Collision energy absorbing structure
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2025-08-27
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025030193_30072026_PF_FP_ABST
Abstract
Description
Collision Energy Absorption Structure
[0001] The present invention relates to a collision energy absorption structure that absorbs collision energy (crash energy) during a frontal collision of an automobile.
[0002] Some vehicles have a sub-frame installed that connects a suspension arm (suspension arm) and the vehicle body. In conventional engine vehicles, since the engine is installed and the degree of freedom in vehicle design is limited, no particular crashworthiness has been required for the sub-frame. In contrast, electric vehicles need to carry a battery, and the vehicle weight has increased. Therefore, crashworthiness is now required for the sub-frame, which contributed little to crash performance in engine vehicles.
[0003] To improve the crashworthiness of the sub-frame, there is a method of making the side members (side members) extending in the vehicle front-rear direction linear without curving in the vehicle up-down direction to increase the collision load. Also, there is a method of improving the crashworthiness for a small overlap test by arranging the side members in a V-shaped (V-shaped) configuration such that the front ends of the side members arranged on both the left and right sides of the vehicle spread outward in the vehicle width direction.
[0004] In addition to these methods, several techniques for improving the crashworthiness of the sub-frame have been proposed. For example, Patent Document 1 discloses a technique including a cross member (cross member) that connects the front sides of the left and right side members extending while deflecting outward in the width direction. According to this technique, it is said that unnecessary deformation of the side members can be suppressed and the required crashworthiness can be exhibited.
[0005] Furthermore, Patent Document 2 discloses a technique in which a high-rigidity portion is formed at the connecting portion of a cross member connected to the front end of a side frame part (corresponding to the side member in this application) of a suspension subframe (corresponding to the subframe in this application), and a protruding portion is provided at the side end in the vehicle width direction of a front beam member (corresponding to the bumper in this application) that protrudes toward the rear of the vehicle.According to this technique, in the event of a small overlap frontal collision (small overlap frontal crash), the protruding portion contacts the high-rigidity portion from the outside in the vehicle width direction, generating a lateral force in the vehicle width direction, thereby improving collision performance.
[0006] Furthermore, Patent Document 3 discloses a technology that provides a deformation-promoting part in the intermediate portion of each longitudinal member (corresponding to the side member in the present application) along the vehicle's longitudinal direction, between the cross member and the stabilizer mounting portion, which promotes downward bending deformation of each longitudinal member during a vehicle collision. According to this technology, in addition to the deformation-promoting effect of downward bending deformation of each longitudinal member, deformation is also promoted by the difference in strength between the longitudinal portion of each longitudinal member and the vehicle's longitudinal portion. As a result, it is possible to reliably absorb the collision load at the deformation-promoting part and suppress the transmission of the collision load from the front subframe to the vehicle body.
[0007] Japanese Patent Publication No. 2022-74054, Japanese Patent Publication No. 2022-80058, Japanese Patent No. 6803885
[0008] The technologies described in Patent Documents 1 to 3 cannot adequately absorb collision energy and protect occupants when the vehicle weight increases due to electrification or other reasons, or when the collision speed increases because deceleration becomes difficult due to the increased vehicle weight.
[0009] 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 frontal collision, even when the vehicle weight is heavy, such as in an electric vehicle, or when the collision speed is high.
[0010] The collision energy absorbing structure according to the present invention absorbs collision energy during a frontal collision of an automobile equipped with a subframe and a bumper at the front 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 in front of the subframe and has both ends attached to the subframe, and whose cross section 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 from the bumper directly or via other members during a frontal collision of the automobile to absorb collision energy.
[0011] The energy absorbing portion is preferably widened in width from the cross member side towards the bumper side.
[0012] The energy absorbing portion is preferably such that its width narrows as it moves from the cross member side toward the bumper side.
[0013] 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.
[0014] The energy absorbing section may include a wave-shaped member having a wave-shaped 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 wave-shaped member in the vehicle's width direction is connected.
[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] The energy absorbing section is preferably 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, with both ends of the corrugated member in the vehicle width direction connected to the cylindrical member.
