Reinforcing member for side sill

Abstract

To provide a reinforcing member for a side sill capable of restraining reduction in an energy absorbing quantity per unit weight, while controlling a deformation form.SOLUTION: The side sill reinforcement member includes a plurality of closed cross-sectional portions 10 disposed along the vehicle-width direction, each of the plurality of closed cross-sectional portions 10 has a wall portion 1y orthogonal to the vehicle-height direction, the plurality of closed cross-sectional portions 10 includes a first closed cross-sectional portion 11 disposed on an outermost side in the vehicle and a second closed cross-sectional portion 12 disposed second from the outer side in the vehicle, an initial irregularity 2 is set in the second closed cross-sectional portion 12, and the initial irregularity 2 is not set in the first closed cross-sectional portion 11.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a reinforcing member for a side sill. [Background technology]

[0002] An automobile is provided with an energy absorbing member in a part of the body that collapses and deforms during a collision to absorb collision energy. Patent Document 1 discloses an energy absorbing member as a reinforcing member for reinforcing the side sill of an automobile, in which closed cross-sectional portions (compartments in Patent Document 1) are arranged in series in the width direction of the vehicle. In the energy absorbing member disclosed in Patent Document 1, the compartment-forming portion that forms the compartment located closest to the collision surface is curved and biased so that it juts outward. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-25058 Summary of the Invention [Problem to be solved by the invention]

[0004] In the energy absorption member disclosed in Patent Document 1, the initial deformation load is reduced and it is not possible to ensure the amount of energy absorbed per unit weight. In other words, if a part of the reinforcing member is biased to control the deformation form, the deformation load is reduced, resulting in a problem of a decrease in the amount of energy absorbed per unit weight.

[0005] The present invention has been made in view of the above-mentioned problems, and provides a reinforcing member for a side sill that can suppress a decrease in the amount of energy absorption per unit weight while controlling deformation. [Means for solving the problem]

[0006] The present invention provides a reinforcing member for a side sill, comprising a plurality of closed cross-sectional portions arranged along the vehicle width direction of the vehicle, each of the plurality of closed cross-sectional portions having a wall portion perpendicular to the vehicle height direction of the vehicle, the plurality of closed cross-sectional portions including a first closed cross-sectional portion arranged at the outermost position of the vehicle and a second closed cross-sectional portion arranged second from the outside of the vehicle, wherein an initial irregularity is set for the second closed cross-sectional portion and the initial irregularity is not set for the first closed cross-sectional portion.

[0007] According to the above configuration, since the second closed cross-sectional portion has an initial irregularity, it is possible to control the deformation mode during a collision. Furthermore, since the first closed cross-sectional portion has no initial irregularity, it is possible to suppress a decrease in the deformation load and a decrease in the amount of energy absorbed per unit weight. In other words, according to the above configuration, it is possible to suppress a decrease in the amount of energy absorbed per unit weight while controlling the deformation mode.

[0008] The plurality of closed cross-sectional portions may further include a third closed cross-sectional portion that is arranged third from the outside of the vehicle, and the initial irregularity of the third closed cross-sectional portion may not be set.

[0009] According to the above-described configuration, it is possible to suppress a decrease in the amount of energy absorbed per unit weight.

[0010] When the number of the multiple closed cross-sectional portions is odd, the initial irregularity may be set to an inward convex shape that protrudes inward, and when the number of the multiple closed cross-sectional portions is even, the initial irregularity may be set to an outward convex shape that protrudes outward.

[0011] During a collision, the directions of buckling deformation of adjacent closed cross-sectional portions tend to be alternate. Specifically, a closed cross-sectional portion adjacent to a closed cross-sectional portion that has undergone outward protruding deformation (outward buckling deformation) is more likely to undergo inward protruding deformation (inward buckling deformation). For this reason, as in the above configuration, when the number of closed cross-sectional portions is odd, the initial irregularity set in the second-outer closed cross-sectional portion is set to an inward convex shape. When the number of closed cross-sectional portions is even, the initial irregularity set in the second-outer closed cross-sectional portion is set to an outward convex shape. This allows the innermost closed cross-sectional portion (farthest from the collision surface) to induce outward deformation. This makes it possible to suppress the collapse deformation of the side sill reinforcement member.

[0012] The amount of protrusion of the initial irregularity relative to the wall portion may be 50% or more and 150% or less of the thickness of the wall portion.

[0013] According to the above-described configuration, it is possible to suppress a decrease in the amount of energy absorption per unit weight while controlling the deformation form.

[0014] The initial irregularity may have a thick portion that is thickened, and the thickness of the thick portion may be 10% or more and 30% or less of the thickness of a thin portion that is thinner than the thick portion.

[0015] According to the above-described configuration, it is possible to suppress a decrease in the amount of energy absorption per unit weight while controlling the deformation form.

[0016] The wall portion may be thicker on an outer side of the vehicle in the vehicle width direction than on an inner side of the vehicle.

