JP2021020531A - Side sill - Google Patents

Abstract

To provide a side sill which can suppress folding deformation in small overlapping collision of an automobile.SOLUTION: In the side sill 1, a side sill outer 3 having a hat cross-sectional shape and a side sill inner 5 having a hat cross-sectional shape are joined to each other to form a closed cross section, a front end in a vehicle longitudinal direction is joined to the lower part of an A-pillar lower 21 so that the front end is covered with the lower part thereof and a central part in the vehicle longitudinal direction is joined to the lower part of a B pillar 23, bead shape parts 11 and 13 that extend toward the rear vehicle body from the same position as the rear end of the lower part of the A-pillar lower 21 and project outward are provided on an upper flange ridge line part 7 and a hat upper bottom ridge part 9 on the upper side of the vehicle, and when a length from the front end of the side sill 1 to the front end of the lower part of the B pillar 23 is represented by L0, a length of the front end is represented by L1 and lengths of the bead shape parts 11 and 13 are represented by L2, relations of 0.265≤L1/L0≤0.290 and 0.21≤L2/L0≤0.27 are satisfied.SELECTED DRAWING: Figure 1

Description

The present invention relates to an automobile side sill, and more particularly to a side sill that improves collision characteristics in a small overlap collision.

The requirements for collision safety performance of automobiles are becoming stricter year by year, and the body frame structure is required to have a function corresponding to collision as passive safety. The general body skeleton structure of an automobile is composed of a cabin, which is a passenger compartment, and crushable zones arranged in front of and behind the vehicle so as to sandwich the cabin. The crushable zone plays a role of absorbing impact by being greatly deformed at the time of a collision. On the other hand, the cabin is said to have higher collision safety if the deformation is minimized from the viewpoint of occupant protection.

In recent years, a small overlap (hereinafter abbreviated as "SOL") collision test has been adopted as a collision safety performance test. The SOL collision test is a test in which a part 25% of the width of the vehicle collides with a rigid wall at a speed of 64 km / h with respect to the front side of the vehicle. In a SOL collision, it is difficult to absorb the load at the time of a collision in a crushable zone such as a front side member, so that the impact on the cabin becomes large and tires and accessories invade the cabin. In particular, when a tire enters the side sill, the side sill is axially compressed and deformed in the front-rear direction of the vehicle. At this time, when the tire enters a position offset upward from the side sill due to the positional relationship between the tire and the side sill, the front of the side sill is likely to be bent and deformed so as to be convex downward from the vehicle. In such a bending deformation of the side sill in the SOL collision, the starting point is near the boundary with the rear end of the lower part of the A pillar lower covered by the outer peripheral surface of the side sill.

On the other hand, when a collision load is input to the closed cross-section member without being offset upward on the vehicle, as in the case of axial crushing of a general closed cross-section member, the input load is borne by the entire cross section. The closed cross-section member deforms in the axial direction.
Comparing such a deformation mode with the deformation mode of the side sill in the SOL collision, the deformation mode in the SOL collision in which the bending deformation occurs at the time of axial crushing, the energy absorption efficiency decreases when the same collision energy is given, and the bending deformation occurs. There is a tendency for the amount of intrusion into the cabin to be larger. Therefore, it is important to suppress the bending deformation of the side sill caused by the intrusion of the tire in the SOL collision in order to improve the collision safety performance. Therefore, as one of the methods for improving the collision safety in the SOL collision, various techniques for suppressing the bending deformation of the side sill have been proposed.

Patent Document 1 describes a hinge pillar extending in the vertical direction on the side portion of the front portion of the vehicle body, a gusset joined to the inner wall of the hinge pillar, and a side sill having a front end connected to the lower end of the hinge pillar and extending in the front-rear direction of the vehicle. In the side body structure of a vehicle equipped with a front wheel arranged in front of the hinge pillar, a gusset is arranged at the joint between the lower end of the hinge pillar and the front end of the side sill so as to face the front wheel of the vehicle, resulting in a small over. A technique for suppressing deformation of the hinge pillar in the vehicle direction due to the front wheels retracting during a lap collision is disclosed.

In Patent Document 2, in a side sill in which a hat-shaped side sill outer and a hat-shaped side sill inner are spot-joined at their respective flanges, the inner wall surface of a wall portion that continuously rises from the flanges of the side sill outer and the side sill inner. Disclosed is a technique for suppressing a decrease in the amount of impact energy absorbed due to spot breakage when an impact load accompanied by axial crush deformation is applied to a side sill by joining a specific portion with a bonding plate.

Patent Document 3 describes that in a vehicle side body structure including a hinge pillar and a side sill extending rearward from the lower end of the hinge pillar, a portion near the upper side of the front end of the side sill has a higher bearing capacity than the front end of the side sill. By providing a shock absorbing member having a small size and an apron reinforcement extending forward from the front end of the hinge pillar, the shock absorbing member absorbs the collision load input from the apron reinforcement at the time of a small overlap collision. However, a technique for transmitting to the side sill to prevent deformation of the passenger compartment space is disclosed.

