Vehicle lower part structure

Abstract

To provide vehicle lower part structure that is able to prevent a load from being input to an accommodated object below a vehicle seat in the event of a head-on collision of the vehicle, in a configuration allowing the upper surface of a battery case to function as a floor panel.SOLUTION: Vehicle lower part structure includes: a battery case 12 provided in a lower part of a vehicle and accommodating a battery, an upper surface of the battery case constituting a vehicle cabin floor portion; a cover 32 covering a to-be-protected object provided on a vehicle upper side of the battery case 12, and supporting a seat cushion 35 of a vehicle seat VS from a vehicle lower side; and a reinforcing cross member 40 provided on a vehicle front side of the cover 32, extending in a vehicle width direction, and having an upper end part provided with a support portion 40A supporting the cover 32 from below.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a vehicle with a battery mounted on the lower side of the floor panel. In the vehicle disclosed in Patent Document 1, a battery module is housed inside a battery case. In addition, a raised portion is formed at the rear of the battery case and houses a large battery module, and the raised portion of the battery case is located below the seat cushion of the rear seat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-142763 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, in order to reduce the number of parts and increase the interior space of a vehicle, a structure has been developed in which the floor panel is removed and the top surface of the battery case functions as the floor panel. In such a structure, if an excessive load is applied to the seat cushion by a rear seat occupant during a frontal collision of the vehicle, the load may be applied to items such as the battery module located below the seat cushion because the load is not distributed by the floor panel or cross member.

[0005] The present invention aims to provide a vehicle undercarriage structure that can prevent load from being input to items stored below a vehicle seat in the event of a frontal collision of the vehicle, in a structure in which the upper surface of a battery case functions as a floor panel. [Means for solving the problem]

[0006] The first embodiment of the vehicle undercarriage structure comprises a battery case that is provided under the vehicle, houses a battery, and has an upper surface that forms the vehicle compartment floor; a cover that covers a protected object provided above the battery case and supports the seat cushion of a vehicle seat from the underside of the vehicle; and a front reinforcing cross member that is provided on the front side of the cover, extends in the vehicle width direction, and has a support portion at its upper end that supports the cover from below.

[0007] In the vehicle undercarriage structure of the first aspect, the battery case that houses the battery is provided in the lower part of the vehicle, and the upper surface forms the vehicle interior floor. This eliminates the need for a floor panel, and allows for a larger interior space than in a structure that includes a floor panel.

[0008] A cover is provided above the battery case. The cover covers the object to be protected from the outside and supports the seat cushion of the vehicle seat from below. A front reinforcing cross-member is provided on the vehicle front side of the cover. The front reinforcing cross-member extends in the vehicle width direction, and a support portion that supports the cover from below is provided at the upper end of the front reinforcing cross-member. This allows the collision load to be transmitted in the vehicle width direction via the front reinforcing cross-member, even if an excessive load is applied to the cover from an occupant seated in the vehicle seat during a frontal collision of the vehicle. This prevents the collision load from being applied to the object to be protected. In the following description, "in the event of a frontal collision" may be simply referred to as "in the event of a frontal collision." The term "support portion that supports the cover from below" is not limited to a configuration that directly supports the cover, but broadly encompasses a configuration that indirectly supports the cover.

[0009] The second aspect of the vehicle undercarriage structure is the first aspect, in which the cover includes an upper wall portion that supports the seat cushion and a front wall portion that extends from the front end of the upper wall portion toward the lower side of the vehicle, and the front reinforcing cross member is positioned in a position that overlaps with the front wall portion in a planar view.

[0010] In the second embodiment of the vehicle undercarriage structure, the cover includes an upper wall portion, a front wall portion, and a rear wall portion, and the upper wall portion supports the seat cushion. Furthermore, the front reinforcing cross-member is positioned so as to overlap with the front wall portion in a plan view, thereby effectively transmitting load from the front wall portion to the front reinforcing cross-member.

[0011] The vehicle undercarriage structure of a third aspect is the second aspect, wherein the upper wall portion of the cover is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle.

[0012] In the vehicle undercarriage structure of the third aspect, the cover is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle, so that in the event of a frontal collision, a load is input forward and downward from the occupant's buttocks to the cover, thereby efficiently transmitting the load to the front reinforcing cross-member. In addition, a reaction force acts from the cover on the occupant's buttocks toward the rear and upper sides of the vehicle, thereby suppressing inertial movement of the occupant toward the front of the vehicle.

[0013] The vehicle underbody structure of a fourth aspect is the first aspect, wherein both ends in the vehicle width direction of the front reinforcing cross member are connected to a pair of left and right side members extending in the vehicle front-rear direction.

[0014] In the vehicle undercarriage structure of the fourth aspect, the load input to the front reinforcing cross member is transmitted to the pair of left and right side members via the cover, thereby suppressing the load from being input to the battery case. Note that the "both ends in the vehicle width direction" here is a concept that indicates a predetermined range that includes both ends in the vehicle width direction.

[0015] The fifth aspect of the vehicle undercarriage structure is the fourth aspect, in which the pair of left and right side members each include a main body portion extending in the fore-and-aft direction of the vehicle and a front protruding portion protruding from the main body portion toward the inside in the vehicle width direction and to which the front reinforcing cross member is connected.

[0016] In the vehicle undercarriage structure of the fifth aspect, each side member includes a main body portion and a front protruding portion, which makes it possible to suppress stress concentration at the connection portion between the front reinforcing cross member and the side member, compared to a configuration in which the front reinforcing cross member is fixed by abutting it against the side member, and to effectively transmit load from the front reinforcing cross member to the side member.

