The lower body structure of the car

Abstract

The lower body structure of the automobile includes multiple first frame parts, second frame parts and impact absorbing components, the second frame part has a first wall part and a second wall part, the impact absorbing component has a first beam part, a second beam part and a corrugated plate part, the corrugated plate part has a first diagonal support part, a second diagonal support part, a first top part and a second top part, and the corrugated plate part is at least provided in the area of ​​the second frame part connecting with two adjacent first frame parts.

Description

Technical Field

[0001] The present invention relates to a lower body structure of an automobile. Background Art

[0002] The lower body structure of an automobile, comprised of structural members such as side sills and cross members, is required to have energy absorption performance to absorb impact during a collision. Patent Document 1 discloses an impact-absorbing structure in which a serrated connecting member is installed between the side of the vehicle body and the chassis. Patent Document 2 discloses a bumper bracket in which X-shaped reinforcement ribs are provided within a hollow portion comprising a front wall, a rear wall, and curved side walls.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-087321

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-335241 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Energy absorption performance is evaluated in a side pole impact test, where the vehicle collides with a pole. In a side pole impact test, the part of the vehicle that collides with the pole is predetermined. Therefore, to ensure the energy absorption performance required of an automobile, it is preferable to place a cross member at a location that contacts the pole.

[0009] On the other hand, in actual side collisions of automobiles, collisions sometimes occur between two adjacent crossbeams, where no crossbeams are provided. In such side collisions, the lower structure of the vehicle body is required not only to have energy absorption performance, but also to suppress the amount of structural members such as the lower side beams from entering the vehicle interior. In particular, since electric vehicles in recent years have adopted a vehicle body layout in which batteries are mounted under the floor, reducing the amount of structural members from entering the vehicle interior during a collision will also help to further enhance the battery protection function. In addition, problems related to the entry of structural members into the vehicle interior as described above also arise not only in the case of side collisions between crossbeams, but also in collisions with anti-collision beams between front longitudinal beams. Therefore, it is preferred that the deformation of structural members toward the vehicle interior be suppressed during a collision, regardless of the direction of the collision.

[0010] However, the structure disclosed in Patent Document 1 utilizes a zigzag connecting member to transmit the collision load to the rocker, rather than suppressing deformation of the rocker itself. The bumper bracket of Patent Document 2 functions as a crash box, rather than suppressing deformation of the structural member toward the vehicle interior during a collision.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the amount of penetration of structural members into the vehicle interior during a collision.

[0012] Solutions for solving problems

[0013] A technical solution of the present invention for solving the above-mentioned problem is a vehicle body lower structure, characterized in that the vehicle body lower structure includes: a plurality of first frame parts, which are arranged at intervals; a second frame part, which extends in a manner that the axial direction of the first frame part becomes a normal direction when viewed from the vehicle height direction and has a hollow part; and a shock absorbing member, which is arranged in the hollow part of the second frame part, the second frame part having a first wall part and a second wall part opposite to the first wall part, the first wall part being connected to the axial vehicle outer side end face of the first frame part, the shock absorbing member having: a first beam part, which extends along the axial direction of the second frame part; a second beam part, which is opposite to the first beam part; and a corrugated plate part, which is between the first beam part and the second wall part. The second beam portion is connected to the first beam portion and the second beam portion, the first beam portion is connected to the first wall portion of the second frame portion, and the second beam portion is connected to the second wall portion of the second frame portion, and the corrugated plate portion has: a first diagonal bracing portion, which extends in a direction from the second beam portion toward the first beam portion; a second diagonal bracing portion, which extends in a direction from the first beam portion toward the second beam portion; a first top portion, which is a connecting portion of the first diagonal bracing portion and the second diagonal bracing portion on the side of the first beam portion; and a second top portion, which is a connecting portion of the first diagonal bracing portion and the second diagonal bracing portion on the side of the second beam portion, and the corrugated plate portions are respectively provided at least in the area of ​​the second frame portion connected to two adjacent first frame portions.

