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: A plurality of closed cross-sectional portions 10 disposed along a vehicle-width direction of the vehicle, and wall portions 1y, 1t, and 1k defining the plurality of closed cross-sectional portions 10, wherein the plurality of closed cross-sectional portions 10 are disposed on an outermost side of the vehicle in the vehicle-width direction and include a first closed cross-sectional portion 11 having a trapezoidal shape; The 1t portion includes a plurality of vertical walls 1y, two horizontal walls 1y, and two inclined walls 1k that are inclined with respect to each of the two horizontal walls 1t, the plurality of vertical walls 11t includes a first vertical wall 11t that is disposed on the outermost side in the vehicle and a second vertical wall 11t that is adjacent to the first vertical wall 12t and is longer than the first vertical wall, and the first vertical wall, the second vertical wall, and the two inclined walls define the first closed cross-sectional portion 11, 11t 12t 1k, An inclination angle θ of the inclined 1k with respect to the lateral 1y is 8 degrees or more, and a length of the first vertical 11t in the vehicle height direction is 20mm or more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Automobiles are equipped 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 sills of automobiles, in which closed cross-sectional portions (compartments in Patent Document 1) are arranged in series in the vehicle width direction. In the energy absorbing member disclosed in Patent Document 1, in order to achieve deformation in a desired manner, the compartment-forming portion that forms the compartment located closest to the collision surface is curved and biased so that it protrudes 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 side sill reinforcing member comprising a plurality of closed cross-sectional portions arranged along a vehicle width direction of a vehicle, and wall portions defining the plurality of closed cross-sectional portions, wherein the plurality of closed cross-sectional portions are arranged outermost of the vehicle in the vehicle width direction and have first closed cross-sectional portions that are trapezoidal when viewed along the vehicle length direction of the vehicle, and the wall portions have a plurality of vertical walls perpendicular to the vehicle width direction, two lateral walls perpendicular to a vehicle height direction of the vehicle, and two inclined walls inclined with respect to each of the two lateral walls, and the plurality of vertical walls include a first vertical wall that is arranged outermost of the vehicle in the vehicle width direction, and a second vertical wall that is adjacent to the first vertical wall and is longer than the first vertical wall, the first vertical wall, the second vertical wall, and the two inclined walls define the first closed cross-sectional portions, an inclination angle of the inclined walls with respect to the lateral walls is 8 degrees or more, and the length of the first vertical wall in the vehicle height direction is 20 mm or more.

[0007] According to the above configuration, since the outermost closed cross-sectional portion (collision surface side) is trapezoidal, deformation when the outermost closed cross-sectional portion is crushed by a collision imparts initial irregularity (deviation of deformation strength) to the inner closed cross-sectional portion, thereby making it possible to control the deformation form. Furthermore, since the reinforcing member has side walls, the side walls can withstand the collision load and ensure the deformation load. Therefore, 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 form.

[0008] The plurality of closed cross-sectional portions may include three of the closed cross-sectional portions.

[0009] During a collision, adjacent closed cross-sectional portions tend to buckle in different directions. 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). According to the above configuration, if the outermost closed cross-sectional portion has a trapezoidal shape when viewed along the vehicle length direction and the upper and lower wall angles (the angles of the inclined walls relative to the side walls, i.e., the inclination angles) that form this trapezoidal shape are set appropriately (within a predetermined range), the closed cross-sectional portion will undergo outward protruding deformation (outward buckling). Therefore, when there are three closed cross-sectional portions, the closed cross-sectional portion located at the innermost position of the vehicle is induced to protrude outward. This suppresses the collapse of the side sill reinforcement member.

[0010] The closed cross-sectional portions other than the first closed cross-sectional portion among the plurality of closed cross-sectional portions may have a rectangular shape when viewed along the vehicle length direction.