[0017] According to the above configuration, the energy absorption efficiency can be improved and the amount of energy absorption per unit weight can be improved compared to when the initial irregularity is set in the closed cross-sectional portion on the closest impact surface side. [Effects of the Invention]

[0018] According to the reinforcing member for a side sill according to the present invention, it is possible to suppress a decrease in the amount of energy absorption per unit weight while controlling deformation. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic view of a vehicle equipped with a side sill reinforcing member according to a first embodiment of the present invention. [Figure 2] 1 is a schematic view showing a lower space and its vicinity according to a first embodiment of the present invention. [Figure 3] 1A and 1B are diagrams showing the configuration of a reinforcing member according to a first embodiment of the present invention. [Figure 4A] FIG. 3 is a diagram showing the configuration of a reinforcing member according to Comparative Example 1 of the present invention. [Figure 4B] FIG. 10 is a diagram showing the configuration of a reinforcing member according to Comparative Example 2 of the present invention. [Figure 5] 2 is a graph showing the load-displacement relationship for an example of the present invention and comparative examples 1 and 2. [Figure 6] 1 is a graph showing the relationship between EA efficiency and EA amount per unit weight for an example of the present invention and comparative examples 1 and 2. [Figure 7] 1A and 1B are diagrams showing modified embodiments of an example of the present invention and comparative examples 1 and 2. [Figure 8A] FIG. 4 is a view showing a reinforcing member according to a first modified example of the first embodiment of the present invention. [Figure 8B] FIG. 10 is a view showing a reinforcing member according to a second modified example of the first embodiment of the present invention. [Figure 8C] FIG. 10 is a view showing a reinforcing member according to a third modified example of the first embodiment of the present invention. [Figure 9] FIG. 6 is a view showing a reinforcing member according to a second embodiment of the present invention. [Figure 10] 10A and 10B are diagrams showing the configuration of a reinforcing member according to a reference example of the present invention. [Figure 11] 1 is a graph showing the relationship between load and EA amount and displacement in Comparative Example 1 and Reference Examples 1 and 2 of the present invention. [Figure 12] 1 is a graph showing the relationship between EA efficiency and EA amount per unit weight in Comparative Example 1 and Reference Examples 1 and 2 of the present invention. [Figure 13]10A and 10B are views showing modified examples of a reinforcing member according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] (First embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings referred to below, hatching indicating cross sections is omitted.

[0021] 1, a side sill reinforcing member 1 (hereinafter referred to as "reinforcing member 1") is provided on a vehicle V such as a passenger car, a truck, a work vehicle, or other mobility vehicle. The reinforcing member 1 is used as a member for reinforcing a side sill 100, which will be described later.

[0022] In this embodiment, the vehicle V is an electric vehicle equipped with a motor and a battery B (secondary battery), not shown. The vehicle V runs by driving the motor with power supplied from the battery B. Note that the vehicle V is not limited to an electric vehicle, and may be a hybrid vehicle.

[0023] In the following, the vehicle length direction of the vehicle V is referred to as the "X direction," the vehicle width direction of the vehicle V is referred to as the "Y direction," and the vehicle height direction of the vehicle V is referred to as the "Z direction." The front side in the X direction is referred to as the "+X side," the rear side is referred to as the "-X side," the right side in the Y direction is referred to as the "-Y side," the left side is referred to as the "+Y side," the upper side in the Z direction is referred to as the "+Z side," and the lower side is referred to as the "-Z side." In this embodiment, the direction from the +Y side to the -Y side is the direction of the collision load (collision direction) when a colliding object such as a pole collides with the vehicle V.

[0024] (Configuration of the lower space and its surroundings) Fig. 2 is a schematic diagram of the lower space SU of the vehicle V and its vicinity. In detail, Fig. 2 is a diagram of the lower space SU on the +Y side and its vicinity as viewed along the X direction (from the front). Note that the -Y side of the lower space SU is reversed from the +Y side, and the other configurations are substantially the same.

[0025] 2, the vehicle V further includes a floor panel FP, a floor cloth FC, and a side sill 100 in addition to the battery B. The vehicle V further includes a ladder frame (not shown) and the like in the lower space SU.

[0026] The floor panel FP forms the lower surface of the vehicle compartment SR and separates the vehicle compartment SR from the lower space SU.

[0027] The floor cross member FC is a frame member for increasing the rigidity of the vehicle V. The floor cross member FC is disposed on the +Z side of the floor panel FP and extends in the Y direction.

[0028] The side sill 100 extends along the X direction and forms the lower edge of the door opening of the vehicle V. The side sill 100 is disposed further outward in the Y direction from the floor panel FP and the floor cloth FC. In this specification, the outer side of the vehicle V in the Y direction is referred to as the "outside of the vehicle V," and the inner side of the vehicle V in the Y direction is referred to as the "inside of the vehicle V." Furthermore, since the outermost side of the vehicle V is the side that is expected to be hit by a colliding object, hereinafter, the outer side of the vehicle V may be referred to as the "collision surface side," and the opposite side may be referred to as the "rear side."

[0029] (Side sill) The side sill 100 has an outer member 101 and an inner member 102. The outer member 101 is disposed further outward from the vehicle V than the inner member 102. The inner member 102 is joined to the floor panel FP and the floor cross member FC by welding (e.g., resistance spot welding) and fastening members SW (e.g., bolts).

[0030] The outer member 101 and the inner member 102 each have a hat-shaped cross section when viewed along the X direction. The outer member 101 and the inner member 102 are joined by welding or the like at the flanges of the outer member 101 and the inner member 102. This forms an internal space SS between the outer member 101 and the inner member 102.