[0014] Effects of the Invention

[0015] According to the present invention, the amount of penetration of structural members into the vehicle interior during a collision can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing an example of a vehicle body frame.

[0017] Figure 2 It is a diagram showing a schematic configuration of a vehicle body lower structure according to a first embodiment of the present invention.

[0018] Figure 3 Yes Figure 2 Figure AA section in.

[0019] Figure 4 It is a perspective view showing the shock absorbing member according to the first embodiment.

[0020] Figure 5 This is an enlarged view of the impact absorbing member viewed from the vehicle's height.

[0021] Figure 6 It is a diagram showing an example of arrangement of shock absorbing members.

[0022] Figure 7 It is a diagram showing a schematic configuration of a vehicle body understructure according to a second embodiment of the present invention.

[0023] Figure 8 It is a perspective view showing a shock absorbing member according to a second embodiment.

[0024] Figure 9 It is a figure which shows the shape example of the corrugated plate part.

[0025] Figure 10 It is a figure which shows the shape example of the corrugated plate part.

[0026] Figure 11 This is a diagram showing the analysis model of the side pole collision simulation (1) and the deformation state of the rocker after the simulation.

[0027] Figure 12 This is a diagram showing the analysis model of the side pole collision simulation (2) and the deformation state of the rocker after the simulation.

[0028] Figure 13 This is a diagram showing the results of the side pole impact simulation (3). DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals to omit repeated descriptions.

[0030] Figure 1 This is a diagram showing an example of a car body frame. Figure 1 As shown, the vehicle body frame includes, for example, a cross member (floor cross member) extending in the vehicle width direction, a side sill extending in the vehicle length direction, an anti-collision beam extending in the vehicle width direction, and a longitudinal beam extending in the vehicle length direction.

[0031] <First embodiment>

[0032] Figure 21 is a diagram showing a schematic structure of a vehicle body lower structure 1 according to a first embodiment. The vehicle body lower structure 1 according to this embodiment includes a plurality of first frame portions 10 extending in the X direction and a second frame portion 20 extending in the Y direction. Figure 2 This is a diagram of the lower vehicle body structure 1 viewed from the vehicle height direction (Z direction), so the "second frame portion 20 extending along the Y direction" can also be referred to as the second frame portion 20 extending in such a manner that the axial direction (extension direction) of the first frame portion 10 becomes the normal direction when viewed from the vehicle height direction.

[0033] The first frame portions 10 are spaced apart from each other along the axial direction (Y direction) of the second frame portion 20. Furthermore, the second frame portion 20 is connected to the vehicle outer side end surface of the first frame portion 10. The first frame portion 10 and the second frame portion 20 may be directly connected to each other or indirectly connected by providing a member between the first frame portion 10 and the second frame portion 20.

[0034] The first frame portion 10 is a structural member, such as a crossbeam or longitudinal beam, that exhibits energy absorption or impact resistance when a collision load is input from the axial direction. If the first frame portion 10 is a crossbeam, the second frame portion 20 is a side sill. The side sill extends with the crossbeam's axial direction (X direction) forming a normal direction and is connected to the vehicle's outer end surface. In this case, when the first frame portion 10 is a crossbeam and the second frame portion 20 is a side sill, the X direction in this specification and the accompanying drawings represents the vehicle width direction, and the Y direction represents the vehicle length direction.

[0035] On the other hand, when the first frame portion 10 is a longitudinal beam, the second frame portion 20 is a crash beam. The crash beam extends with the longitudinal beam's axial direction (X direction) as the normal direction and is connected to the vehicle's outer end surface of the longitudinal beam via a crash box. In this case, when the first frame portion 10 is a longitudinal beam and the second frame portion 20 is a crash beam, the X direction in this specification and the accompanying drawings represents the vehicle's length, and the Y direction represents the vehicle's width.

[0036] Furthermore, the longitudinal beam can be either a front longitudinal beam or a rear longitudinal beam. Furthermore, the anti-collision beam can be either a front anti-collision beam or a rear anti-collision beam. For example, if the first frame portion 10 is a front longitudinal beam, the second frame portion 20 is a front anti-collision beam. If the first frame portion 10 is a rear longitudinal beam, the second frame portion 20 is a rear anti-collision beam.

