Automobile structural components and electric vehicles

Abstract

An automotive frame member includes a cap member and a closing plate. The cap member includes a top plate, two longitudinal walls, and two flanges. The two longitudinal walls are respectively located between the top plate and the flanges, the two longitudinal walls are opposite to each other, the two flanges are respectively joined to the closing plate, the two longitudinal walls respectively include a plurality of groove portions extending in a direction perpendicular to the length direction of the cap member. The groove portion includes a bottom surface and two side surfaces. The two side surfaces are opposite to each other, the two side surfaces are located on both sides of the bottom surface, and the width a of the groove portion, the depth b of the groove portion, and the height c of the longitudinal wall in the direction perpendicular to the top plate in a cross-section parallel to the top plate satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3.

Description

Technical Field

[0001] The present disclosure relates to automotive frame members that exhibit high energy absorption efficiency, for example, during a collision of an automobile. Background Art

[0002] In recent years, fuel consumption restrictions have been tightened worldwide, demanding improved collision performance and lightweighting of automobile bodies. However, simply replacing the material of automotive frame members with a high-strength and thin-thickness material may cause buckling at an early stage during a collision depending on the shape of the frame member, and it may not necessarily achieve high energy absorption efficiency. The more the portion where the frame member undergoes plastic deformation, the higher the energy absorption performance. However, in the case of early buckling during a collision, a large portion where plastic deformation does not occur remains, and even if the material strength is increased, the degree of improvement in energy absorption performance is small. Therefore, research has been continuously promoted on frame members that can exert the original strength of the material so as not to cause early buckling during a collision. In addition, in electric vehicles, the development of a vehicle body structure in which a large-capacity battery is mounted under the floor has been continuously promoted, and the improvement of frame members such as side sills has also been continuously promoted.

[0003] As a technique for improving energy absorption performance, Patent Document 1 discloses a partition having a substantially U-shaped cross section provided between a side sill and a cross member. The partition of Patent Document 1 is composed of a front face portion, a rear face portion, and a flange, and has recesses in the front face portion and the rear face portion. Patent Document 2 discloses a shock absorption member having a corrugated deformation promoting mechanism provided in a hollow member. Regarding the shock absorption member of Patent Document 2, when a bending load caused by an impact is applied, the corrugated deformation promoting mechanism buckles, thereby converting the bending load into a compressive load in the longitudinal direction, and suppressing cross-sectional collapse. Patent Document 3 discloses a metal shock absorber in which concave or convex ribs are formed on the longitudinal wall of a cap member.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-205797

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2006-207679

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2008-265738 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] The body structure of Patent Document 1 is not a structure aimed at suppressing the buckling of the lower side member itself, so there is room for improvement in terms of improving the energy absorption performance by exerting the material strength. In addition, as a result of the simulation conducted by the present inventor on the impact absorption member of Patent Document 2, there is room for improvement in terms of improving the energy absorption performance by exerting the material strength because a large part of the impact absorption member where no plastic deformation occurs remains. The shock absorber of Patent Document 3 is aimed at protecting the legs of a pedestrian when the pedestrian collides with an automobile, and there is room for improvement in terms of improving the energy absorption performance on the vehicle body side.

[0011] The present disclosure is an invention completed in view of the above problems, and its object is to improve the energy absorption efficiency (mass efficiency of absorbing energy) of automotive framework members.

[0012] Solutions to Solve the Problems

[0013] One technical solution of the present disclosure for solving the above problems is an automotive framework member, characterized in that the automotive framework member includes a cap member and a closing plate, the cap member includes a top plate, two longitudinal walls, and two flanges, the two longitudinal walls are respectively located between the top plate and the flanges, the two longitudinal walls are opposite to each other, the two flanges are respectively joined to the closing plate, the two longitudinal walls respectively include a plurality of groove portions extending in a direction perpendicular to the length direction of the cap member, the groove portion includes a bottom surface and two side surfaces, the two side surfaces are opposite to each other, the two side surfaces are located on both sides of the bottom surface, and the width a of the groove portion, the depth b of the groove portion, and the height c of the longitudinal wall in a direction perpendicular to the top plate in a cross section parallel to the top plate satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3.

[0014] One technical solution of the present disclosure according to another aspect is an automotive framework member, characterized in that the automotive framework member includes a hollow member, the hollow member includes a top plate and two longitudinal walls, the two longitudinal walls are respectively adjacent to the top plate, the two longitudinal walls are opposite to each other, the two longitudinal walls respectively include a plurality of groove portions extending in a direction perpendicular to the length direction of the hollow member, the groove portion includes a bottom surface and two side surfaces, the two side surfaces are opposite to each other, the two side surfaces are located on both sides of the bottom surface, and the width a of the groove portion, the depth b of the groove portion, and the height c of the longitudinal wall in a direction perpendicular to the top plate in a cross section parallel to the top plate satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3.

[0015] Effects of the Invention

[0016] The energy absorption efficiency of the automotive framework member can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view showing the schematic structure of the automotive frame member of the first embodiment.

[0018] Figure 2 It is a view showing a cross-section perpendicular to the member length direction of the portion of the automotive frame member where no groove portion is provided.

[0019] Figure 3 It is a view showing the periphery of the lower side member in a cross-section perpendicular to the vehicle height direction of the electric vehicle.

[0020] Figure 4 It is a top view of the periphery of the groove forming portion of the cap member.

[0021] Figure 5 It is a side view of the periphery of the groove forming portion of the cap member.

[0022] Figure 6 It is Figure 5 The A-A cross-sectional view in

[0023] Figure 7 It is a view showing an example of the deformation mode (out-of-plane bending mode) of the automotive frame member.

