Reinforcement member for side sill

Abstract

This reinforcement member for a side sill comprises, as three closed cross-section parts disposed so as to follow the vehicle-width direction of a vehicle, a first closed cross-section part disposed closest to a collision surface side, a second closed cross-section part adjacent to the first closed cross-section part, and a third closed cross-section part that faces the first closed cross-section part so as to sandwich the second closed cross-section part. Wall parts that demarcate the three closed cross-section parts comprise a first wall part that demarcates the first closed cross-section part and a second wall part that demarcates the second closed cross-section part. The first wall part includes a pair of first horizontal walls that face one another in a vehicle-height direction, and the second wall part includes a pair of second horizontal walls that face one another in the vehicle-height direction. The ratio of length of the first closed cross-section part to the length of the second closed cross-section part in the vehicle-width direction is 0.32–0.60.

Description

Reinforcement member for side sill

[0001] The present disclosure relates to a reinforcement member for a side sill.

[0002] Conventionally, improvement of the safety of vehicle occupants has been demanded. For this purpose, the collision safety performance has been improved by improving the strength of the vehicle body. In particular, a side collision (hereinafter also referred to as a side impact) is likely to apply a strong impact to the passenger compartment, and high impact absorption performance is required for side impacts. That is, when an object such as a pole collides with the side of the vehicle body due to the vehicle body spinning or the like, it is necessary to absorb the impact energy and protect the passenger compartment. On the other hand, against the backdrop of the deepening of global warming and other issues, the movement to improve the fuel efficiency of automobiles has been accelerating. It is known that weight reduction of the vehicle body is effective for improving fuel efficiency.

[0003] For example, Patent Document 1 discloses a vehicle body lower structure that achieves both improvement in safety performance against side impacts and weight reduction. In this vehicle body lower structure, a reinforcing member is disposed under a skeletal member disposed on a side portion of the vehicle body called a rocker or a side sill, and the reinforcing member absorbs impact energy during a side impact.

[0004] Japanese Patent Application Laid-Open No. 2018-90020

[0005] In a side impact of a vehicle, the impact load tends to increase as the deformation amount (displacement) of the reinforcing member in the vehicle width direction increases. In the above-mentioned reinforcing member, there is room for improvement in the amount of impact energy absorbed (energy absorption per unit weight).

[0006] The present disclosure has been made in view of the above problems, and provides a reinforcement member for a side sill that can improve the energy absorption per unit weight.

[0007] This disclosure provides a side sill reinforcing member comprising three closed cross-sectional portions arranged along the vehicle width direction, and a wall portion defining the three closed cross-sectional portions, wherein the three closed cross-sectional portions include a first closed cross-sectional portion located closest to the collision surface, a second closed cross-sectional portion adjacent to the first closed cross-sectional portion, and a third closed cross-sectional portion facing the first closed cross-sectional portion with the second closed cross-sectional portion in between; the wall portion includes a first wall portion defining the first closed cross-sectional portion and a second wall portion defining the second closed cross-sectional portion, the first wall portion includes a pair of first lateral walls facing each other in the vehicle height direction, the second wall portion includes a pair of second lateral walls facing each other in the vehicle height direction, the thickness of the second lateral walls is greater than the thickness of the first lateral walls, and in the vehicle width direction, the length of the first closed cross-sectional portion relative to the length of the second closed cross-sectional portion is 0.32 or more and 0.60 or less.

[0008] When a cylindrical object (for example, a utility pole) collides with a vehicle from the width direction (side collision), the deformation region gradually expands in the longitudinal direction of the vehicle as the deformation progresses. Therefore, by setting the thickness (length in the vehicle height direction) of the second lateral wall defining the second closed section, which has a relatively large deformation region in the longitudinal direction, to be greater than the thickness (length in the vehicle height direction) of the first lateral wall defining the first closed section, which has a relatively small deformation region in the longitudinal direction, it is possible to improve the amount of collision energy absorbed while reducing weight. Furthermore, as in the above configuration, by setting the length (width) of the second closed section in the width direction to the length (width) of the first closed section in the width direction, as in the above configuration, within the range of 0.32 to 0.60 in relation to the length of the second closed section in the vehicle width direction, it is possible to control the deformation load (the peak of the deformation load can be timed appropriately, and the decrease in the deformation load can be suppressed) while reducing weight. In other words, according to the above configuration, the deformation load can be controlled, and the amount of energy absorbed per unit weight can be improved.

[0009] The length of the first closed section in the vehicle width direction may be 18 mm or more and 35 mm or less.

[0010] According to the above configuration, the amount of energy absorbed per unit weight can be improved.

[0011] The maximum length of the second closed section in the vehicle height direction is greater than or equal to the maximum length of the first closed section in the vehicle height direction, and the angle made by the second side wall with respect to the vehicle width direction may be 0 degrees or more and 4.0 degrees or less.

[0012] According to the above configuration, the deformation shape can be controlled to deform convexly outward, thereby suppressing collapse deformation. Furthermore, when the second closed section undergoes crush deformation, the second lateral wall becomes approximately parallel to the collision direction, making it easier for the second lateral wall to receive the load. As a result, the deformation load is improved, and the collision energy efficiency can be improved.

[0013] The wall portion further comprises a third wall portion defining the third closed cross-section, the third wall portion including a pair of third transverse walls facing each other in the vehicle height direction and a pair of vertical walls facing each other in the vehicle width direction, the pair of vertical walls including an inner vertical wall on the side farther from the collision surface and an outer vertical wall on the side closer to the collision surface, the height of the inner vertical wall in the vehicle height direction being smaller than the height of the outer vertical wall, and the angle made by the third transverse wall with respect to the vehicle width direction being 3 degrees or more and 15 degrees or less.