[0011] According to the above configuration, the closed cross-sectional portions other than the first closed cross-sectional portion are rectangular when viewed along the vehicle length direction, and no initial irregularity is set, so that the collision load can be absorbed and deformation load can be ensured.

[0012] The wall portion 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.

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

[0015] According to the above-mentioned configuration, the outer side of the vehicle, i.e., the trapezoidal closed cross-section portion, is thickest, which results in a weight reduction effect compared to when the rectangular portion is thickest, and also improves the amount of energy absorption per unit weight.

[0016] The first closed cross-sectional portion may have an isosceles trapezoidal shape when viewed along the vehicle length direction.

[0017] According to the above configuration, the shape of the first closed cross-sectional portion is an isosceles trapezoid, that is, symmetrical in the vehicle height direction, so that the deformation form can be stabilized. [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] FIG. 2 is a view showing a lower space and its vicinity according to the 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] 1 is a graph showing the relationship between load and EA amount and displacement in Example 1 of the present invention and Comparative Examples 1 and 2. [Figure 6A] 1 is a graph showing the amount of EA per unit weight in Example 1 of the present invention and Comparative Examples 1 and 2. [Figure 6B] 1 is a graph showing EA efficiency in Example 1 of the present invention and Comparative Examples 1 and 2. [Figure 7A] 1 is a graph showing the EA efficiency and the EA amount per unit weight in Examples 1 to 4 of the present invention and Comparative Examples 1, 3, and 4. [Figure 7B] 1 is a graph showing the EA efficiency and the EA amount per unit weight in Examples 1 to 4 of the present invention and Comparative Examples 1, 3, and 4. [Figure 8A] 2 is a graph showing the load-displacement relationship in Examples 1 and 2 of the present invention and Comparative Examples 1 and 4. [Figure 8B] 1 is a graph showing the relationship between EA amount and displacement in Examples 1 and 2 of the present invention and Comparative Examples 1 and 4. [Figure 9] 1 is a diagram showing modified embodiments of Examples 1 to 4 and Comparative Examples 1, 3, and 4 of the present invention. [Figure 10] 1 is a diagram showing modified embodiments of Examples 1 to 4 and Comparative Examples 1, 3, and 4 of the present invention. [Figure 11] 5A and 5B are views showing modified examples of the reinforcing member according to the first embodiment of the present invention. [Figure 12] 5A and 5B are diagrams showing the configuration of a reinforcing member according to a second embodiment of the present invention. [Figure 13] 10A and 10B are diagrams showing the configuration of a reinforcing member according to a reference example of the present invention. [Figure 14] 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 15] 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 16] 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, four vertical walls 1t, and two inclined walls 1k.

[0034] The two lateral walls 1y have a first lateral wall 11y (upper wall) and a second lateral wall 12y (lower wall) that are perpendicular to the vehicle height direction. Each of the first lateral wall 11y and the second lateral wall 12y has an XY plane (hereinafter referred to as "main surface 1S") that is perpendicular to the Z direction and faces each other in the Z direction.

[0035] The four vertical walls 1t include a first vertical wall 11t, a second vertical wall 12t, a third vertical wall 13t, and a fourth vertical wall 14t. Each of the first vertical wall 11t, the second vertical wall 12t, the third vertical wall 13t, and the fourth vertical wall 14t has an XZ plane perpendicular to the Y direction. The first vertical wall 11t, the second vertical wall 12t, the third vertical wall 13t, and the fourth vertical wall 14t are arranged in this order from the outside of the vehicle V. In other words, the second vertical wall 12t is arranged so as to be adjacent to the first vertical wall 11t in the Y direction. The third vertical wall 13t faces the first vertical wall 11t in the Y direction across the second vertical wall 12t, and the fourth vertical wall 14t faces the second vertical wall 12t in the Y direction across the third vertical wall 13t.

[0036] In the Z direction, the second vertical wall 12t is longer than the first vertical wall 11t, and the second vertical wall 12t, the third vertical wall 13t, and the fourth vertical wall 14t are configured to have the same lengths.