[0024] Figure 8 It is Figure 7 The B-B cross-sectional view in

[0025] Figure 9 It is a view showing an example of the deformation mode (in-plane bending mode) of the automotive frame member.

[0026] Figure 10 It is a view showing an example of the deformation mode (axial crushing mode) of the automotive frame member.

[0027] Figure 11 It is Figure 10 The C-C cross-sectional view in

[0028] Figure 12 It is a perspective view showing the schematic structure of the automotive frame member of the second embodiment.

[0029] Figure 13 It is the equivalent of the automotive frame member of the second embodiment Figure 5 The A-A cross-sectional view in

[0030] Figure 14 It is the equivalent of showing an example of the shape of the groove portion Figure 5 The A-A cross-sectional view in

[0031] Figure 15 It is the equivalent of the automotive frame member of the third embodiment Figure 5 The A-A cross-sectional view in

[0032] Figure 16 This is a diagram corresponding to the A-A cross-section of an automotive frame member in which both the first cap member and the second cap member have groove portions. Figure 5 in

[0033] Figure 17 This is a perspective view showing the schematic structure of the automotive frame member of the fourth embodiment.

[0034] Figure 18 This is a diagram corresponding to the A-A cross-section of the automotive frame member of the fourth embodiment. Figure 5 in

[0035] Figure 19 This is a diagram showing an example of the shape of the groove portion.

[0036] Figure 20 This is a diagram showing an example of the shape of the groove portion.

[0037] Figure 21 This is a diagram showing an example of the shape of the groove portion.

[0038] Figure 22 This is a diagram showing the analysis model of the collision simulation.

[0039] Figure 23 This is the load-stroke diagram of simulation (1).

[0040] Figure 24 This is a diagram showing the analysis model of the collision simulation.

[0041] Figure 25 This is the load-stroke diagram of simulation (2).

[0042] Figure 26 This is a diagram showing the relationship between a / c, b / c and the energy absorption efficiency of simulation (3).

[0043] Figure 27 This is a diagram showing the relationship between a / c, b / c and the deformation mode of simulation (3).

[0044] Figure 28 This is a diagram showing the relationship between e / c and the energy absorption efficiency of simulation (4).

[0045] Figure 29 This is a diagram showing the relationship between the interval d of the groove portion and the energy absorption efficiency of simulation (5).

[0046] Figure 30 This is a diagram showing the relationship between a / c, b / c and the energy absorption efficiency of simulation (6). Detailed implementation manners

[0047] An embodiment of the present disclosure will be described below with reference to the accompanying drawings. In addition, in this specification and the drawings, elements having substantially the same functional structure are denoted by the same reference numerals, and redundant descriptions are omitted.

[0048] <First Embodiment>

[0049] Figure 1 FIG. is a schematic view showing the general structure of the vehicle body frame member 1 of the first embodiment. The vehicle body frame member 1 is a member such as a side sill or a bumper skeleton that bears a bending load. The vehicle body frame member 1 of the first embodiment has a cap member 10 and a flat closing plate 20. The cap member 10 is a member whose cross section perpendicular to the member length direction ( Figure 1 the Y direction) is cap-shaped, and the closing plate 20 is a bottom plate joined to the cap member 10. In addition, Figure 1 The X direction, Y direction, and Z direction shown are mutually perpendicular directions. When the vehicle body frame member 1 is a member constituting a side sill, for example, the X direction is the vehicle height direction, the Y direction is the vehicle length direction, and the Z direction is the vehicle width direction. In addition, when the vehicle body frame member 1 is a member constituting a bumper skeleton, for example, the X direction is the vehicle height direction, the Y direction is the vehicle width direction, and the Z direction is the vehicle length direction.

[0050] As Figure 2 shown, the cap member 10 has a top plate 11, two longitudinal walls 12 connected to the top plate 11, and two flanges 13 connected to the longitudinal walls 12. The two longitudinal walls 12 are respectively located between the top plate 11 and the flange 13, and the two longitudinal walls 12 are opposed to each other. In the first embodiment, the vehicle body frame member 1 is constituted by joining the two flanges 13 of the cap member 10 to the closing plate 20. The cap member 10 is formed of, for example, a steel material having a tensile strength of 440 MPa to 1500 MPa, but the raw material of the cap member 10 is not particularly limited, and for example, it may also be an aluminum alloy member, a magnesium alloy member, or the like. Similarly, the closing plate 20 is formed of, for example, a steel material having a tensile strength of 440 MPa to 1500 MPa, but the raw material of the closing plate 20 is not particularly limited, and for example, it may also be an aluminum alloy member, a magnesium alloy member, or the like.

[0051] When the vehicle body frame member 1 is installed on the vehicle body, the top plate 11 of the cap member 10 can be arranged either on the vehicle outer side or on the vehicle inner side with respect to the closing plate 20. Particularly in the case of a side sill, the top plate 11 is preferably arranged on the vehicle outer side with respect to the closing plate 20. This is because if the flange of the cap member is on the vehicle outer side, the flange interferes with the door and the door cannot be closed. In addition, it is preferable to apply the present disclosure to an electric vehicle. This is because by absorbing the impact by the side sill, damage to the battery arranged on the vehicle inner side relative to the side sill can be avoided. Figure 3 FIG. is a view showing the periphery of the side sill 41 in a cross section perpendicular to the vehicle height direction of the electric vehicle 40. As Figure 3As shown, when the vehicle body frame member 1 is a member constituting the lower side member 41, it is preferable that the closing plate 20 is adjacent to the battery 42 placed on the floor (not shown), and the top plate 11 is disposed on the outer side of the vehicle among the outer side and the inner side of the vehicle. In addition, in the present embodiment and the embodiments described later, the top plate 11 is disposed on the outer side of the vehicle among the outer side and the inner side of the vehicle.

