such as clamps, insulating coatings for the electrical wiring 23, and protective covers such as corrugated tubes, making it possible to reduce the number of parts of the vehicle underbody structure 1 and reduce manufacturing costs.

[0031] The foamed resin 7 can be made of a material having heat insulating properties and shock absorbing properties, such as urethane foam. This can improve the shock absorbing ability of the shock absorbing member 5, so that the thicknesses of the upper plate 61, the bottom plate 62A, 62B, the vertical plate 65, and the like that form the shock absorbing member 5 can be reduced, making it possible to reduce the weight of the shock absorbing member 5. In addition, since the amount of aluminum or the like that has a high thermal conductivity can be reduced, for example, when a heat exchanger such as a heat sink and the shock absorbing member 5 are in contact with each other, it is possible to suppress heat exchange between the heat sink and the shock absorbing member 5. Furthermore, since the coolant pipe 22 and the hydraulic pipe 24 are covered with the foamed resin 7, the coolant pipe 22 and the hydraulic pipe 24 can be insulated.

[0032] In the vehicle interior region 52A, near where the coolant piping 22 or the hydraulic piping 24 is arranged and near the partition member 64, a hollow space 60 that is not filled with the foamed resin 7 is provided. The range in which the hollow space 60 is provided can be determined appropriately. By providing the hollow space 60, even if the impact absorbing member 5 absorbs the external force F and deforms, causing the hollow portion to collapse, the foamed resin 7 that has received the stress deforms so as to expand into the hollow space 60, so that no stress is applied from the foamed resin 7 to the hydraulic piping 24 or the electrical wiring 23. This makes it possible to suppress damage to the coolant piping 22, etc., when absorbing an impact.

[0033] FIG. 3 shows a vertical cross-sectional view of the impact absorbing member 5 when it absorbs the external force F and is deformed. In FIG. 3, the coolant piping 22, the electrical wiring 23, the hydraulic piping 24, and the foamed resin 7 are omitted. The external force F is first applied to the outer side regions 51B and 52B, and is transmitted to the inner side regions 51A and 52A, and then to the floor cross member 4. On the other hand, since the inner side region 52A of the lower impact absorbing portion 52 is disposed at a position spaced a predetermined distance from the battery pack 2 in the X direction, the external force F transmitted to the inner side region 52A is not transmitted to components, etc., disposed on the inner side of the vehicle than the inner side region 52A. Therefore, the external force F is mainly absorbed by the upper impact absorbing portion 51 in contact with the floor cross member 4, and the upper impact absorbing portion 51 is deformed so that its hollow portion is crushed. Conversely, the force applied to the lower impact absorbing portion 52 is smaller than that applied to the upper impact absorbing portion 51, and therefore the deformation amount is smaller than that of the upper impact absorbing portion 51. In particular, the force applied to the interior region 52A is the smallest, and therefore the hollow portion of the interior region 52A is hardly crushed, and deforms to maintain its space. Therefore, if the coolant pipe 22, etc. is inserted into the hollow portion of the interior region 52A, no stress is applied to the coolant pipe 22, etc., even if the impact absorbing member 5 is deformed. In addition, the displacement of the position of the interior region 52A after absorbing the external force F is small, and therefore damage to the coolant pipe 22, etc. can be reduced.

[0034] The amount of foamed resin 7 filled in the interior region 52A may be determined according to the volume of the hollow part in the interior region 52A when the impact absorbing member 5 absorbs an external force and deforms. By designing the hollow space 60 to absorb the change in volume of the hollow part in the interior region 52A before and after impact absorption, it is possible to prevent compressive stress from the foamed resin 7 from being generated in the coolant pipe 22.

[0035] Next, a manufacturing method of the impact absorbing member 5 in this embodiment will be described. First, the coolant pipe 22, the electric wiring 23, and the hydraulic pipe 24 are inserted into the vehicle interior region 52A of the impact absorbing member 5. At this time, these may be temporarily fixed. Thereafter, the foaming resin 7 is poured into the vehicle interior regions 51A, 52A, and the surface of the impact absorbing member 5 is heat-treated to foam the foaming resin 7. In this manner, the impact absorbing member 5 can be manufactured. When pouring the foaming resin 7, a mold or the like for forming the hollow space 60 may be used. Note that the coolant pipe 22 and the like may be inserted after the foaming resin 7 is filled into the vehicle interior regions 51A, 52A. The coolant pipe 22 and the like may be inserted before or after the heat treatment of the foaming resin 7.