[0031] (reinforcing member) In the event of a collision from the Y direction of the vehicle V (side collision), the reinforcing member 1 absorbs collision energy while undergoing crushing deformation sequentially from the colliding side, thereby reinforcing the side sill 100. In this embodiment, the reinforcing member 1 is disposed in the internal space SS of the side sill 100. The inner portion of the reinforcing member 1 of the vehicle V is joined to the floor panel FP and the floor cloth FC. The inner portion of the reinforcing member 1 is joined together with the side sill 100 by fastening members SW. Meanwhile, the outer portion of the reinforcing member 1 of the vehicle V is joined to an outer member 101. The outer portion of the vehicle V is joined to the outer member 101 by adhesive G or the like.

[0032] The reinforcing member 1 is a hollow extrusion formed by extruding metal. The reinforcing member 1 extends parallel to the side sill 100, that is, in the X direction, and has a uniform cross section (transverse cross section) perpendicular to the X direction. In this embodiment, the reinforcing member 1 has a dimension of 1600 mm in the X direction, a dimension (external dimension) of 155 mm in the Y direction, and a dimension (external dimension) of 50 mm in the Z direction. For example, the dimension (external dimension) in the Y direction is a maximum of 250 mm and is generally 200 mm or less. The dimension (external dimension) in the Z direction is 30 mm or more and 80 mm or less. Since an increase in the dimension in the Z direction increases the weight, it is desirable to set it small. In this embodiment, the reinforcing member 1 is an extrusion made of a 6000 series aluminum alloy.

[0033] Fig. 3 is a diagram showing the reinforcing member 1 shown in Fig. 2. As shown in Fig. 3, the reinforcing member 1 has two horizontal walls 1y (an example of a wall portion) and four vertical walls 1t. The wall thickness dt of the wall portions constituting the reinforcing member 1 is uniform, and the thickness dt of each of the horizontal walls 1y and the vertical walls 1t is equal. In this embodiment, the thickness dt is 5 mm.

[0034] The two lateral walls 1y include a first lateral wall 11y (upper wall) and a second lateral wall 12y (lower wall). The first lateral wall 11y and the second lateral wall 12y have an XY plane perpendicular to the Z direction and face each other in the Z direction.

[0035] The four vertical walls 1t include a first vertical wall 11t (outer wall), a second vertical wall 12t (outer partition wall), a third vertical wall 13t (inner partition wall), and a fourth vertical wall 14t (inner wall). The first vertical wall 11t, the second vertical wall 12t, the third vertical wall 13t, and the fourth vertical wall 14t have an XZ plane perpendicular to the Y direction and face each other in the Y direction.

[0036] In this embodiment, the reinforcing member 1 has a hollow portion (a space defined by the first horizontal wall 11y, the second horizontal wall 12y, the first vertical wall 11t, and the fourth vertical wall 14t) that is divided into three portions by two vertical walls 1t (the second vertical wall 12t and the third vertical wall 13t). In other words, the reinforcing member 1 has a so-called harmonica structure, and the three divided spaces are fixed to the side sill 100 so as to be aligned in the Y direction.

[0037] Hereinafter, each of the three partitioned spaces will be referred to as a "closed cross-sectional portion 10," and the three closed cross-sectional portions 10 will be referred to as a "first closed cross-sectional portion 11," a "second closed cross-sectional portion 12," and a "third closed cross-sectional portion 13," in that order from the outside of the vehicle V. In other words, the first closed cross-sectional portion 11 is located on the outermost side of the vehicle V, the second closed cross-sectional portion 12 is located second from the outside, and the third closed cross-sectional portion 13 is located third from the outside.

[0038] In this embodiment, the first closed cross-sectional portion 11 and the third closed cross-sectional portion 13 each have a rectangular shape (a rectangular cross section) when viewed along the X direction, and the second closed cross-sectional portion 12 has a rectangular shape in the Y direction with a portion recessed inward in the Z direction. The first closed cross-sectional portion 11, the second closed cross-sectional portion 12, and the third closed cross-sectional portion 13 each have the same dimension in the Y direction. Specifically, the dimension of the first closed cross-sectional portion 11, the second closed cross-sectional portion 12, and the third closed cross-sectional portion 13 in the Y direction is each 45 mm.

[0039] (Initial irregularity) In this embodiment, the initial irregularity 2 is set only in the second closed cross-sectional portion 12. In other words, the initial irregularity 2 is not set in the first closed cross-sectional portion 11 and the third closed cross-sectional portion 13.

[0040] The initial imperfection 2 is provided to control the deformation form of the reinforcing member 1. The initial imperfection 2 is set to cause the reinforcing member 1 to buckle and deform into a desired form. The initial imperfection 2 is a deviation (asymmetry) from a configuration in which stress is uniform when a load is applied to the reinforcing member 1, and is, for example, an uneven shape portion set to cause preferential deformation by providing a difference in strength compared to the other closed cross-sectional portions 10 (the first closed cross-sectional portion 11 and the third closed cross-sectional portion 13) in the initial shape, or to control the direction of deformation.

[0041] The initial imperfections 2 are configured so that when a load acts on the reinforcing member 1, a part of the second closed cross-sectional portion 12 is preferentially deformed, and such initial imperfections 2 are not provided in the first closed cross-sectional portion 11 and the third closed cross-sectional portion 13. In this embodiment, the initial imperfections 2 are provided only in the lateral walls 1y (each of the first lateral wall 11y and the second lateral wall 12y) that define the second closed cross-sectional portion 12, and each of the first lateral wall 11y and the second lateral wall 12y is configured so as to easily buckle and deform in a desired direction.