Japanese Unexamined Patent Publication No. 2014-11809 WO2017 / 142062 JP-A-2017-140874

The requirements for collision safety performance and weight reduction of automobiles are becoming stricter year by year, and it is necessary to propose a structure that satisfies both requirements, and it is necessary to satisfy the same requirements in the SOL collision test.
However, the techniques disclosed in Patent Document 1 and Patent Document 2 require the placement of new members in order to improve the collision performance, and an increase in weight is unavoidable.
Further, since the technique disclosed in Patent Document 3 does not suppress the bending deformation that becomes convex downward in the vehicle due to the tire collision with the side sill, the collision energy absorption effect is sufficiently sufficient when the side sill is bent and deformed. In some cases, it could not be demonstrated.

The present invention has been made to solve the above problems, and suppresses bending deformation of the side sill caused by the tire entering a position offset upward in the vehicle with respect to the side sill in a small overlap collision. It is an object of the present invention to provide a side sill capable of improving collision performance without increasing the weight.

(1) The side sill according to the present invention has a side sill outer having a hat cross-sectional shape that extends in the front-rear direction of the vehicle and opens toward the inside of the vehicle in the vehicle width direction, and a hat cross section that opens toward the outside of the vehicle in the vehicle width direction. A side sill inner having a shape is provided, and the side sill outer and the side sill inner are joined so that the opening sides face each other to form a closed cross section, and the outer surface of the side sill outer at the front end portion in the front-rear direction of the vehicle is oriented in the vertical direction of the vehicle. The lower part of the A-pillar lower to be arranged is covered and joined, and the central portion in the vehicle front-rear direction is joined to the lower part of the B-pillar arranged in the vehicle vertical direction. The side sill outer and the side sill inner are joined. , Each of which has a wall portion on the vehicle upper side, a vehicle side side, and a vehicle lower side, a flange portion on each of the vehicle upper side and the vehicle lower side, a flange portion on the vehicle upper side, and a wall portion on the vehicle upper side. The side sill outer and the side sill inner have an upper flange ridge line portion connecting the above and a hat upper bottom ridge line portion connecting the wall portion on the upper side of the vehicle and the wall portion on the side side of the vehicle. A pair of upper flange ridges between the side sill outer and the wall of the side sill inner on the upper side of the vehicle, the side sill outer, and the side sill outer are joined at the flanges on the upper side of the vehicle and the lower side of the vehicle. The side sill inners extend toward the rear of the vehicle body from the same position as the rear end of the lower part of the A pillar lower in the side sill outer on the upper bottom ridge of the hat, and are convex outward with respect to the closed cross section. A bead shape portion is provided, and the length from the front end of the side sill to the front end of the lower part of the B pillar in the vehicle front-rear direction is L ₀ , the length of the front end portion in the vehicle front-rear direction is L ₁ , and the bead shape portion. When the length in the front-rear direction of the vehicle is L ₂ , the relationship of 0.265 ≤ L ₁ / L ₀ ≤ 0.290 and 0.21 ≤ L ₂ / L ₀ ≤ 0.27 is satisfied.

In the present invention, by providing a convex bead-shaped portion having a predetermined length on the upper flange ridge portion on the upper side of the vehicle and the upper bottom ridge portion of the hat, from the central axis at the front end of the side sill in the front-rear direction of the vehicle to the upper side of the vehicle. When a collision load is input to an offset position, it suppresses bending deformation that becomes convex downward in the vehicle, and further increases the amount of collision energy absorbed to improve collision performance without increasing the weight. Can be done.