[0037] The shape and material of the first frame portion 10 are not particularly limited as long as they are suitable as structural members of the lower body structure 1 of the automobile. For example, the cross section of the first frame portion 10 perpendicular to the axial direction (X direction) is a closed cross section shape, and is a shape having a square tube-shaped hollow portion. In addition, for example, the material of the first frame portion 10 can be a metal material such as a steel plate with a tensile strength of 590 MPa or more, or a metal material such as an aluminum alloy member or a magnesium alloy member. The axial length of the first frame portion 10 is, for example, 500 mm to 1500 mm, and the plate thickness of the first frame portion 10 is, for example, 1 mm to 5 mm. In the case where the cross section of the first frame portion 10 perpendicular to the axial direction is a square tube shape, the cross-sectional size of the first frame portion 10 is, for example, 30 mm to 200 mm square.

[0038] Figure 3 Yes Figure 2 The AA cross section in FIG. 1 shows a cross section perpendicular to the axial direction (Y direction) of the second frame portion 20. The second frame portion 20 has a hollow portion 21 extending in the axial direction (Y direction). Figure 3 As shown, the hollow portion 21 of this embodiment is formed by joining two members, an inner member 22 and an outer member 23. In this embodiment, the inner member 22 is a cap-shaped member including a top plate 22a, a vertical wall 22b, and a flange 22c, and the outer member 23 is a cap-shaped member including a top plate 23a, a vertical wall 23b, and a flange 23c.

[0039] In addition, while the hollow portion 21 in this embodiment is formed by two cap-shaped members, for example, either of the two cap-shaped members may be a flat plate. Furthermore, the hollow portion 21 is not limited to being formed by connecting multiple members; for example, it may be formed by extrusion. Furthermore, the shape of the hollow portion 21 in a cross-section perpendicular to the axial direction of the second frame portion 20 is not limited to a rectangular tube.

[0040] The second frame portion 20 can be made of, for example, a metal material such as steel plate with a tensile strength of 590 MPa or greater, or a metal material such as an aluminum alloy or magnesium alloy. The axial length (Y direction) of the second frame portion 20 is, for example, 1000 mm to 3000 mm, and the thickness of the second frame portion 20 is, for example, 1 mm to 5 mm. If the cross-section of the second frame portion 20 perpendicular to the axial direction is a square tube, the cross-sectional dimensions of the second frame portion 20 are, for example, 50 mm to 200 mm square.

[0041] The second frame portion 20 includes a first wall portion 20a and a second wall portion 20b. The first wall portion 20a and the second wall portion 20b face each other, and the first wall portion 20a is connected to the vehicle outer side end surface of the first frame portion 10 in the axial direction (X direction). In the present embodiment, the first wall portion 20a corresponds to the top plate 22a of the inner member 22, and the second wall portion 20b corresponds to the top plate 23a of the outer member 23.

[0042] like Figures 2 to 5 As shown, the vehicle body lower structure 1 includes a shock absorbing member 30 in the hollow portion 21 of the second frame portion 20. The shock absorbing member 30 includes a first beam portion 31, a second beam portion 32, and a corrugated plate portion 33.

[0043] The first beam portion 31 and the second beam portion 32 are opposed to each other, and each of the first beam portion 31 and the second beam portion 32 extends along the axial direction (Y direction) of the second frame portion 20. The length of the first beam portion 31 and the second beam portion 32 in the extension direction (Y direction) is at least longer than the distance between two adjacent first frame portions 10, and the first beam portion 31 and the second beam portion 32 have a length that spans two adjacent first frame portions 10. The first beam portion 31 of this embodiment is formed into a plate shape and connected to the first wall portion 20a of the second frame portion 20. In addition, the second beam portion 32 of this embodiment is formed into a plate shape and connected to the second wall portion 20b of the second frame portion 20.