[0017] According to the present invention, in a frontal collision of an automobile, deformation of the automobile cabin can be suppressed and occupants can be protected, even when the vehicle weight is heavy or the collision speed is high. Furthermore, according to the present invention, the weight of the automobile can be reduced by reducing the plate thickness while maintaining collision performance.
[0018] 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 c-c'). 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 d-d'). Figure 5 is a diagram illustrating a collision energy absorption structure according to embodiment C of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from e-e'). Figure 6 is a diagram illustrating a collision energy absorption structure according to embodiment D of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from f-f'). Figure 7 is a diagram illustrating a collision energy absorption structure according to embodiment E of the present invention ((a) top view, (b) cross-sectional view of the energy absorption section from g-g'). Figure 8 illustrates a collision energy absorption structure in which a second cross member is provided on the bumper side in the present invention. Figure 9 illustrates an example in which a space is provided between the bumper and the energy absorption part in the present invention. Figure 10 is a graph showing the relationship between the load obtained on the impactor side and the displacement of the central part of the vehicle body in a micro-lap collision test in an embodiment. Figure 11 is a diagram showing a conventional collision energy absorption structure in which crash boxes are provided on the bumper side from both ends of the subframe.
[0019] [Background to the Invention] As described above, the inventor diligently studied a collision energy absorption structure that could suppress cabin deformation and protect occupants even in frontal collisions when the vehicle weight is heavy or the collision speed is high.
[0020] As mentioned above, in conventional engine-powered vehicles, when the engine system is located at the front of the vehicle, there is limited space to place structures and components that absorb collision energy during a frontal collision. Therefore, as illustrated in Figure 11, in automobile 100, which is provided with a subframe 111 connecting the vehicle body 101 and the suspension arm 103, a crash box 131 is attached between the front end of the side member 113 and the bumper 121.
[0021] In response, the inventor focused on the fact that when an electric vehicle is built on the basis of an engine-powered vehicle as described above, the engine and its surrounding components become unnecessary, creating space at the front of the vehicle. The inventor considered whether a structure that absorbs collision energy could be installed in this space. Therefore, the inventor diligently studied a specific structure that could sufficiently absorb collision energy in the space at the front of the vehicle in front of the subframe 111.
[0022] The present invention was completed based on such considerations, 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.
[0023] [Embodiment] The collision energy absorption structure 1 according to an embodiment of the present invention absorbs collision energy during a frontal collision of an automobile 100, which is provided with a subframe 111 and a bumper 121 on the front side of the vehicle, as shown in Figure 1.
[0024] The subframe 111 is located in front of the vehicle body 101 and comprises side members 113 and cross panels 115. The side members 113 extend in the longitudinal direction of the vehicle on each side in the vehicle width direction, and their rear ends are connected to the vehicle body 101. The cross panels 115 are positioned between the left and right side members 113, and their side ends are connected to each side member 113. The bumper 121 is located in front of the subframe 111 and extends in the vehicle width direction.
[0025] As shown in Figure 1, the collision energy absorption structure 1 comprises a cross member 11 and an energy absorption section 21.
[0026] The cross member 11 extends in the vehicle width direction in front of the subframe 111, with both ends 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, with both ends attached to the front ends of the left and right side members 113 that constitute the subframe 111. As shown in Figure 2(a), the cross member 11 has a polygonal cross-section perpendicular to the vehicle width direction 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 along the line b-b' (the same applies to Figures 2(b) to (d) described later).
[0027] The energy absorption section 21 is disposed between the cross member 11 and the bumper 121, and in the event of a frontal collision, it deforms due to the collision energy directly input from the bumper 121 to absorb the collision energy. In the collision energy absorption structure 1, as shown in Figures 1(b) and 1(i), the energy absorption section 21 has cylindrical members 23 disposed from each of the ends of the cross member 11 in the vehicle width direction toward the bumper 121. The cylindrical members 23 have a polygonal or circular cross-section perpendicular to the vehicle's longitudinal direction, with the rear end supported by the cross member 11 and the front end connected to the bumper 121.