[0037] The length h of the first vertical wall 11t in the Z direction is a length that can withstand an impact load during a collision and that can join the reinforcing member 1 to the outer member 101 of the side sill 100, and is preferably 20 mm or more. In this embodiment, the length h of the first vertical wall 11t in the Z direction is set to 30 mm.

[0038] The two inclined walls 1k include a first inclined wall 11k and a second inclined wall 12k. The first inclined wall 11k connects the upper end of the first vertical wall 11t to the upper end of the second vertical wall 12t. The second inclined wall 12k connects the lower end of the first vertical wall 11t to the lower end of the second vertical wall 12t. The first inclined wall 11k is inclined at a first inclination angle θ1 relative to the main surface 1S of the first horizontal wall 11y, and the second inclined wall 12k is inclined at a second inclination angle θ2 relative to the main surface 1S of the second horizontal wall 12y. In this embodiment, the first inclination angle θ1 and the second inclination angle θ2 are set to the same angle (absolute value). Hereinafter, the first inclination angle θ1 and the second inclination angle θ2 are collectively referred to as the "inclination angle θ." The inclination angle θ is preferably 8 degrees or more, more preferably 10 degrees or more, and in this embodiment, it is set to 10.8 degrees (10.78 degrees). By setting the inclination angle θ to 8 degrees or more, it is possible to suppress a decrease in the amount of energy absorbed per unit weight (hereinafter, sometimes referred to as "EA amount"). Note that the upper limit of the inclination angle θ is not particularly defined because it depends on the length h of the first vertical wall 11t in the Z direction, but it is, for example, about 20 degrees.

[0039] 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, the fourth vertical wall 14t, the first inclined wall 11k, and the second inclined wall 12k) that is divided into three portions by the second vertical wall 12t and the third vertical wall 13t. In other words, the reinforcing member 1 has a harmonica structure, and the three divided spaces are fixed to the side sill 100 so as to be aligned in the Y direction.

[0040] The first horizontal wall 11y, the second horizontal wall 12y, the first vertical wall 11t, the second vertical wall 12t, the third vertical wall 13t, the fourth vertical wall 14t, the first inclined wall 11k, and the second inclined wall 12k are examples of wall portions. In this embodiment, the wall thickness dt of the wall portions constituting the reinforcing member 1 is uniform, and the wall thickness dt of the first horizontal wall 11y, the second horizontal wall 12y, the first vertical wall 11t, the second vertical wall 12t, the third vertical wall 13t, the fourth vertical wall 14t, the first inclined wall 11k, and the second inclined wall 12k is configured to be equal. In this embodiment, the wall thickness dt is 5 mm.

[0041] 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. 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 45 mm, respectively.

[0042] In this embodiment, the first closed cross-sectional portion 11 is defined by a first vertical wall 11t, a second vertical wall 12t, a first inclined wall 11k, and a second inclined wall 12k. The first closed cross-sectional portion 11 has a trapezoidal shape (a trapezoidal cross section) when viewed along the X direction, and in this embodiment, the first closed cross-sectional portion 11 is an isosceles trapezoid when viewed along the X direction. Because the first closed cross-sectional portion 11 is an isosceles trapezoid when viewed along the X direction, the deformation shape can be stabilized.

[0043] The second closed cross-sectional portion 12 has a rectangular shape when viewed along the X direction, and is defined by a second vertical wall 12t, a third vertical wall 13t, a first horizontal wall 11y, and a second horizontal wall 12y.

[0044] The third closed cross-sectional portion 13 has a rectangular shape when viewed along the X direction, and is defined by a third vertical wall 13t, a fourth vertical wall 14t, a first horizontal wall 11y, and a second horizontal wall 12y.