[0014] According to the above configuration, after the second closed section undergoes crushing deformation, the third lateral wall becomes approximately parallel to the impact direction, making it easier for the third lateral wall to receive the load. As a result, the deformation load is improved, and the amount of energy absorbed per unit weight can be increased.

[0015] The thickness of the third side wall may be less than the thickness of the second side wall.

[0016] According to the above configuration, it is possible to suppress the deformation load of the third closed section, which is furthest from the collision surface and has a larger deformation region in the front-rear direction than the second closed section, from becoming too high. This makes it possible to suppress damage to the components placed inside the reinforcing member.

[0017] The wall portion includes a first vertical wall, a second vertical wall, a third vertical wall, and a fourth vertical wall perpendicular to the vehicle width direction, in order from the collision surface side, wherein the thickness of the second vertical wall may be greater than the thickness of the first vertical wall, and the thickness of the fourth vertical wall may be greater than the thickness of the third vertical wall.

[0018] According to the above configuration, by setting the thickness (length in the vehicle width direction) of the second vertical wall, which has a larger deformation region in the front-rear direction than the first vertical wall, to be greater (thicker) than the thickness (length in the vehicle width direction) of the first vertical wall, it is possible to efficiently control the deformation load while reducing weight. Furthermore, the fourth vertical wall is further away from the collision surface than the third vertical wall and forms the outer shell of the rearmost side (the side furthest from the collision surface to the passenger compartment) of the side sill reinforcing member, and is required to withstand a higher deformation load than the third vertical wall. For this reason, by setting the thickness (length in the vehicle width direction) of the fourth vertical wall to be greater (thicker) than the thickness (length in the vehicle width direction) of the third vertical wall, it is possible to efficiently control the deformation load while reducing weight.

[0019] The reinforcing member for the side sill according to this disclosure can improve the amount of energy absorbed per unit weight.

[0020] A schematic diagram of a vehicle equipped with a side sill reinforcing member according to the first embodiment of this disclosure. A diagram showing the lower space and its vicinity according to the first embodiment of this disclosure. A diagram showing the configuration of the reinforcing member according to the first embodiment of this disclosure. A graph showing the relationship between load and displacement of the reinforcing member according to the first embodiment of this disclosure. A graph showing the relationship between the width ratio b1 / b2 and EA amount / unit weight of the reinforcing member according to the first embodiment of this disclosure. A graph showing the relationship between the width ratio b1 / b2 and EA efficiency of the reinforcing member according to the first embodiment of this disclosure. A graph showing the relationship between the first width b1 and EA amount / unit weight of the reinforcing member according to the first embodiment of this disclosure. A graph showing the relationship between the load and displacement of the reinforcing member according to the first embodiment of this disclosure. A diagram showing the configuration of the reinforcing member according to the second embodiment of this disclosure. A partially enlarged view of the reinforcing member shown in Figure 8A. A graph showing the relationship between the first inclination angle θ1, EA amount / unit weight, and EA efficiency of the reinforcing member according to the second embodiment of this disclosure. A graph showing the relationship between the second inclination angle θ2, EA amount / unit weight, and EA efficiency of the reinforcing member according to the second embodiment of this disclosure. A figure showing a modified form of the reinforcing member according to the second embodiment of this disclosure. A figure showing a modified example of the reinforcing member according to the second embodiment of this disclosure. A figure showing a modified example of the reinforcing member according to the second embodiment of this disclosure.

[0021] (First Embodiment) The first embodiment of the present disclosure will be described below with reference to the attached drawings. Note that in the drawings referred to below, hatching indicating cross-sections has been omitted.

[0022] As shown in Figure 1, the side sill reinforcing member 1 (hereinafter referred to as "reinforcing member 1") is installed in a vehicle V such as a passenger car, truck, work vehicle, or other mobility vehicle. The reinforcing member 1 is used as a member to reinforce the side sill 100, which will be described later.

[0023] In this embodiment, vehicle V is an electric vehicle equipped with a motor (not shown) and a battery B (secondary battery). Vehicle V moves by power supplied from battery B to drive the motor. Note that vehicle V is not limited to an electric vehicle, but may be a hybrid vehicle.

[0024] In the following, the vehicle length direction of vehicle V will be referred to as the "X direction," the vehicle width direction as the "Y direction," and the vehicle height direction as the "Z direction." The front side of the X direction will be referred to as the "-X side," and the rear side as the "+X side." The right side of the Y direction will be referred to as the "+Y side," and the left side as the "-Y side." The upper side of the Z direction will be referred to as the "+Z side," and the lower side 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 the colliding object collides with vehicle V. The colliding object is a cylindrical object, for example, a pole (utility pole, etc.) with a diameter of φ254 mm.

[0025] (Configuration of the lower space and its vicinity) Figure 2 is a schematic diagram of the lower space SU of vehicle V and its vicinity. More specifically, Figure 2 is a view of the lower space SU on the -Y side and its vicinity along the X direction (from the front). Note that the +Y side of the lower space SU is almost the same as the -Y side, except that the left and right sides are reversed.

[0026] As shown in Figure 2, in addition to the battery B, the vehicle V further comprises a floor panel FP, a floor cloth FC, and a side sill 100. The vehicle V also further comprises a ladder frame and other components (not shown) in the lower space SU.

[0027] The floor panel FP forms the underside of the passenger compartment SR and separates the passenger compartment SR from the lower space SU.

[0028] The floor cross FC is a frame member that increases the rigidity of the vehicle V. The floor cross FC is positioned on the +Z side of the floor panel FP and extends in the Y direction.

[0029] 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 positioned outside the vehicle V in the Y direction, relative to the floor panel FP and floor cloth FC. In this specification, the outside of the vehicle V in the Y direction is referred to as the "outside of the vehicle V," and the inside of the vehicle V in the Y direction is referred to as the "inside of the vehicle V." Furthermore, since the outermost part of the vehicle V is the side where collision with an object is expected, the outside of the vehicle V may be referred to as the "collision surface side," and the opposite side as the "rear side."

