Collision energy absorbing structure

Abstract

This collision energy absorbing structure 1 is provided with: a steel plate crossmember 101 that absorbs collision energy when a rear-end collision occurs with respect to an automobile 100 having a subframe 111 and a bumper 121 provided to the vehicle rear side, that extends in a vehicle width direction in front of the subframe 111 so that both end sections thereof are attached to the subframe 111, that has a cross-sectional shape which is polygonal, circular, C-shaped, or hat-shaped, in a direction orthogonal to the vehicle width direction, and that has a tensile strength of 980 MPa class or greater; and an energy absorbing section 21 that is disposed between the crossmember 11 and the bumper 121, and when a rear-end collision occurs with respect to the automobile 100, deforms due to a collision load received directly from the bumper 121 or via another member to absorb collision energy.

Description

Collision energy absorption structure

[0001] This invention relates to a collision energy absorbing structure that absorbs collision energy during a rear-end collision of an automobile.

[0002] Some automobiles have a subframe that connects the suspension arm to the vehicle body. In conventional engine-powered cars, the design freedom is limited by the presence of the engine, so crashworthiness was not a particular requirement for the subframe. In contrast, electric vehicles need to carry batteries, which increases the vehicle weight compared to engine-powered cars. Therefore, in a rear-end collision where an electric vehicle collides from behind, the kinetic energy of the colliding electric vehicle, that is, the collision energy input to the car that was hit, is large. Consequently, automobiles equipped with a subframe at the rear of the vehicle are now required to have greater crashworthiness against rear-end collisions than ever before.

[0003] Several structures have been proposed to improve collision performance against rear-end collisions. For example, Patent Document 1 discloses a structure comprising a bar for connecting a front cross member and a rear cross member, which are stretched between the left and right rear side frames, and a bracket for attaching the rear end of the bar to the rear cross member. According to Patent Document 1, the rear of the vehicle body can be reinforced against rear-end collisions by providing the bar and bracket.

[0004] In Patent Document 2, a low-strength portion with a lower strength than the front portion is formed at the rear portion of the left and right rear frames in the rear part of the vehicle, and left and right gussets are provided above or below the low-strength portion to expand the cross-section step-like (step-like) toward the rear. And according to Patent Document 2, it is said that it is possible to prevent the rear frame from bending during a rear-end collision and to stably cause buckling to absorb impact.

[0005] In Patent Document 3, a breakage promoting member having a protruding portion attached to the rear portion of the rear side member and extending downward, and a crash load transfer member having a contact portion facing the protruding portion and having a rear end protruding rearward from the rear end of the rear side member are disclosed. And according to Patent Document 3, the impact load during a rear-end collision is efficiently absorbed by the bending deformation (bending deformation) in a very wide range at the rear portion of the rear side member, and the influence on the occupants and the fuel tank (fuel tank) is extremely small, and it is said that safety can be improved.

[0006] In Patent Document 4, a structure is disclosed that includes a reinforcing panel that covers the lower part of the fuel tank disposed at the rear of the vehicle and has a thickness for transmitting the load during a rear-end collision to the front skeletal member. And according to Patent Document 4, it is said that the collision safety performance can be improved by the reinforcing panel transmitting the load during a rear-end collision to the front skeletal member, and the aerodynamic performance during running can be improved.

[0007] In Patent Document 5, a structure is disclosed that includes a rear frame having a displacement-load characteristic in which the ratio of load to displacement increases, and a tank lower frame (tank lower frame) disposed below the rear frame and the fuel tank and having its cross-sectional deformation suppressed. And according to Patent Document 5, it is said that even when a large load is input during a rear-end collision, it can bear the load and has excellent energy absorption ability.

[0008] Japanese Patent Publication No. 2011-6053, Japanese Patent Publication No. 2010-13053, Japanese Patent Publication No. 2009-262660, Japanese Patent Publication No. 2008-174122, Japanese Patent Publication No. 2008-174121

[0009] Conventional structures, such as those described in Patent Documents 1 to 5, were unable to adequately absorb the collision energy input to the vehicle when the vehicle in a rear-end collision had increased in weight due to electrification or other reasons, or when the increased weight made deceleration difficult, resulting in a higher collision speed. As a result, conventional structures may not be able to suppress cabin deformation during a rear-end collision, and thus may not be able to protect the occupants.