It is a figure explaining the side sill which concerns on embodiment of this invention. It is a figure which shows the cross-sectional shape of the side sill which concerns on embodiment of this invention (the cross-sectional view of the cross section P in FIG. 1). It is a figure which illustrates the shape of the bead shape part provided in the side sill which concerns on embodiment of this invention ((a) cross-sectional view of the bead shape part provided in the upper flange ridge line part, (b) the hat upper bottom ridge line. Cross-sectional view of the bead shape portion provided in the portion). It is a figure which shows the CAE model used for the collision analysis which simulated the small overlap collision analysis in an Example ((a) perspective view, (b) side view, (c) cross-sectional view). In the example, it is a figure which shows the analysis result of the collision analysis of the CAE model which concerns on the invention example, ((a) before a collision, (b) after a collision). In the Example, it is a figure which shows the CAE model which concerns on the prior art, and the analysis result of the collision analysis of the CAE ((a) before a collision, (b) after a collision). In the example, it is a figure which shows the analysis result of the collision analysis of the CAE model which concerns on the comparative example 1 which provided the bead shape part only in the upper flange ridge line part, and ((a) cross-sectional view, (b) collision. rear). It is a figure which shows the analysis result of the collision analysis of the CAE model which concerns on the comparative example 2 which provided the bead shape part only in the upper bottom ridge line part of the hat in an Example, ((a) cross-sectional view, (b). After the collision). It is a figure explaining the definition of the axis angle which used as the evaluation index of bending deformation in an Example. It is the figure which plotted the evaluation result of the bending deformation at the time of performing a collision analysis by changing L ₁ / L ₀ and L ₂ / L ₀ in an Example. It is a figure which shows the analysis result of the collision analysis of the CAE model which concerns on the comparative example 3 which made the length L ₂ of the bead shape part out of the range of this invention in an Example, ((a) before collision, (B) After the collision). It is a figure which plotted the evaluation result of the bending deformation at the time of performing a collision analysis by changing the dimension (width w and height h) of a bead shape part in an Example. In the Example, it is a graph which plotted the relationship between the invading amount of a colliding body, a load, and absorbed energy. In the example, it is a graph which compared the penetration amount when the absorbed energy was made equal in the collision analysis of the CAE model which concerns on the prior art example and the invention example. It is a figure which shows the analysis result of the collision analysis of the CAE model which concerns on the comparative example 4 which extended the range which covers and joins the lower part of A pillar lower without providing the bead shape part in an Example. It is a graph which shows the improvement rate of the absorbed energy per weight in the invention example and the comparative example 4 in an Example.

As shown as an example in FIG. 1, the side sill 1 according to the embodiment of the present invention has a closed cross section in which a side sill outer 3 extending in the vehicle front-rear direction and a side sill inner 5 extending in the vehicle front-rear direction are joined to each other. None, the lower part of the A pillar lower 21 arranged in the vehicle vertical direction on the outer surface of the front end portion in the vehicle front-rear direction is covered from the tip of the side sill 1 and joined, and the central portion in the vehicle front-rear direction is arranged in the vehicle vertical direction. It is joined to the lower part of the B pillar 23, and is attached to each of the upper flange ridge line portion 7 and the hat upper bottom ridge line portion 9 on the upper side of the vehicle from the same position as the rear end of the lower portion of the A pillar lower 21 toward the rear of the vehicle. The extending convex bead-shaped portions 11 and 13 are provided.
Hereinafter, each configuration will be described.
In this specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals, and duplicate description is omitted or simplified.

As shown in FIG. 2, the side sill outer 3 has a cross-sectional shape of a hat that opens inward in the vehicle width direction, and has a wall portion 3a and a wall portion 3b on the vehicle upper side, the vehicle side side, and the vehicle lower side, respectively. The wall portion 3c and the flange portion 3d and the flange portion 3e are provided on the upper side of the vehicle and the lower side of the vehicle, respectively. Further, the side sill outer 3 connects the upper flange ridge line portion 7a that connects the flange portion 3d on the upper side of the vehicle and the wall portion 3a on the upper side of the vehicle, and the wall portion 3a on the upper side of the vehicle and the wall portion 3b on the side of the vehicle. It has an upper bottom ridge line portion 9a of the hat.

As shown in FIG. 2, the side flange inner 5 has a cross-sectional shape of a hat that opens outward in the vehicle width direction, and has a wall portion 5a and a wall portion 5b on the vehicle upper side, the vehicle side side, and the vehicle lower side, respectively. The wall portion 5c and the flange portion 5d and the flange portion 5e are provided on the upper side of the vehicle and the lower side of the vehicle, respectively. Further, the side sill inner 5 connects the upper flange ridge line portion 7b that connects the flange portion 5d on the upper side of the vehicle and the wall portion 5a on the upper side of the vehicle, and the wall portion 5a on the upper side of the vehicle and the wall portion 5b on the side of the vehicle. The hat has an upper bottom ridge line portion 9b.

As shown in FIG. 2, the side sill outer 3 and the side sill inner 5 face each other on the opening side, the flange portion 3d and the flange portion 5d on the upper side of the vehicle are joined, and the flange portion 3e and the flange portion on the lower side of the vehicle are joined. 5e are joined to form a closed cross section.

Then, as shown in FIG. 1, the side sill 1 is joined by covering the outer surface of the side sill outer 3 at the front end portion in the front-rear direction of the vehicle with the lower portion of the A pillar lower 21 extending in the vertical direction of the vehicle. In the present embodiment, the A pillar lower 21 has a hat cross-sectional shape that opens toward the inside of the vehicle body in the vehicle width direction, and the lower portion thereof is curved toward the rear side of the vehicle body while maintaining the hat cross-sectional shape. It has a substantially L-shape in extension and side view.

Further, as shown in FIG. 1, the side sill 1 is joined to the lower portion of the B pillar 23 extending in the vertical direction of the vehicle by joining the outer surface of the side sill outer 3 in the central portion in the front-rear direction of the vehicle. In the present embodiment, the B-pillar 23 has a cross-sectional shape of a hat that opens toward the inside of the vehicle body in the vehicle width direction, and its lower portion is curved and extends toward both the front side of the vehicle body and the rear side of the vehicle body. It has a substantially T-shape when viewed from the side.