[0030] (Side sill) The side sill 100 has an outer member 101 and an inner member 102. The outer member 101 is positioned outside the vehicle V compared to the inner member 102. The inner member 102 is joined to the floor panel FP and floor cloth FC mainly by welding (e.g., resistance spot welding).

[0031] The outer member 101 and the inner member 102 each have a hat shape when viewed in an X-Z cross section (cross section). The flange portions of the outer member 101 and the inner member 102 are joined together by welding or the like. This creates an internal space SS between the outer member 101 and the inner member 102.

[0032] (Reinforcement Member) The reinforcement member 1 reinforces the side sill 100 by absorbing collision energy while sequentially deforming from the collision side when the vehicle V is hit from the Y direction (side collision). In this embodiment, the reinforcement member 1 is placed in the internal space SS of the side sill 100. The inner portion of the reinforcement member 1 is joined to a component (not shown) inside the inner member 102 via an inner member 102 by a fastening member SW. As a result, at least a portion of the inner portion of the reinforcement member 1 is connected to the floor panel FP and floor cloth FC via the inner member 102. On the other hand, the outer portion of the reinforcement member 1 is joined to the outer member 101. The outer portion of the vehicle V is joined to the outer member 101 by an adhesive G or the like.

[0033] The reinforcing member 1 is a hollow extruded material formed by extruding metal. The reinforcing member 1 extends parallel to the side sill 100, that is, in the X direction, and the cross-section (transverse plane) perpendicular to the X direction has a constant shape. In this embodiment, the reinforcing member 1 has dimensions of 1700 mm in the X direction, dimensions (outer dimensions) of 135 mm in the Y direction, and a maximum dimension (outer dimensions) of 32.9 mm in the Z direction. For example, the dimensions (outer dimensions) in the Y direction are a maximum of 250 mm, and are generally 200 mm or less and 100 mm or more. Also, the dimensions (outer dimensions) in the Z direction are 30 mm or more and 80 mm or less. It is desirable to set the dimensions in the Z direction to be small because the weight increases as the dimensions in the Z direction increase. In this embodiment, the reinforcing member 1 is an extruded profile made of 6000 series aluminum alloy.

[0034] Figure 3 shows the reinforcing member 1 shown in Figure 2. As shown in Figure 3, the reinforcing member 1 has two horizontal walls (webs) 1y and four vertical walls (side walls) 1t. The two horizontal walls 1y and the four vertical walls 1t constitute a wall portion 1g.

[0035] (Side walls) The two side walls 1y have an XY plane perpendicular to the Z direction and face each other in the Z direction. In this embodiment, the thickness of the two side walls 1y is not uniform but set to be non-uniform. The thickness of the side walls 1y will be described later.

[0036] (Vertical Walls) The four vertical walls 1t have an XZ plane perpendicular to the Y direction and face each other in the Y direction. Hereinafter, the four vertical walls 1t will be referred to as "first vertical wall 11t", "second vertical wall 12t", "third vertical wall 13t", and "fourth vertical wall 14t".

[0037] 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. That is, the second vertical wall 12t is arranged 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 with the second vertical wall 12t in between, and the fourth vertical wall 14t faces the second vertical wall 12t in the Y direction with the third vertical wall 13t in between. In this embodiment, the heights (lengths in the Z direction) of the first to fourth vertical walls 11t to 14t are equal to each other, for example, set to 32.9 mm.

[0038] The thicknesses (lengths in the Y direction) of the first vertical wall 11t to the fourth vertical wall 14t are not constant, but each has a different value. Specifically, the thickness tw2 of the second vertical wall 12t is set to be the largest, followed by the thickness tw4 of the fourth vertical wall 14t, the thickness tw1 of the first vertical wall 11t, and the thickness tw3 of the third vertical wall 13t, in that order. Specifically, the thickness tw1 of the first vertical wall 11t is set to, for example, 4.6 mm, the thickness tw2 of the second vertical wall 12t is set to, for example, 6.4 mm, the thickness tw3 of the third vertical wall 13t is set to, for example, 3.0 mm, and the thickness tw4 of the fourth vertical wall 14t is set to, for example, 6.3 mm.

[0039] The reinforcing member 1 has a hollow section (a space defined by two horizontal walls 1y, a first vertical wall 11t, and a fourth vertical wall 14t) which is divided into three sections by a second vertical wall 12t and a third vertical wall 13t. In other words, the reinforcing member 1 is a reinforcing member of 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] (Configuration of Closed Sections) Hereinafter, each of the three partitioned spaces will be referred to as a "closed section 10". The three closed sections 10 will be referred to as the "first closed section 11", the "second closed section 12", and the "third closed section 13", in order from the outside of the vehicle V. The first closed section 11 is located on the outermost side (collision surface side) of the vehicle V, the second closed section 12 is located second from the outside and adjacent to the first closed section 11, and the third closed section 13 is located third from the outside. In this embodiment, the first closed section 11, the second closed section 12, and the third closed section 13 are each rectangular in shape when viewed in the X direction.

[0041] The first closed section 11 is partitioned by a first vertical wall 11t, a second vertical wall 12t, and a portion of two horizontal walls 1y. Hereinafter, the upper and lower horizontal walls 1y that partition the first closed section 11 will be referred to as the "pair of first horizontal walls 11y," and the first vertical wall 11t, the second vertical wall 12t, and the pair of first horizontal walls 11y that partition the first closed section 11 will be collectively referred to as the "first wall section 11g." In this embodiment, the thickness tf1 (length in the Z direction) of the first horizontal wall 11y is set to 4.8 mm.