[0017] The vehicle undercarriage structure of the sixth aspect is the fifth aspect, in which the front protrusion is formed in an inverted U-shape with the lower side of the vehicle open when viewed from the side of the vehicle so as to cover the upper surface, front surface and rear surface of the front reinforcing cross member.

[0018] In the vehicle undercarriage structure of the sixth aspect, the front protrusion is formed in an inverted U-shape that is open toward the bottom of the vehicle when viewed from the side of the vehicle. This allows the front protrusion to cover three surfaces of the front reinforcing cross-member: the top surface, front surface, and rear surface. As a result, the front protrusion can be fastened to the front protrusion on any of the top surface, front surface, and rear surface of the front reinforcing cross-member, improving assembly ease.

[0019] The vehicle undercarriage structure of the seventh aspect is the fifth aspect, which has a rear reinforcing cross member that is provided on the rear side of the cover, extends in the vehicle width direction, and has a support portion at its upper end that supports the cover from below.

[0020] In the vehicle undercarriage structure of the seventh aspect, a rear reinforcing cross-member is provided on the vehicle rear side of the cover, and the rear reinforcing cross-member extends in the vehicle width direction. This allows loads acting on the front side of the cover to be borne by the front reinforcing cross-member, and loads acting on the rear side of the cover to be borne by the rear reinforcing cross-member. As a result, even if an excessive load is applied, the rear portion of the cover can be prevented from collapsing.

[0021] The vehicle undercarriage structure of the eighth aspect is the seventh aspect, in which the pair of left and right side members each include a rear protruding portion that protrudes from the main body portion toward the inside in the vehicle width direction and to which the rear reinforcing cross member is connected, and the rear reinforcing cross member is connected to the side member at the rear protruding portion.

[0022] In the vehicle undercarriage structure of the eighth aspect, each side member includes a main body portion and a rear protrusion portion, which makes it possible to suppress stress concentration at the connection portion between the rear reinforcing cross-member and the side member, compared to a configuration in which the rear reinforcing cross-member is fixed by abutting it against the side member, and to effectively transmit load from the rear reinforcing cross-member to the side member.

[0023] The ninth aspect of the vehicle undercarriage structure is the eighth aspect, in which the rear protrusion is formed in an inverted U-shape with the lower side of the vehicle open when viewed from the side of the vehicle so as to cover the upper surface, front surface and rear surface of the rear reinforcing cross member.

[0024] In the vehicle undercarriage structure of the ninth aspect, the rear-side protrusion is formed in an inverted U-shape that is open toward the lower side of the vehicle when viewed from the side of the vehicle. This allows the rear-side protrusion to cover three surfaces of the rear-side reinforcing cross-member: the top surface, front surface, and rear surface. As a result, the rear-side protrusion can be fastened to the rear-side protrusion on any of the top surface, front surface, and rear surface of the rear-side reinforcing cross-member, improving assembly ease.

[0025] The vehicle underbody structure of a tenth aspect is the fourth aspect, and further includes a pair of left and right rockers extending in the vehicle front-rear direction on both sides in the vehicle width direction, and front portions of the side members are fixed to the rockers.

[0026] In the vehicle underbody structure of the tenth aspect, the front portions of the side members are fixed to the rockers, so that the load input to the side members via the front reinforcing cross member during a frontal collision is transmitted to the front of the vehicle via the rockers, thereby dispersing the collision load more effectively.

[0027] The vehicle underbody structure of an eleventh aspect is the fourth aspect, wherein the pair of left and right side members are integrally formed by casting.

[0028] In the vehicle undercarriage structure of the eleventh aspect, the pair of left and right side members are integrally formed by casting, so that a load input to the left and right side members can be borne by the high-strength members integrally formed by casting.

[0029] A twelfth aspect of the vehicle underbody structure is the first aspect, wherein the cover is formed separately from the battery case and covers auxiliary machinery that is an object to be protected.

[0030] In the vehicle underbody structure of the twelfth aspect, the cover is formed separately from the battery case, so that the cover can be attached to the vehicle seat as a module. Furthermore, maintenance of the accessories can be performed simply by removing the cover.

[0031] The vehicle undercarriage structure of the 13th aspect is the 10th aspect, in which the front reinforcing cross member is formed in a closed cross section and is provided with a partition portion that separates the internal space into upper and lower portions, and the partition portion is located at the same height as the upper surface of the rocker.

[0032] In the vehicle undercarriage structure of the thirteenth aspect, the partition increases rigidity. Furthermore, by making the partition flush with the top surface of the rocker, the load can be effectively transferred from the rocker to the front reinforcing cross-member during a collision, such as a side collision. As a result, the collision load can be smoothly transferred to the side opposite the collision. [Effects of the Invention]

[0033] As described above, the vehicle undercarriage structure of the present invention, in a structure in which the upper surface of the battery case functions as a floor panel, can prevent load from being input to items stored below the vehicle seat in the event of a frontal collision of the vehicle. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a perspective view showing a main part of a vehicle to which a vehicle undercarriage structure according to a first embodiment is applied. [Figure 2]1 is a schematic cross-sectional side view of a vehicle underbody structure according to a first embodiment. [Figure 3] 1 is a schematic cross-sectional plan view of a vehicle underbody structure according to a first embodiment. [Figure 4] 1 is an exploded perspective view showing a main part of a vehicle undercarriage structure according to a first embodiment. [Figure 5] 1 is a perspective view showing a main part of a vehicle underbody structure according to a first embodiment. [Figure 6] 1 is an enlarged perspective view showing a main part of a vehicle undercarriage structure according to a first embodiment. FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 3. [Figure 8] FIG. 10 is a schematic cross-sectional side view of a vehicle underbody structure according to a second embodiment. [Figure 9] FIG. 11 is a schematic cross-sectional side view of a vehicle underbody structure relating to a third embodiment. [Figure 10] FIG. 11 is a perspective view showing a main part of a vehicle undercarriage structure relating to a third embodiment. [Figure 11] Fig. 10 is a schematic cross-sectional side view of a vehicle underbody structure relating to a fourth embodiment Fig. 11 is a schematic cross-sectional side view of a vehicle underbody structure relating to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] First Embodiment A vehicle underbody structure according to a first embodiment will be described with reference to the drawings.