[0045] (Effects of the first embodiment) As described above, because the outermost first closed cross-sectional portion 11 (on the collision surface side) has a trapezoidal shape when viewed along the X direction, the deformation of the first closed cross-sectional portion 11 when it is crushed by a collision imparts initial imperfections (deviations in deformation strength) to the inner closed cross-sectional portions 10, making it possible to control the deformation form. The initial imperfections are provided to control the deformation form of the reinforcing member 1 and are set to buckle and deform the reinforcing member 1 into a desired form. The initial imperfections are deviations (asymmetries) from a configuration in which stress is uniform when a load is applied to the reinforcing member 1. For example, the initial imperfections are unevenly shaped portions that are set to preferentially deform by providing a strength difference 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.

[0046] Furthermore, since the reinforcing member 1 has a side wall 1y that is parallel to the direction of the collision load, the collision load can be received by the side wall 1y, and a high deformation load can be ensured. Therefore, according to this embodiment, it is possible to suppress a decrease in the amount of energy absorbed per unit weight while controlling the deformation form.

[0047] By setting the length h of the first vertical wall 11t to 20 mm or more (30 mm in this embodiment), it is possible to withstand the impact load during a collision. In addition, the reinforcing member 1 can be joined to the outer member 101 of the side sill 100.

[0048] During a collision, the directions of buckling deformation of adjacent closed cross-sectional portions 10 tend to be alternate. Specifically, a closed cross-sectional portion 10 adjacent to a closed cross-sectional portion 10 that has undergone outward protruding deformation (outward buckling deformation) is likely to undergo inward protruding deformation (inward buckling deformation). In the above embodiment, if the outermost first closed cross-sectional portion 11 has a trapezoidal shape when viewed along the X direction and the upper and lower wall angles (the angle of the inclined wall relative to the lateral wall, i.e., the inclination angle θ) forming this trapezoidal shape are set appropriately (within a predetermined range), the first closed cross-sectional portion 11 will undergo outward protruding deformation (outward buckling). Therefore, if there are three closed cross-sectional portions 10, the third closed cross-sectional portion 13, which is located innermost on the vehicle V, will be induced to undergo outward protruding deformation. This can suppress the collapse deformation of the reinforcing member 1. As a result, components (e.g., battery B) arranged inside the reinforcing member 1 can be protected.

[0049] Furthermore, according to the above embodiment, the closed cross-sectional portions 10 (the second closed cross-sectional portion 12 and the third closed cross-sectional portion 13) other than the first closed cross-sectional portion 11 are rectangular when viewed along the X direction. In other words, no initial irregularity is set in the closed cross-sectional portions 10 other than the first closed cross-sectional portion 11, so that the collision load can be received and the deformation load can be ensured.

[0050] (Example) The present invention will be further described below with reference to examples, although the present invention is not limited to the following examples.

[0051] 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 as Example 1, 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 explicit dynamics analysis software, was used.

[0052] In the above analysis, the model according to Example 1 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 Example 1.

[0053] (Evaluation of the shape of the reinforcing member) First, in order to evaluate the shape of the reinforcing member, reinforcing members 91 and 92 shown in FIGS. 4A and 4B were modeled as comparative examples 1 and 2, and a similar analysis was performed.

[0054] (Comparative Example 1) The reinforcing member 91 according to Comparative Example 1 has the same configuration as that of Example 1, except that all closed cross-sectional portions are rectangular when viewed along the X direction (see FIG. 4A).

[0055] (Comparative Example 2) In the reinforcing member 92 according to Comparative Example 2, the shape of the outermost closed cross-sectional portion is not trapezoidal but hexagonal, and the portions corresponding to the first inclined wall and the second inclined wall according to the example have a bent portion C. The other configurations are the same as those of Example 1 (see FIG. 4B).

[0056] The evaluation results are shown in FIGS. 5 to 6B.