[0042] The second closed section 12 is demarcated by the second vertical wall 12t, the third vertical wall 13t, and a portion of the two horizontal walls 1y. Hereinafter, the upper and lower horizontal walls 1y that demarcate the second closed section 12 will be referred to as the "pair of second horizontal walls 12y," and the second vertical wall 12t, the third vertical wall 13t, and the pair of second horizontal walls 12y that demarcate the second closed section 12 will be collectively referred to as the "second wall section 12g." In this embodiment, the thickness tf2 (length in the Z direction) of the second horizontal wall 12y is set to a value greater than the thickness tf1 of the first horizontal wall 11y. Specifically, the thickness tf2 of the second horizontal wall 12y is set to 6.4 mm.

[0043] The third closing portion 13 is defined by a part of the third vertical wall 13t, the fourth vertical wall 14t, and two lateral walls 1y. Hereinafter, the upper and lower lateral walls 1y that define the third closing portion 13 are referred to as "pair of third lateral walls 13y", and the third vertical wall 13t, the fourth vertical wall 14t, and the pair of third lateral walls 13y that define the third closing portion 13 are collectively referred to as "third wall portion 13g". In the present embodiment, the thickness tf3 (length in the Z direction) of the third lateral wall 13y is set to a value smaller than that of the first lateral wall ll y and the second lateral wall 12y. Specifically, the thickness tf3 of the third lateral wall 13y is set to 4.4 mm. Note that the third vertical wall 13t and the fourth vertical wall 14t are examples of a pair of vertical walls. Further, the third vertical wall 13t is an example of an outer vertical wall on the side closer to the collision surface side, and the fourth vertical wall 14t is an example of an inner vertical wall on the side farther from the collision surface side.

[0044] The second vertical wall 12t defines the first closing portion 11 on the side closer to the first closing portion 11 than the column core, and defines the second closing portion 12 on the side closer to the second closing portion 12 than the column core. Similarly, the third vertical wall 13t defines the second closing portion 12 on the side closer to the second closing portion 12 than the column core, and defines the third closing portion 13 on the side closer to the third closing portion 13 than the column core.

[0045] (Configuration of width of closing portion) The first closing portion 11, the second closing portion 12, and the third closing portion 13 are set to different values for their inner dimensions in the Y direction (hereinafter referred to as "width"). Specifically, the second width b2 (length in the vehicle width direction of the second closing portion 12) of the second closing portion 12 is the largest, and the first width b1 (length in the vehicle width direction of the first closing portion 11) of the first closing portion 11 and the third width b3 (length in the vehicle width direction of the third closing portion 13) of the third closing portion 13 are set to smaller values in this order.

[0046] The ratio of the first width b1 of the first closing surface portion 11 to the second width b2 of the second closing surface portion 12 (hereinafter referred to as "width ratio b1 / b2") is preferably 0.32 or more and 0.60 or less (preferably around 0.40). Specifically, the lower limit value of the width ratio b1 / b2 is set to 0.32 or more, preferably 0.35 or more, and the upper limit value of the width ratio b1 / b2 is set to 0.60 or less, more preferably 0.5 or less. The width ratio b1 / b2 can arbitrarily combine the above lower limit value and upper limit value. In the present embodiment, the first width b1 of the first closing surface portion 11 is 30.60 mm, the second width b2 of the second closing surface portion 12 is 65.90 mm, and the third width b3 of the third closing surface portion 13 is 15.70 mm, and the width ratio b1 / b2 is 0.46.

[0047] FIG. 4 is a graph showing the relationship between the displacement and the deformation load (hereinafter referred to as "load") obtained by modeling the configuration of the reinforcing member 1 (see FIG. 3) described in the embodiment and analyzing it under predetermined analysis conditions (CAE analysis). The horizontal axis shown in FIG. 4 indicates the displacement S (mm) under the analysis conditions shown below, and the vertical axis indicates the load P (kN).

[0048] In the above analysis, using the general-purpose dynamic explicit method software LS-DYNA, with the above model in a state where only the Z direction of the end cross-section is constrained by a rigid wall, a cylindrical impact object with a diameter of φ254 mm is displaced in the Y direction (from the -Y side to the +Y side), and the result is obtained by causing crushing deformation. The rigid wall is installed with complete restraint on the -Y side compared to the model according to the example. The graphs of FIGS. 5A to 7 are also obtained by analysis under the same conditions.

[0049] As shown in FIG. 4, in the configuration (Comparative Example 1) where the width ratio b1 / b2 is set to 0.19, it can be seen that the peak of the deformation load becomes less than the displacement S = 20 mm, and then the deformation load S rapidly decreases. Also, in the configuration (Comparative Example 2) where the width ratio b1 / b2 is set to 0.92, the peak of the deformation load becomes after the displacement S = 40 mm, and the load in the first half of the collision (S = 20 mm or less) does not increase. It can be seen that the EA amount in both conditions is lower than the ideal state.

[0050] On the other hand, in the configuration with a width ratio b1 / b2 = 0.35 (Example 1) and the configuration with a width ratio b1 / b2 = 0.60 (Example 2), which fall within the above range (width ratio b1 / b2 = 0.32 or more and 0.60 or less), the timing of the occurrence of the first load peak occurs when the displacement S = 20 mm or more and less than 40 mm, which is an appropriate timing that can secure a high deformation load over a long stroke. Note that in Example 2, b3 / b2 = 0.6.

[0051] Figure 5A is a graph showing the relationship between the width ratio b1 / b2 and the amount of energy absorbed per unit weight (hereinafter referred to as "EA amount / unit weight"). In Figure 5A, the horizontal axis shows the width ratio b1 / b2, and the vertical axis shows the amount of EA / unit weight (kJm / kg). Figure 5B is a graph showing the relationship between the width ratio b1 / b2 and EA efficiency. In Figure 5B, the horizontal axis shows the width ratio b1 / b2, and the vertical axis shows the energy efficiency (hereinafter referred to as EA efficiency) η (%). Note that the amount of energy absorbed (EA amount) is calculated as maximum load × collision stroke (displacement S). The energy absorption efficiency η is calculated as EA amount / ideal EA amount. Here, the ideal EA amount is calculated as maximum load × collisionable stroke.