[0036] 1 is a perspective view showing a main part of a vehicle V to which a vehicle undercarriage structure according to a first embodiment is applied. Note that the arrows FR, UP, and RH in the figure indicate the front, upper, and right directions of the vehicle, respectively. In the following description, when the front-rear, up-down, and left-right directions are used unless otherwise specified, they refer to front and rear in the front-rear direction of the vehicle, up and down in the up-down direction of the vehicle, and left and right in the left-right direction (width direction) of the vehicle, respectively.

[0037] 1, a battery case 12 is provided in the center of the vehicle V in the longitudinal direction. The battery case 12 is provided in the lower part of the vehicle. In addition, since the upper surface of the battery case 12 forms the floor of the vehicle compartment, the vehicle V of this embodiment is not provided with a floor panel.

[0038] 4, the battery case 12 is formed in a generally box-like shape and includes an upper case 14 and a lower case 16. A battery (battery pack) (not shown) is mounted inside the battery case 12. The battery case may also be configured with a battery cover that covers the top of the battery. In this case, a member that supports the battery from below may be provided instead of the lower case 16.

[0039] As shown in Fig. 1, a pair of left and right rockers 18 extending in the vehicle front-rear direction are provided on both sides of the battery case 12 in the vehicle width direction, and the battery case 12 is attached to the rockers 18. As shown in Fig. 7, the rocker 18 is a framework member formed in a substantially rectangular closed cross section, and inside the rocker 18 are provided upper and lower partition walls 18A and 18B that extend in the vehicle width direction and divide the internal space of the rocker 18 into upper and lower sections.

[0040] The locker 18 is also formed with vertical ribs 18C that connect the upper partition wall 18A and the lower partition wall 18B vertically. Furthermore, ribs are also formed in the space below the lower partition wall 18B. However, this is not limiting, and the cross-sectional shape of the locker 18 may be changed as appropriate. For example, a locker that does not have the upper partition wall 18A, the lower partition wall 18B, and the vertical ribs 18C may be used.

[0041] Upper flanges 14A extend outward in the vehicle width direction from both ends of the upper case 14 that constitute the battery case 12 in the vehicle width direction, and lower flanges 16A extend outward in the vehicle width direction from both ends of the lower case 16 in the vehicle width direction. The upper flanges 14A and the lower flanges 16A are located below the rocker 18 and are joined in an overlapping state. Fasteners such as bolts are inserted into the upper flanges 14A and the lower flanges 16A from below and fastened to the rocker 18.

[0042] 1, the front end of the rocker 18 is connected to a front module 20. The front module 20 is integrally formed, for example, by casting, and is configured to include a dash panel portion 21, a suspension tower portion 23, a front side member portion 25, etc.

[0043] The dash panel portion 21 extends in the vehicle width direction and the vehicle up-down direction, separating the interior space from the exterior space. The front side member portions 25 extend from both ends of the dash panel portion 21 in the vehicle width direction toward the front of the vehicle, forming a load path in the event of a frontal collision. A pair of suspension tower portions 23 are provided on the left and right, and each is configured to support a suspension (not shown).

[0044] A first cross member 22 and a second cross member 24 are provided in the vehicle widthwise central portion of the rocker 18. The first cross member 22 and the second cross member 24 each extend in the vehicle width direction and are installed between the pair of left and right rockers 18. In addition, front vehicle seats (not shown) are attached to the first cross member 22 and the second cross member 24.

[0045] Next, the vehicle rear side portion of the rocker 18, which is the main part of the present invention, will be described.

[0046] Fig. 2 is a schematic side cross-sectional view of the vehicle undercarriage structure according to the first embodiment. As shown in Fig. 2, auxiliary equipment 100 as an object to be protected is provided above the vehicle battery case 12. The auxiliary equipment 100 is configured to include a plurality of auxiliary equipment, such as an inverter, a DC / DC converter, a charger, and an ECU (Electronic Control Unit).

[0047] The accessories 100 are arranged in two levels, an upper level and an lower level. Specifically, a substantially flat partition plate 30 extending in the vehicle width direction and the vehicle front-rear direction is provided in the space where the accessories 100 are arranged, with some of the accessories 100 arranged below the partition plate 30 and the remaining accessories of the accessories 100 arranged on the upper surface of the partition plate 30.

[0048] 1, the partition plate 30 extends from one end to the other end in the vehicle width direction and is formed larger than an auxiliary equipment cover 32, which will be described later. The material of the partition plate 30 is not particularly limited, but a material with high thermal conductivity, such as aluminum, is preferable from the viewpoint of improving the heat dissipation performance of the auxiliary equipment 100. The partition plate 30 also has a plurality of openings formed therein, through which connectors for connecting a wire harness to the auxiliary equipment 100 from the outside may be exposed.

[0049] Here, the accessories 100 are covered by an accessory cover 32. As shown in Fig. 2, the accessory cover 32 is formed separately from the battery case 12, and is provided above the battery case 12 to support a seat cushion 35 of the rear vehicle seat VS from below the vehicle. Note that another member may be interposed between the accessory cover 32 and the seat cushion 35.

[0050] The accessory cover 32 includes an upper wall portion 32A that supports the seat cushion 35, a front wall portion 32B that extends from the front end of the upper wall portion 32A toward the lower side of the vehicle, and a rear wall portion 32C that extends from the rear end of the upper wall portion 32A toward the lower side of the vehicle.