[0042] Specifically, the initial irregularity 2 is constituted by a concave portion (inwardly convex shape) or a convex portion (outwardly convex shape) formed on the lateral wall 1y that defines the second closed cross-sectional portion 12. In other words, the second closed cross-sectional portion 12 has a concave portion or a convex portion, and the lateral wall 1y that defines the first closed cross-sectional portion 11 and the lateral wall 1y that defines the third closed cross-sectional portion 13 are constituted only by flat walls (flat walls perpendicular to the Z direction in this embodiment). In other words, the lateral wall 1y that defines the first closed cross-sectional portion 11 and the lateral wall 1y that defines the third closed cross-sectional portion 13 do not have a concave portion or a convex portion.

[0043] In this embodiment, the initial irregularities 2 are provided in the entire region of each of the first lateral wall 11y and the second lateral wall 12y that define the second closed cross-sectional portion 12. More specifically, the initial irregularities 2 are all positioned differently in the Z direction from the lateral walls 1y that define the adjacent closed cross-sectional portions 10. More specifically, all of the lateral walls 1y that define the second closed cross-sectional portion 12 are positioned more inward of the closed cross-sectional portion 10 than the lateral walls 1y that define the adjacent closed cross-sectional portions 10. In other words, the initial irregularities 2 provided in each of the first lateral wall 11y and the second lateral wall 12y have an inwardly convex shape.

[0044] Hereinafter, the initial irregularity 2 provided in the first lateral wall 11y will be referred to as a "first initial irregularity 21," and the initial irregularity 2 provided in the second lateral wall 12y will be referred to as a "second initial irregularity 22."

[0045] (1st initial irregularity) The first initial irregularity 21 protrudes further inward (in the -Z direction) of the second closed cross-sectional portion 12 than the first horizontal wall 11y that defines the adjacent closed cross-sectional portion 10. The first initial irregularity 21 has a first flat portion 21a and two first connecting portions 21b. The first connecting portions 21b have a flat surface that is an XY plane perpendicular to the Z direction.

[0046] The first flat portion 21a is located inside (on the −Z side of) the second closed cross-sectional portion 12 by a distance d1 from the first lateral wall 11y of the adjacent closed cross-sectional portion .

[0047] The two first connecting portions 21b each have both ends of the first flat portion 21a in the Y direction as their base ends and extend to the first horizontal wall 11y of the adjacent closed cross-sectional portion 10. The first connecting portions 21b are inclined so that the further they are from the first flat portion 21a in the Y direction, the further they are from the first flat portion 21a in the Z direction.

[0048] (2nd initial irregularity) The second initial irregularity 22 protrudes inward (in the +Z direction) of the second closed cross-sectional portion 12 beyond the second lateral wall 12y that defines the adjacent closed cross-sectional portion 10. The second initial irregularity 22 has a second flat portion 22a and two second connecting portions 22b. The second flat portion 22a has a flat surface that is an XY plane perpendicular to the Z direction.

[0049] The second flat portion 22a is located inside (on the +Z side of) the second closed cross-sectional portion 12 by a distance d2 from the second lateral wall 12y of the adjacent closed cross-sectional portion .

[0050] The two second connection portions 22b each have both ends of the second flat portion 22a in the Y direction as their base ends and extend to the second horizontal wall 12y of the adjacent closed cross-section portion 10. The second connection portions 22b are inclined so that the further they are from the second flat portion 22a in the Y direction, the further they are from the second flat portion 22a in the Z direction. Note that the first connection portion 21b and the second connection portion 22b may be perpendicular to the first flat portion 21a and the second flat portion 22a.

[0051] Hereinafter, in the Z direction, the distance (an example of the protrusion amount) of the first flat portion 21a from the first transverse wall 11y of the adjacent closed cross-sectional portion 10 will be referred to as the "first depth d1" of the first initial irregularity 21, and the distance (an example of the protrusion amount) of the second flat portion 22a from the second transverse wall 12y of the adjacent closed cross-sectional portion 10 will be referred to as the "second depth d2" of the second initial irregularity 22. In this embodiment, the first depth d1 and the second depth d1 are set to be equal depths (values). Hereinafter, the first depth d1 and the second depth d1 will be collectively referred to as the "depth d".

[0052] If the depth d of the initial imperfection 2 is too shallow, the control of the deformation mode becomes unstable, whereas if it is too deep, the weight of the reinforcing member 1 increases, reducing the deformation load. Therefore, the depth d of the initial imperfection 2 is set in consideration of the balance between the control of the deformation mode and the reduction in the deformation load.

[0053] In this embodiment, the depth d of the initial irregularities 2 is preferably set to 50% or more and 150% or less of the thickness dt of the lateral walls 1y (first lateral walls 11y and second lateral walls 12y), and more preferably set to 100%. In this embodiment, the depth d of the initial irregularities 2 is set to a value that is 100% of the thickness dt of the lateral walls 1y. This makes it possible to control the deformation form while suppressing a decrease in the energy absorption amount per unit weight (hereinafter, sometimes referred to as "EA amount").