[0052] As Figure 1 and Figures 4 to 6 shown, the cap member 10 of the first embodiment has a groove portion 31 extending in a direction perpendicular to the member length direction. From the viewpoint of effectively improving the energy absorption efficiency, it is preferable that the groove portion 31 is formed so as to straddle from the ridge line portion 14 to the ridge line portion 15 as Figure 1 and Figures 4 to 6 shown, that is, it is formed in the range from the inner side end portion of the vehicle of the longitudinal wall 12 to the outer side end portion of the vehicle. The groove portion 31 is provided in the two longitudinal walls 12 of the pair of longitudinal walls 12. The forming method of the groove portion 31 is not particularly limited. For example, after forming the cap member 10, press working is repeatedly performed to gradually increase the depth of the groove portion 31 for forming. In the present specification, the portion where the groove portion 31 is formed as Figure 4 shown is referred to as the "groove forming portion 30". In addition, as Figure 6 shown, in the present specification, the portion of the top plate 11 in the groove forming portion 30 is referred to as the "groove portion top plate 32", the portion of the longitudinal wall 12 in the groove forming portion 30 is referred to as the "groove portion longitudinal wall 33", and the portion of the flange 13 in the groove forming portion 30 is referred to as the "groove portion flange 34".

[0053] The groove portion top plate 32 and the portion of the top plate 11 other than the groove forming portion 30 are in the same plane, and the groove portion flange 34 and the portion of the flange 13 other than the groove forming portion 30 are in the same plane. As Figure 4 shown, the groove portion longitudinal wall 33 of the first embodiment has a bottom surface 31a and side surfaces 31b of the groove portion 31. The bottom surface 31a is a surface parallel to the portion of the longitudinal wall 12 other than the groove forming portion 30, and the side surfaces 31b are a pair of planes connecting the portion of the longitudinal wall 12 other than the groove forming portion 30 and the bottom surface 31a of the groove portion 31. That is, the groove portion 31 includes the bottom surface 31a and two side surfaces 31b, and the two side surfaces 31b are opposite and located on both sides of the bottom surface 31a.

[0054] A plurality of groove forming portions 30 are provided at intervals along the member length direction of the cap member 10. That is, the two longitudinal walls 12 have a plurality of groove portions 31 along the member length direction of the cap member 10. In the first embodiment, the region where the groove forming portion 30 exists only becomes the central portion in the member length direction of the cap member 10, but the groove forming portion 30 can also be provided, for example, in the entire region in the member length direction of the cap member 10. The portion of the longitudinal wall 12 between adjacent groove forming portions 30 forms a shape protruding from the bottom surface 31a of the groove portion 31 by providing a plurality of groove forming portions 30.

[0055] The vehicle body frame member 1 of the first embodiment is configured as described above. In this vehicle body frame member 1, a load is locally applied from the Z direction during a collision, and bending deformation occurs due to the generation of a moment. In the case of the vehicle body frame member 1 of the first embodiment, the groove portions 31 of the cap member 10 are provided not only on the longitudinal walls 12 but also on the ridge line portions 14 between the longitudinal walls 12 and the top plate 11 and the ridge line portions 15 between the longitudinal walls 12 and the flange 13. Thus, compared with the case where the groove portions 31 are not provided on the respective ridge line portions 14 and 15, the surface stiffness of the top plate 11 is increased, and thus the load required for the deformation of the vehicle body frame member 1 can be increased. In addition, since the groove portion 31 has a shape with three planes, i.e., the bottom surface 31a of the groove portion 31 and two side surfaces 31b, the surface stiffness of the top plate 11 can be further increased, and the load required for the deformation of the vehicle body frame member 1 can be further increased. In the vehicle body frame member 1 of the first embodiment, by utilizing their effects, the energy absorption performance can be improved. In addition, since the vehicle body frame member 1 of the first embodiment does not have a structure in which a reinforcing member is newly added, the mass efficiency related to the energy absorption performance can be improved.

[0056] In addition, when the vehicle body frame member 1 is deformed, one of the following deformation modes occurs.

[0057] (Out-of-plane bending mode)

[0058] As Figure 7 and Figure 8 shown, the out-of-plane bending mode is a mode in which the main deformation is the bending of the longitudinal wall 12 of the cap member 10 in the out-of-plane direction in a cross section perpendicular to the member length direction.

[0059] (In-plane bending mode)

[0060] As Figure 9 shown, the in-plane bending mode is a mode in which the main deformation is the bending of the longitudinal wall 12 of the cap member 10 along the member length direction, and the deformation of the longitudinal wall 12 in the out-of-plane direction in a cross section perpendicular to the member length direction is small.

[0061] (Axial crushing mode)

[0062] AsFigure 10 and Figure 11 As shown in Figure 11 , the shaft crushing mode is as follows: in a cross-section perpendicular to the longitudinal direction of the member, the longitudinal walls 12 of the hat member 10 are crushed at shorter intervals, resulting in a corrugated deformation as a whole.

[0063] In order to stably increase the load required for deformation from the initial stage to the final stage of a collision, it is preferable that the automotive frame member 1 is deformed in the shaft crushing mode.