[0028] In this embodiment, the energy absorption section 21 further includes two cylindrical members 25 between the 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 rear end supported at the center of the cross member 11 and their front end connected to the bumper 121. Furthermore, the energy absorption section 21 includes two cylindrical members 25 provided between the cylindrical members 23 on both sides in the vehicle's width direction, a top plate 27 covering the upper surface, and a bottom plate 29 covering the lower surface.
[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 in a frontal collision. As a result, the amount of collision energy absorbed by the energy absorption section 21 (cylindrical member 23) can be increased compared to the crash box 131 shown in Figure 11. As a result, the collision energy absorption structure 1 can suppress deformation of the automobile 100's cabin (not shown) and protect the occupants, even when the vehicle weight is heavy or the collision speed is high. Furthermore, the collision energy absorption structure 1 can also reduce weight by making the plate thickness of the cross member 11 and the energy absorption section 21 thinner while maintaining collision performance.
[0030] Furthermore, the collision energy absorption structure 1 has a cylindrical member 25 supported in the center of the cross member 11 that extends in the vehicle width direction. As a result, in the event of a frontal collision of the automobile 100, the cylindrical member 25 deforms due to the collision load input via the bumper 121, thereby further increasing the amount of collision energy absorbed.
[0031] The energy absorption section 21 of the collision energy absorption structure 1 had two cylindrical members 25 between two cylindrical members 23 on both sides in the vehicle width direction. However, the collision energy absorption structure 1 is not limited to having cylindrical members 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 stabilizes the buckling mode of the cylindrical members 23 and 25 during a frontal 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 to F.
[0034] <Aspect A> The collision energy absorption structure 1A according to aspect A has a cross member 11 and an energy absorption section 21A, as shown in Figure 3.
[0035] The energy absorption section 21A is arranged from each end of the cross member 11 toward the bumper 121 and has two cylindrical members 23A with polygonal cross-sections perpendicular to the vehicle's longitudinal direction. The width of the cylindrical members 23A widens from the cross member 11 side toward the bumper 121 side. As a result, the width of the energy absorption section 21A widens from the cross member 11 side toward the bumper 121 side.
[0036] In the collision energy absorption structure 1A, when a collision object enters during a minute lap collision, the collision load is transmitted to the cylindrical member 23A, which is tilted relative to the vehicle's longitudinal direction. The component of the transmitted collision load in the vehicle's width direction becomes a lateral force that moves the automobile 100 in the opposite direction to the collision object. As a result, the collision load input to the cabin side of the automobile 100 is reduced, further suppressing cabin deformation and protecting the occupants.
[0037] Similar to the energy absorption section 21 described above, the presence or number of cylindrical members 25 provided between the cylindrical members 23 on both sides of the energy absorption section 21A is not particularly limited.
[0038] Furthermore, although the energy absorption section 21A shown in Figure 3 has a top plate 27 covering the upper surface and a bottom plate 29 covering the lower surface, as shown in Figure 3(b)(iii), it is not necessary to have a top plate 27 and a bottom plate 29. However, it is preferable that the top plate 27 and bottom plate 29 cover the upper and lower surfaces of the cylindrical members 23 and 25, respectively, as this stabilizes the buckling mode of the cylindrical members 23 and 25 during a frontal collision of the automobile 100.
[0039] <Aspect B> The collision energy absorption structure 1B according to aspect B has a cross member 11 and an energy absorption section 21B, as shown in Figure 4.
[0040] The energy absorption part 21B is disposed from each of both ends of the cross member 11 toward the bumper 121, and has two cylindrical members 23B whose cross section orthogonal to the vehicle front-rear direction is polygonal. The width of the cylindrical member 23B becomes narrower from the cross member 11 side toward the bumper 121 side. Thereby, the width of the energy absorption part 21B becomes narrower from the cross member 11 side toward the bumper 121 side.
[0041] In the collision energy absorption structure 1B, when a collision object that has entered the automobile 100 at the time of a minor overlap collision collides with the cylindrical member 23B, the automobile 100 rotates about the collided portion of the cylindrical member 23B. Thereby, since the collision load input to the cabin side of the automobile 100 is reduced, deformation of the cabin can be suppressed and the occupant can be protected.