[0052] As shown in Figures 5A and 5B, by setting the width ratio b1 / b2 value within the above range (width ratio b1 / b2 = 0.32 or more and 0.60 or less), it is possible to ensure a higher EA volume / unit weight (7 kJm / kg or more) and a higher EA efficiency (70% or more) compared to cases outside this range.

[0053] In other words, by setting the width ratio b1 / b2 within the range of 0.32 to 0.60, the deformation load can be controlled, and the EA amount / unit weight can be improved.

[0054] Furthermore, as shown in Figures 6A and 6B, the first width b1 of the first closed section 11 is preferably set to 18 mm or more and 35 mm or less (preferably 25 mm). Specifically, the lower limit of the first width b1 of the first closed section 11 is set to 18 mm or more, preferably 20 mm or more. Also, the upper limit of the first width b1 of the first closed section 11 is preferably set to 35 mm or less, and more preferably 30 mm or less. The first width b1 of the first closed section 11 can be any combination of the above lower and upper limits.

[0055] Figure 6A is a graph showing the relationship between the first width b1 and the amount of EA / unit weight. In Figure 6A, the horizontal axis represents the first width b1 (mm), and the vertical axis represents the amount of EA / unit weight (kJm / kg). Figure 6B is a graph showing the relationship between the first width b1 and the EA efficiency. In Figure 6B, the horizontal axis represents the first width b1 (mm), and the vertical axis represents the EA efficiency η (%). Figures 6A and 6B are graphs showing the changes in the amount of EA / unit weight and the EA efficiency η when the range of the first width b1 is displaced from 15 mm to 45 mm, for a configuration with a width ratio b1 / b2 of 0.35 and a configuration with a width ratio b1 / b2 of 0.60.

[0056] As shown in Figures 6A and 6B, by setting the value of the first width b1 within the above range (18 mm or more, 35 mm or less), a high EA amount / unit weight and high EA efficiency can be ensured. Furthermore, as shown in Figure 7, the peak of the deformation load occurs when the displacement S = 20 mm or more and less than 40 mm, which is an appropriate timing for ensuring a high deformation load over a long stroke. If the width of the first width b1 is too large, the peak of the deformation load will be delayed beyond the appropriate timing, resulting in a decrease in the EA amount in the initial stages of the collision. Conversely, if it is too small, although the load peak occurs at an earlier timing, the deformation load decreases in the latter half of the collision, and the EA amount in the latter half of the collision decreases. As a result, the EA amount will be lower compared to the appropriate range described above. Figure 7 is a graph showing the relationship between the displacement and deformation load (hereinafter referred to as "load") of three different first widths b1 of the reinforcing member 1. The horizontal axis in Figure 7 shows the displacement S (mm) under the analysis conditions shown below, and the vertical axis shows the load P (kN).

[0057] (Effects of the First Embodiment) As described above, when a cylindrical object (for example, a pole such as a utility pole) collides with a vehicle from the width direction (side collision), the deformation region gradually expands in the longitudinal direction of the vehicle as the deformation progresses. If the thickness tf1 of the first lateral wall 11y that defines the first closed section 11, which has a relatively small deformation region in the longitudinal direction, is set to be large, it is inefficient in terms of energy absorption and weight reduction. For this reason, by setting the thickness tf2 of the second lateral wall 12y that defines the second closed section 12, which has a larger deformation region in the longitudinal direction than the first longitudinal wall 11t, to be larger than the thickness tf1 of the first lateral wall 11y that defines the first closed section 11, the amount of energy absorption / unit weight can be improved. Furthermore, by setting the width ratio b1 / b2, which is the ratio of the thin-walled first width b1 to the thick-walled second width b2, within the range of 0.32 to 0.60, it is possible to reduce weight while ensuring the peak of the deformation load occurs at an appropriate timing, thereby suppressing a decrease in the deformation load. At the same time, tilting deformation can also be suppressed. Moreover, in the latter half of the collision (displacement S > 70 mm), the wall constituting the third closed section 13 (third lateral wall 13y) comes into contact with the impacted object, which prevents the deformation load from decreasing too much. In other words, the deformation load can be controlled, and the EA amount / unit weight (energy absorption efficiency) can be improved.

[0058] Furthermore, if the first width b1 of the first closed section 11 is set to a small value, the timing of the deformation load peak becomes too early, and the deformation load in the latter half of the collision decreases. On the other hand, if the first width b1, which has a relatively small deformation region in the longitudinal direction as described above, is set to a large value, the timing of the load peak in the first half of the collision is delayed, and the amount of EA decreases in both conditions. In other words, by setting the first width b1 to 18 mm or more and 35 mm or less, the amount of EA / unit weight can be improved.

[0059] In the above embodiment, the thickness tf1 of the first side wall 11y of the first closed section 11 is set to be thinner than the thickness tf2 of the second side wall 12y. As described above, the deformation region (deformation range) of the first closed section 11 in the vehicle longitudinal direction during a pole collision is smaller than the deformation region (deformation range) of the second closed section 12, and thickening this part is inefficient from the viewpoint of energy absorption and weight reduction. Also, the thickness tf3 of the third side wall 13y constituting the third closed section 13 is set to be thinner than the thickness tf2 of the second side wall 12y. The deformation region (deformation range) of the third closed section 13 in the vehicle longitudinal direction is even wider than that of the second closed section 12, but if the deformation load becomes too high accordingly, it is likely to cause damage to parts inside the side sill 100. In order to efficiently absorb collision energy while preventing this, it is desirable to set the thickness tf3 of the third side wall 13y to be thinner than the thickness tf2 of the second side wall 12y, so that the deformation progresses under a generally constant load and the collision energy is absorbed.