[0044] The corrugated plate portion 33 is connected to the first beam portion 31 and the second beam portion 32 in a manner spanning between the first beam portion 31 and the second beam portion 32. The corrugated plate portion 33 of this embodiment extends continuously along the axial direction (Y direction) of the second frame portion 20. The corrugated plate portion 33 has a first diagonal bracing portion 34, a second diagonal bracing portion 35, a first top portion 36, and a second top portion 37. The first diagonal bracing portion 34 extends in a direction from the second beam portion 32 toward the first beam portion 31, and the second diagonal bracing portion 35 extends in a direction from the first beam portion 31 toward the second beam portion 32. The first top portion 36 and the second top portion 37 are respectively the portions where the first diagonal bracing portion 34 and the second diagonal bracing portion 35 are connected. The first top portion 36 is the connecting portion on the first beam portion 31 side, and the second top portion 37 is the connecting portion on the second beam portion 32 side.

[0045] In this embodiment, the first top portion 36 and the second top portion 37 are each formed in a flat plate shape. The first top portion 36 is connected to the first beam portion 31, and the second top portion 37 is connected to the second beam portion 32. In this embodiment, there are multiple first top portions 36 and multiple second top portions 37, each of which is located at alternating positions in the axial direction of the second frame portion 20. To effectively reduce the amount of intrusion of the second frame portion 20 into the vehicle interior during a collision, it is preferable that all first top portions 36 are connected to the first beam portion 31. However, as long as the position of the corrugated plate portion 33 relative to the first beam portion 31 can be fixed, not all first top portions 36 need be connected to the first beam portion 31. For example, some first top portions 36 may be unconnected to the first beam portion 31 but may simply contact or be close to the first beam portion 31. For similar reasons, not all second top portions 37 may be connected to the second beam portion 32.

[0046] The angle θ formed by the first diagonal support portion 34 and the second diagonal support portion 35 ( Figure 5 ) can be arbitrarily set, but from the perspective of effectively suppressing the amount of intrusion of the second frame portion 20 into the vehicle interior as shown in the embodiments described below, when the corrugated plate portion 33 is provided in the region where the second frame portion 20 connects to the first frame portion 10, the angle θ is preferably 70 degrees or less. More preferably, it is 60 degrees or less. Furthermore, when the corrugated plate portion 33 is provided between adjacent first frame portions 10, the angle θ is preferably 40 degrees to 80 degrees. In this case, the angle θ is preferably 50 degrees or more and preferably 70 degrees or less.

[0047] The first beam portion 31, the second beam portion 32, and the corrugated plate portion 33 can be made of, for example, a metal material such as a steel plate having a tensile strength of 590 MPa or greater, or a metal material such as an aluminum alloy member or a magnesium alloy member. Furthermore, the thickness of the first beam portion 31, the second beam portion 32, and the corrugated plate portion 33 is, for example, 1 mm to 10 mm.

[0048] The means for connecting the first beam portion 31 of the shock absorbing member 30 to the first wall portion 20a of the second frame portion 20, the means for connecting the second beam portion 32 of the shock absorbing member 30 to the second wall portion 20b of the second frame portion 20, the means for connecting the corrugated plate portion 33 of the shock absorbing member 30 to the first beam portion 31, and the means for connecting the corrugated plate portion 33 to the second beam portion 32 are not particularly limited. For example, mechanical joining means such as rivets, or joining means such as arc welding or spot welding may be employed. Furthermore, the shapes of the first top portion 36 and the second top portion 37 are not limited to the flat plate shape of the present embodiment and may be modified appropriately depending on the connecting means employed.

[0049] In the impact absorbing member 30 of this embodiment, the first beam portion 31, the second beam portion 32, and the corrugated plate portion 33 are each formed from separate components, but they may also be integrally formed, for example, by extrusion. Furthermore, the lengths of the first beam portion 31, the second beam portion 32, and the corrugated plate portion 33 in the vehicle height direction may be appropriately modified depending on the required energy absorption performance and weight restrictions.