[0054] (Effects of the first embodiment) As described above, according to this embodiment, since the initial irregularity 2 is set in the second closed cross-sectional portion 12, it is possible to control the deformation form.

[0055] Furthermore, when the colliding object is cylindrical, the deformation range due to the collision is small in the outermost region (collision surface side) of the reinforcing member 1, and then the deformation region expands in the X direction as the collision progresses. Therefore, in a configuration in which an initial imperfection is set at the outermost portion, a load is applied locally due to the collision, which easily causes deformation in response to the concentrated load. Furthermore, buckling deformation of the innermost closed cross-sectional portion is promoted, reducing the initial deformation load. However, according to this embodiment, since the initial imperfection 2 is not set in the first closed cross-sectional portion 11, the decrease in the initial deformation load, i.e., the decrease in the energy absorption capacity per unit weight, can be suppressed. Furthermore, the initial imperfection 2 set in the second closed cross-sectional portion 12 slightly deforms the second closed cross-sectional portion 12 in a predetermined direction, making it possible to control the deformation direction of the first closed cross-sectional portion 11 and the third closed cross-sectional portion 13. In other words, according to this embodiment, the decrease in the energy absorption capacity per unit weight can be suppressed while controlling the deformation form.

[0056] As described above, when the colliding object is cylindrical, the region to which stress is applied expands in the X direction as the closed cross-sectional portion 10 is farther from the collision direction (the second closed cross-sectional portion 12 than the first closed cross-sectional portion 11, and furthermore the third closed cross-sectional portion 13 than the first closed cross-sectional portion 11). In other words, when the initial imperfection 2 is provided in the second closed cross-sectional portion 12, the load at which the initial imperfection 2 deforms is higher than when the initial imperfection 2 is provided in the first closed cross-sectional portion 11. This suppresses excessive deformation of the initial imperfection 2 and also suppresses a decrease in the deformation load compared to when the initial imperfection 2 is provided in the first closed cross-sectional portion 11. Furthermore, if the initial imperfection 2 is provided in the third closed cross-sectional portion without providing the initial imperfection 2 in the first and second closed cross-sectional portions 11 and 12, the initial imperfection 2 is set too far back, which causes the first closed cross-sectional portion 11 to deform before the initial imperfection 2 deforms. This makes it impossible to control the deformation shape to the desired shape using the initial imperfection 2. For this reason, it is preferable to provide the initial imperfection 2 in the second closed cross-sectional portion 12.

[0057] Since the effect of imparting an initial imperfection is obtained by deforming the initial imperfection 2 set in the second closed cross-sectional portion 12, it is possible to control the deformation form without setting an initial imperfection 2 in the third closed cross-sectional portion 13. Furthermore, by not setting an initial imperfection 2 in the third closed cross-sectional portion 13, it is possible to suppress a decrease in the amount of energy absorbed per unit weight.

[0058] In the above embodiment, the second closed cross-sectional portion 12, which is the second from the outside among the three closed cross-sectional portions 10, has an initial irregularity 2 of an inwardly convex shape. Therefore, during a collision, the second closed cross-sectional portion 12 deforms inward (inward buckling), and the third closed cross-sectional portion 13 (the innermost closed cross-sectional portion 10) adjacent to the second closed cross-sectional portion 12 can be induced to deform outward (outward buckling) from the third closed cross-sectional portion 13. The outward deformation of the third closed cross-sectional portion 13 can suppress collapse deformation of the reinforcing member 1 (a member located more inward of the vehicle V than the reinforcing member 1). This can protect a component located more inward than the reinforcing member 1 (for example, the battery B).

[0059] (Example) The present invention will be further described below with reference to examples, although the present invention is not limited to the following examples.

[0060] (Evaluation of initial irregularities) In order to verify the effects of the present invention, the configuration of the reinforcing member 1 described in the first embodiment (see FIG. 3) was modeled, and a CAE analysis was carried out assuming a collision with a cylindrical collision object (pole). For the CAE analysis, LS-DYNA, a general-purpose dynamic explicit method software, was used.

[0061] In the above analysis, the model according to the example was subjected to crushing deformation by displacing a cylindrical collision object with a diameter of 254 mm in the Y direction (from the +Y side to the -Y side) with the rigid wall restraining only the Z direction of the end cross section. Note that the rigid wall was installed so as to be more completely restrained on the +Y side than the model according to the example.

[0062] For comparison, a reinforcing member 91 shown in FIG. 4A was modeled as Comparative Example 1, and a reinforcing member 92 shown in FIG. 4B was modeled as Comparative Example 2, and similar analyses were performed.

[0063] (Comparative Example 1) The reinforcing member 91 according to Comparative Example 1 has the same configuration as that of the example, except that no initial irregularity is set in any of the closed cross-sectional portions.

[0064] (Comparative Example 2) The reinforcing member 92 according to Comparative Example 2 has the same configuration as that of the embodiment, except that an initial irregularity (same shape and depth as in the embodiment) is set only in the outermost closed cross-sectional portion of the vehicle V.

[0065] The evaluation results are shown in FIGS.

[0066] (EA volume evaluation) Fig. 5 shows the relationship (load-displacement curve) between deformation load (hereinafter sometimes referred to as "load") and displacement (stroke) for Example and Comparative Examples 1 and 2. The horizontal axis of Fig. 5 represents displacement S (mm), and the vertical axis represents load P (kN).