[0060] In the above embodiment, the thickness tw2 of the second vertical wall 12t is greater than the thickness tw1 of the first vertical wall 11t, and the thickness tw4 of the fourth vertical wall 14t is greater than the thickness tw3 of the third vertical wall 13t. Here, because the first vertical wall 11t and the second vertical wall 12t are located on the collision surface side, a load is applied locally to a narrow area during a pole collision. In this case, in order to suppress buckling deformation of the lateral walls (first lateral wall 11y, second lateral wall 12y) connected to the rear side, the thickness of the vertical walls (first vertical wall 11t, second vertical wall 12t) needs to be somewhat thick (large). Specifically, the thickness of the vertical walls (first vertical wall 11t and second vertical wall 12t) needs to be about the same as the thickness of the lateral walls (first lateral wall 11y and second lateral wall 12y) connected to the inside of the vehicle V, respectively. In this embodiment, the thickness tw2 of the second vertical wall 12t and the thickness tf2 of the second horizontal wall 12y are set to equal values.

[0061] As mentioned above, from the viewpoint of energy absorption and weight reduction, the thickness tf1 of the first transverse wall 11y needs to be set thinner than the thickness tf2 of the second transverse wall 12y, and accordingly, it is desirable that the thickness tw1 of the first longitudinal wall 11t be set thinner than the thickness tw2 of the second longitudinal wall 12t. Furthermore, the third longitudinal wall 13t, located on the inside of the vehicle V in the second closed section 12, is subjected to loads over a wider range in the longitudinal direction compared to the first longitudinal wall 11t on the side closest to the collision surface or the second longitudinal wall 12t, which is the second from the collision surface, and localized loads are less likely to be applied. Also, because the deformation region (deformation range) in the longitudinal direction is wide, it is rather necessary to keep the load associated with the deformation of the third transverse wall low. For this reason, it is desirable that the third longitudinal wall 13t be thinner than the first longitudinal wall 11t and the second longitudinal wall 12t, and by making the third longitudinal wall 13t thinner, weight reduction can be achieved. Regarding the fourth vertical wall 14t located on the rearmost side, no localized load is applied, similar to the third vertical wall 13t. However, if it becomes too thin, tilting deformation of the entire cross-section is likely to occur. From the viewpoint of preventing this, the fourth vertical wall 14t cannot be made as thin as the third vertical wall 13t. Therefore, in order to restrain the rotational deformation of the third horizontal wall 13y, it is desirable to set its thickness to be equal to (similar to) or greater than that of the third horizontal wall 13y.

[0062] In summary, the thickness of the vertical walls (vertical ribs) should ideally be such that the third vertical wall 13t has the thinnest thickness tw3, the first vertical wall 11t has a thickness tw1 equal to (similar to) or greater than (slightly thicker than) the first horizontal wall 11y has a thickness tf1. Similarly, the second vertical wall 12t has a thickness tw2 equal to the second horizontal wall 12y has a thickness tf2, and the fourth vertical wall 14t has a thickness tw4 equal to (similar to) or greater than (slightly thicker than) the third horizontal wall 13y. In other words, the thickness of the vertical walls, excluding the third vertical wall, should ideally be equal to (similar to) the thickness of the adjacent (connected) horizontal wall in the vehicle width direction. Alternatively, the thickness of the vertical walls should ideally be greater than (slightly thicker than) the thickness of the adjacent (connected) horizontal wall in the vehicle width direction. Furthermore, by setting the third vertical wall thinner than the third horizontal wall 13y, further weight reduction can be achieved. This structure allows for weight reduction while efficiently controlling the deformation form.

[0063] (Modification of the First Embodiment) In the above embodiment, a configuration in which the first width b1 of the first closed section portion 11 and the third width b3 of the third closed section portion 13 are different was described, but the first width b1 and the third width b3 may be set to the same value.

[0064] (Second Embodiment) Next, the reinforcing member 1 according to the second embodiment will be described with reference to Figures 8A to 11. In the second embodiment, the horizontal wall 1y is inclined, and the height (length in the vehicle height direction) of the vertical walls constituting the second closed section 12 and the third closed section 13 is different from that of the first embodiment. Note that the other configurations are the same as in the first embodiment, so the same or similar components as in the first embodiment are denoted by the same reference numerals and detailed descriptions are omitted.

[0065] As shown in Figures 8A and 8B, in this embodiment, the second closed section 12 and the third closed section 13 are each trapezoidal in shape when viewed along the X direction. The height (length in the vehicle height direction) C1-Z of the third vertical wall 13t constituting the second closed section 12 is greater than the height A1-Z of the first vertical wall 11t constituting the first closed section 11 and the second height B1-Z of the second vertical wall 12t, and the height D1-Z of the fourth vertical wall 14t constituting the third closed section 13 is smaller than the height C1-Z of the third vertical wall 13t. Furthermore, the height D1-Z of the fourth vertical wall 14t is greater than the height A1-Z of the first vertical wall 11t.

[0066] The height A1-Z (length in the Z direction) of the first vertical wall 11t is set to, for example, 30.0 mm, the height B1-Z (length in the Z direction from the column center of the second vertical wall 12t) is set to, for example, 31.8 mm, the height C1-Z (length in the Z direction from the column center of the third vertical wall 13t) is set to, for example, 38.0 mm, and the height D1-Z (length in the Z direction) of the fourth vertical wall 14t is set to, for example, 33.4 mm.

[0067] In this embodiment, the maximum height of the second closed section 12 is greater than or equal to the maximum height of the first closed section 11, and the height of the second closed section 12 increases as it moves from the collision surface side to the rear side (from the -Y side to the +Y side). Specifically, the inclination angle (angle with respect to the vehicle width direction) of the first side wall 11y constituting the first closed section 11 is very small and almost horizontal, but the pair of second side walls 12y are inclined with respect to the vehicle width direction so that they move away from each other as they move from the collision surface side to the rear side. Specifically, the first inclination angle θ1 made by the second side walls 12y with respect to the vehicle width direction is 2.5 degrees in this embodiment.