[0051] The upper wall portion 32A is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle to correspond to the inclination of the seat cushion 35. The front wall portion 32B extends substantially vertically from the front end of the upper wall portion 32A downward toward the vehicle. The lower end of the front wall portion 32B forms a front flange 32D that is bent toward the front of the vehicle along a front reinforcing cross-member 40 (described later), and is fixed to the front reinforcing cross-member 40 via the partition plate 30. The method for fixing the accessory cover 32 is not particularly limited, and the accessory cover 32 may be mechanically fastened with bolts, rivets, or the like, or may be joined by welding or the like.

[0052] The rear wall portion 32C extends substantially perpendicularly from the rear end of the upper wall portion 32A toward the vehicle lower side. The lower end of the rear wall portion 32C forms a rear flange 32E that is bent toward the vehicle rear along a rear reinforcing cross-member 42 (described later), and is fixed to the rear reinforcing cross-member 42 via the partition plate 30. The front flange 32D and the rear flange 32E may be fastened directly to the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 without using the partition plate 30.

[0053] A front reinforcing cross-member 40 is disposed below the front flange 32D of the accessory cover 32. In addition, a rear reinforcing cross-member 42 is disposed below the rear flange 32E of the accessory cover 32, and both the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 are skeletal members with a closed cross-section structure.

[0054] 4 and 6, the front reinforcing cross-member 40 is provided on the vehicle front side of the accessory cover 32, and extends outward in the vehicle width direction beyond the accessory cover 32. The front reinforcing cross-member 40 has a cross-sectional shape formed by bending a single rigid plate into a substantially S-shape, with two upper and lower closed cross sections, and an upper surface 40A of the front reinforcing cross-member 40 forms a support portion that supports the accessory cover 32 from below.

[0055] A partition 41 that separates the interior space into upper and lower sections is provided within the cross section of the front reinforcing cross member 40. As shown in Fig. 7, the partition 41 is located at the same height as the upper surface of the rocker 18. In other words, an imaginary line extending the partition 41 in the vehicle width direction coincides with the upper surface of the rocker 18.

[0056] 4, the rear reinforcing cross-member 42 is provided on the vehicle rear side of the accessory cover 32 and, like the front reinforcing cross-member 40, extends outward in the vehicle width direction beyond the accessory cover 32. The rear reinforcing cross-member 42 has a smaller cross-sectional area than the front reinforcing cross-member 40 and is formed by bending a single rigid plate into a substantially rectangular shape to have a single closed cross section. Furthermore, the upper surface 42A of the rear reinforcing cross-member 42 forms a support portion that supports the accessory cover 32 from below.

[0057] 2, the front reinforcing cross-member 40 is disposed at a position overlapping the front wall portion 32B of the accessory cover 32 in a plan view. Similarly, the rear reinforcing cross-member 42 is disposed at a position overlapping the rear wall portion 32C of the accessory cover 32 in a plan view.

[0058] 1, both ends of the front reinforcing cross member 40 in the vehicle width direction are connected to a pair of left and right side members 52 extending in the vehicle front-rear direction. The pair of left and right side members 52 are integrally formed by casting. Specifically, the pair of left and right side members 52 constitute part of a rear module 50 that is integrally formed by casting.

[0059] As shown in FIG. 4, the side member 52 includes a main body portion 53 extending in the longitudinal direction of the vehicle, and a front protruding portion 54 and a rear protruding portion 56 protruding from the main body portion 53.

[0060] The main body portion 53 of the side member 52 is composed of an upper surface 52A, an outer surface 52B extending downward from the outer side of the upper surface 52A in the vehicle width direction, and an inner surface 52C extending downward from the inner side of the upper surface 52A in the vehicle width direction.

[0061] The front protrusion 54 is formed to protrude inward in the vehicle width direction from the front end of the main body 53, and has a shape that allows the front reinforcing cross-member 40 to be connected to it. Specifically, the front protrusion 54 includes an upper surface 54A located above, a front surface 54B extending downward from the front end of the upper surface 54A, and a rear surface 54C extending downward from the rear end of the upper surface 54A, and is formed into an inverted U-shape that is open toward the lower side of the vehicle in a side view of the vehicle. The upper surface 54A, the front surface 54B, and the rear surface 54C of the front protrusion 54 cover the upper surface, front surface, and rear surface of the front reinforcing cross-member 40.

[0062] Two bolt holes 54D are formed in the upper surface 54A of the front protruding portion 54. Furthermore, bolt holes 40B are formed in the upper surface 40A of the front reinforcing cross member 40 at positions corresponding to the bolt holes 54D of the front protruding portion 54, and bolts 58 are inserted through the bolt holes 54D and 40B to fasten the front reinforcing cross member 40 to the front protruding portion 54 (side member 52) (see FIG. 5).

[0063] The rear-side protruding portion 56 is formed to protrude inward in the vehicle width direction from a position rearward of the front-side protruding portion 54 on the main body portion 53, and has a shape that allows the rear-side reinforcing cross-member 42 to be connected thereto. Specifically, the rear-side protruding portion 56 includes an upper surface 56A located above, a front surface 56B extending downward from the front end of the upper surface 56A, and a rear surface 56C extending downward from the rear end of the upper surface 56A, and is formed into an inverted U-shape that is open toward the lower side of the vehicle in a side view of the vehicle. The upper surface 56A, the front surface 56B, and the rear surface 56C of the rear-side protruding portion 56 cover the upper surface, front surface, and rear surface of the rear-side reinforcing cross-member 42.