[0050] Furthermore, the connection position of the shock absorbing member 30 with respect to the second frame portion 20 in the vehicle height direction (Z direction) (the arrangement height of the shock absorbing member 30) is preferably located within the region where the second frame portion 20 is connected to the first frame portion 10. For example, Figure 3 The middle impact absorbing member 30 is arranged at the center of the second frame portion 20 in the vehicle height direction, but Figure 6 When the first frame portion 10 is arranged near the upper end portion of the second frame portion 20 as described above, the shock absorbing member 30 is also preferably arranged near the upper end portion of the second frame portion 20 .

[0051] The vehicle body understructure 1 of the present embodiment is constructed as described above. In the vehicle body understructure 1 of the present embodiment, when a collision load in the X direction is input to the region of the second frame portion 20 between two adjacent first frame portions 10, the provision of the impact absorbing member 30 facilitates the dispersion of the collision load to regions other than the collision site.

[0052] Specifically, because the impact absorbing member 30 includes the second beam portion 32 extending in the Y direction, the collision load input to the second frame portion 20 from the X direction also propagates in the Y direction during the deformation of the second beam portion 32, and is also transmitted to the first and second diagonal braces 34, 35 in areas other than the collision site. Furthermore, because the first and second diagonal braces 34, 35 are arranged at an angle to each other, the collision load transmitted to the first and second diagonal braces 34, 35 is further propagated in the Y direction. Furthermore, similar to the second beam portion 32, the collision load transmitted from the first and second diagonal braces 34, 35 to the first beam portion 31 is further propagated in the Y direction during the deformation of the first beam portion 31.

[0053] The impact absorbing member 30 of the vehicle body understructure 1 of this embodiment disperses the collision load as described above, allowing the material portion in areas other than the collision site to withstand the collision load. Consequently, the amount of intrusion of the second frame portion 20 into the vehicle interior during a collision can be reduced.

[0054] <Second embodiment>

[0055] Figure 7 1 is a diagram showing a schematic structure of a vehicle body lower structure 1 according to a second embodiment. Figure 83 is a perspective view of the shock absorbing member 30 according to the second embodiment. In the shock absorbing member 30 according to the present embodiment, there is a region in which the corrugated plate portion 33 is not provided in the extending direction (Y direction) of the shock absorbing member 30 .

[0056] In other words, the shock absorbing member 30 includes a plurality of corrugated plate portions 33a, 33b, each of which is spaced apart along the extending direction of the shock absorbing member 30. Each of the corrugated plate portions 33a, 33b is provided in a region R of the second frame portion 20 connected to the first frame portion 10, and a region where no corrugated plate portion 33 is provided is located between two adjacent first frame portions 10b and 10c.

[0057] In the vehicle body understructure 1 according to the present embodiment, when a collision load is applied to the region of the second frame portion 20 between the adjacent first frame portions 10b and 10c, the collision load is transmitted to the adjacent corrugated plate portions 33 connected by the second beam portion 32, and the collision load is borne by these corrugated plate portions 33a and 33b. On the other hand, in the region where the corrugated plate portion 33 is not provided, the first diagonal brace portion 34 and the second diagonal brace portion 35 are absent, so the second beam portion 32 is more likely to deform toward the vehicle interior than in the first embodiment.

[0058] In the region where the corrugated plate portion 33 is not provided, the first diagonal brace portion 34 and the second diagonal brace portion 35 that transmit force from the second beam portion 32 to the first beam portion 31 are absent. Therefore, the first beam portion 31 is less likely to deform toward the vehicle interior before the second beam portion 32 contacts the first beam portion 31. Furthermore, in this region, since the collision load is not transmitted to the first diagonal brace portion 34 and the second diagonal brace portion 35, the collision load is propagated to a wider area of ​​the impact absorbing member 30 in the Y direction.