[0064] Here, as shown in Figure 4 , the width of the groove portion 31 in a cross-section parallel to the top plate 11 of the hat member 10 is defined as "a", and the depth of the groove portion 31 in a cross-section parallel to the top plate 11 of the hat member 10 is defined as "b". As shown in Figure 6 , the height of the longitudinal wall 12 in a direction perpendicular to the top plate 11 of the hat member 10 is defined as "c". In addition, the width a of the groove portion 31 refers to the distance between the opposing side surfaces 31b in the longitudinal direction (Y direction) of the member of the hat member 10. The depth b of the groove portion 31 refers to the length from the longitudinal wall 12 to the bottom surface 31a of the groove portion 31 in a direction perpendicular to the longitudinal direction of the member of the hat member 10 in a cross-section parallel to the top plate 11 of the hat member 10 (X direction). The height c of the longitudinal wall 12 refers to the length from the flange 13 to the top plate 11 in a direction perpendicular to the longitudinal direction of the member of the hat member 10 (Z direction). In addition, in the first embodiment, the height c of the longitudinal wall 12 is equal to the height from the groove flange 34 to the groove top plate 32.

[0065] In order for the automotive frame member 1 to easily generate deformation in the shaft crushing mode, the width a of the groove portion 31, the depth b of the groove portion 31, and the height c of the longitudinal wall 12 of the hat member 10 preferably satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3. When this numerical range is satisfied, as shown in the embodiments described later, the deformation of the automotive frame member 1 easily changes to the shaft crushing mode, and the load required for deformation stably increases from the initial stage to the final stage of a collision. Thereby, the energy absorption performance can be further improved.

[0066] In addition, the interval d between adjacent groove portions 31 is preferably 50 mm or less. Since the interval d between the groove portions 31 is 50 mm or less, the deformation in the shaft crushing mode is easily generated, thereby improving the energy absorption efficiency. The smaller the interval d between the groove portions 31, the higher the energy absorption efficiency. However, from the viewpoint of the formability of the hat member 10 having the groove portions 31, the interval d between the groove portions 31 is preferably 10 mm or more. In addition, in order to more easily cause deformation in the shaft crushing mode, the angle θ1 formed by the bottom surface 31a and the side surface 31b of the groove portion 31 is preferably 90 degrees to 95 degrees, and more preferably perpendicular. In addition, in order to more easily cause deformation in the shaft crushing mode, as shown in Figure 6 Figure 6 ​​​​As shown, the angle θ2 formed by the longitudinal wall 33 of the groove portion and the flange 34 of the groove portion is preferably 90 degrees to 100 degrees, and more preferably perpendicular.

[0067] <Second Embodiment>

[0068] As Figure 12 and Figure 13 shown, in the automotive structural member 1 of the second embodiment, the groove portion 31 does not extend to the ridge line portion 14 of the cap member 10. That is, in the automotive structural member 1 of the second embodiment, although one end of the groove portion 31 extends to the vehicle inner side end of the longitudinal wall 12 (in the Figure 14 example is the ridge line portion 15), the other end of the groove portion 31 does not extend to the vehicle outer side end of the longitudinal wall 12 (in the Figure 14 example is the ridge line portion 14). Even for a groove portion 31 having such a shape, when the width a of the groove portion 31, the depth b of the groove portion 31, and the height c of the longitudinal wall 12 of the cap member 10 satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3, the deformation of the axial crushing mode is likely to occur, thereby improving the energy absorption efficiency.

[0069] Figure 14 is a diagram showing an example of the shape of the groove portion 31. Different from the Figure 13 example, Figure 14 in the example of the automotive structural member 1, one end of the groove portion 31 extends to the vehicle outer side end of the longitudinal wall 12 (in the Figure 14 example is the ridge line portion 14), while the other end of the groove portion 31 does not extend to the vehicle inner side end of the longitudinal wall 12 (in the Figure 14 example is the ridge line portion 15). Compared with the automotive structural member 1 having a structure like Figure 14 , the automotive structural member 1 having a structure like Figure 13 can improve the energy absorption efficiency more. When an impact load is input to the automotive structural member 1, the buckling region expands toward the vehicle inner side end of the longitudinal wall 12 starting from the portion where the longitudinal wall 12 first buckles. Therefore, it is advantageous to set the portion where buckling first occurs on the vehicle outer side of the longitudinal wall 12 in terms of improving the energy absorption efficiency. There are two reasons for this. First, since the portion where buckling first occurs is closer to the vehicle outer side end of the longitudinal wall 12, the more regions with corrugated deformation. Second, if the vehicle inner side of the longitudinal wall 12 bends first, the misalignment between the extending direction of the groove portion 31 on the vehicle outer side and the impact input direction increases, making it difficult to cause the deformation of the axial crushing mode. That is, the groove portion 31 is preferably extended to the vehicle inner side end of the longitudinal wall 12. The portion where buckling first occurs is the portion without the groove portion 31. If there is no groove portion 31, buckling first occurs because the deformation resistance is smaller without the groove portion 31. In the case of the Figure 13 automotive structural member 1, the groove portion 31 extends to the vehicle inner side end of the longitudinal wall 12 (inFigure 13 In the example of Figure 13 , the groove portion 31 is not formed at the vehicle outer side end portion of the longitudinal wall 12 (in the example of Figure 13 , the vehicle skeletal member 1 is prone to buckling near the vehicle outer side end portion of the longitudinal wall 12 (in the example of Figure 13 , the ridge line portion 14). On the other hand, Figure 14 , the vehicle skeletal member 1 is prone to buckling near the vehicle inner side end portion of the longitudinal wall 12 (in the example of Figure 14 , the ridge line portion 15). Therefore, compared with the vehicle skeletal member 1 having a structure like Figure 14 , the vehicle skeletal member 1 having a structure like Figure 13 can ensure a relatively large area of corrugated deformation, thereby improving the energy absorption efficiency.