[0068] The first inclination angle θ1 is preferably set to 0 degrees or more and 4.0 degrees or less (preferably 2.0 degrees). More specifically, the lower limit of the first inclination angle θ1 is preferably set to 0 degrees or more, more preferably 1 degree or more. The upper limit of the first inclination angle θ1 is preferably set to 4.0 degrees or less, preferably 3.0 degrees or less. The first inclination angle θ1 can be any combination of the above upper and lower limits.

[0069] Furthermore, in this embodiment, the third closed section 13 is configured such that its height decreases as it moves from the collision surface side towards the rear side. That is, as it moves from the collision surface side towards the rear side, the pair of third side walls 13y are inclined with respect to the vehicle width direction (Y direction) so that they move closer to each other. Specifically, the second inclination angle θ2 made by the third side walls 13y with respect to the vehicle width direction is 5.6 degrees in this embodiment.

[0070] The second inclination angle θ2 is preferably set to 3 degrees or more and 15 degrees or less (preferably 6.0 degrees). More specifically, the lower limit of the second inclination angle θ2 is set to 3 degrees or more, preferably 5.0 degrees or more. The upper limit of the second inclination angle θ2 is set to 15 degrees or less, preferably 10.0 degrees or less. The upper and lower limits of the second inclination angle θ2 can be arbitrarily combined. If the value of the second inclination angle θ2 is too large, the third closed section 13 may deform before the first closed section 11 and the second closed section 12. Also, if the value of the second inclination angle θ2 is too large, the length of the fourth vertical wall 14t in the vehicle height direction will be shortened, which may hinder joining or bonding with the inner member 102 located inside the fourth vertical wall 14t. Therefore, it is desirable to set the second inclination angle θ2 within the above range.

[0071] As shown in Figures 9 and 10, by setting the value of the first inclination angle θ1 within the above range (0 degrees to 4.0 degrees) and the second inclination angle θ2 within the above range (3 degrees to 15 degrees), a high EA quantity / unit weight and high EA efficiency can be ensured. Figure 9 is a graph showing the relationship between the first inclination angle θ1, EA quantity / unit weight, and EA efficiency. In Figure 9, the horizontal axis shows the first inclination angle θ1, and the vertical axis shows the EA quantity / unit weight (kJm / kg) and EA efficiency η (%). Figure 10 is a graph showing the relationship between the second inclination angle θ2, EA quantity / unit weight, and EA efficiency. In Figure 10, the horizontal axis shows the second inclination angle θ2, and the vertical axis shows the EA quantity / unit weight (kJm / kg) and EA efficiency η (%). Figures 9 and 10 are graphs obtained from analysis under the same conditions as the graph in Figure 4.

[0072] (Effects of the second embodiment) As described above, by setting the first inclination angle θ1 within the above range (0 degrees or more and 4.0 degrees or less), the deformation load is improved and the EA amount / unit weight can be improved (see Figure 9). This is because when the second closed section 12 is crushed, the second lateral wall 12y becomes approximately parallel to the collision direction, making it easier for the second lateral wall 12y to receive the load.

[0073] Furthermore, by setting the second inclination angle θ2 within the above range (3 degrees to 15 degrees), the deformation load is improved, and the EA amount / unit weight can be increased (see Figure 10). This is because, after the second closed section 12 undergoes crush deformation, the third lateral wall 13y becomes approximately parallel to the collision direction, making it easier for the third lateral wall 13y to receive the load.

[0074] According to the above embodiment, as shown in Figure 11, the deformation shape can be controlled so that the second closed cross-section portion 12 deforms convexly outward. As a result, tilting deformation can be suppressed. Figure 11 is a diagram showing the deformation shape of the reinforcing member 1 according to the second embodiment. Note that Figure 11 was obtained by analysis under the same conditions as the graph in Figure 4.

[0075] (Modification of the second embodiment) As shown in Figure 12A, only the second side wall 12y (first inclination angle θ1) may be inclined with respect to the vehicle width direction. Alternatively, as shown in Figure 12B, only the third side wall 13y (second inclination angle θ2) may be inclined with respect to the vehicle width direction.

[0076] (Other Modifications) In the above embodiment, the present disclosure was described in the case where it is applied to a reinforcing member 1 located in the internal space SS of the side sill 100. However, the present disclosure is also applicable to a reinforcing member 1 located below or to the side (rear side) of the side sill 100.

[0077] Furthermore, the reinforcing member 1 can also be applied to the frame of the vehicle V other than the side sill 100.

[0078] Furthermore, in the description of the above embodiments, expressions such as parallel, perpendicular, orthogonal, equal, and identical include not only strictly parallel, perpendicular, orthogonal, equal, and identical, but also substantially parallel, perpendicular, orthogonal, equal, and identical.

[0079] This disclosure may include the following aspects:

[0080] (Aspect 1) A side sill reinforcing member comprising: three closed cross-sectional portions arranged along the vehicle width direction; and a wall portion defining the three closed cross-sectional portions, wherein the three closed cross-sectional portions each have a first closed cross-sectional portion located closest to the collision surface, a second closed cross-sectional portion adjacent to the first closed cross-sectional portion, and a third closed cross-sectional portion facing the first closed cross-sectional portion with the second closed cross-sectional portion in between; the wall portion each has a first wall portion defining the first closed cross-sectional portion and a second wall portion defining the second closed cross-sectional portion; the first wall portion includes a pair of first lateral walls facing each other in the vehicle height direction; the second wall portion includes a pair of second lateral walls facing each other in the vehicle height direction; the thickness of the second lateral walls is greater than the thickness of the first lateral walls; and in the vehicle width direction, the length of the first closed cross-sectional portion relative to the length of the second closed cross-sectional portion is 0.32 or more and 0.60 or less. (Aspect 2) The side sill reinforcing member according to Aspect 1, wherein the length of the first closed section in the vehicle width direction is 18 mm or more and 35 mm or less. (Aspect 3) The side sill reinforcing member according to Aspect 1, wherein the maximum length of the second closed section in the vehicle height direction is greater than or equal to the maximum length of the first closed section in the vehicle height direction, and the angle made by the second side wall with respect to the vehicle width direction is 0 degrees or more and 4.0 degrees or less. (Aspect 4) The side sill reinforcing member according to Aspect 2, wherein the maximum length of the second closed section in the vehicle height direction is greater than or equal to the maximum length of the first closed section in the vehicle height direction, and the angle made by the second side wall with respect to the vehicle width direction is 0 degrees or more and 4.0 degrees or less. (Aspect 5) The side sill reinforcing member according to any one of aspects 1 to 4, wherein the wall portion further comprises a third wall portion defining the third closed cross-section, the third wall portion includes a pair of third transverse walls facing each other in the vehicle height direction and a pair of vertical walls facing each other in the vehicle width direction, the pair of vertical walls includes an inner vertical wall on the side farther from the collision surface and an outer vertical wall on the side closer to the collision surface, the height of the inner vertical wall in the vehicle height direction is smaller than the height of the outer vertical wall, and the angle made by the third transverse wall with respect to the vehicle width direction is 3 degrees or more and 15 degrees or less. (Aspect 6) The side sill reinforcing member according to any one of aspects 1 to 5, wherein the thickness of the third transverse wall is smaller than the thickness of the second transverse wall.(Aspect 7) The wall portion includes a first vertical wall, a second vertical wall, a third vertical wall, and a fourth vertical wall perpendicular to the vehicle width direction, in order from the collision surface side, wherein the thickness of the second vertical wall is greater than the thickness of the first vertical wall, and the thickness of the fourth vertical wall is greater than the thickness of the third vertical wall, as described in any one of aspects 1 to 4.

[0081] This application is based on a Japanese patent application, Japanese Patent Application No. 2024-189807, filed on 29 October 2024. Japanese Patent Application No. 2024-189807 is incorporated herein by reference.

[0082] 1 Reinforcement member (reinforcement member for side sill) 1g Wall section 1t Vertical wall 10 Closed section 11 First closed section 11g First wall section 11t First vertical wall 11y First horizontal wall 12 Second closed section 12g Second wall section 12t Second vertical wall 12y Second horizontal wall 13 Third closed section 13g Third wall section 13t Third vertical wall (example of outer vertical wall) 13y Third horizontal wall 14t Fourth vertical wall (example of inner vertical wall) 100 Side sill 101 Outer member 102 Inner member B Battery b1 First width b2 Second width b3 Third width FC Floor cloth FP Floor panel G Adhesive SR Compartment SS Interior space SU Lower space SW Fastening member V Vehicle θ1 First inclination angle θ2 2nd angle of inclination

Claims

1. A side sill reinforcing member comprising: three closed cross-sectional portions arranged along the vehicle width direction; and a wall portion defining the three closed cross-sectional portions, wherein the three closed cross-sectional portions each have a first closed cross-sectional portion located closest to the collision surface, a second closed cross-sectional portion adjacent to the first closed cross-sectional portion, and a third closed cross-sectional portion facing the first closed cross-sectional portion with the second closed cross-sectional portion in between; the wall portion each has a first wall portion defining the first closed cross-sectional portion and a second wall portion defining the second closed cross-sectional portion; the first wall portion includes a pair of first lateral walls facing each other in the vehicle height direction; the second wall portion includes a pair of second lateral walls facing each other in the vehicle height direction; the thickness of the second lateral walls is greater than the thickness of the first lateral walls; and in the vehicle width direction, the length of the first closed cross-sectional portion relative to the length of the second closed cross-sectional portion is 0.32 or more and 0.60 or less.

2. The side sill reinforcing member according to claim 1, wherein the length of the first closed section in the vehicle width direction is 18 mm or more and 35 mm or less.

3. The side sill reinforcing member according to claim 1, wherein the maximum length of the second closed section in the vehicle height direction is greater than or equal to the maximum length of the first closed section in the vehicle height direction, and the angle made by the second side wall with respect to the vehicle width direction is 0 degrees or more and 4.0 degrees or less.

4. The side sill reinforcing member according to claim 2, wherein the maximum length of the second closed section in the vehicle height direction is greater than or equal to the maximum length of the first closed section in the vehicle height direction, and the angle made by the second side wall with respect to the vehicle width direction is 0 degrees or more and 4.0 degrees or less.

5. The side sill reinforcing member according to any one of claims 1 to 4, wherein the wall portion further comprises a third wall portion defining the third closed cross-section, the third wall portion includes a pair of third transverse walls facing each other in the vehicle height direction and a pair of vertical walls facing each other in the vehicle width direction, the pair of vertical walls includes an inner vertical wall on the side farther from the collision surface and an outer vertical wall on the side closer to the collision surface, the height of the inner vertical wall in the vehicle height direction is smaller than the height of the outer vertical wall, and the angle made by the third transverse wall with respect to the vehicle width direction is 3 degrees or more and 15 degrees or less.

6. The reinforcing member for the side sill according to claim 5, wherein the thickness of the third side wall is smaller than the thickness of the second side wall.

7. The side sill reinforcing member according to any one of claims 1 to 4, wherein the wall portion includes a first vertical wall, a second vertical wall, a third vertical wall, and a fourth vertical wall perpendicular to the vehicle width direction, in order from the collision surface side, the thickness of the second vertical wall is greater than the thickness of the first vertical wall, and the thickness of the fourth vertical wall is greater than the thickness of the third vertical wall.

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