[0036] Second Embodiment The vehicle underbody structure 1 according to the second embodiment will be described with reference to FIG. 4. FIG. 4 is a vertical cross-sectional view of the vehicle underbody structure 1. The impact absorbing member 5 in this embodiment includes a partition member 66 that partitions the interior region 52A into an upper chamber 53 and a lower chamber 54. The partition member 66 has substantially the same thickness as the bottom plate 62B and is located on the same plane as the bottom plate 62B. That is, the upper chamber 53 and the exterior region 52B partitioned by the partition member 66 have substantially the same size. The upper chamber 53 and the lower chamber 54 may be formed to have substantially the same size. In this embodiment, the coolant pipe 22, the electric wiring 23, and the hydraulic pipe 24 are each inserted into the lower chamber 54. In addition, the interior region 51A, the upper chamber 53, and a part of the lower chamber 54 are filled with a foamed resin 7. Since the other configurations are the same as those in the first embodiment, the description of the similar configurations will be omitted.

[0037] FIG. 5 shows a vertical cross-sectional view of the impact absorbing member 5 when it absorbs an external force F and is deformed. In FIG. 5, the coolant pipe 22, the electric wiring 23, the hydraulic pipe 24, and the foamed resin 7 are omitted. The magnitude of the external force F is the same as that of the external force F applied to the impact absorbing member 5 according to the first embodiment. In this embodiment, the vehicle exterior region 52B of the upper impact absorbing portion 51 and the lower impact absorbing portion 52 is deformed and their hollow portions are crushed, while the upper chamber 53 and the lower chamber 54 maintain their hollow portions. In particular, the lower chamber 54 is less deformed, and the displacement in the X direction before and after shock absorption is also small. Therefore, it can be seen that the vehicle interior region 52A has the partition member 66, which can further reduce the deformation of the lower chamber 54. Therefore, by inserting the coolant pipe 22, etc. into the lower chamber 54, it is possible to reduce damage to the coolant pipe 22, etc. during shock absorption.

[0038] Third Embodiment The vehicle underbody structure 1 according to the third embodiment will be described with reference to FIG. 6. FIG. 6 is a longitudinal sectional view of the vehicle underbody structure 1. The impact absorbing member 5 in this embodiment has a small chamber 55 in the vehicle interior region 52A of the lower impact absorbing portion 52. The small chamber 55 is partitioned from the vehicle interior region 52A by a vertical plate 65, a bottom plate 62A, and a partition member 67. The partition member 67 is an L-shaped member made of iron or aluminum. The partition member 67 may be integrally formed with the vertical plate 65 and the bottom plate 62A, or may be fixed thereto by welding or the like. The dimension of the partition member 67 in the X direction is smaller than the dimension of the vehicle interior region 52A in the X direction, and is preferably large enough to insert the coolant pipe 22 or the like into the small chamber 55. The dimension of the partition member 67 in the Z direction is preferably large enough to insert the coolant pipe 22 or the like into the small chamber 55. The surface of the partitioning member 67 parallel to the X direction (XY plane) may be on the same plane as the surface on which the bottom plate 62B is arranged. The partitioning member 67 may have the same thickness as the partitioning member 64, or may be larger or smaller than the thickness of the partitioning member 64. The impact absorbing member 5 may have a partitioning member that further partitions the small chamber 55.

[0039] The cooling liquid pipe 22, the electric wiring 23, and the hydraulic pipe 24 are inserted into the small chamber 55. The small chamber 55 is filled with a foamed resin 7, and the cooling liquid pipe 22 and the like are fixed by the foamed resin 7. In this embodiment, the interior regions 51A, 52A other than the small chamber 55 are not filled with the foamed resin 7. This makes it possible to fix the cooling liquid pipe 22 and the like, obtain a heat insulating effect, and reduce the amount of foamed resin 7 used. Note that the foamed resin 7 may also be filled in these regions. The other configurations are the same as those in the first embodiment, and therefore a description of the similar configurations will be omitted.

[0040] In this embodiment as well, even if the vehicle exterior region 52B of the upper impact absorbing portion 51 and the lower impact absorbing portion 52 deforms and their hollow portions are crushed due to the absorption of the external force F, the hollow portion of the vehicle interior region 52A is maintained. Therefore, it is possible to suppress the deformation of the small chamber 55, and by inserting the coolant pipe 22 etc. into the small chamber 55, it is possible to reduce damage to the coolant pipe 22 etc. when absorbing an impact.