[0064] Bolt holes 56D are formed in an upper surface 56A of the rear protruding portion 56. Furthermore, bolt holes 42B are formed in an upper surface 42A of the rear reinforcing cross member 42 at positions corresponding to the bolt holes 56D of the rear protruding portion 56, and the rear reinforcing cross member 42 is fastened to the rear protruding portion 56 (side member 52) by inserting bolts through the bolt holes 56D and the bolt holes 42B.

[0065] 3 and 5, the front portion of the side member 52 is fixed to the rocker 18. Specifically, a fixing piece 55 extending outward in the vehicle width direction is formed on the front portion of the side member 52, and the fixing piece 55 is fastened to the rocker 18 by a bolt 60 in a state where it is superimposed on the upper surface of the rocker 18. In the present embodiment, as an example, four bolts 60 are provided in the front-rear direction of the vehicle, but the arrangement and number of the bolts 60 are not particularly limited.

[0066] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0067] 1, in the vehicle undercarriage structure according to this embodiment, a battery case 12 that houses a battery is provided in the lower part of the vehicle V, and the upper surface of the battery case 12 forms the vehicle interior floor. This eliminates the need for a floor panel, and allows for an expanded interior space in the vehicle compared to a configuration in which a floor panel is provided.

[0068] 2, an accessory cover 32 is provided above the battery case 12. The accessory cover 32 covers the accessories 100, which are objects to be protected, from the outside and supports a seat cushion 35 of the vehicle seat VS from below the vehicle.

[0069] 4, a front reinforcing cross-member 40 is provided on the vehicle front side of the accessory cover 32. The front reinforcing cross-member 40 extends in the vehicle width direction, and an upper surface 40A of the front reinforcing cross-member 40 forms a support portion that supports the accessory cover 32 from below. As a result, as shown in FIG. 2, even if an excessive load is input from an occupant P seated in a vehicle seat VS to the accessory cover 32 in the direction indicated by the arrow in the figure during a frontal collision of the vehicle V, the collision load is transmitted in the vehicle width direction via the front reinforcing cross-member 40, thereby preventing the collision load from being input to the accessory 100.

[0070] Specifically, in the event of a frontal collision of the vehicle V, the inertial movement of the occupant P causes a load to be input from the occupant P's ischium (buttocks) to the front and lower sides of the vehicle onto the seat cushion 35. The load input from the occupant P is transmitted from the seat cushion 35 to the accessory cover 32. Here, if the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 were not provided, the accessory cover 32 would be crushed, and the load would be input to the accessory 100.

[0071] In this embodiment, since the front reinforcing cross-member 40 is provided, the load is transmitted from the accessory cover 32 to the front reinforcing cross-member 40, and the load is distributed to both sides in the vehicle width direction via the front reinforcing cross-member 40. This prevents the accessory cover 32 from collapsing and inputting the load to the accessories 100. That is, in a structure in which the upper surface of the battery case 12 functions as a floor panel, it is possible to prevent the load from being input to items stored below the vehicle seat VS in the event of a frontal collision of the vehicle V.

[0072] In this embodiment, the accessory cover 32 includes an upper wall portion 32A, a front wall portion 32B, and a rear wall portion 32C, and the upper wall portion 32A supports the seat cushion 35. Furthermore, since the front reinforcing cross-member 40 is disposed at a position overlapping the front wall portion 32B in a plan view, the load can be effectively transmitted from the front wall portion 32B to the front reinforcing cross-member 40.

[0073] Furthermore, in this embodiment, the accessory cover 32 is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle, so that in the event of a frontal collision, a load is more likely to be input forward and downward from the buttocks of the occupant P to the accessory cover 32, and the load can be efficiently transmitted to the front reinforcing cross-member 40. In addition, a reaction force acts from the accessory cover 32 on the rear and upper sides of the vehicle on the buttocks of the occupant P, so inertial movement of the occupant P toward the front of the vehicle can be suppressed.

[0074] Furthermore, in this embodiment, the accessory cover 32 is formed separately from the battery case 12, so that the accessory cover 32 can be attached as a module to the vehicle seat VS. Also, maintenance of the accessories 100 can be performed simply by removing the accessory cover 32.

[0075] 3, in this embodiment, both ends of the front reinforcing cross member 40 in the vehicle width direction are connected to the side members 52, so that a load input to the front reinforcing cross member 40 via the accessory cover 32 is transmitted to the pair of left and right side members 52. This makes it possible to suppress input of the load to the battery case 12. Furthermore, because there is no need to fix the front reinforcing cross member 40 to the battery case 12, the rear vehicle seat VS and the battery case 12 can be easily separated.

[0076] 4, in this embodiment in particular, each side member 52 is configured to include a main body portion 53 and a front protruding portion 54. This makes it possible to suppress stress concentration at the connection portion between the front reinforcing cross member 40 and the side member 52, compared to a configuration in which the front reinforcing cross member 40 is fixed by abutting it against the side member 52, and allows the load to be transmitted from the front reinforcing cross member 40 to the side member 52 more effectively.

[0077] Furthermore, the front protrusion 54 of this embodiment is formed in an inverted U-shape that is open toward the vehicle lower side when viewed from the side of the vehicle. As a result, the front protrusion 54 covers three surfaces of the front reinforcing cross-member 40: the upper surface 40A, the front surface, and the rear surface. As a result, the front protrusion 54 can be fastened to the front reinforcing cross-member 40 from any of the upper surface 40A, the front surface, and the rear surface, improving ease of assembly.