[0067] As shown in Fig. 5, at the initial stage of collision (displacement S = 40 mm or less), Comparative Example 2 has a lower load and a lower EA amount than the Examples. On the other hand, the Examples have a load-displacement relationship similar to that of Comparative Example 1 (initial irregularity 2 not set), and it can be seen that the decrease in EA amount is suppressed even when initial irregularity is set.

[0068] 5, the load in Comparative Examples 1 and 2 is higher than that in the Example at the final stage of the collision (near displacement S=90). If the load becomes higher at the final stage of the collision, there is a risk that parts (such as battery B) located inside the vehicle V relative to the reinforcing member will be deformed.

[0069] Figure 6 shows the relationship between EA efficiency and EA amount per unit weight (hereinafter referred to as "EA amount / unit weight W") when displacement S = 90 mm. EA efficiency η is calculated by EA amount / (maximum load PmaX × displacement S). The horizontal axis of Figure 6 shows EA amount / unit weight W (kJ·m / kg), and the vertical axis of Figure 6 shows EA efficiency η (%).

[0070] As shown in FIG. 6, it is clear that the Example is superior to both Comparative Examples 1 and 2 in EA efficiency η.

[0071] From the above, it can be seen that according to the examples, the decrease in the amount of EA per unit weight can be suppressed.

[0072] (Evaluation of variant forms) Fig. 7 shows deformations (deformations of the cross section of the central portion in the longitudinal direction) of the Example and Comparative Examples 1 and 2 at each displacement S (displacement S = 20 mm, displacement S = 40 mm, displacement S = 60 mm, displacement S = 90 mm). In Fig. 7, the broken lines in the outline of the reinforcing member indicate the fractured portions of the reinforcing member.

[0073] As shown in FIG. 7, in Comparative Example 1, at a displacement S of 60 mm, the middle (second from the outside) closed cross-section portion deforms protruding outward, and then at a displacement S of 90 mm, the innermost (third from the outside) closed cross-section portion deforms protruding outward (outer buckling). It is clear that the adjacent closed cross-section portions do not buckle alternately (for example, outer buckling, inner buckling, outer buckling), and the deformation form is unstable.

[0074] In Comparative Example 2, at displacement S = 60 mm, the middle (second from the outside) closed cross-section deforms so as to protrude outward, and then at displacement S = 90 mm, the innermost (third from the outside) closed cross-section deforms so as to protrude inward (internal buckling). When the innermost closed cross-section deforms so as to protrude inward, there is a risk of collapse deformation, and it is clear that the deformation form of Comparative Example 2 is not preferable. In Comparative Example 2, as described above, the initial imperfection is set closest to the impact surface, and therefore the load decreases at the initial stage of the impact (displacement S = 20 mm).

[0075] On the other hand, in the example, at displacement S=60, the middle (second from the outside) closed cross-sectional portion deforms by protruding inward, and at displacement S=90, the innermost (third from the outside) closed cross-sectional portion deforms by protruding outward, thereby suppressing the collapse deformation. In other words, according to the example, it can be said that the deformation form can be stably controlled.

[0076] From the above, it can be seen that according to the embodiment, it is possible to suppress the decrease in the EA amount while controlling the deformation form.

[0077] (Modification of the first embodiment) Modifications of the reinforcing member 1 of the first embodiment will be described below with reference to FIGS. 8A to 8C.

[0078] In the above embodiment, the first closed cross-sectional portion 11 has a rectangular shape when viewed along the X direction, but the first closed cross-sectional portion 11 of the reinforcing member 1 is not limited to a rectangular shape when viewed along the X direction. For example, as in a first modified example shown in FIG. 8A , the first closed cross-sectional portion 11 may have a trapezoidal shape when viewed along the X direction. This makes it possible to avoid interference with the outer design of the vehicle V, and improves the degree of freedom in designing the outer design of the vehicle V.

[0079] In the above embodiment, the initial irregularity 2 is provided in the entire region of the lateral wall 1y that defines the second closed cross-sectional portion 12, but as in a second modified example shown in Fig. 8B, the initial irregularity 2 of the reinforcing member 1 may be set only in a part (the central part in the Y direction) of the lateral wall 1y that defines the second closed cross-sectional portion 12. In other words, in the second modified example, the initial irregularity 2 may include a part that is located at the same position in the Z direction as the lateral wall 1y that defines the adjacent closed cross-sectional portion 10.

[0080] In the above embodiment, the reinforcing member 1 has three closed cross-sectional portions 10. However, the number of closed cross-sectional portions 10 is not limited to three and may be four or more. A reinforcing member 1 according to a third modified example shown in FIG. 8C has four closed cross-sectional portions 10, namely, a first closed cross-sectional portion 11, a second closed cross-sectional portion 12, a third closed cross-sectional portion 13, and a fourth closed cross-sectional portion 14 (including a fifth vertical wall 15t). The initial irregularity 2 is provided in the second closed cross-sectional portion 12 even when the number of closed cross-sectional portions 10 is four or more. In other words, the initial irregularity 2 is provided in the second closed cross-sectional portion 12 regardless of the number of closed cross-sectional portions 10.