[0010] The present invention was made to solve the above problems, and its objective is to provide a collision energy absorbing structure that can sufficiently absorb collision energy during a rear-end collision of an automobile, even when the vehicle weight is heavy or the collision speed is high.

[0011] The collision energy absorbing structure according to the present invention absorbs collision energy during a rear collision of an automobile equipped with a subframe and a bumper at the rear of the vehicle, and comprises a cross member made of steel plate with a tensile strength of 980 MPa or higher, which extends in the vehicle width direction behind the subframe and has both ends attached to the subframe, and whose cross shape perpendicular to the vehicle width direction is polygonal, circular, U-shaped, or hat-shaped, and an energy absorbing part provided between the cross member and the bumper, which deforms in response to a collision load input directly from the bumper or via other members during a rear collision of the automobile to absorb collision energy.

[0012] The energy absorbing section is arranged from each of the ends of the cross member in the vehicle width direction toward the bumper, and preferably has a cylindrical member with a polygonal or circular cross-section perpendicular to the vehicle's longitudinal direction.

[0013] The energy absorbing section may include a wave-shaped member having a cross-section perpendicular to the vehicle's longitudinal direction and a side plate extending in the vehicle's longitudinal direction such that each side end of the wave-shaped member in the vehicle's width direction is connected.

[0014] The energy absorbing section is arranged toward the bumper from each of the two ends of the cross member in the vehicle width direction and comprises a cylindrical member having a polygonal or circular cross-section perpendicular to the vehicle longitudinal direction and a corrugated member having a corrugated cross-section perpendicular to the vehicle longitudinal direction, provided between the cylindrical members, wherein both ends of the corrugated member in the vehicle width direction are connected to the cylindrical members.

[0015] The energy absorbing portion may further include a top portion and a bottom portion that cover the upper and lower surfaces of the corrugated member, respectively.

[0016] According to the present invention, in a rear-end collision of an automobile, even when the colliding vehicle is heavy or the collision speed is high, deformation of the cabin of the collided vehicle can be suppressed and the occupants can be protected. Furthermore, according to the present invention, the weight of the automobile can be reduced by reducing the plate thickness while maintaining collision performance.

[0017] Figure 1 is a diagram illustrating the configuration of a collision energy absorption structure according to an embodiment of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from a-a'). Figure 2 is a diagram illustrating the cross-sectional shape of the cross member in the collision energy absorption structure according to an embodiment of the present invention. Figure 3 is a diagram illustrating a collision energy absorption structure according to embodiment A of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from b-b'). Figure 4 is a diagram illustrating a collision energy absorption structure according to embodiment B of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from c-c'). Figure 5 is a diagram illustrating a collision energy absorption structure in which a second cross member is provided on the bumper side in the present invention. Figure 6 is a diagram illustrating an example in which a space is provided between the bumper and the energy absorption section in the present invention. Figure 7 is a graph showing the relationship between the load obtained on the collision body side and the displacement of the central part of the vehicle body in a full-width rear-end collision test in an embodiment. Figure 8 shows a conventional collision energy absorption structure in which crash boxes are provided on both ends of the subframe towards the bumper.

[0018] [Background to the Invention] As described above, the inventor diligently studied a collision energy absorption structure that could suppress deformation of the cabin of the vehicle being hit and protect the occupants, even when the vehicle that collided with the other vehicle was heavy or the collision speed was high during a rear-end collision.

[0019] Conventionally, as illustrated in Figure 8 (automobile 140), a crash box 131 has been attached between the rear ends of the left and right side members 113 constituting the subframe 111 and the bumper 121 as a collision energy absorbing structure 3 that absorbs collision energy during a rear collision.

[0020] However, such crash boxes 131 can only be attached to both ends of the subframe 111 in the vehicle width direction. Therefore, when the vehicle on the side that is hit is heavy or the collision speed is high during a rear-end collision, the collision energy cannot be sufficiently absorbed by the vehicle that is hit. Also, when a vehicle collides unevenly to one side during a rear-end collision, the load is not sufficiently transmitted to the crash box 131 on the opposite side, so the collision energy that can be absorbed by the crash box 131 is limited.

[0021] Therefore, the inventors diligently studied a specific structure that can sufficiently absorb collision energy at the rear of the subframe 111 during a rear-end collision. The present invention was completed based on such studies, and its specific configuration will be described below with reference to the drawings. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and redundant explanations are omitted or simplified.