[0041] In the above-described embodiment, the following configurations are envisaged. (1) A vehicle understructure 1 comprising a floor cross member 4 arranged above a battery (battery pack 2) and an impact absorbing member 5 arranged to the side of the battery (battery pack 2), wherein the impact absorbing member 5 has an upper impact absorbing portion 51 arranged opposite the floor cross member 4 and a lower impact absorbing portion 52 connected to the upper impact absorbing portion 51, wherein the upper impact absorbing portion 51 and the lower impact absorbing portion 52 each include an interior side region 51A, 52A and an exterior side region 51B, 52B, wherein the vertical dimension of the interior side region 52A of the lower impact absorbing portion 52 is larger than the vertical dimension of the exterior side region 52B, and wherein electrical wiring 23 or piping (coolant piping 22, hydraulic piping 24) is inserted into the interior side region 52A of the lower impact absorbing portion 52.

[0042] According to this configuration, the external force F applied to the impact absorbing member 5 is transmitted to the floor cross member 4 via the upper impact absorbing portion 51, so there is no need to arrange a cross member (strength member) below the battery (battery pack 2). This allows the vehicle underbody structure 1 to be made smaller, so that the vehicle interior space and the battery loading space can be expanded. In addition, the number of parts of the vehicle underbody structure 1 can be reduced, so that the vehicle C can be made lighter and the vehicle underbody structure 1 can be manufactured efficiently. Furthermore, since the electric wiring 23 or piping (coolant piping 22, hydraulic piping 24) is inserted in the vehicle interior area 52A of the lower impact absorbing portion 52, it is not necessary to route these above, to the side, or below the battery (battery pack 2), so that a space for arranging these is not required, and it is possible to expand the vehicle interior space and the battery loading space. Here, since the vertical dimension (Z direction) of the interior region 52A is larger than the vertical dimension (Z direction) of the exterior region 52B, the external force transmitted to the lower impact absorbing portion 52 via the upper impact absorbing portion 51 becomes smaller toward the lower side of the interior region 52A, and the crushing amount of the interior region 52A becomes smaller. Therefore, by inserting the electric wiring 23 and the like into the interior region 52A, it is possible to suppress damage to them and displacement of their arrangement positions. In addition, since parts such as an insulating coating that are necessary when the electric wiring 23 and the piping (coolant piping 22, hydraulic piping 24) are arranged above, beside, or below the battery (battery pack 2) are not required, it is also possible to reduce the manufacturing cost of the vehicle underbody structure 1. In this way, the vehicle underbody structure 1 makes effective use of the space beside the battery (battery pack 2).

[0043] (2) In the vehicle undercarriage structure 1 of (1), it is preferable that the electrical wiring 23 or piping (coolant piping 22, hydraulic piping 24) is inserted into the vehicle interior region 52A of the lower impact absorbing portion 52 below the lowest end of the vehicle exterior region 52B.

[0044] Since external force in the vehicle width direction (X direction) is unlikely to be transmitted to the inside region 52A below the lowest end of the outside region 52B, the lower portion of the inside region 52A is unlikely to deform and the amount of crushing is smallest. Therefore, according to this configuration, by inserting the electrical wiring 23, etc., below the lowest end of the outside region 52B of the inside region 52A, it is possible to further suppress damage to these and displacement of their arrangement positions when absorbing an impact.

[0045] In the vehicle undercarriage structure 1 of (3)(2), the lower impact absorbing portion 52 includes a partition member 66 that divides the vehicle interior area 52A into an upper chamber 53 and a lower chamber 54, and it is preferable that the electrical wiring 23 or piping (coolant piping 22, hydraulic piping 24) is housed in the lower chamber 54.

[0046] According to this configuration, the deformation amount of the lower chamber 54 of the lower impact absorbing section 52 during shock absorption can be minimized, so that it is possible to reduce the displacement of the arrangement positions of the electric wiring 23 and the piping (coolant piping 22, hydraulic piping 24) and to suppress damage thereto. As a result, it is possible to reduce parts such as protective covers, so that it is possible to reduce the manufacturing costs of the electric wiring 23 and the piping (coolant piping 22, hydraulic piping 24).

[0047] (4) In any one of the vehicle undercarriage structures 1 of (1) to (3), when an external force is applied in the vehicle width direction (X direction), it is preferable that the lower impact absorbing portion 52 is configured so that the vertical plate 65 forming the side surface of the interior region 52A facing the battery (battery pack 2) bends toward the interior of the vehicle before the bottom plate 62A forming the bottom surface of the interior region 52A bends in the up-down direction (Z direction).