[0070] Furthermore, according to the vehicle skeletal member 1 of the second embodiment, since the groove portion 31 is not formed in the ridge line portion 14 of either the ridge line portion 14 or the ridge line portion 15, the cap member 10 is easier to form compared with the vehicle skeletal member 1 of the first embodiment. That is, the vehicle skeletal member 1 of the second embodiment is a member that can balance the energy absorption efficiency and formability at a relatively high level.

[0071] In the case where the groove portion 31 extends to the vehicle inner side end portion of the cap member 10 (in the example of Figure 13 , the ridge line portion 15) as in the second embodiment, the length e of the groove portion 31 in the direction perpendicular to the top plate 11 of the cap member 10 is preferably 80% or more of the height c of the longitudinal wall 12 of the cap member 10. Thus, when an impact load is input, the deformation of the axial crushing mode is likely to occur, thereby improving the energy absorption efficiency. In addition, the length e of the groove portion 31 refers to the length from the flange 13 to the rounded corner node on the groove portion 31 side of the longitudinal wall 12 at the groove forming portion 30. From the viewpoint of further improving the energy absorption efficiency, the length e of the groove portion 31 is more preferably 90% or more of the height c of the longitudinal wall 12, and further preferably 95% or more of the height c of the longitudinal wall 12.

[0072] <The Third Embodiment>

[0073] In the vehicle skeletal member 1 of the first embodiment, the mating member of the cap member 10 is the closing plate 20. In Figure 15 the vehicle skeletal member 1 of the second embodiment shown in Figure 15 , the mating member also becomes a cap member. In the following description, the cap member described in the first embodiment ( Figure 15The lower member (in the figure) is called the "second cap member 10b". The second cap member 10b also has a top plate 11, a pair of longitudinal walls 12 connected to the top plate 11, and a flange 13 connected to the longitudinal walls 12, just like the first cap member 10a. The vehicle frame member 1 is constituted by joining the first cap member 10a and the second cap member 10b with their respective flanges 13. Also in the vehicle frame member 1 of the second embodiment, the groove portion 31 of the first cap member 10a has a bottom surface 31a and a pair of side surfaces 31b when viewed from a direction perpendicular to the top plate 11, and the groove portion 31 is provided in the range from the ridge line portion 14 to the ridge line portion 15 as Figure 4 shown. Therefore, the energy absorption efficiency can be improved. Figure 15 shown. Therefore, the energy absorption efficiency can be improved.

[0074] In addition, as Figure 16 shown, the groove portion 31 may also be provided in the second cap member 10b in the same manner as in the first cap member 10a. Thereby, the energy absorption efficiency can be further improved. In addition, for the case where the groove portion 31 is provided in the second cap member 10b, it is preferable that the ratio (a / c) of the width a of the groove portion 31 to the sum c of the height c1 of the first cap member 10a and the height c2 of the second cap member 10b is 0.2 to 0.3, and the ratio (b / c) of the depth b of the groove portion 31 to the sum c of the height c1 of the first cap member 10a and the height c2 of the second cap member 10b is 0.2 to 0.3. In addition, the angle θ1 formed by the bottom surface 31a of the groove portion 31 and the side surface 31b of the groove portion 31 is preferably 90 degrees to 95 degrees, and more preferably perpendicular. In addition, the angle θ2 formed by the groove longitudinal wall 33 and the groove flange 34 is preferably 90 degrees to 100 degrees, and more preferably perpendicular.

[0075] Furthermore, when both the first cap member and the second cap member 10b have the groove forming portion 30, the ratio (c2 / c1) of the height c2 of the second cap member 10b to the height c1 of the first cap member 10a is preferably 0.25 or less. When this numerical range is satisfied, deformation in the axial crushing mode is more likely to occur, and the energy absorption efficiency can be improved compared to the case where c2 / c1 exceeds 0.25. c2 / c1 is more preferably 0.2 or less, and further preferably 0.1 or less. That is, the smaller c2 / c1 is, the more preferable it is.

[0076] <Fourth Embodiment>

[0077] The vehicle frame member 1 of the foregoing first embodiment to the third embodiment is constituted by joining a plurality of members, but the vehicle frame member 1 of the fourth embodiment is as Figure 17 and Figure 18It is composed of a hollow member 2 in the shape of a square tube. The hollow member 2 has a top plate 11, two longitudinal walls 12 connected to the top plate 11, and a bottom plate 16 connected to the two longitudinal walls 12. The two longitudinal walls 12 are respectively located between the top plate 11 and the bottom plate 16, and the two longitudinal walls 12 are opposite to each other. In addition, the top plate 11 and the bottom plate 16 are also opposite to each other. The raw material of the hollow member 2 is not particularly limited, for example, it is a steel material, an aluminum alloy member, a magnesium alloy member, etc. In the case where the vehicle frame member 1 of the fourth embodiment is, for example, a member constituting the lower side beam 41 of the electric vehicle 40, similar to the example of Figure 3 , the bottom plate 16 of the hollow member 2 is adjacent to the battery 42 placed on the floor (not shown).

[0078] The vehicle frame member 1 of the fourth embodiment, like the first to third embodiments, has a plurality of groove portions 31 extending in a direction perpendicular to the member length direction of the hollow member 2. From the viewpoint of effectively improving the energy absorption efficiency, it is preferable that the groove portions 31 are formed in such a way as to straddle from the ridge line portion 14 to the ridge line portion 17, that is, formed within the range from the vehicle inner side end portion to the vehicle outer side end portion of the longitudinal wall 12. The groove portions 31 are provided on the two longitudinal walls 12 of a pair of longitudinal walls 12. The forming method of the groove portions 31 is not particularly limited. For example, after forming a square tube-shaped hollow member by using extrusion forming, pressing processing is repeatedly performed to gradually increase the depth of the groove portions 31 for forming. In addition, for example, the groove portions 31 can also be formed by using hydroforming.