[0081] However, the shape (projecting direction) of the initial irregularity 2 is set according to the number of closed cross-sectional portions 10 that the reinforcing member 1 has. Specifically, as shown in FIG. 8C , when the number of closed cross-sectional portions 10 that the reinforcing member 1 has is even, the initial irregularity 2 is set to an outward convex shape (so as to project outward). On the other hand, when the number of closed cross-sectional portions 10 that the reinforcing member 1 has is odd, the initial irregularity 2 is set to an inward convex shape (so as to project inward), as shown in FIG. 3 . This makes it possible to control the deformation form so that the closed cross-sectional portion 10 located closest to the vehicle V projects outward from the closed cross-sectional portions 10.

[0082] (Second embodiment) 9 to 13, a reinforcing member 1 according to a second embodiment will be described. The second embodiment differs from the first embodiment in that the thickness dt of the reinforcing member 1 is not uniform, but has a thickness distribution.

[0083] As shown in FIG. 9, the lateral walls 1y defining each closed cross-sectional portion 10 each have a thick portion 1m and a thin portion 1h that is shorter (thinner) or thinner in the Z direction than the thick portion 1m. The thick portion 1m may be provided at the center (the center in the X direction) of the lateral wall 1y defining each closed cross-sectional portion 10. That is, the thick portion 1m may be provided at the initial irregularity 2 of the second closed cross-sectional portion 12. The thick portion 1m is provided so as to include the center in the Y direction of the first flat portion 21a or the second flat portion 22a. The portion other than the thick portion 1m corresponds to the thin portion 1h. In this embodiment, the thickness dt of the thin portion 1h is 5 mm.

[0084] It is desirable that the thickness dc of the thick portion 1m is 10% or more and 30% or less of the thickness dt of the thin portion 1h, thereby improving the amount of EA per unit weight.

[0085] (Effects of the second embodiment) As described above, by setting the thick-walled portion 1m, it is possible to minimize the weight increase of the reinforcing member 1 and efficiently improve the bending deformation strength. In particular, bending deformation is more likely to occur near the boundary between the thin-walled portion 1h and the thick-walled portion 1m, and the bending starting points are dispersed. This makes it possible to efficiently improve the deformation strength.

[0086] In the example shown in Figure 9, thick-walled portions 1m are set in the side walls 1y that define all of the closed cross-sectional portions 10, but the thick-walled portions 1m may be set in only one side wall 1y as long as they are set in the side walls 1y that define at least one of the multiple closed cross-sectional portions 10.

[0087] (Thickening evaluation) The effect of thickening the closed cross-sectional portion 10 will be described below with reference to Figs. 10 to 12. In order to verify the effect of thickening the closed cross-sectional portion 10, CAE analysis was carried out in the same manner as in the above-described examples. In the verification of thickening, a model according to Comparative Example 1 and modeled reinforcing member 93 shown in Fig. 10 were used as reference examples 1 and 2.

[0088] (Reference example 1) As Reference Example 1, a reinforcing member 93 having a thick portion with dc=0.5 mm thickened relative to a thin portion with dt=5.0 mm was modeled.

[0089] (Reference example 2) As Reference Example 2, a reinforcing member 93 having a thick portion with dc=1.0 mm thickened relative to a thin portion with dt=5.0 mm was modeled.

[0090] The reinforcing members according to Comparative Example 1 and Reference Examples 1 and 2 all had no initial irregularity set, and the reinforcing members used in Comparative Example 1 (see FIG. 4A) and Reference Examples 1 and 2 had the same outer dimensions and were made of the same material.

[0091] The evaluation results of thickening are shown in Figures 11 and 12. Note that the results shown in Figures 11 and 12 are analysis results for a model in which initial imperfection 2 is not set. However, the deformation strength is determined according to the bending deformation of the side wall (substantially horizontal rib) that constitutes the closed cross section and extends in the vehicle width direction, and it is thought that the effect of setting a thickness distribution here will produce relatively similar results regardless of whether or not initial imperfection is set.

[0092] (EA amount per unit weight) Fig. 11 shows the relationship between load (deformation load) and EA amount-displacement (stroke) for Comparative Example 1 and Reference Examples 1 and 2. The horizontal axis of Fig. 11 represents displacement S (mm), and the vertical axis represents load P (kN) and EA amount (kJ). In Fig. 11, the EA amount is shown by a sloping (increasing) approximately linear graph, and the load is shown by a sawtooth graph.

[0093] Figure 12 shows the relationship between EA efficiency and EA amount per unit weight (EA amount / unit weight W) at a displacement S of 90 mm. The horizontal axis of Figure 12 shows EA amount / unit weight W (kJ·m / kg), and the vertical axis shows EA efficiency η (%).

[0094] As shown in Figure 11, the load and EA amount of Reference Examples 1 and 2 are higher than those of Comparative Example 1, which shows that thickening improves the load and EA amount, and therefore the EA amount per unit weight. However, as shown in Figure 12, the difference in EA efficiency between Reference Examples 1 and 2 is relatively small, which shows that the effect of the thickness dc of the thick-walled portion is relatively small when evaluated in terms of the EA amount per unit weight, and that there is no need to make an extreme difference in thickness. Furthermore, excessive thickening of a portion of the wall (edge) constituting the closed cross-sectional portion is likely to cause problems in terms of manufacturing by extrusion molding.