[0057] Fig. 5 shows the relationship between deformation load (hereinafter sometimes referred to as "load") and EA amount (energy absorption amount)-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) and EA amount (kJ). In Fig. 5, the EA amount is shown by a sloping (increasing) approximately linear graph, and the load is shown by a sawtooth graph.

[0058] Fig. 6A is a graph showing the EA amount per unit weight (hereinafter referred to as "EA amount / unit weight W") for Example 1, Comparative Examples 1, and 2 when the displacement S was less than 90 mm and when the displacement S was less than 110 mm. The vertical axis of Fig. 6A shows the EA amount / unit weight W (kJ m / kg).

[0059] Fig. 6B is a graph showing the EA efficiency of Example 1 and Comparative Examples 1 and 2 when the displacement S is less than 90 mm and when the displacement S is less than 110 mm. The vertical axis of Fig. 6B shows the EA efficiency η (%). The EA efficiency η is calculated by dividing the EA amount by the maximum load Pmax × displacement S.

[0060] 5 to 6B, it can be seen that in both the displacement S=<90 mm and the displacement S=<110 mm, Example 1 is superior in both the EA amount per unit weight and the EA efficiency to Comparative Examples 1 and 2. In other words, if the shape of the outermost closed cross-sectional portion is trapezoidal and the angle of the trapezoidal shape is appropriately selected, it can be said that the decrease in the EA amount per unit weight and the EA efficiency can be suppressed.

[0061] As shown in FIG. 5, in Comparative Example 2, the load is too low compared to the Example at the beginning of the collision (displacement S=40 mm or less), while the load is too high in the latter half of the collision (displacement S=90 mm or more), resulting in a decrease in the EA amount and EA efficiency per unit weight (see FIGS. 6A and 6B). These results show that when a bent portion C is provided in the wall (rib) that extends approximately in the vehicle width direction and that constitutes the closed cross-sectional portion on the most impact side, the initial deformation load is low, and accordingly, the EA amount and EA efficiency are reduced. For this reason, it can be said that a configuration (i.e., Example) in which the inclined wall with the inclination angle θ set within a predetermined range is linear and the load can be directly transmitted to the adjacent closed cross-sectional portion is desirable.

[0062] (Evaluation of tilt angle θ) Next, in order to evaluate the inclination angle θ, a reinforcing member with a stepwise change in the inclination angle θ was modeled, and a CAE analysis was carried out in the same manner as above.

[0063] (Comparative Examples 1, 3, and 4) In addition to the above-mentioned Comparative Example 1 (where the outermost closed cross-sectional portion is rectangular when viewed along the X direction, i.e., the inclination angle θ = 0.0 degree), a reinforcing member with an inclination angle θ = 2.7 degrees (h = 45 mm) was modeled as Comparative Example 3, and a reinforcing member with an inclination angle θ = 5.4 degrees (h = 40 mm) was modeled as Comparative Example 4. Note that in both the reinforcing members according to Comparative Examples 3 and 4, the cross section of the outermost closed cross-sectional portion is trapezoidal.

[0064] (Examples 2, 3, and 4) As examples, in addition to the above Example 1 (inclination angle θ = 10.8 degrees, h = 30 mm), reinforcing members were modeled with an inclination angle θ = 8.1 degrees (h = 35 mm) as Example 2, an inclination angle θ = 13.4 degrees (h = 25 mm) as Example 3, and an inclination angle θ = 15.9 degrees (h = 20 mm) as Example 4. Note that the reinforcing members according to Examples 2 to 4 all have a trapezoidal cross section at the outermost closed cross-sectional portion.

[0065] The evaluation results are shown in FIGS. 7A to 10.

[0066] Figure 7A shows the EA amount and EA efficiency per unit weight for displacement S = < 90 mm, and Figure 7B shows the EA amount and EA efficiency per unit weight for displacement S = < 110 mm for Examples 1 to 4 and Comparative Examples 1, 3, and 4. The horizontal axes in Figures 7A and 7B respectively represent the tilt angle θ (DEG.), and the vertical axes respectively represent the EA efficiency η (%) and the EA amount / unit weight W (kJ m / kg).