[0079] A plurality of groove forming portions 30 are provided along the member length direction of the hollow member 2. That is, the two longitudinal walls 12 have a plurality of groove portions 31 along the member length direction of the hollow member 2. In this specification, the part at the groove forming portion 30 of the top plate 11 is referred to as "groove portion top plate 32", the part at the groove forming portion 30 of the longitudinal wall 12 is referred to as "groove portion longitudinal wall 33", and the part of the groove forming portion 30 of the bottom plate 16 is referred to as "groove portion bottom plate 35". The groove portion top plate 32 and the part of the top plate 11 other than the groove forming portion 30 are in the same plane, and the groove portion bottom plate 35 and the part of the bottom plate 16 other than the groove forming portion 30 are in the same plane. The shape of the groove portion 31 when viewed from above is the same as that of the first to third embodiments. That is, similar to the case of Figure 4 , in the vehicle frame member 1 of the fourth embodiment as well, the groove portion longitudinal wall 33 has a bottom surface 31a and side surfaces 31b of the groove portion 31. The bottom surface 31a is a plane parallel to the part of the longitudinal wall 12 other than the groove forming portion 30, and the side surfaces 31b are a pair of planes connecting the part of the longitudinal wall 12 other than the groove forming portion 30 and the bottom surface 31a of the groove portion 31. That is, the groove portion 31 has a bottom surface 31a and two side surfaces 31b, and the two side surfaces 31b are opposite to each other and located on both sides of the bottom surface 31a.

[0080] The vehicle skeletal member 1 of the fourth embodiment is configured as described above. In the vehicle skeletal member 1 of the fourth embodiment, the width a ( Figure 4 ) of the groove portion 31, the depth b ( Figure 4 ) of the groove portion 31, and the height c ( Figure 18 ) of the longitudinal wall 12 of the hollow member 2 also satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3. Therefore, similarly to the vehicle skeletal members 1 of the first to third embodiments, the energy absorption efficiency can be improved. In addition, the height c of the longitudinal wall 12 of the hollow member 2 is the length from the bottom plate 16 to the top plate 11 in the direction (Z direction) perpendicular to the member length direction. Further, the height c of the longitudinal wall 12 of the hollow member 2 in the fourth embodiment is equal to the height from the groove bottom plate 35 to the groove top plate 32.

[0081] The interval d ( Figure 4 ) between adjacent groove portions 31 is preferably 50 mm or less, similarly to the first to third embodiments. Thereby, the deformation of the axial crushing mode is likely to occur, and the energy absorption efficiency can be improved. From the viewpoint of the formability of the hollow member 2 having the groove portion 31, the interval d of the groove portion 31 is preferably 10 mm or more. In addition, in order to more easily cause the deformation of the axial crushing mode, the angle θ1 ( Figure 4 ) formed by the bottom surface 31a and the side surface 31b of the groove portion 31 is preferably 90 degrees to 95 degrees, and more preferably perpendicular. In addition, in order to more easily cause the deformation of the axial crushing mode, as Figure 18 shows, the angle θ3 formed by the groove longitudinal wall 33 and the groove bottom plate 35 is preferably 80 degrees to 90 degrees, and more preferably perpendicular.

[0082] Similar to the case of the second embodiment shown in Figure 12 , when the vehicle skeletal member 1 is composed of the hollow member 2, the groove portion 31 may not be formed in the entire area from the vehicle inner side end portion of the longitudinal wall 12 (the ridge line portion 17 in the example of Figure 19 ) to the vehicle outer side end portion (the ridge line portion 14 in the example of Figure 19 ). When the groove portion 31 is not formed to the vehicle outer side end portion as in Figure 19 , the length e of the groove portion 31 in the direction perpendicular to the top plate 11 of the hollow member 2 is preferably a length of 80% or more of the height c of the longitudinal wall 12 of the hollow member 2. Thereby, similar to Figure 19 , Figure 13The vehicle frame member 1 of the second embodiment as described above can also achieve a high level of balance between energy absorption efficiency and formability. From the perspective of further improving the energy absorption efficiency, the length e of the groove portion 31 is preferably 90% or more of the height c of the longitudinal wall 12, and more preferably 95% or more. In addition, when the vehicle frame member 1 is composed of the hollow member 2, the length e of the groove portion 31 refers to the length from the bottom plate 16 of the hollow member 2 to the rounded corner node on the groove portion 31 side of the longitudinal wall 12 at the groove forming portion 30.

[0083] One embodiment of the present disclosure has been described above, but the present disclosure is not limited to this example. Obviously, those skilled in the art can conceive of various modification examples or alteration examples within the scope of the technical idea described in the claims, and it can be understood that these modification examples or alteration examples also belong to the protection scope of the present disclosure.

[0084] For example, in the above embodiment, the shape of the groove portion 31 provided with respect to the longitudinal wall 12 is concave, but it may be convex like Figure 20 or Figure 21 In this case as well, as long as the width a of the groove portion 31, the depth b of the groove portion 31, and the height c of the longitudinal wall 12 satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3, the deformation of the axial crushing mode is likely to occur, thereby improving the energy absorption efficiency. In addition, in the case of the convex groove portion 31, similarly to the foregoing embodiment, the length e of the groove portion 31 is preferably 80% or more of the height c of the longitudinal wall 12. In addition, in the case of the convex groove portion 31, similarly to the foregoing embodiment, the interval d between the groove portions 31 is preferably 50 mm or less.