[0059] Therefore, compared to the first embodiment, the impact load can be absorbed over a wider area of ​​the impact absorbing member 30 in the Y direction. Furthermore, the impact load can be withstood by the two adjacent corrugated plate portions 33a and 33b connected by the first beam portion 31 and the second beam portion 32. Thus, even if there are areas of the impact absorbing member 30 where the corrugated plate portion 33 is not provided, the impact can be fully absorbed until the second beam portion 32 contacts the first beam portion 31, resulting in a reduction in the amount of intrusion of the second frame portion 20 into the vehicle interior.

[0060] To effectively reduce the amount of intrusion of the second frame portion 20 into the vehicle interior, the first top portion 36 of the corrugated plate portion 33 is preferably not located between two adjacent first frame portions 10 in the axial direction (Y direction) of the second frame portion 20. The reason for this is as follows.

[0061] When a collision load is applied to the second wall portion 20b of the second frame portion 20, the collision load is propagated toward the first top portion 36. Therefore, the first wall portion 20a is likely to deform toward the vehicle interior at the location where the first top portion 36 is located. When the corrugated plate portion 33 is continuously provided in the axial direction of the second frame portion 20, as in the first embodiment described above, the first top portions 36 are connected to each other via the first diagonal bracing portions 34 and the second diagonal bracing portions 35. This facilitates the distribution of the collision load among the first top portions 36. Consequently, deformation of the first wall portion 20a is suppressed even at locations where the first top portions 36 are located.

[0062] On the other hand, if the corrugated plate portion 33 is discontinuously arranged in the axial direction of the second frame portion 20, for example, when the first top portion 36 is located in the region between the two first frame portions 10, the collision load tends to concentrate on the first top portion 36 closest to the collision site, and the first wall portion 20a tends to deform toward the vehicle interior at this location. In contrast, by arranging the corrugated plate portion 33 so that the first top portion 36 is not located between the two first frame portions 10, as in the second embodiment, the first frame portions 10 can suppress deformation of the first wall portion 20a toward the vehicle interior at the location where the first top portion 36 is located. This also suppresses deformation of the entire first wall portion 20a toward the vehicle interior.

[0063] In addition, in this embodiment, the area where the corrugated plate portion 33 is not provided is located Figure 7 Although the first top portion 36 of the corrugated plate portion 33 is shown between the first frame portion 10b and the first frame portion 10c, it may also be located between the first frame portion 10a and the first frame portion 10b, or may be located between all the first frame portions 10a to 10c. In either case, it is preferred that the first top portion 36 of the corrugated plate portion 33 is not located in the area between two adjacent first frame portions 10.

[0064] Furthermore, as described in this embodiment, even if the corrugated plate portion 33 of the impact absorbing member 30 is not provided between two adjacent first frame portions 10, the amount of penetration of the second frame portion 20 into the vehicle interior can be reduced. Therefore, the corrugated plate portion 33 only needs to be provided at least in the region R of the second frame portion 20 that connects to the two adjacent first frame portions 10. For example, the corrugated plate portion 33 may also be provided as Figure 9 Set it up like that. Figure 9 In the example shown in FIG. 3 , a first diagonal bracing portion 34 and a second diagonal bracing portion 35 are provided on one corrugated plate portion 33 , and there are three first top portions 36 and three second top portions 37 in total.

[0065] In addition, for example, the corrugated plate portion 33 may also be Figure 10 Set it up like that. Figure 10In the example, two first diagonal bracing portions 34 and two second diagonal bracing portions 35 are provided on one corrugated plate portion 33, and there are five first top portions 36 and second top portions 37 in total. In terms of effectively improving the energy absorption performance, it is preferred that Figure 10 Thus, each corrugated plate portion 33 is provided with a plurality of first diagonal bracing portions 34 and a plurality of second diagonal bracing portions 35 , and a total of five or more first top portions 36 and second top portions 37 are provided.

[0066] The above describes an example of an embodiment of the present invention, but the present invention is not limited to this example. Obviously, anyone skilled in the art will be able to conceive of various variations or modifications within the scope of the technical concept described in the claims, and will understand that these variations or modifications naturally fall within the scope of protection of the present invention.