[0067] Fig. 8A shows the relationship between load (deformation load) and displacement (stroke) for Examples 1 and 2 and Comparative Examples 1 and 4. The horizontal axis in Fig. 8A represents displacement S (mm), and the vertical axis represents load P (kN). Fig. 8B shows the relationship between EA amount and displacement (stroke) for Examples 1 and 2 and Comparative Examples 1 and 4. The horizontal axis in Fig. 8B represents displacement S (mm), and the vertical axis represents EA amount (kJ).

[0068] As shown in Figure 7A, when the displacement S is less than or equal to 90, all models of Examples 1 to 4 (with an inclination angle θ of 8 degrees or more) have higher EA amount per unit weight and EA efficiency than Comparative Examples 1, 3, and 4.

[0069] Furthermore, as shown in Figure 7B, when the displacement S is less than or equal to 110, all models of Examples 1, 3, and 4 (at an inclination angle θ of 9 degrees or more) have higher EA amount per unit weight and EA efficiency than Comparative Examples 1, 3, and 4.

[0070] 8A and 8B, it can be seen that in Comparative Examples 1 and 4, the load is low in the intermediate region (near displacement S=60) and the EA amount is low. On the other hand, it can be seen that in Example 2, the load decreases and the EA amount decreases at the final stage of the collision (displacement S=90 mm or more), but the maximum load does not change significantly. It can be seen that the decrease in load at the final stage of the collision (displacement S=90 mm or more) in Example 2 is due to fracture (see FIGS. 9 and 10).

[0071] That is, when the displacement S is less than or equal to 90, the tilt angle θ is set to 8 degrees or more to increase the EA efficiency and suppress the decrease in the EA amount and EA efficiency. Also, when the displacement S is less than or equal to 110, the tilt angle θ is set to 9 degrees or more to increase the EA efficiency and suppress the decrease in the EA amount and EA efficiency.

[0072] (Evaluation of variants) 9 and 10 show deformations (deformations of the cross section of the central portion in the longitudinal direction) of Examples 1 to 4 and Comparative Examples 1, 3, and 4 at each displacement S (20 mm, 40 mm, 60 mm, 90 mm). In Fig. 9 and Fig. 10, the broken lines in the outline of the reinforcing members indicate the fractured portions of the reinforcing members.

[0073] As shown in FIGS. 9 and 10 , in Comparative Examples 1, 3, and 4, the outermost closed cross-sectional portion was deformed inwardly (inward buckling deformation), whereas in Examples 1 to 4, the outermost closed cross-sectional portion was deformed outwardly (outward buckling deformation). Furthermore, in Examples 1 to 4, the timing of fracture occurrence was later than in Comparative Examples 1, 3, and 4, demonstrating stable energy absorption until the final stage of the collision. Regarding Example 2, although the outermost closed cross-sectional portion was deformed outwardly, the effect of correcting the inward protruding deformation relative to the adjacent closed cross-sectional portions was somewhat smaller, resulting in a tendency for fracture to occur toward the final stage of the collision. In the fracture evaluation, it was confirmed that fracture occurred on the inner side (rear side) in models with a tilt angle θ of 0 degrees < 8 degrees at a displacement S = 100. On the other hand, in the model with a tilt angle θ >= 10 degrees, it was confirmed that no fracture occurred on the inner side (rear side) at a displacement S = 100.

[0074] From the above, it can be seen that the decrease in the EA amount per unit weight can be suppressed while controlling the deformation mode according to Examples 1 to 4. Furthermore, it can be seen that the decrease in the EA amount per unit weight can be suppressed while controlling the deformation mode even in a wider range (displacement S<=110) according to Examples 1, 3, and 4.

[0075] (Modification of the first embodiment) Next, a modified example of the reinforcing member 1 of the first embodiment will be described with reference to FIG.