[0022] [Embodiment] The collision energy absorption structure 1 according to an embodiment of the present invention absorbs collision energy during a rear collision of an automobile 100 equipped with a subframe 111 and a bumper 121 at the rear of the vehicle, as shown in Figure 1.

[0023] The subframe 111 is located at the rear of the vehicle body 101 and comprises side members 113 and a torsion beam 115. The side members 113 extend in the vehicle longitudinal direction on both the left and right sides in the vehicle width direction, with their front ends connected to the rear end of the vehicle body 101. The torsion beam 115 extends in the vehicle width direction between the left and right side members 113, with both ends connected to the side members 113. The bumper 121 is located at the rear of the subframe 111 and extends in the vehicle width direction.

[0024] As shown in Figure 1, the collision energy absorption structure 1 comprises a cross member 11 and an energy absorption section 21.

[0025] The cross member 11 extends in the vehicle width direction behind the subframe 111, and both ends are attached to the subframe 111. In this embodiment, the cross member 11 extends in the vehicle width direction so as to span the entire width of the subframe 111, and both ends are attached to the rear ends of the left and right side members 113 that constitute the subframe 111. The cross member 11 has a polygonal shape (such as a quadrilateral) in the cross section perpendicular to the vehicle width direction, as shown in Figure 2(a), and is made of steel plate with a tensile strength of 980 MPa or higher. Figure 2(a) is a cross-sectional view of the cross member 11 shown in Figure 1(a) along the line b-b' (the same applies to Figures 2(b) to (d) described later).

[0026] The energy absorption section 21 is positioned between the cross member 11 and the bumper 121, and in the event of a rear collision, it deforms due to the collision energy directly input from the bumper 121 to absorb the collision energy.

[0027] In the collision energy absorption structure 1, the energy absorption section 21 has cylindrical members 23 arranged from both ends of the cross member 11 in the vehicle width direction toward the bumper 121, as shown in Figure 1(a). The cylindrical members 23 have a polygonal or circular cross-section perpendicular to the vehicle longitudinal direction, as shown in Figure 1(b)(i), with the front end supported by the cross member 11 and the rear end connected to the bumper 121. Figure 1(b)(i) is a cross-sectional view of the energy absorption section 21 shown in Figure 1(a) along the line a-a' (the same applies to Figures 1(b)(ii) and (iii) described later).

[0028] In this embodiment, the energy absorption section 21 further includes two cylindrical members 25 between the left and right cylindrical members 23 disposed at both ends of the cross member 11, as shown in Figures 1(a) and (b)(i). The cylindrical members 25, like the cylindrical members 23, have a polygonal or circular cross-section perpendicular to the vehicle's longitudinal direction, with their front end supported at the center of the cross member 11 and their rear end connected to the bumper 121. Furthermore, the energy absorption section 21 includes a top plate 27 that covers the upper surfaces of the cylindrical members 23 and 25, and a bottom plate 29 that covers the lower surfaces.

[0029] The cross member 11 bears the load in the vehicle width direction during the deformation of the energy absorption section 21 (cylindrical member 23) due to the collision load input from the bumper 121 when the automobile 100 is hit from the rear. As a result, the amount of collision energy absorbed by the energy absorption section 21 can be increased compared to the crash box 131 shown in Figure 8. As a result, the collision energy absorption structure 1 can suppress the deformation of the cabin (not shown) of the hit automobile 100 and protect the occupants, even when the weight of the colliding vehicle is heavy or the collision speed is high during a rear collision. Furthermore, the collision energy absorption structure 1 can also be made lighter by reducing the plate thickness of the cross member 11 and the energy absorption section 21 (cylindrical member 23) while maintaining collision performance.

[0030] Furthermore, the collision energy absorption structure 1 can further increase the amount of collision energy absorbed by deforming the cylindrical member 25 supported in the center of the cross member 11 due to the collision load input via the bumper 121.

[0031] The collision energy absorption structure 1 is not limited to having a cylindrical member 25, nor is the number of cylindrical members 25 particularly limited; as shown in Figures 1(b) and 1(ii), it may consist of only one cylindrical member 25.

[0032] Furthermore, although the energy absorption section 21 had a top plate 27 covering the upper surface and a bottom plate 29 covering the lower surface, as shown in Figure 1(b)(iii), it is not necessary to have a top plate 27 and a bottom plate 29. However, it is preferable to cover the top and bottom surfaces of the energy absorption section 21 with a top plate 27 and a bottom plate 29, as this can stabilize the buckling mode of the cylindrical members 23 and 25 during a rear collision of the automobile 100.