[0042] Also, in the collision energy absorption structure 1B, similar to the collision energy absorption structure 1A according to the aspect A, the presence or absence and the number of the cylindrical members 25 provided between the cylindrical members 23B disposed at both ends in the vehicle width direction of the cross member 11 are not particularly limited (see FIGS. 4(b)(i) and (ii)).
[0043] Furthermore, as shown in FIG. 4(b)(iii), the energy absorption part 21B may not be covered on the upper and lower surfaces by the top plate 27 and the bottom plate 29. However, the energy absorption part 21B covered by the top plate 27 and the bottom plate 29 is preferable because it can stabilize the buckling mode of the cylindrical member 23 and the cylindrical member 25.
[0044] <Aspect C> As shown in FIG. 5, the collision energy absorption structure 1C according to the aspect C includes a cross member 11 and an energy absorption part 21C.
[0045] The energy absorption part 21C has a corrugated member 31 and side plates 33. The corrugated member 31 has a waveform in a cross section orthogonal to the vehicle front-rear direction, the rear end side is connected to the cross member 11, and the front end side is connected to the bumper 121. The side plates 33 extend in the vehicle front-rear direction so as to be connected to each side end in the vehicle width direction of the corrugated member 31, the front end is connected to the bumper 121, and the rear end is connected to the cross member 11.
[0046] In the collision energy absorption structure 1C, even when the collision body collides with one side in the vehicle width direction as in a minor wrap collision, the cross member 11 bears the load during the deformation of the corrugated member 31 over the vehicle width direction, so that the range in which the corrugated member 31 deforms is enlarged. As a result, the amount of absorbed collision energy can be increased, and thus, even when the vehicle weight is heavy or the collision speed is high, the deformation of the cabin of the automobile 100 can be suppressed and the occupants can be protected. Further, when the energy absorption part 21C deforms, a load in the vehicle width direction is generated, so that a force to move the entire vehicle in the direction opposite to the collision body is generated, causing a slip between the vehicle and the collision body, and as a result, the deformation of the vehicle can be suppressed and the occupants can be protected.
[0047] In the collision energy absorption structure 1C, similar to the above-described mode A and mode B, by having a top plate 27 covering the upper surface of the corrugated member 31 and a bottom plate 29 covering the lower surface (see FIGS. 5(b)(i)), it is possible to stabilize the buckling mode of the corrugated member 31, which is preferable.
[0048] <Mode D> As illustrated in FIG. 6, the collision energy absorption structure 1D according to mode D includes a cross member 11 and an energy absorption part 21D. The energy absorption part 21D has a cylindrical member 23A and a corrugated member 31A.
[0049] Similar to the above-described mode A, the cylindrical member 23A is disposed from each of both ends of the cross member 11 toward the bumper 121. The corrugated member 31A is provided between the cylindrical members 23A disposed at both ends of the cross member 11 and has a corrugated cross section orthogonal to the vehicle longitudinal direction. The rear end side of the corrugated member 31A is connected to the cross member 11, and the front end side is connected to the bumper 121. Further, both side ends of the corrugated member 31A in the vehicle width direction are connected to the cylindrical member 23A.
[0050] In the collision energy absorption structure 1D, when a collision load is applied to one side in the vehicle width direction, such as in a minute lap collision, the cylindrical member 23A on that side receives the collision load and deforms. Furthermore, as the corrugated member 31C deforms 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 31C deforms. As a result, the collision energy absorption structure 1D increases the amount of collision energy absorbed, so that even when the vehicle weight is heavy or the collision speed is high, deformation of the cabin (not shown) of the automobile 100 can be suppressed and occupants can be protected. Furthermore, as in embodiment C, when the energy absorption section 21D deforms, a load is generated in the vehicle width direction, which generates a force that moves the entire vehicle in the opposite direction to the collision body, causing the vehicle and the collision body to pass each other, thereby suppressing vehicle deformation and protecting occupants.
[0051] The energy absorption section 21D does not necessarily have to be covered on its top and bottom surfaces by the top plate 27 and the bottom plate 29 (Figure 6(b)(ii)), but it is preferable that it be covered by the top plate 27 and the bottom plate 29, as this can stabilize the buckling modes of the cylindrical member 23A and the corrugated member 31C.