[0076] In the above embodiment, the number of closed cross-sectional portions 10 included in the reinforcing member 1 is three, but the number of closed cross-sectional portions 10 is not limited to three and may be four or more. The reinforcing member 1 according to a modified example shown in FIG. 11 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 (also a fifth vertical wall 15t). Even if the number of closed cross-sectional portions 10 is four or more, the shape of the first closed cross-sectional portion 11 as viewed along the X direction is a trapezoid. In other words, the shape of the first closed cross-sectional portion 11 as viewed along the X direction is a trapezoid regardless of the number of closed cross-sectional portions 10.

[0077] In the above embodiment, the first inclination angle θ1 and the second inclination angle θ2 are equal in angle (absolute value), but the first inclination angle θ1 and the second inclination angle θ2 do not have to be equal to each other as long as they are set to a value of 8 degrees or more. In other words, the first closed cross-sectional portion 11 does not have to be an isosceles trapezoid when viewed along the X direction.

[0078] (Second embodiment) A reinforcing member 1 according to a second embodiment will be described below with reference to Figures 12 to 16. The second embodiment differs from the first embodiment in that the thickness dt of the reinforcing member 1 is not uniform, but has a set thickness distribution.

[0079] As shown in FIG. 12, the inclined wall 1k defining the first closed cross-sectional portion 11 and the lateral walls 1y defining the second closed cross-sectional portion 12 and the third closed cross-sectional portion 13 each have a thick portion 1m and a thin portion 1h that is thinner or has a shorter length (thinner thickness) in the Z direction than the thick portion 1m. The thick portion 1m may be provided at the center of the inclined wall 1k or the center of the lateral wall 1y (the center in the Y direction). The thick portion 1m is provided so as to include the center of the inclined wall 1k or the lateral wall 1y in the Y direction. The portions other than the thick portion 1m correspond to the thin portion 1h. In this embodiment, the thickness dt of the thin portion 1h is 5 mm.

[0080] 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.

[0081] (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.

[0082] 12, the thick-walled portions 1m are provided in all of the inclined walls 1k that define the first closed cross-sectional portion 11 and the lateral walls 1y that define each of the second closed cross-sectional portion 12 and the third closed cross-sectional portion 13. However, the thick-walled portions 1m may be provided in at least one of the inclined walls 1k that define the first closed cross-sectional portion 11, the lateral walls 1y that define the second closed cross-sectional portion 12, and the lateral walls 1y that define the third closed cross-sectional portion 13. For example, the thick-walled portions 1m may be provided in only one of the inclined walls 1k that define the first closed cross-sectional portion 11, the lateral walls 1y that define the second closed cross-sectional portion 12, and the lateral walls 1y that define the third closed cross-sectional portion 13.

[0083] (Thickening evaluation) The effect of thickening the closed cross-sectional portion 10 will be described below with reference to Figs. 12 to 15. 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 verifying the thickening, a model according to Comparative Example 1 and modeled reinforcing member 93 shown in Fig. 13 were used as reference examples 1 and 2.

[0084] (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.

[0085] (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.

[0086] In addition, for Comparative Example 1 and Reference Examples 1 and 2, reinforcing members were used in which the cross section of the outermost closed cross-sectional portion was not trapezoidal, and the external dimensions and materials of Comparative Example 1 (see Figure 4A) and Reference Examples 1 and 2 were the same as each other.

[0087] The evaluation results of thickening are shown in Figures 14 and 15. Note that the results shown in Figures 14 and 15 are for a model in which the cross section of the outermost closed cross section portion is not trapezoidal. However, the deformation load in the latter half of the collision is determined according to the deformation of the second and subsequent closed cross sections from the collision surface side. The structure of this region is the same even in the case of a trapezoidal shape. Furthermore, the deformation load accompanying the crushing deformation of these closed cross sections is determined according to the bending deformation of the side walls (approximately horizontal ribs) extending in the vehicle width direction, and it is thought that the effect of setting the thickness distribution here will produce relatively similar results regardless of the shape of the outermost collision surface side.