[0033] The collision energy absorption structure 1 is one embodiment of the present invention, but other embodiments of this embodiment include the following embodiments A and B.

[0034] <Aspect A> The collision energy absorption structure 1A according to aspect A comprises a cross member 11 and an energy absorption section 21A, as shown in Figure 3.

[0035] The energy absorption section 21A includes a corrugated member 31 and a side plate 33. As shown in Figure 3(b)(i), the corrugated member 31 has a corrugated shape in cross-section perpendicular to the vehicle's longitudinal direction, with its front end connected to the cross member 11 and its rear end connected to the bumper 121. Figure 3(b)(i) is a c-c' cross-sectional view of the energy absorption section 21A shown in Figure 3(a) (the same applies to Figure 3(b)(ii), which will be described later). The side plate 33 extends in the vehicle's longitudinal direction so as to connect to each side end of the corrugated member 31 in the vehicle's width direction, with its front end connected to the cross member 11 and its rear end connected to the bumper 121.

[0036] In the collision energy absorption structure 1A, during a rear collision in which the collision load is applied to one side in the vehicle width direction, the cross member 11 bears the load on the corrugated member 31 during deformation across the vehicle width direction, thereby expanding the range of deformation of the corrugated member 31. As a result, even when the vehicle weight of the colliding vehicle is heavy or the collision speed is high during a rear collision, the amount of collision energy absorbed by the vehicle 100 that was hit can be increased. Therefore, deformation of the cabin of the vehicle 100 can be suppressed and the occupants can be protected.

[0037] The energy absorption section 21A does not necessarily have to have a top plate 27 covering the upper surface and a bottom plate 29 covering the lower surface of the corrugated member 31, as shown in Figure 3(b)(ii). However, it is preferable that the energy absorption section 21A is configured such that the top and bottom surfaces of the corrugated member 31A are covered by the top plate 27 and the bottom plate 29, as shown in Figure 3(b)(i), as this stabilizes the buckling mode of the corrugated member 31.

[0038] <Aspect B> The collision energy absorption structure 1B according to aspect B comprises a cross member 11 and an energy absorption section 21B, as illustrated in Figure 4. The energy absorption section 21B comprises a cylindrical member 23 and a corrugated member 31A.

[0039] The cylindrical members 23 are arranged toward the bumper 121 from each of the ends of the cross member 11, similar to embodiment A described above. The corrugated member 31A is provided between the cylindrical members 23 arranged at both ends of the cross member 11, and as shown in Figure 4(b)(i), its cross section perpendicular to the vehicle's longitudinal direction is corrugated. The front end of the corrugated member 31A is connected to the cross member 11, and the rear end is connected to the bumper 121. Furthermore, both ends of the corrugated member 31A in the vehicle width direction are connected to the cylindrical members 23. Figure 4(b)(i) is a d-d' cross-sectional view of the energy absorption section 21B shown in Figure 4(a) (the same applies to Figure 4(b)(ii) described later).

[0040] In the collision energy absorption structure 1B, during a rear collision in which a collision load is applied to one side in the vehicle width direction, the cylindrical member 23 on that side receives the collision load and deforms. Furthermore, while the corrugated member 31A is deforming due to the collision load applied from the bumper 121, the cross member 11 bears the load across the vehicle width direction, thus expanding the range over which the corrugated member 31A deforms. As a result, in the collision energy absorption structure 1B, even when the weight of the colliding vehicle is heavy or the collision speed is high during a rear collision, the amount of collision energy absorbed by the collided vehicle 100 can be increased. Therefore, deformation of the cabin of the vehicle 100 can be suppressed and the occupants can be protected.

[0041] The energy absorption section 21B does not necessarily have to have its upper and lower surfaces covered by the top plate 27 and the bottom plate 29 (Figure 4(b)(ii)), but it is preferable that it be covered by the top plate 27 and the bottom plate 29, as this stabilizes the buckling mode of the cylindrical member 23.