[0095] From the above, it can be said that the EA amount per unit weight can be improved by increasing the thickness dc by 10% or more and 30% or less of the thickness of the thin-walled portion (for example, dc = 0.5 mm when dt = 5.0 mm). Even if the thickness difference is changed to 30% or more, the same effect can be obtained in terms of improving the EA amount per unit width, but as mentioned above, extrusion molding becomes more difficult as the thickness difference increases. Considering extrusion manufacturability when creating a thickness difference in a narrow region within the border that makes up a closed cross-section, it is desirable to limit the thickness difference to around 30%.

[0096] (Modification of the second embodiment) The reinforcing member 1 may have a thickness distribution set such that the lateral wall 1y and the vertical wall 1t that define the closed cross-sectional portion 10 located on the outer side of the vehicle V are thicker. In other words, the lateral wall 1y and the vertical wall 1t that define the closed cross-sectional portion 10 in the Y direction may be thicker than the inner wall 1t of the vehicle V. Specifically, as shown in FIG. 13 , the thicknesses may be increased in the order of first thickness dt1 > second thickness dt2 > third thickness dt3. The first thickness dt1 is the thickness dt of the lateral wall 1y and the inner vertical wall 1t that define the first closed cross-sectional portion 11. The second thickness dt2 is the thickness dt of the lateral wall 1y and the inner vertical wall 1t that define the second closed cross-sectional portion 12. The third thickness dt3 is the thickness dt of the lateral wall 1y and the inner vertical wall 1t that define the third closed cross-sectional portion 13. The thickness dt of the horizontal wall 1y defining each closed cross-sectional portion 10 is equal to the thickness dt of the inner vertical wall 1t. In this way, the first closed cross-sectional portion 11 (outermost closed cross-sectional portion), which does not have the initial imperfection 2, is made the thickest, thereby increasing the deformation load at the initial stage of the collision. Furthermore, the region where deformation occurs later in the collision is made thinner, preventing the load from becoming too high. This allows the load-deformation relationship to approximate a rectangular wave compared to a structure with uniform thickness (uniform thickness). In other words, it is possible to efficiently absorb energy while satisfying the maximum load limit, resulting in excellent energy absorption efficiency. Furthermore, with a component having such a thickness configuration, not setting the initial imperfection 2 in the first closed cross-sectional portion 11 (outermost closed cross-sectional portion) allows the deformation load to be efficiently increased without reducing the deformation load at the initial stage of the collision. In other words, compared to a configuration in which the initial imperfection 2 is set in the first closed cross-sectional portion 11, the EA amount and the EA amount per unit weight can be improved.

[0097] (Other variations) In the above embodiment, the initial irregularity 2 is not set in the third closed cross-sectional portion 13, but the initial irregularity 2 may be set in the third closed cross-sectional portion 13 in addition to the second closed cross-sectional portion 12.

[0098] In addition, in the above embodiment, the present invention has been described as being applied to a reinforcing member 1 arranged in the internal space SS of the side sill 100, but the present invention can also be applied to a reinforcing member 1 arranged below or to the side (back side) of the side sill 100.

[0099] The reinforcing member 1 can also be applied to frames of the vehicle V other than the side sill 100.

[0100] Furthermore, in the description of the above embodiments, expressions such as parallel, vertical, orthogonal, equal, and identical include not only strict parallel, vertical, orthogonal, equal, and identical, but also, for example, substantially parallel, vertical, orthogonal, equal, and identical. [Explanation of symbols]

[0101] 1 Reinforcement member (reinforcement member for side sill) 1h Thin section 1m thick part 1t vertical wall (wall part) 1y side wall (wall) 2 Initial irregularities 10 Closed section 11 First closed section 12 Second closed section 13 Third closed section 100 Side sill V vehicle

Claims

1. a plurality of closed cross-sectional portions arranged along a vehicle width direction of the vehicle; each of the plurality of closed cross-sectional portions has a wall portion perpendicular to a vehicle height direction of the vehicle, the plurality of closed cross-sectional portions include a first closed cross-sectional portion disposed on the outermost side of the vehicle and a second closed cross-sectional portion disposed second from the outer side of the vehicle, an initial irregularity is set in the second closed cross-sectional portion, and the initial irregularity is not set in the first closed cross-sectional portion.

2. the plurality of closed cross-sectional portions further include a third closed cross-sectional portion that is arranged third from the outside of the vehicle, The reinforcing member for a side sill according to claim 1 , wherein the initial irregularity of the third closed cross-sectional portion is not set.

3. When the number of the plurality of closed cross-sectional portions is odd, the initial irregularity is set to an inward convex shape that protrudes inward, The reinforcing member for a side sill according to claim 1 or 2, wherein when the number of the plurality of closed cross-sectional portions is an even number, the initial irregularity is set to an outward convex shape that protrudes outward.

4. 4. The reinforcing member for a side sill according to claim 3, wherein the amount of protrusion of the initial irregularity relative to the wall portion is 50% or more and 150% or less of a thickness of the wall portion.

5. The initial irregularity has a thickened portion, 3. The reinforcing member for a side sill according to claim 1, wherein the thickness of the thick portion is 10% or more and 30% or less of the thickness of the thin portion that is thinner than the thick portion.

6. The reinforcing member for a side sill according to claim 1 or 2, wherein the wall portion is thicker on an outer side of the vehicle than on an inner side of the vehicle in the vehicle width direction.

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