As shown in FIG. 2, the bead shape portion 11 is provided on the pair of upper flange ridge lines 7a and 7b on the upper side of the vehicle so as to be convex outward with respect to the closed cross section of the side sill 1. ..
As shown in FIG. 2, the bead-shaped portion 13 is provided on each of the upper bottom ridges 9a and 9b of the hat on the upper side of the vehicle so as to be convex outward with respect to the closed cross section of the side sill 1. is there.
As shown in FIGS. 3A and 3I, the bead shape portion 11 is formed on the convex portion 11a formed on the upper flange ridgeline portion 7a of the side sill outer 3 and the upper flange ridgeline portion 7b of the side sill innerr 5. It is composed of the formed convex portion 11b.

Then, as shown in FIG. 1, both the bead shape portion 11 and the bead shape portion 13 extend from the same position as the rear end of the lower portion of the A pillar lower 21 toward the rear side of the vehicle body of the side sill 1.

Further, the side sill 1 according to this embodiment, as shown in FIG. 1, the length in the longitudinal direction of the vehicle from the front end of the side sill 1 to the bottom of the front end of the B-pillar 23 suffered by the lower portion of the L _0, A Piraroa 21 When the length of the front end of the side sill 1 joined in the vehicle front-rear direction is L ₁ , and the lengths of the bead shape portion 11 and the bead shape portion 13 in the vehicle front-rear direction are L ₂ , L ₀ , L ₁ and L ₂ satisfies the relationship between the following equations (1) and (2).
0.265 ≤ L ₁ / L ₀ ≤ 0.290 ・ ・ ・ (1)
0.21 ≤ L ₂ / L ₀ ≤ 0.27 ・ ・ ・ (2)

From the above, in the side sill 1 according to the present embodiment, when a collision load is input at a position offset to the upper side of the vehicle from the central axis at the front end thereof, the vehicle starts from the vicinity of the rear end of the lower portion of the A pillar lower 21. It is possible to suppress bending deformation in the vertical direction. Then, by suppressing the bending deformation, the amount of collision energy absorbed can be improved, and the collision performance in a small overlap collision can be improved. Further, the side sill 1 according to the present embodiment undergoes a slight shape change such as providing a bead shape portion 11 and a bead shape portion 13 as shown in FIGS. 1 and 2, and a new member is added. Therefore, it is possible to improve collision performance such as suppression of bending deformation and improvement of collision energy absorption amount without increasing the weight.

In the side sill 1 according to the present embodiment, suppression of bending deformation in small offset collision and improvement of absorption amount of collision energy were demonstrated in Examples described later.

Further, the bead shape portion 11 and the bead shape portion 13 are not limited in their shapes and production methods.
The shape of the bead shape portion 11 is the shape of the upper flange ridge line portion 7 that protrudes outward (FIGS. 3 (a) and (i)), and the flange portion 3d (5d) and the wall portion 3a (5a). A shape in which the space is bent outward (FIGS. 3 (b) and (ii)), or a shape in which the space bulges outward from the upper flange ridge 7 (FIGS. 3 (a) and (iii)), etc. Can be exemplified.

Further, the shape of the bead shape portion 13 is a shape that protrudes outward while maintaining the shape of the upper bottom ridge line portion 9 of the hat (FIGS. 3 (b) and (i)), and extends from the wall portion 3a on the upper side of the vehicle. A shape that protrudes from the side wall 3b (FIGS. 3 (b) and (ii)), and bulges outward from the vehicle side wall 3b in the vehicle width direction to form a vehicle upper wall 3a. Examples thereof include shapes to be connected (FIGS. 3B and 3iii).

On the other hand, regarding the production method, for example, when the side sill outer 3 and the side sill inner 5 are manufactured by press molding, the convex portions 11a and the convex portions 11b constituting the bead shape portion 11 (FIGS. 3A and 3B). And the bead shape portion 13 may be produced at the same time, which is preferable because it does not increase the manufacturing cost or the number of steps.

Further, the dimensions of the bead shape portions 11 and 13 may be appropriately set. However, for example, as shown in FIG. 2, when the dimensions of the bead shape portions 11 and 13 are defined by the width w and the height h, it is preferable that the width w is 10 mm or more and the height h is 3 mm or more. The suitable width w and height h of the bead shape portion were also demonstrated in Examples described later.

In the side sill 1 according to the present embodiment, the lower portion of the A pillar lower 21 covers only the outer surface of the side sill outer 3 and is joined. However, in the present invention, the outer surfaces of both the side sill outer and the side sill inner are covered with the A pillar lower. It may be joined by covering the lower part of the.