[0088] (EA amount per unit weight) Fig. 14 shows the relationship between the load (deformation load) and the EA amount-displacement (stroke) for each of Comparative Example 1 and Reference Examples 1 and 2. The horizontal axis of Fig. 14 represents the displacement S (mm), and the vertical axis represents the load P (kN) and the EA amount (kJ). In Fig. 14, the EA amount is shown by a sloping (increasing) approximately linear graph, and the load is shown by a sawtooth graph.

[0089] Figure 15 shows the relationship between EA efficiency and EA amount per unit weight when displacement S = 90 mm. The horizontal axis of Figure 15 shows EA amount / unit weight W (kJ·m / kg), and the vertical axis shows EA efficiency η (%).

[0090] As shown in Figure 14, 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 15, 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.

[0091] 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%.

[0092] (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 defining 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 defining the closed cross-sectional portion 10 in the Y direction may be thicker than the inner wall 1t. Specifically, as shown in FIG. 16 , 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 inclined wall 1k and the inner vertical wall 1t defining 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 defining 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 defining 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. By setting the thickness distribution in this manner, the load and EA amount are improved, and the EA amount per unit weight can be increased.

[0093] (Other variations) In the above embodiment, the present invention is 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.

[0094] The reinforcing member 1 can also be applied to frames of the vehicle V other than the side sill 100.

[0095] Furthermore, in the description of the above embodiments, expressions such as parallel, vertical, orthogonal, equal, identical, etc. include expressions other than strictly parallel, vertical, orthogonal, equal, identical, and also include, for example, substantially parallel, vertical, orthogonal, equal, identical, etc. [Explanation of symbols]

[0096] 1 Reinforcement member (reinforcement member for side sill) 1h Thin section 1m thick part 1t vertical wall (wall part) 1y side wall (wall) 1k Slanted wall (wall part) 11k 1st inclined wall (inclined wall) 12k 2nd inclined wall (inclined wall) 11y 1st side wall (side wall) 12y 2nd side wall (side wall) 11t First vertical wall (vertical wall) 12t Second vertical wall (vertical wall) 10 Closed section 11 First closed section 12 Second 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; a wall portion defining a plurality of the closed cross-sectional portions; Equipped with the plurality of closed cross-sectional portions are arranged at outermost positions of the vehicle in the vehicle width direction and have first closed cross-sectional portions that are trapezoidal when viewed along the vehicle length direction of the vehicle; the wall portion includes a plurality of vertical walls perpendicular to the vehicle width direction, two horizontal walls perpendicular to the vehicle height direction of the vehicle, and two inclined walls inclined with respect to each of the two horizontal walls, the plurality of vertical walls include a first vertical wall disposed on the outermost side of the vehicle in the vehicle width direction, and a second vertical wall adjacent to the first vertical wall and longer than the first vertical wall, the first vertical wall, the second vertical wall, and the two inclined walls define the first closed cross-sectional portion, A reinforcing member for a side sill, wherein the inclination angle of the inclined wall relative to the lateral wall is 8 degrees or more, and the length of the first vertical wall in the vehicle height direction is 20 mm or more.

2. The side sill reinforcing member according to claim 1 , wherein the plurality of closed cross-sectional portions include three of the closed cross-sectional portions.

3. The side sill reinforcing member according to claim 1 or 2, wherein the closed cross-sectional portions other than the first closed cross-sectional portion among the plurality of closed cross-sectional portions have a rectangular shape when viewed along the vehicle length direction.

4. The wall portion 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.

5. 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.

6. The side sill reinforcing member according to claim 1 , wherein the first closed cross-sectional portion has an isosceles trapezoidal shape when viewed along the vehicle length direction.

Images