[0052] Furthermore, the energy absorption section 21D shown in Figure 6 had a cylindrical member 23A whose width widened from the cross member 11 side toward the bumper 121 side. However, the energy absorption section 21D of the collision energy absorption structure 1D according to embodiment D may have a constant width, as in the energy absorption section 21 of the collision energy absorption structure 1 according to the embodiment described above (Figure 1(a)), or it may have a width that narrows from the cross member 11 toward the bumper 121 side, as in the energy absorption section 21D of embodiment B described above (Figure 3(a)).
[0053] <Aspect E> The collision energy absorption structure 1E according to aspect E comprises a cross member 11 and an energy absorption section 21E, as shown in Figure 7. The energy absorption section 21E is divided into two parts in the vehicle's longitudinal direction: a front energy absorption section 21E-1 and a rear energy absorption section 21E-2. Furthermore, a partition plate 21E-3 is provided between the front energy absorption section 21E-1 and the rear energy absorption section 21E-2 of the collision energy absorption structure 1E.
[0054] The front energy absorption section 21E-1 has a corrugated member 31-1 with a cross section perpendicular to the vehicle's longitudinal direction and a side plate 33-1 connected to its side end, with the front end connected to the bumper 121 and the rear end connected to the partition plate 21E-3. The rear energy absorption section 21E-2 has a corrugated member 31-2 with a cross section perpendicular to the vehicle's longitudinal direction and a side plate 33-1 connected to its side end, with the front end connected to the partition plate 21E-3 and the rear end connected to the cross member 11.
[0055] In the present invention, if the energy absorption section 21 (see Figure 1) is too long in the longitudinal direction of the vehicle, when a collision load is applied during a frontal collision, buckling and breakage may occur, preventing the axial crash mode, which has a high collision energy absorption capacity, from occurring, and potentially reducing the collision energy absorption rate.
[0056] Therefore, as shown in the collision energy absorption structure 1E according to embodiment E, the structure is divided into a front energy absorption section 21E-1 and a rear energy absorption section 21E-2, and the collision load is transmitted via the partition plate 21E-3, making it possible to suppress the decrease in the absorption rate of collision energy due to buckling.
[0057] In Figure 7, the energy absorption section 21E was shown as having a two-part structure, but it may be divided into three or more parts. Furthermore, dividing the energy absorption section 21E into front and rear sections can also be applied to the aforementioned energy absorption section 21 (see Figure 1) and the energy absorption sections 21A to 21D according to embodiments A to D.
[0058] In the above embodiments and embodiments A to E, the cross member 11 was made of steel plate with a tensile strength of 980 MPa class, in order to bear the load during deformation of the cylindrical member 23 (and cylindrical member 25) and corrugated member 31 provided as energy absorption section 21. In addition, the cross member 11 had a polygonal shape such as a square in the cross section perpendicular to the vehicle width direction.
[0059] However, the present invention is not limited to a cross member 11 having a polygonal cross-section; it may also be a circular cross member 11A (see Figure 2(b)), a U-shaped cross member 11B (Figure 2(c)), or a hat-shaped cross member 11C (Figure 2(d)). In the case of a U-shaped cross member 11B or a hat-shaped cross member 11C, it is preferable that it is arranged so that the rear side of the vehicle is open.
[0060] Furthermore, in the present invention, it is preferable to have a bead extending in the vehicle width direction on the front surface of the cross member when it has a polygonal cross section (surface 11a shown in Figure 2(a)), or on the front surface of the cross member when it has a U-shaped or hat-shaped cross section (surface 11Ba shown in Figure 2(c), surface 11Ca shown in Figure 2(d)), thereby improving rigidity and strength.
[0061] Furthermore, while there are no particular restrictions on the material of the energy absorption section, steel plates with material properties (rigidity, thickness, etc.) that make them more easily deformable compared to the cross members are preferred.
[0062] Furthermore, the present invention may also be a collision energy absorption structure 1F in which a second cross member 41 is provided on the bumper 121 side, as shown in Figure 8. In the collision energy absorption structure 1F, the energy absorption section 21A deforms due to the collision load input from the bumper 121 via the second cross member 41, which is another member, during a frontal collision of the automobile 100, thereby absorbing collision energy. As a result, even in the case of a minute overlap collision, compared to the collision energy absorption structure 1 shown in Figure 1, the amount of collision energy absorbed can be further increased because the collision load is input to the side of the energy absorption section 21 that does not enter the collision body, causing it to deform.