Even in such a case, bead-shaped portions may be provided at least at three locations on the upper side of the side sill on the upper side of the vehicle and the upper bottom ridge of the hat on both the outer side and the inner side of the vehicle body. Further, a pair of lower flange ridges on the lower side of the vehicle (between the flange 3e and the wall 3c shown in FIG. 2 and between the flange 5e and the wall 5c) and / or the lower bottom ridge of the hat ( In addition to the wall portion 3b and the wall portion 3c shown in FIG. 2 and between the wall portion 5b and the wall portion 5c), a convex bead-shaped portion may be provided on the outside.

A specific experiment was conducted to confirm the action and effect of the side sill according to the present invention, and the results will be described below.

In the experiment, the side sill collision analysis in the small overlap collision test of automobiles was used to suppress bending deformation and improve the collision energy absorption performance by providing bead-shaped parts on the upper flange ridge of the side sill and the upper bottom ridge of the hat. I verified it.

As shown in FIG. 4, the CAE model 31 includes a side sill model 33 that models the side sill 1 (FIG. 1) and an A pillar lower model 35 that models the lower part of the A pillar lower 21 (FIG. 1). Is.

The side sill model 33 corresponds to the range from the front end in the vehicle front-rear direction to the front end of the lower part of the B pillar 23 in the side sill 1 shown in FIG. 1, and as shown in FIG. 4C, the side sill outer portion 37 having a hat cross-sectional shape. And the side sill inner portion 39 having a cross-sectional shape of the hat form a closed cross section with their opening sides facing each other.

In this example, the A-pillar lower model 35 is joined by covering the outer surface of the front end portion of the side sill model 33, and as shown in FIGS. 4 (c) and 4 (i), the A-pillar lower outer portion 41 having a hat cross-sectional shape. And the A-pillar lower inner portion 43 having a cross-sectional shape of the hat.

In the side sill model 33 and the A pillar lower model 35, the front ends in the front-rear direction of each vehicle are aligned, the outer surface of the side sill outer portion 37 is covered by the A pillar lower outer portion 41, and the outer surface of the side sill inner portion 39 is covered by the A pillar lower inner portion 43. Is covered. Then, it is assumed that the flange portions of the side sill outer portion 37, the side sill inner portion 39, the A pillar lower outer portion 41, and the A pillar lower inner portion 43 are joined by spot welding.

Further, in the CAE model 31, a pair of upper flange ridges 45 on the upper side of the vehicle in the side sill model 33 are provided with a convex bead-shaped portion 49, and the hat upper bottom ridge 47 is provided with a bead-shaped portion 51.
The bead shape portion 49 and the bead shape portion 51 extend from the same position as the rear end of the A pillar lower model 35 toward the rear of the vehicle body, and are convex outward with respect to the closed cross section of the side sill model 33. ..

The plate thickness and material of the side sill model 33 and the A-pillar lower model 35 are both 1.2 mm plate thickness and 1180 MPa class steel plate, and the material model in collision analysis is an isotropic elasto-plastic model considering strain rate dependence. And said.

Then, as shown in FIG. 5A, a collision analysis was performed in which the collision body 53 collides with the CAE model 31. In the collision analysis, the rear end of the CAE model 31 in the vehicle front-rear direction was completely restrained, and the collision body 53 (radius of curvature 100 mmR) collided with the front end of the CAE model 31 at a speed of 36 km / h. Here, the position where the colliding body 53 collides is set to a position offset by 35 mm above the central axis of the side sill model 33.

Although the collision speed in the small offset collision test using an actual vehicle is specified as 64 km / h, the speed at which the tire wheel collides with the front end of the side sill after the start of the collision is lower than the collision speed. Therefore, in the collision analysis according to the embodiment, the speed of the colliding body 53 colliding with the front end of the CAE model 31 is set to the above value (36 km / h).

Then, in the embodiment, as shown in FIG. 5, in the CAE model 31 provided with the bead shape portion 49 and the bead shape portion 51, the length of the side sill model 33 in the vehicle front-rear direction is L ₀ , and the A pillar lower model 35. The length of the front end of the side sill model 33 to be covered and joined is L ₁ , the length of the bead shape portion 49 and the bead shape portion 51 in the vehicle front and rear direction is L _2, and L ₀ , L ₁ and L ₂ is, to satisfy _{0.265 ≦ L 1 / L 0 ≦} 0.290 ( aforementioned formula (1)) and _{0.21 ≦ L 2 / L 0 ≦} 0.27 ( the aforementioned formula (2)), L _0, L ₁ and An example of the invention is one in which L ₂ is set.

Further, as a comparison target, as shown in FIG. 6A, a CAE model 55 composed of a side sill model 57 which is not provided with a bead-shaped portion to which the A pillar lower model 35 is covered and joined is used as a conventional example.