[0078] Furthermore, in this embodiment, a rear reinforcing cross-member 42 is provided on the vehicle rear side of the accessory cover 32, and the rear reinforcing cross-member 42 extends in the vehicle width direction. As a result, a load acting on the front side of the accessory cover 32 can be borne by the front reinforcing cross-member 40, and a load acting on the rear side of the accessory cover 32 can be borne by the rear reinforcing cross-member 42. As a result, even if an excessive load is applied, the rear portion of the accessory cover 32 can be prevented from collapsing. Furthermore, as shown in FIG. 3 , if the rear seat is a three-seater bench seat, loads are input in various directions from the buttocks of the three seated occupants while the vehicle V is traveling. In this case, by adopting a configuration in which the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 are connected to the side members 52, as in this embodiment, the load can be efficiently transmitted to the frame members.

[0079] 4, in this embodiment, the side member 52 is configured to include a rear protrusion 56. This makes it possible to suppress stress concentration at the connection portion between the rear reinforcing cross member 42 and the side member 52, compared to a configuration in which the rear reinforcing cross member 42 is fixed by abutting it against the side member 52, and allows the load to be transmitted from the rear reinforcing cross member 42 to the side member 52 more effectively.

[0080] In particular, the rear protrusion 56 of this embodiment is formed in an inverted U shape that is open toward the lower side of the vehicle when viewed from the side of the vehicle, similar to the front protrusion 54. As a result, the rear protrusion 56 covers three surfaces of the rear reinforcing cross member 42: the upper surface 42A, the front surface, and the rear surface. As a result, assembly is easier.

[0081] Furthermore, in this embodiment, as shown in Figures 1, 3, and 5, the front portions of the side members 52 are fixed to the rocker 18, and therefore the load input to the side members 52 via the front reinforcing cross member 40 during a frontal collision is transmitted to the front side of the vehicle via the rocker 18. This allows the collision load to be distributed more effectively.

[0082] Furthermore, in this embodiment, the pair of left and right side members 52 are integrally formed by casting, so that the load input to the left and right side members 52 can be borne by the high-strength members integrally formed by casting.

[0083] In addition, in this embodiment, as shown in FIG. 7, the front reinforcing cross member 40 is provided with a partition portion 41 that separates the internal space into upper and lower portions, and therefore the partition portion 41 can increase rigidity.

[0084] Furthermore, the partition 41 in this embodiment is located at the same height as the upper surface of the rocker 18. In other words, an imaginary line extending from the partition 41 in the vehicle width direction coincides with the upper surface of the rocker 18. By making the partition 41 at the same height as the upper surface of the rocker 18 in this way, the load can be effectively transmitted from the rocker 18 to the front reinforcing cross member 40 in the event of a side collision of the vehicle V. As a result, the collision load can be transmitted smoothly to the anti-collision side.

[0085] Second Embodiment Next, a vehicle underbody structure according to a second embodiment will be described with reference to the drawings. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted where appropriate.

[0086] Fig. 8 is a schematic side cross-sectional view of a vehicle undercarriage structure according to the second embodiment. As shown in Fig. 8, in this embodiment, the shape of the accessory cover 72 is different from that of the first embodiment, and the configuration other than the accessory cover 72 is the same as that of the first embodiment.

[0087] The accessory cover 72 includes an upper wall portion 72A that supports the seat cushion 35, a front wall portion 72B that extends from the front end of the upper wall portion 72A toward the lower side of the vehicle, and a rear wall portion 72C that extends from the rear end of the upper wall portion 72A toward the lower side of the vehicle.

[0088] The upper wall portion 72A is inclined downward from the front to the rear of the vehicle in a side view of the vehicle to correspond to the inclination of the seat cushion 35. The front wall portion 72B extends substantially vertically from the front end of the upper wall portion 72A downward toward the vehicle. The front wall portion 72B is bent toward the rear of the vehicle along the upper surface of the front reinforcing cross-member 40 and further includes a lower front wall portion 72D that extends downward along the rear surface of the front reinforcing cross-member 40. The lower end of the lower front wall portion 72D abuts against the upper surface of the battery case 12.

[0089] The rear wall portion 72C extends substantially vertically downward from the rear end of the upper wall portion 72A. The lower end of the rear wall portion 72C forms a rear flange 72E that is bent toward the rear of the vehicle along the rear reinforcing cross member 42.

[0090] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0091] In this embodiment, the accessory cover 72 has a lower front wall portion 72D below the front wall portion 72B, and the lower front wall portion 72D extends along the rear surface of the front reinforcing cross-member 40 to the battery case 12. This allows the load input from the occupant P to the accessory cover 72 during a frontal collision to be distributed to both the front reinforcing cross-member 40 and the battery case 12.

[0092] In addition, in this embodiment, the load acting on the accessory cover 72 from the front side of the vehicle can be received by the rear surface of the front reinforcing cross member 40, thereby preventing the front wall portion 72B of the accessory cover 72 from buckling. Other functions are the same as those of the first embodiment.

[0093] <Third embodiment> Next, a vehicle underbody structure according to a third embodiment will be described with reference to the drawings. Note that the same components as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0094] 9 is a schematic side cross-sectional view of a vehicle underbody structure according to the third embodiment. As shown in this Fig. 9, in this embodiment, the accessory cover 32 and the rear module 50 are connected via a bracket 80.

[0095] 10, in this embodiment, the rear module 50 is provided with a belt fastening portion 82 to which the webbing of a seat belt device (not shown) is fastened. In addition, the accessory cover 32 is fastened to the rear module 50 by a bracket 80 at the belt fastening portion 82.

[0096] 9, bracket 80 is formed in a generally crank shape in a side view of the vehicle, and a front end portion 80A of bracket 80 extends in the fore-and-aft direction of the vehicle in a side view of the vehicle. Front end portion 80A is joined in a state where it overlaps the upper surface of rear flange 32E of accessory cover 32. There are no particular limitations on the method of joining bracket 80 and rear flange 32E, and they may be mechanically fastened with bolts and nuts, or may be joined by welding, for example.