[0085] Examples

[0086] <Simulation (1)>

[0087] As an example of the vehicle frame member of the present disclosure, an analysis model (structure 1) as shown in Figure 22 was fabricated, and a simulation of a side pole impact was performed. Figure 22 The analysis model has the same structure as the Figure 1 shown vehicle frame member, and is composed of a cap member 10 and a closing plate 20. The raw materials of the cap member 10 and the closing plate 20 are steel with a tensile strength of 1180 MPa and a plate thickness of 1.6 mm. A plurality of groove forming portions 30 are provided at the central portion in the member length direction of the cap member 10. The overall length of the cap member 10 is 1500 mm, and the height c (length in the Z direction) of the longitudinal wall 12 and the width (length in the X direction) of the top plate 11 are 100 mm respectively. The width a and the depth b of the groove portion 31 are 20 mm respectively. That is, the values of a / c and b / c described above are 0.2 respectively. The interval between the grooves is 20 mm.

[0088] The simulation is carried out by pressing a cylindrical collider 50 with a radius of 127 mm against the closing plate 20 and displacing the collider 50 at a speed of 1.8 km / h. In this simulation, a rigid wall is arranged above the top plate 11. In addition, as a comparative example, an analysis model (structure 2) in which the cap member does not have a groove portion was fabricated and the same simulation as the above conditions was carried out.

[0089] Figure 23 It is the load-stroke diagram in simulation (1). Figure 23 The arrow direction in is the input direction. As Figure 23 shown, the load of structure 1 is larger than that of structure 2 without a groove portion, so the energy absorption performance is improved.

[0090] <Simulation (2)>

[0091] Like Figure 24 that, a simulation was carried out using an analysis model in which a rigid wall is arranged under the closing plate 20 and the collider 50 is brought into contact with the top plate 11 of the cap member 10. In addition, other simulation conditions are the same as those in simulation (1).

[0092] Figure 25 It is the load-stroke diagram in simulation (2). Figure 25 The arrow direction in is the input direction. As Figure 25 shown, the load of structure 1 is larger than that of structure 2 without a groove portion, so the energy absorption performance is improved. According to the results of simulations (1) and (2), it can be seen that whether the top plate 11 is arranged on the vehicle outer side or the vehicle inner side, an improvement effect in energy absorption performance is obtained.

[0093] <Simulation (3)>

[0094] Next, analysis models with different ratios of the width a ( Figure 4 ) of a plurality of groove portions to the height c ( Figure 6 ) of the longitudinal wall and the ratio of the depth b ( Figure 4 ) of the groove portion to the height c ( Figure 6 ) of the longitudinal wall were fabricated, and simulations were carried out using each analysis model. In addition, other simulation conditions are the same as those in simulation (1).

[0095] Summarizing the relationship between a / c, b / c and the energy absorption efficiency in simulation (3), it is as Figure 26 shown. Figure 26 The "suitable range" shown means a range where the energy absorption efficiency (absorbed energy / mass) is 5.0 [kN·mm / kg] or more. As Figure 26 shown, when a / c is 0.2 to 0.3 and b / c is 0.2 to 0.3, the energy absorption efficiency becomes particularly high. As Figure 27As shown, in this simulation, when a / c is 0.2 - 0.3 and b / c is 0.2 - 0.3, axial crushing mode deformation occurred in the automotive structural member.

[0096] <Simulation (4)>

[0097] Next, in a structure where the groove portion 31 does not extend to the ridge line portion 14 on the top plate 11 side of the longitudinal wall 12 as shown in Figure 13 Analysis models with different ratios of the length e of the multiple groove portions to the height c of the longitudinal wall were fabricated, and simulations were performed using each analysis model. In addition, other simulation conditions were the same as those in Simulation (2).

[0098] Figure 28 Fig. shows the relationship between e / c and the energy absorption efficiency in Simulation (4). As shown in Figure 28 When e / c is 0.8 or more, the energy absorption efficiency increases dramatically compared to when e / c is less than 0.8. In addition, under the conditions of this simulation, when e / c is 0.8 and when e / c is 1.0, axial crushing mode deformation occurred in the automotive structural member. That is, when the length e of the groove portion is 80% or more of the height c of the longitudinal wall, axial crushing mode deformation is likely to occur, thereby effectively improving the energy absorption efficiency.

[0099] <Simulation (5)>

[0100] Next, analysis models with different intervals d ( Figure 4 ) of the groove portions were fabricated, and simulations were performed using each analysis model. In addition, other simulation conditions were the same as those in Simulation (2).

[0101] Figure 29 Fig. shows the relationship between the interval d of the groove portion and the energy absorption efficiency in Simulation (5). As shown in Figure 29 Under the conditions of this simulation, when the interval d of the groove portion is 50 mm or less, axial crushing mode deformation occurs and the energy absorption efficiency increases.

[0102] <Simulation (6)>

[0103] Next, an analysis model in which the automotive structural member is composed of a first cap member and a second cap member was fabricated and a simulation was performed. The raw materials of the first cap member and the second cap member are steel with a tensile strength of 1180 MPa. In the first cap member and the second cap member as shown in Figure 16The groove portions are provided separately as described above. In this simulation, the ratio (c2 / c1) of the height c2 of the second cap member to the height c1 of the first cap member is 0.25. The shape of the groove portion is the same in the first cap member and the second cap member except for the different heights of the cap members. Other simulation conditions are the same as those in Simulation (1). The simulation is carried out in a plurality of analysis models with different widths a and depths b of the groove portion.