Further, as a comparison target, as shown in FIG. 7A, a CAE model 61 including a side sill model 63 in which the bead shape portion 49 is provided only on the upper flange ridge line portion 45 to which the A pillar lower model 35 is covered and joined is provided. Comparative Example 1, as shown in FIG. 8A, compares the CAE model 65 composed of the side sill model 67 in which the bead shape portion 51 is provided only on the upper bottom ridge line portion 47 of the hat to which the A pillar lower model 35 is covered and joined. Comparative Example 3, the bead shape portions 49 and 51 are provided for Example 2 and the CAE model 31 in which L ₀ , L ₁ and L ₂ are set so as not to satisfy the above-mentioned equation (1) or equation (2). Comparative Example 4 was a CAE model 69 (see FIG. 15 (a) described later) in which the A-pillar lower model 35 was covered and the joining range was lengthened.

Then, in the conventional example and Comparative Examples 1 to 4, collision analysis was performed in the same manner as in the invention example, and the amount of bending deformation and collision energy absorbed was evaluated.
In the conventional example and Comparative Examples 1 to 4, the same plate thickness (1.2 mm) and material (tensile strength 1180 MPa class steel plate) as those of the invention example were used, and the material model was an isotropic bullet in consideration of strain rate dependence. It was used as a plastic model.

<About bending deformation>
First, the bending deformation due to the collision of the colliding body was examined.
FIG. 5B shows the appearance of the CAE model 31 according to the invention example in which L ₁ / L ₀ = 0.284 and L ₂ / L ₀ = 0.22 (L ₀ = 1040 mm) after the collision body 53 is penetrated by 100 mm. ..
Similarly, FIG. 6B shows the appearance of the CAE model 55 according to the conventional example in which L ₁ / L ₀ = 0.284 (L ₀ = 1040 mm) after the colliding body 53 is penetrated by 100 mm.

In the CAE model 55 according to the conventional example, as shown in FIG. 6B, a bending deformation that becomes convex downward in the vehicle occurs starting from the rear end portion of the A pillar lower model 35. This is because the plate thickness is actually different between the part covered by the A-pillar lower model 35 (corresponding to the front end of the side sill model 57) and the part not covered (the part from the front end of the side sill model 57 to the rear side of the vehicle body). It is considered that when the collision body 53 collides with the side sill model 57 at the front end offset from the central axis, the stress is concentrated at the boundary where the plate thickness changes.

On the other hand, in the CAE model 31 according to the invention example, the side sill model 33 is axially crushed with almost no bending deformation. This is because the bead shape portion 49 and the bead shape portion 51 are provided on the upper flange ridge line portion 45 and the hat upper bottom ridge line portion 47 of the side sill model 33, respectively, so that the A pillar lower model 35 in the side sill model 33 is covered. It is considered that this is because the rigidity of the non-existent portion is improved and the bending deformation due to the collision of the colliding body 53 with the front end of the side sill model 33 is suppressed.

FIG. 7B shows a collision analysis of the CAE model 61 according to Comparative Example 1 in which the bead shape portion 49 is provided only on the upper flange ridge line portion 45 on the upper side of the vehicle, and after the collision body 53 has penetrated 100 mm. Show the appearance.
Further, in FIG. 8B, a collision analysis was performed on the CAE model 65 according to Comparative Example 2 in which the bead-shaped portion 51 was provided only on the upper bottom ridgeline portion 47 of the hat on the upper side of the vehicle, and the collision body 53 was penetrated by 100 mm. The appearance after the ridge is shown.

From FIGS. 7 (b) and 8 (b), both Comparative Example 1 and Comparative Example 2 are bent downward in the vehicle starting from the rear end of the A-pillar lower model 35 in the side sill model 63 or 67. It can be seen that the deformation has occurred. As a result, the bead-shaped portion 49 or the bead-shaped portion 51 alone cannot sufficiently suppress the bending deformation.

Next, in the CAE model 31 shown in FIG. 5, L ₀ , L ₁ and L ₂ were changed, and the range of L ₁ / L ₀ and L ₂ / L ₀ capable of suppressing bending deformation was examined.

The suppression of bending deformation was evaluated based on the axial angle shown in FIG.
The axis angles shown in FIG. 9 are the central axis of the side sill model 57 before the collision (before deformation) and the central axis of the front end of the side sill model 33 when the collision body 53 penetrates 100 mm in the collision analysis of the CAE model 55. The angle was set to be sharp.

Further, a collision analysis was similarly performed on the CAE model 31 provided with the bead shape portion 49 and the bead shape portion 51, and the axial angle was obtained in the same manner as in FIG. Since the shaft angle was about 20 ° in the CAE model 55 according to the conventional example, when the shaft angle is within ± 5 ° in the collision analysis of the CAE model 31 provided with the bead shape portion 49 and the bead shape portion 51. , It was evaluated that the bending deformation of the side sill model 33 was suppressed. Then, the results of _{L 1 / L 0, L 2} / L 0 where the shaft angle is within ± 5 °, to define the scope of the present invention relates to L ₁ / L ₀ and L ₂ / L _0.