[0097] A rear end portion 80B of the bracket 80 extends in the front-to-rear direction of the vehicle in a side view of the vehicle, and this rear end portion 80B is fastened to a belt fastening portion 82 of the rear module 50 in a state where it is overlapped therewith.

[0098] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0099] In this embodiment, by connecting the accessory cover 32 and the rear module 50 with the bracket 80, it is possible to effectively prevent the accessory cover 32 from coming off even when a load is input during a frontal collision.

[0100] In particular, in this embodiment, by fastening the bracket 80 to the belt fastening portion 82, space efficiency can be improved compared to a structure in which the bracket 80 is fastened to another location. In other words, the belt fastening portion 82 needs to be formed with high strength in advance in order to fasten the webbing. Therefore, by fastening the bracket 80 to the belt fastening portion 82, it is no longer necessary to form a separate high-strength portion, and space can be secured for other uses. Other functions are the same as in the first embodiment.

[0101] <Fourth embodiment> Next, a vehicle underbody structure according to a fourth embodiment will be described with reference to the drawings. Note that the same components as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0102] Fig. 11 is a schematic side cross-sectional view of a vehicle underbody structure according to a fourth embodiment. As shown in Fig. 11, this embodiment is similar to the first embodiment except that a reinforcing bracket 84 is provided.

[0103] A reinforcing bracket 84 is provided on the accessory cover 32. The reinforcing bracket 84 is provided on the front end portion of the accessory cover 32, and is installed between the lower surface of the upper wall portion 32A and the rear surface of the front wall portion 32B.

[0104] Here, the reinforcing bracket 84 extends in a direction substantially perpendicular to the upper wall portion 32A of the accessory cover 32. In other words, the reinforcing bracket 84 extends along the direction of the load input from the occupant P to the accessory cover 32 during a frontal collision (the direction of the arrow in the figure).

[0105] (action) Next, the operation of the vehicle underbody structure according to this embodiment will be described.

[0106] In this embodiment, the reinforcing bracket 84 can effectively prevent deformation of the accessory cover 32. Furthermore, the reinforcing bracket 84 can effectively transmit the load input from the occupant P during a frontal collision to the front reinforcing cross member 40. Other functions are the same as those of the first embodiment.

[0107] Although the vehicle underbody structure according to the present invention has been described above, it is needless to say that the present invention can be embodied in various forms without departing from the spirit and scope of the present invention. For example, the vehicle underbody structures according to the first to fourth embodiments may be combined with each other.

[0108] 2, the front flange 32D of the accessory cover 32 extends toward the front of the vehicle, but this is not limited thereto, and the accessory cover 32 may extend toward the rear of the vehicle along the upper surface of the front reinforcing cross-member 40. Similarly, the rear flange 32E of the accessory cover 32 may extend toward the front of the vehicle along the upper surface of the rear reinforcing cross-member 42.

[0109] Furthermore, in the above embodiment, the front wall portion 32B of the accessory cover 32 extends substantially vertically from the front end of the upper wall portion 32A, but is not limited to this. For example, the front wall portion may be configured to extend obliquely from the upper wall portion 32A toward the front and bottom of the vehicle.

[0110] Furthermore, in this embodiment, the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 are not fastened to the battery case 12, but this is not limiting. For example, the front reinforcing cross-member 40 and the rear reinforcing cross-member 42 may be fastened to the upper surface of the battery case 12.

[0111] In addition, in this embodiment, as shown in FIG. 4, the front protrusion 54 and the rear protrusion 56 are formed in an inverted U-shape with the lower side of the vehicle open when viewed from the side of the vehicle, but this is not limited to this and other shapes may also be used.

[0112] Furthermore, the cross-sectional shapes of the front reinforcing cross-member 40, the rear reinforcing cross-member 42 and the rocker 18 are not limited to the structures of the above embodiment, and may be other shapes.

[0113] Furthermore, in the above embodiment, the accessory cover 32 that covers the accessory 100 as the object to be protected has been described, but the present invention is not limited to this. For example, the object to be protected may be a cover that covers a battery cell. In this case, the cover may be formed separately from the battery case 12 that constitutes the vehicle interior floor and provided above the battery case 12.

[0114] The following notes are provided regarding the above embodiment.