[0042] In the above-described embodiments, Mode A, and Mode B, the cross member 11 was made of a steel sheet with a tensile strength of 980 MPa class. This was to bear the load during the deformation of the cylindrical member 23 (and the cylindrical member 25) and the corrugated member 31 provided as the energy absorption part 21. Also, the cross member 11 had a polygonal cross-section orthogonal to the vehicle width direction, such as a quadrilateral. However, the present invention is not limited to the cross member 11 with a polygonal cross-section, and a circular cross member 11A (see Fig. 2(b)) may be used, or a U-shaped cross member 11B (Fig. 2(c)) or a hat-shaped cross member 11C (Fig. 2(d)) may be used. In the case of the U-shaped cross member 11B or the hat-shaped cross member 11C, it is preferable that they are arranged so that the vehicle front side is open.

[0043] Also, in the present invention, when the cross member has a polygonal cross-section, it has beads extending in the vehicle width direction on the vehicle rear side surface (the surface 11a shown in Fig. 2(a)), and when it has a U-shaped or hat-shaped cross-section, it has beads extending in the vehicle width direction on the vehicle rear side surface (the surface 11Ba shown in Fig. 2(c), the surface 11Ca shown in Fig. 2(d)). By doing so, it is possible to improve the rigidity and strength, which is preferable.

[0044] Furthermore, the material of the energy absorption part is not particularly limited, but a steel sheet with material characteristics (rigidity, plate thickness, etc.) that are more easily deformed than the cross member is preferable.

[0045] Also, as shown in Fig. 5, the present invention may be a collision energy absorption structure 1C in which a second cross member 41 extending over the entire vehicle width direction of the subframe 111 is provided on the bumper 121 side.

[0046] In the collision energy absorption structure 1C, in a rear collision, the energy absorption part 21 absorbs the collision energy by deforming when a collision load input from the bumper 121 through the second cross member 41, which is another member, acts on it. As a result, in a rear collision where a collision load is input to one side in the vehicle width direction, compared with the collision energy absorption structure 1 shown in FIG. 1, a collision load is also input to and deforms the side where the collision object does not intrude in the energy absorption part 21. Therefore, the amount of absorbed collision energy can be further increased.

[0047] The material of the second cross member 41 does not necessarily have to be a high-tensile steel sheet, but when the strength of the bumper 121 is insufficient or when the bumper 121 does not exist, etc., it is desirable that, similar to the cross member 11, it is made of a steel sheet with a tensile strength of 980 MPa or more. This is because when a collision object collides with a bias to either the left or right during a rear collision of the automobile 100, the collision load is transmitted to the energy absorption part (such as the cylindrical member 23) on the opposite side to efficiently deform it.

[0048] The above description was for the case where the second cross member 41 is provided in the collision energy absorption structure 1 according to the embodiment. However, the present invention may also be provided with the second cross member 41 on the bumper 121 side as shown in FIG. 5 in the collision energy absorption structure 1A according to aspect A or the collision energy absorption structure 1B according to aspect B.

[0049] The subframe 111 includes a pair of side members 113 disposed on both the left and right sides and a torsion beam 115 disposed between the side members 113. However, the configuration of the subframe in the present invention is not limited to this, and it may be any structure as long as both ends of a cross member extending in the vehicle width direction can be attached behind the subframe.

[0050] Furthermore, in the above description, the cross member 11 extended in the vehicle width direction so as to span the entire width of the subframe 111, with both ends attached to the rear ends of the left and right side members 113, respectively. However, in the present invention, the cross member does not have to extend in the vehicle width direction so as to span the entire width of the subframe 111, and it is sufficient that both ends are supported by the subframe 111.

[0051] Furthermore, in the above description, the energy absorption section was connected to the bumper directly or via a second cross member. However, the present invention may also be a collision energy absorption structure 1D in which the energy absorption section 21A and the bumper 121 are connected via crash boxes 141 disposed at both ends in the vehicle width direction, and a space 143 is formed between them, as illustrated in Figure 6.

[0052] Even with such a collision energy absorbing structure 1D, in the event of a frontal collision of a vehicle, after the crash box 141 is crushed, the energy absorbing section 21A deforms due to the collision load input directly from the bumper 121 or via the crash box 141, thereby absorbing the collision energy.

[0053] We conducted tests to verify the effects of the collision energy absorption structure according to the present invention, and we will now describe the results.