FIG. 10 shows the result of evaluating the bending deformation of the side sill model 33 based on the axial angle at the time of 100 mm penetration. In FIG. 10, ○ indicates a combination of L ₁ / L ₀ and L ₂ / L _{0 with} an axial angle within ± 5 °, and × indicates L ₁ / L ₀ with an axial angle exceeding + 5 ° or less than -5 °. It is a combination of L ₂ / L ₀ .

From FIG. 10, by setting L ₀ , L ₁ and L ₂ so as to satisfy 0.265 ≤ L ₁ / L ₀ ≤ 0.290 and 0.21 ≤ L ₂ / L ₀ ≤ 0.27, the side sill model 33 can be bent and deformed. It was shown to be suppressed.

In FIG. 11, the length L _{2 of} the bead shape portion 49 and the bead shape portion 51 provided on the upper flange ridge line portion 45 and the hat upper bottom ridge line portion 47 in the vehicle front-rear direction and the length of the side sill model 33 in the vehicle front-rear direction are shown in FIG. the ratio L ₂ / L ₀ with L ₀ is, in crash analysis of CAE model 31 is set to L ₂ so as not to satisfy the equation (2) shows an appearance at the time the collision object is 100mm intrusion.

From FIG. 11, it can be seen that the bending deformation that becomes convex downward in the vehicle occurs starting from the rear end portion of the A pillar lower model 35. This is because when the length L ₂ of the bead shape portion 49 and the bead shape portion 51 becomes longer than the range defined by the equation (2), when the colliding body 53 collides with a position offset from the central axis, A It is considered that this is because the bending moment starting from the rear end of the pillar lower model 35 has increased.

FIG. 12 shows a collision analysis of the CAE model 31 in which the width w and height h of the bead shape portions 49 and 51 (see FIG. 4C) are combined as shown below, and the axis at the time when the colliding body penetrates 100 mm. The result of evaluating the bending deformation of the side sill model 33 based on the angle (FIG. 9) is shown.
In FIG. 12, the horizontal axis is the width w of the bead shape portions 49 and 51, the vertical axis is the height h of the bead shape portions 49 and 51, and the circles in FIG. 12 indicate the axis angles within ± 5 ° and the cross marks. Is a plot of the combination of the width w and the height h of the bead shape portions 49 and 51 whose axial angles were more than + 5 ° or less than -5 °.

From FIG. 12, it can be seen that the bead shape portions 49 and 51 can sufficiently suppress the bending deformation of the side sill model 33 by setting the width w to 10 mm or more and the height h to 3 mm or more.
If the width w and the height h of the bead shape portions 49 and 51 are too large, they interfere with other parts when the automobile is assembled. Therefore, the width w is preferably 25 mm or less and the height h is preferably 6 mm or less.

<Collision energy absorption performance>
FIG. 13 shows the collision load and the intrusion amount of the colliding body 53 obtained by the collision analysis of the CAE model 31 (FIG. 5 (a)) according to the invention example and the CAE model 55 (FIG. 6 (a)) according to the conventional example. The relationship (hereinafter referred to as "load-penetration amount curve") is shown. Further, FIG. 13 also shows the amount of collision energy absorbed (hereinafter referred to as “absorbed energy”) calculated by the collision analysis. Here, the absorbed energy was calculated from the area of the load-intrusion amount curve from the start of the collision to the predetermined intrusion amount shown in FIG.

From FIG. 13, in the conventional example, the load reached the maximum value when the intrusion amount was about 6 mm, and then continued to decrease until 100 mm intrusion. On the other hand, in the invention example, the load was almost constant from the time when the load reached the maximum value at the initial stage of the collision until the 25 mm intrusion, which was almost the same as the load in the conventional example. After that, the load in the invention example maintained a higher value than that in the conventional example, and decreased once at 40 mm to 50 mm intrusion, but increased again at 50 mm to 70 mm intrusion. As a result, the absorbed energy in the invention example was improved 1.61 times as compared with the conventional example in 100 mm penetration.

Next, as an evaluation of collision safety performance, the amount of intrusion when the same absorbed energy was input was compared between the invention example and the conventional example.
FIG. 14 shows a collision between the CAE model 31 according to the invention example in which L ₁ / L ₀ = 0.274 and L ₂ / L ₀ = 0.23 and the CAE model 55 according to the conventional example in which L ₁ / L ₀ = 0.274. An analysis is performed, and the result of comparing the penetration amount of the collision body 53 in the invention example in which the absorption energy is the same as the absorption energy when the penetration amount of the collision body 53 is 100 mm in the conventional example is shown.

In FIG. 14, the collision energy absorbed by the collision body 53 until the penetration amount of the collision body 53 reaches 100 mm in the conventional example is equal to the collision energy absorbed by the collision body 53 in the invention example until the penetration amount reaches 65 mm. In comparison, in the example of the invention, it can be seen that the amount of collision of the colliding body can be reduced by 35 mm. From this, it was shown that in the side sill according to the present invention, the invasion of the colliding body into the cabin is suppressed by reducing the amount of deformation of the side sill, and the collision safety performance is improved.