[0115] (Appendix 1) a battery case provided in a lower portion of the vehicle, accommodating a battery and having an upper surface that forms a vehicle interior floor; a cover provided above the battery case to support a seat cushion of a vehicle seat from below the vehicle and to cover an object to be protected from the outside; a front reinforcing cross member that covers an object to be protected provided on the vehicle front side of the cover, extends in the vehicle width direction, and has a support portion at its upper end that supports the cover from below; A vehicle undercarriage having: (Appendix 2) the cover includes an upper wall portion that supports the seat cushion and a front wall portion that extends from a front end of the upper wall portion toward a vehicle lower side, 2. The vehicle undercarriage structure according to claim 1, wherein the front reinforcing cross member is positioned so as to overlap with the front wall portion in a plan view. (Appendix 3) 3. The vehicle undercarriage structure according to claim 2, wherein the upper wall portion of the cover is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle. (Appendix 4) 4. The vehicle underbody structure according to any one of claims 1 to 3, wherein both ends of the front reinforcing cross member in the vehicle width direction are connected to a pair of left and right side members extending in the vehicle front-rear direction. (Appendix 5) A vehicle undercarriage structure as described in Appendix 4, wherein each of the pair of left and right side members includes a main body portion extending in the fore-and-aft direction of the vehicle and a front protruding portion protruding from the main body portion toward the inside in the vehicle width direction and to which the front reinforcing cross member is connected. (Appendix 6) A vehicle undercarriage structure as described in Appendix 5, wherein the front protrusion is formed in an inverted U-shape with the lower side of the vehicle open in a side view of the vehicle so as to cover the upper surface, front surface, and rear surface of the front reinforcing cross member. (Appendix 7) A vehicle undercarriage structure as described in any one of appendices 4 to 6, having a rear reinforcing cross member provided on the rear side of the cover, extending in the vehicle width direction, and having a support portion at its upper end that supports the cover from below. (Appendix 8) Each of the pair of left and right side members includes a rear protruding portion that protrudes from the main body portion toward the inside in the vehicle width direction and to which the rear reinforcing cross member is connected, 8. The vehicle undercarriage structure according to claim 7, wherein the rear reinforcing cross member is connected to the side member at the rear protrusion. (Appendix 9) A vehicle undercarriage structure as described in Appendix 8, wherein the rear protrusion is formed in an inverted U-shape with an open lower side of the vehicle in a side view of the vehicle so as to cover the upper surface, front surface, and rear surface of the rear reinforcing cross member. (Appendix 10) A pair of left and right rockers extending in the vehicle front-rear direction on both sides in the vehicle width direction are provided, 9. The vehicle underbody structure according to any one of claims 4 to 8, wherein a front portion of the side member is fixed to the rocker. (Appendix 11) 10. The vehicle underbody structure according to any one of appendix 4 to appendix 9, wherein the pair of left and right side members are integrally formed by casting. (Appendix 12) 12. The vehicle underbody structure according to any one of claims 1 to 11, wherein the cover is formed separately from the battery case and covers auxiliary machinery that is an object to be protected. (Appendix 13) The front reinforcing cross member is formed with a closed cross section and is equipped with a partition that separates the interior space into upper and lower sections. 11. The vehicle undercarriage structure according to claim 10, wherein the partition portion is located at the same height as an upper surface of the rocker. (Appendix 14) a battery case provided under the vehicle and accommodating a battery; a cover provided above the battery case to support a seat cushion of a vehicle seat from below the vehicle and to cover an object to be protected from the outside; a front reinforcing cross member provided on the vehicle front side of the cover, extending in the vehicle width direction, and having a support portion at an upper end thereof that supports the cover from below; A vehicle undercarriage having: [Explanation of symbols]

[0116] 12 Battery case 18 Rocca 32 Auxiliary equipment cover (cover) 32A Upper wall part 32B Front wall 32C rear wall 35 seat cushion 40 Front reinforcing cross member 40A Top surface (support part) 41 Partition 42 Rear reinforcing cross member 42A Top surface (support part) 52 Side member 53 Main body 54 Front protrusion 56 Posterior protrusion 100 Auxiliary equipment (protected items) V vehicle VS vehicle seats

Claims

1. a battery case provided in a lower portion of the vehicle, accommodating a battery and having an upper surface that forms a vehicle interior floor; a cover that covers an object to be protected provided above the battery case and supports a seat cushion of a vehicle seat from below the vehicle; a front reinforcing cross member provided on the vehicle front side of the cover, extending in the vehicle width direction, and having a support portion at an upper end thereof that supports the cover from below; A vehicle undercarriage having:

2. the cover includes an upper wall portion that supports the seat cushion and a front wall portion that extends from a front end of the upper wall portion toward a vehicle lower side, The vehicle underbody structure according to claim 1 , wherein the front reinforcing cross member is disposed at a position overlapping the front wall portion in a plan view.

3. The vehicle underbody structure according to claim 2 , wherein the upper wall portion of the cover is inclined downward from the front of the vehicle to the rear of the vehicle in a side view of the vehicle.

4. 2. The vehicle underbody structure according to claim 1, wherein both ends of the front reinforcing cross member in the vehicle width direction are connected to a pair of left and right side members extending in the vehicle front-rear direction.

5. 5. The vehicle undercarriage structure according to claim 4, wherein each of the pair of left and right side members includes a main body portion extending in the fore-and-aft direction of the vehicle and a front protruding portion protruding from the main body portion toward the inside in the vehicle width direction and to which the front reinforcing cross member is connected.

6. 6. The vehicle undercarriage structure according to claim 5, wherein the front protrusion is formed in an inverted U-shape with an open lower side in a vehicle side view so as to cover the upper surface, front surface, and rear surface of the front reinforcing cross member.

7. 6. The vehicle undercarriage structure according to claim 5, further comprising a rear reinforcing cross member provided on the vehicle rear side of the cover, extending in the vehicle width direction, and having a support portion at an upper end thereof that supports the cover from below.

8. Each of the pair of left and right side members includes a rear protruding portion that protrudes from the main body portion toward the inside in the vehicle width direction and to which the rear reinforcing cross member is connected, The vehicle underbody structure according to claim 7, wherein the rear reinforcing cross member is connected to the side member at the rear protrusion.

9. 9. The vehicle undercarriage structure according to claim 8, wherein the rear protrusion is formed in an inverted U-shape with an open lower side in a vehicle side view so as to cover the upper surface, front surface, and rear surface of the rear reinforcing cross member.

10. A pair of left and right rockers extending in the vehicle front-rear direction on both sides in the vehicle width direction are provided, 5. The vehicle undercarriage structure according to claim 4, wherein a front portion of the side member is fixed to the rocker.

11. 5. The vehicle underbody structure according to claim 4, wherein the pair of left and right side members are integrally formed by casting.

12. 2. The vehicle underbody structure according to claim 1, wherein the cover is formed separately from the battery case and covers auxiliary machinery that is an object to be protected.

13. The front reinforcing cross member is formed with a closed cross section and is equipped with a partition that separates the interior space into upper and lower sections. The vehicle undercarriage structure according to claim 10, wherein the partition portion is located at the same height as an upper surface of the rocker.

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