[0063] The second cross member 41 does not necessarily have to be made of high-tensile steel plate, but if the strength of the bumper 121 is insufficient, or if the bumper 121 is absent, it is desirable that it be made of steel plate with a tensile strength of 980 MPa or higher, similar to the cross member 11.
[0064] In this embodiment, the subframe 111 comprises a pair of side members 113 arranged on both the left and right sides, and a cross panel 115 arranged between the side members 113. However, the present invention is not limited to this configuration of the subframe; it is sufficient if both ends of a cross member extending in the vehicle width direction in front of the subframe can be attached.
[0065] 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 front 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.
[0066] 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 1G 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 9.
[0067] Even with such a collision energy absorbing structure 1G, 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, and can absorb the collision energy.
[0068] 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.
[0069] In this embodiment, a micro-lap 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 micro-lap collision test, the offset ratio was set to 25%, and the collision speed of the collision body was set to 64 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 micro-lap collision test was also conducted on an automobile 100 equipped with the conventional collision energy absorption structure 3 described in Figure 11.
[0070] Figure 10 shows a graph of the load applied to the automobile 100 and the displacement of the automobile 100, as measured by a micro-lap collision test. In Figure 10, the inventive example is the collision energy absorption structure 1, and the comparative example is the conventional collision energy absorption structure 3.
[0071] As shown in Figure 10, 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 while the energy absorption section 21 (cylindrical member 23, cylindrical member 25) of the collision energy absorption structure 1 was deforming. 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.
[0072] 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.
[0073] According to the present invention, it is possible to provide a collision energy absorbing structure that can sufficiently absorb collision energy during a frontal collision, even when the vehicle weight is heavy, such as in an electric vehicle, or when the collision speed is high.
[0074] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G Collision energy absorption structure (invention) 3 Collision energy absorption structure (conventional) 11, 11A, 11B, 11C Cross member 11a, 11Ba, 11Ca Surface part 21, 21A, 21B, 21C, 21D, 21E Energy absorption part 21E-1 Front energy absorption part 21E-2 Rear energy absorption part 21E-3 Partition plate 23, 23A, Cylindrical member 25 Cylindrical member 27 Top plate 29 Bottom plate 31 Corrugated member 33 Side plate 41 Second cross member 100 Automobile 101 Body 103 Suspension arm 111 Subframe 113 Side member 115 Cross panel 121 Bumper 131 Crash box 141 Crash Box 143 Space
Claims
1. A collision energy absorbing structure for absorbing collision energy during a frontal collision of an automobile having a subframe and a bumper at the front of the vehicle, comprising: a cross member made of steel plate with a tensile strength of 980 MPa or higher, extending in the vehicle width direction in front of the subframe and having both ends attached to the subframe, having a polygonal, circular, U-shaped, or hat-shaped cross section perpendicular to the vehicle width direction; and an energy absorbing section 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 frontal collision of the automobile to absorb collision energy.
2. The collision energy absorbing structure according to claim 1, wherein the width of the energy absorbing portion increases from the cross member side toward the bumper side.
3. The collision energy absorbing structure according to claim 1, wherein the width of the energy absorbing portion narrows from the cross member side toward the bumper side.
4. The collision energy absorbing structure according to any one of claims 1 to 3, wherein the energy absorbing portion is disposed toward the bumper from each of the two ends of the cross member in the vehicle width direction, and has a cylindrical member with a polygonal or circular cross-section perpendicular to the vehicle longitudinal direction.
5. The collision energy absorbing structure according to any one of claims 1 to 3, 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.
6. The collision energy absorbing structure according to claim 5, 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.
7. The collision energy absorbing structure according to any one of claims 1 to 3, wherein the energy absorbing section comprises: a cylindrical member disposed toward the bumper from each of the 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 the ends of the corrugated member in the vehicle width direction are each connected to the cylindrical members.