[0104] Summarizing the relationship between a / c, b / c and the energy absorption efficiency in Simulation (6), it is as Figure 30 shown. "c" is the sum of the height c1 of the first cap member and the height c2 of the second cap member. As Figure 30 shown, the "suitable range" means the range where the energy absorption efficiency is 5.0 [kN*mm / kg] or more. When a / c is 0.2 to 0.3 and b / c is 0.2 to 0.3, which is the same as in Simulation (3), axial crushing mode deformation occurs in the automotive frame member, and the mass efficiency of the energy absorption performance is improved. In addition, in this simulation, when a / c is less than 0.2 and b / c is 0.2 to 0.3, the deformation mode of the automotive frame member is an in-plane deformation mode, but the energy absorption efficiency is 5.0 [kN*mm / kg] or more. The reason for such a result is that when the automotive frame member deforms, the load increases by the contact between the longitudinal wall located between the groove portions and the adjacent longitudinal wall.

[0105] Industrial Applicability

[0106] The technology of the present disclosure can be applied to the lower side beam, bumper skeleton, etc. of an automobile.

[0107] Explanation of Reference Signs

[0108] 1. Automotive frame member; 2. Hollow member; 10. Cap member; 10a. First cap member; 10b. Second cap member; 11. Top plate; 12. Longitudinal wall; 13. Flange; 14. Ridge line portion; 15. Ridge line portion; 16. Bottom plate; 17. Ridge line portion; 20. Closing plate; 30. Groove forming portion; 31. Groove portion; 31a. Bottom surface of the groove portion; 31b. Side surface of the groove portion; 32. Groove portion top plate; 33. Groove portion longitudinal wall; 34. Groove portion flange; 35. Groove portion bottom plate; 40. Electric vehicle; 41. Lower side beam; 42. Battery; 50. Collider; a. Width of the groove portion; b. Depth of the groove portion; c. Height of the longitudinal wall; d. Interval of the groove portion; e. Length of the groove portion; θ1. Angle formed by the bottom surface and the side surface of the groove portion; θ2. Angle formed by the groove portion longitudinal wall and the groove portion flange; θ3. Angle formed by the groove portion longitudinal wall and the groove portion bottom plate.

Claims

1. An automotive structural member, wherein, the automotive structural member includes a cap member and a closing plate, the cap member includes a top plate, two longitudinal walls, and two flanges, the two longitudinal walls are respectively located between the top plate and the flanges, the two longitudinal walls are opposite to each other, the two flanges are respectively joined to the closing plate, the two longitudinal walls respectively include a plurality of groove portions extending in a direction perpendicular to the length direction of the cap member, the groove portion includes a bottom surface and two side surfaces, the two side surfaces are opposite to each other, the two side surfaces are located on both sides of the bottom surface, the width a of the groove portion, the depth b of the groove portion, and the height c of the longitudinal wall in a direction perpendicular to the top plate in a cross-section parallel to the top plate satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3, the automotive structural member deforms in an axial crushing mode, and the axial crushing mode is a mode in which the longitudinal walls of the cap member are crushed at a short interval in a cross-section perpendicular to the length direction, resulting in a corrugated deformation as a whole.

2. The automotive structural member according to claim 1, wherein, the groove portion extends to the vehicle inner side end of the longitudinal wall, the length e of the groove portion in a direction perpendicular to the top plate is a length of 80% or more of the height c of the longitudinal wall.

3. The automotive structural member according to claim 1 or 2, wherein, the interval d of the groove portion is 50 mm or less.

4. An automotive structural member, wherein, the automotive structural member includes a hollow member, the hollow member includes a top plate, a bottom plate, and two longitudinal walls, the top plate is opposite to the bottom plate, the two longitudinal walls are respectively located between the top plate and the bottom plate, the two longitudinal walls are opposite to each other, the two longitudinal walls respectively include a plurality of groove portions extending in a direction perpendicular to the length direction of the hollow member, the groove portion includes a bottom surface and two side surfaces, the two side surfaces are opposite to each other, the two side surfaces are located on both sides of the bottom surface, the width a of the groove portion, the depth b of the groove portion, and the height c of the longitudinal wall in a direction perpendicular to the top plate in a cross-section parallel to the top plate satisfy the relationship of 0.2 ≤ a / c ≤ 0.3 and 0.2 ≤ b / c ≤ 0.3, the automotive structural member deforms in an axial crushing mode, and the axial crushing mode is a mode in which the longitudinal walls of the hollow member are crushed at a short interval in a cross-section perpendicular to the length direction, resulting in a corrugated deformation as a whole.

5. The automotive structural member according to claim 4, wherein, the groove portion extends to the vehicle inner side end of the longitudinal wall, the length e of the groove portion in a direction perpendicular to the top plate is a length of 80% or more of the height c of the longitudinal wall.

6. The automotive structural member according to claim 4 or 5, wherein, the interval d of the groove portion is 50 mm or less.

7. An electric vehicle, wherein, the electric vehicle includes: a lower side beam having the automotive structural member according to any one of claims 1 to 3; and a battery, in a cross-section perpendicular to the vehicle height direction, the closing plate is adjacent to the battery, and the top plate is disposed on the vehicle outer side.

8. An electric vehicle, wherein, The electric vehicle includes: a lower side beam of the vehicle bone structure member according to any one of claims 4 to 6; and a battery, In a cross section perpendicular to the vehicle height direction, the bottom plate is adjacent to the battery, The top plate is disposed on the outer side of the vehicle.

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