[0067] For example, although in the above embodiment, the corrugated plate portion 33 of the impact absorbing member 30 extending along the axial direction (Y direction) of the second frame portion 20 is only provided in one row, the impact absorbing member 30 extending along the Y direction can also be arranged in parallel in a plurality of rows in a manner arranged along the axial direction (X direction) of the first frame portion 10.

[0068] Example

[0069] <Simulation (1)>

[0070] use Figure 11 Side pole impact simulations were performed on the analytical models of the vehicle body lower structures shown in Configurations 1 and 2. In this embodiment, the first frame portion is a cross member, and the second frame portion is a rocker. Configuration 1 is a model in which the corrugated plate portion is provided throughout the entire area in the direction in which the impact absorbing member extends. Configuration 2 is a model in which the corrugated plate portion is not provided between the cross members. Configuration 2 is identical to Configuration 1, except for the difference in the area in which the corrugated plate portion is provided.

[0071] In this simulation, a pillar was forced to intrude at a constant speed into the exterior wall of a rocker, and the deformation state of each structure and the amount of penetration into the interior wall of the rocker were evaluated. In the simulation for Structure 1, the pillar collided with the cross member and between the cross members. In the simulation for Structure 2, the pillar collided with the cross member.

[0072] This simulation was conducted using multiple models with varying thicknesses of the beams (first beam and second beam) and the corrugated plate. The material, thickness, and other conditions of the impact absorbing member are shown in Table 1 below. In this simulation, the angle θ ( Figure 5) is set to 60 degrees. Furthermore, the cross member and rocker are made of the same 980 MPa tensile strength steel sheet as the impact absorbing member. Table 1 also shows the amount of intrusion into the inner side wall of the rocker (the amount of deformation at the location experiencing the greatest inward deformation) as simulation results.

[0073] [Table 1]

[0074]

[0075] As shown in the results in Table 1, the amount of intrusion of the rocker into the vehicle interior of the model of Structure 2, in which no corrugated plate portion is provided between the cross members, is reduced compared to Structure 1, in which a corrugated plate portion is provided over the entire area in the extending direction of the impact absorbing member. Figure 11 As can be seen from the deformation states of Structures 1 and 2, the axial deformation area of ​​the rocker in Structure 2 is larger. Furthermore, in this simulation, the model with Structure 2 was approximately 10% to 20% lighter than the model with Structure 1. Therefore, as shown by the simulation results, a structure without corrugated plate sections between the cross members can reduce the amount of rocker intrusion into the vehicle interior and also achieve a lighter impact absorbing member.

[0076] <Simulation (2)>

[0077] like Figure 12 As shown, side pole collision simulations were performed using structures 3 to 5 obtained by changing the interval D of the corrugated plate portion of structure 2 in simulation (1). Figure 12 The structures 1 and 2 shown are the same structures as simulation (1). The gap D is narrowest in structure 3 and gradually widens in the order of structure 3, structure 4, structure 5, and structure 2. Among structures 2 to 5, structure 2 is a model in which the first top 36 of the corrugated plate portion is not located between two adjacent horizontal beams, and structures 3 to 5 are models in which the first top 36 of at least one of the two corrugated plate portions is located between two horizontal beams. Structures 1 to 5 were simulated under the same conditions except that the gap D between the corrugated plate portions was different.

[0078] Focus on Figure 12 In the post-collision deformation states of Configurations 3 to 5 shown, the first top portion 36 of the corrugated plate portion located between the crossmembers exhibits greater deformation, resulting in a slightly greater amount of rocker penetration compared to Configuration 1. On the other hand, Configuration 2, in which the first top portion 36 of the corrugated plate portion is located in the region where the rocker connects to the crossmember, suppresses rocker deformation and significantly reduces rocker penetration compared to the other configurations. The simulation results indicate that, when no corrugated plate portion is provided between the crossmembers, it is preferable that the first top portion 36 of the corrugated plate portion not be located between the crossmembers.