Next, as shown in FIG. 15 (a), a collision analysis was performed on the CAE model 69 according to Comparative Example 4 in which the range covering the front end portion of the side sill model 33 was lengthened by the A pillar lower model 35, and the bending deformation due to the collision was performed. The weight efficiency for the suppression of the collision energy and the absorption of the collision energy was examined.

FIG. 15B shows the appearance of the CAE model 69 according to Comparative Example 4 when the colliding body 53 has penetrated 100 mm.
It can be seen that by increasing the range covered by the A-pillar lower model 35, the bending deformation of the side sill model 33 is suppressed as in the above-described invention example (FIG. 5B).

FIG. 16 shows energy absorption per weight in the invention example (CAE model 31) and the comparative example 4 (CAE model 69) based on the absorbed energy in the conventional example (CAE model 55) in which the bead shape portion is not provided. Shows the improvement rate.
The energy absorption improvement rate per weight is determined by assuming that the absorbed energy in the conventional example is A _E0 , the absorbed energy in the invention example or comparative example 4 is A _E , and the weight of each CAE model of the invention example or comparative example 4 is M (A _E). It is calculated by −A _E0 ) × 100 / (A _E0 × M).

While the absorbed energy in the invention example was 13.5 kJ, the absorbed energy in the comparative example 4 was almost the same as 13.6 kJ. However, in Comparative Example 4, since the weight was increased due to the increase in the range covered by the A-pillar lower model 35, the improvement rate of the absorbed energy per weight in Comparative Example 4 was lower than that in the invention example. As a result, when the absorption energy improvement rate was converted per weight and compared with the conventional example, the improvement of 1.46 times was obtained in the invention example, but the improvement was only 1.25 times in the comparative example 4.

Therefore, it has been demonstrated that in the side sill according to the present invention, in addition to suppressing bending deformation, the absorbed energy can be increased while avoiding the weight increase, and the collision performance can be efficiently improved.

1 Side sill 3 Side sill Outer 3a, 3b, 3c Wall part 3d, 3e Flange part 5 Side sill inner 5a, 5b, 5c Wall part 5d, 5e Flange part 7, 7a, 7b Upper flange ridge part 9 Hat Upper bottom ridge part 11 Bead shape Part 11a, 11b Convex part 13 Bead shape part 21 A pillar lower part 23 B pillar 31 CAE model 33 Side sill model 35 A pillar lower model 37 Side sill outer part 39 Side sill inner part 41 A pillar lower outer part 43 A pillar lower inner part 45 Upper flange line Part 47 Hat Upper bottom ridge line 49 Bead shape 51 Bead shape 53 Collision 55 CAE model (conventional example)
57 Side sill model 61 CAE model (Comparative example 1)
63 Side sill model 65 CAE model (Comparative example 2)
67 Side sill model 69 CAE model (Comparative example 4)

Claims (1)

The side sill is provided with a side sill outer having a hat cross section that extends in the front-rear direction of the vehicle and opens toward the inside of the vehicle in the vehicle width direction, and a side sill inner having a hat cross section that opens toward the outside of the vehicle in the vehicle width direction. The outer and the side sill inner are joined so that the opening sides face each other to form a closed cross section, and the outer surface of the side sill outer at the front end in the front-rear direction of the vehicle is covered with the lower portion of the A pillar lower arranged in the vertical direction of the vehicle. It is a side sill that is joined to the lower part of the B pillar whose central part in the front-rear direction of the vehicle is arranged in the vertical direction of the vehicle.
Each of the side sill outer and the side sill inner has a wall portion on the vehicle upper side, the vehicle side side, and the vehicle lower side, a flange portion on each of the vehicle upper side and the vehicle lower side, and a flange portion on the vehicle upper side. It has an upper flange ridge line portion that connects the wall portion on the upper side of the vehicle and a hat upper bottom ridge line portion that connects the wall portion on the upper side of the vehicle and the wall portion on the side side of the vehicle. The side sill outer and the side sill inner are joined at the flanges on the upper side and the lower side of the vehicle, respectively.
The pair of upper flange ridges between the side sill outer and the wall on the vehicle upper side of the side sill inner, and the upper bottom ridge of the hat of each of the side sill outer and the side sill inner, and the A in the side sill outer. A bead-shaped portion extending outward from the same position as the rear end of the lower part of the pillar lower and extending toward the rear of the vehicle body is provided.
The length from the front end of the side sill to the front end of the lower part of the B pillar in the vehicle front-rear direction is L ₀ ,
The length of the front end in the vehicle front-rear direction is L ₁ ,
When the length of the bead shape portion in the vehicle front-rear direction is L ₂ ,
A side sill characterized by satisfying the relationship of 0.265 ≤ L ₁ / L ₀ ≤ 0.290 and 0.21 ≤ L ₂ / L ₀ ≤ 0.27.