[0048] According to this configuration, when absorbing an impact, the vertical plate 65 forming the side surface facing the battery (battery pack 2) is likely to deform earlier than the bottom plate 62A forming the bottom surface of the interior area 52A, thereby suppressing deformation of the lower impact absorbing part 52. This makes it possible to reduce displacement of the arrangement positions of the electrical wiring 23 and piping (coolant piping 22, hydraulic piping 24) inserted into the interior area 52A and suppress damage thereto.

[0049] Other embodiments (a) As shown in Fig. 7, for each of the vehicle interior region 51A, 52A and the vehicle exterior region 51B, 52B, the upper plate 61, the partition member 63, or the bottom plate 62A, 62B constituting the hollow portion may each have a taper. Specifically, the lower surface of the upper plate 61, the upper and lower surfaces of the partition member 63, or the upper surface of the bottom plate 62A, 62B may be formed so that the thickness increases toward the four corners of the hollow portion. This makes it easier for the partition member 63 and the bottom plate 62B, which have a surface perpendicular to the Z direction (XY plane), to bend when subjected to an external force F, making it easier to absorb impact. Note that the bottom plate 62A does not need to be tapered.

[0050] (b) In the above embodiment, the thicknesses of the upper plate 61, the vertical plate 65, and the bottom plates 62A, 62B are different, but these thicknesses may be the same.

[0051] (c) In the above embodiment, the impact absorbing member 5 has an interior region 52A and an exterior region 52B, but another region may be provided between these, or these regions may be further divided.

[0052] (d) In the above embodiment, the coolant piping 22, the electrical wiring 23, and the hydraulic piping 24 are fixed to the vehicle interior area 52A by foamed resin 7, but they may also be fixed to the vehicle interior area 52A by adhesive or the like.

[0053] (e) In the above embodiment, the foamed resin 7 is provided in the vehicle interior areas 51A, 52A. However, the foamed resin 7 may also be provided in the vehicle exterior areas 51B, 52B.

[0054] (f) In the above embodiment, the thickness of the bottom plate 62A is formed to be greater than the thickness of the vertical plate 65, but it is preferable that the vertical plate 65 is configured to bend toward the inside of the vehicle before the bottom plate 62A bends in the up-down direction (Z direction) when an external force in the vehicle width direction is applied. Specifically, the vertical plate 65 may be provided with a groove or the like that serves as a starting point of bending, and the bending strength of the vertical plate 65 may be set to be smaller than that of the bottom plate 62A. [Industrial Applicability]

[0055] The present invention can be used in a vehicle underbody structure that allows an expansion of the storage space for a battery. [Explanation of symbols]

[0056] 1: vehicle underbody structure, 2: battery pack (battery), 4: floor cross member, 5: impact absorbing member, 22: coolant piping (piping), 23: electrical wiring, 24: hydraulic piping (piping), 51: upper impact absorbing portion, 51A: vehicle interior area, 51B: vehicle exterior area, 52: lower impact absorbing portion, 52A: vehicle interior area, 52B: vehicle exterior area, 53: upper chamber, 54: lower chamber, 62A: bottom plate, 65: vertical plate, 66: partition member, X: vehicle width direction, Z: vehicle height direction (up and down direction)

Claims

1. A vehicle underbody structure including a floor cross member disposed above a battery and an impact absorbing member disposed to a side of the battery, The impact absorbing member has an upper impact absorbing portion arranged to face the floor cross member and a lower impact absorbing portion connected to the upper impact absorbing portion, Each of the upper impact absorbing portion and the lower impact absorbing portion includes an interior side region and an exterior side region, The lower impact absorbing portion has a vertical dimension of the interior region that is larger than a vertical dimension of the exterior region, A vehicle underbody structure, wherein an electric wire or a pipe is inserted through the vehicle interior area of ​​the lower impact absorbing portion.

2. The vehicle underbody structure according to claim 1 , wherein the electrical wiring or the piping is inserted below a lowermost end of the outer side area of ​​the lower impact absorbing portion in the inner side area of ​​the lower impact absorbing portion.

3. The lower impact absorbing portion includes a partition member that partitions the interior area into an upper chamber and a lower chamber, The vehicle underbody structure according to claim 2 , wherein the electric wiring or the piping is accommodated in the lower chamber.

4. The vehicle underbody structure according to any one of claims 1 to 3, wherein the lower impact absorbing portion is configured such that, when subjected to an external force in the vehicle width direction, a vertical plate forming a side surface facing the battery in the interior region of the vehicle bends toward the interior of the vehicle before a bottom plate forming a bottom surface of the interior region bends in the vertical direction.

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