[0079] <Simulation (3)>

[0080] By changing the angle θ between the first and second diagonal bracing parts, Figure 5 ) were subjected to a side pole impact simulation. This simulation used models with angles θ of 30 degrees, 60 degrees, and 90 degrees. The model with an angle θ of 60 degrees was identical to that of Configuration 1. The models with angles θ of 30 and 60 degrees were identical to those of Configuration 1 except for the differences in angles.

[0081] Figure 13 is a graph showing the results of this simulation. Figure 13 As shown in (a), in the model where a corrugated plate portion is provided at the connection between the side rail and the crossbeam, the smaller the angle θ is, the more the amount of entry of the side rail can be suppressed. According to the results of this simulation, the angle θ in the case where a corrugated plate portion is provided at the connection between the side rail and the crossbeam is preferably 70 degrees or less. More preferably, it is 60 degrees or less. In addition, as Figure 13 As shown in (b), for a model with corrugated plate sections between the crossmembers, the closer the angle θ is to 60 degrees, the more the rocker's intrusion is suppressed. Based on the results of this simulation, the angle θ when corrugated plate sections are provided between the crossmembers is preferably between 40 and 80 degrees. It is more preferably 50 degrees or greater, and even more preferably 70 degrees or less.

[0082] Industrial applicability

[0083] The present invention can be applied to the lower body structure of an automobile.

[0084] Description of Reference Numerals

[0085] 1. Vehicle body lower structure; 10. First frame portion; 20. Second frame portion; 20a. First wall portion; 20b. Second wall portion; 21. Hollow portion; 22. Internal member; 22a. Top plate; 22b. Vertical wall; 22c. Flange; 23. External member; 23a. Top plate; 23b. Vertical wall; 23c. Flange; 30. Impact absorbing member; 31. First beam portion; 32. Second beam portion; 33. Corrugated plate portion; 34. First diagonal brace portion; 35. Second diagonal brace portion; 36. First top portion; 37. Second top portion; D. Interval between two adjacent corrugated plate portions; R. Area of ​​the second frame portion connected to the first frame; θ. Angle between the first diagonal brace portion and the second diagonal brace portion.

Claims

1. A lower body structure of an automobile, characterized in that: The lower body structure includes: a plurality of first frame portions arranged at intervals; a second frame portion extending so that the axial direction of the first frame portion becomes a normal direction when viewed from the vehicle height direction and having a hollow portion; and a shock absorbing member disposed in the hollow portion of the second frame portion; The second frame portion includes a first wall portion and a second wall portion facing the first wall portion. The first wall portion is connected to the axially outer side end surface of the first frame portion. The shock absorbing member has: a first beam portion extending along the axial direction of the second frame portion; a second beam portion, which is opposite to the first beam portion; and a corrugated plate portion connected to the first beam portion and the second beam portion between the first beam portion and the second beam portion, The first beam portion is connected to the first wall portion of the second frame portion, The second beam portion is connected to the second wall portion of the second frame portion, The corrugated plate portion has: a first diagonal bracing portion extending from the second beam portion toward the first beam portion; a second diagonal bracing portion extending from the first beam portion toward the second beam portion; a first top portion, which is a connecting portion of the first diagonal bracing portion and the second diagonal bracing portion on the first beam portion side; and The second top portion is a connecting portion between the first diagonal bracing portion and the second diagonal bracing portion on the second beam portion side. The corrugated plate portions are provided at least in regions of the second frame portion connected to two adjacent first frame portions.

2. The automobile lower body structure according to claim 1, wherein: The shock absorbing member has a plurality of the corrugated plate portions. The corrugated plate portions are arranged at intervals along the extending direction of the shock absorbing member. The first top portion of the corrugated plate portion is not located in a region between two adjacent first frame portions.

3. The automobile lower body structure according to claim 1 or 2, characterized in that: The total number of the first top portions and the second top portions is five or more.

4. The automobile underbody structure according to any one of claims 1 to 3, wherein: The second frame portion is a rocker.

5. The vehicle underbody structure according to any one of claims 1 to 3, wherein: The second frame portion is a crash beam.

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