[0054] In this embodiment, a full-wrap rear-end collision test was conducted on an automobile 100 equipped with the collision energy absorption structure 1 according to the embodiment of the present invention described above. The relationship between the collision load applied to the automobile 100 and the displacement of the automobile 100 was measured as a measure of collision performance. In the full-wrap rear-end collision test, the collision speed of the collision body was set to 36.4 km / h. The collision load was defined as the load on the collision body that collided with the automobile 100, and the displacement of the automobile 100 was defined as the displacement of the center pillar in the central part of the automobile body. Furthermore, for comparison, a similar full-wrap rear-end collision test was also conducted on an automobile 100 equipped with the conventional collision energy absorption structure 3 shown in Figure 8 described above.

[0055] Figure 7 shows a graph of the load applied to the automobile 100 and the displacement of the automobile 100, measured by a full-wrap rear-end collision test. In Figure 7, the inventive example is the collision energy absorption structure 1, and the comparative example is the conventional collision energy absorption structure 3.

[0056] As shown in Figure 7, the difference between the inventive example and the comparative example was small in the initial stages of the collision, but the load on the inventive example was higher after a certain displacement. The reason the load on the inventive example was higher after a certain displacement is that the cross member 11 bore the load across the vehicle width direction during the deformation of the energy absorption section 21 (cylindrical member 23, cylindrical member 25) of the collision energy absorption structure 1. Subsequently, in the later stages of the collision, the loads on the inventive example and the comparative example were almost identical. This is because the deformation of the energy absorption section 21 (cylindrical members 23, 25) was completed. Thus, since the load on the inventive example was higher than that on the comparative example from the initial stages of the collision to the later stages, the amount of collision energy absorbed by the inventive example was increased.

[0057] As described above, according to the present invention, the cross member 11 bears the load during the deformation of the energy absorption section 21 across the vehicle width direction, resulting in a higher load and an increased amount of collision energy absorbed by the energy absorption section 21. Furthermore, these results suggest that even when the vehicle weight is heavy or the collision speed is high, deformation of the automobile cabin can be suppressed and occupants can be protected.

[0058] According to the present invention, it is possible to provide a collision energy absorbing structure that can sufficiently absorb collision energy during a rear-end collision of an automobile, even when the vehicle weight is heavy or the collision speed is high.

[0059] 1, 1A, 1B, 1C, 1D Collision energy absorption structure (invention) 3 Collision energy absorption structure (conventional) 11, 11A, 11B, 11C Cross member 11a, 11Ba, 11Ca Surface portion 21, 21A, 21B Energy absorption portion 23 Cylindrical member 25 Cylindrical member 27 Top plate 29 Bottom plate 31, 31A Corrugated member 33 Side plate 41 Second cross member 100 Automobile 101 Body 111 Subframe 113 Side member 115 Torsion beam 121 Bumper 131 Crash box 141 Crash box 143 Space

Claims

1. A collision energy absorbing structure for absorbing collision energy during a rear collision of an automobile having a subframe and a bumper at the rear of the vehicle, comprising: a cross member made of steel plate that extends in the vehicle width direction behind the subframe and has both ends attached to the subframe, and whose cross shape perpendicular to the vehicle width direction is polygonal, circular, U-shaped, or hat-shaped, and has a tensile strength of 980 MPa or higher; and an energy absorbing part provided between the cross member and the bumper, which deforms in response to a collision load input directly from the bumper or via other members during a rear collision of the automobile to absorb collision energy.

2. The collision energy absorbing structure according to claim 1, wherein the energy absorbing portion is disposed from each of the ends of the cross member in the vehicle width direction toward the bumper and has a cylindrical member with a polygonal or circular cross-section perpendicular to the vehicle longitudinal direction.

3. The collision energy absorbing structure according to claim 1, wherein the energy absorbing portion comprises a corrugated member having a cross-section perpendicular to the vehicle's longitudinal direction, and side plates extending in the vehicle's longitudinal direction such that each side end of the corrugated member in the vehicle's width direction is connected.

4. The collision energy absorbing structure according to claim 1, wherein the energy absorbing section comprises: a cylindrical member disposed toward the bumper from each of the two ends of the cross member in the vehicle width direction, and having a polygonal or circular cross-section perpendicular to the vehicle longitudinal direction; and a corrugated member provided between the cylindrical members, having a corrugated cross-section perpendicular to the vehicle longitudinal direction, and both ends of the corrugated member in the vehicle width direction are each connected to the cylindrical member.

5. The collision energy absorbing structure according to claim 3 or 4, wherein the energy absorbing section further comprises a top plate and a bottom plate that cover the upper surface and the lower surface of the corrugated member, respectively.

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