JP7039398B2 - Vehicle energy absorption components and energy absorption assemblies - Google Patents

Description

The present invention relates to an energy absorbing member and an energy absorbing assembly arranged substantially parallel to each other in the front-rear direction of a vehicle such as an automobile.

A vehicle such as an automobile is provided with an energy absorbing member arranged substantially parallel to the front-rear direction of the vehicle, such as a bumper stay, a side sill, and a crash box. These energy absorbing members are required to have a function of absorbing energy at the time of a collision from the front or the rear. As for the vertically crushing type energy absorbing member arranged substantially parallel to the collision direction, various cross-sectional shapes have been proposed so far.

Patent Document 1 discloses a crash box as a shock absorbing member. This crash box is formed in a substantially square cylinder shape, and a first partition wall and a second partition wall extending along an axis are provided inside the crash box in a manner orthogonal to each other. In this crash box, at the tip portion in the longitudinal direction, the peripheral edge of the outer wall having a substantially square cylinder shape and the tip edge of the first and second partition walls are in the same plane. Further, the crash box of Patent Document 1 is provided with a flange in which the amount of protrusion gradually increases from one side of the axis extending in the front-rear direction toward the other side for the purpose of absorbing sufficient impact energy.

Japanese Unexamined Patent Publication No. 2002-155981

By the way, in order to increase the energy absorption efficiency of the energy absorbing member, it is necessary to reduce the maximum load at the initial stage of collision and to suppress the load fluctuation after that.

However, in the structure of the crash box of Patent Document 1, a portion that becomes the starting point of buckling at the initial stage of collision is not set, and the maximum load at the initial stage of collision is relatively high. Further, the crash box of Patent Document 1 has a wide area to be deformed by receiving a load from one side to the other along its axis, so that the deformation strength with respect to the axial compressive load gradually increases, so that the plastic deformation progresses. Along with this, the corresponding shaft compression load gradually increases. Therefore, in the case of the crash box of Patent Document 1, the maximum load at the initial stage of the collision is relatively high, and the load in the latter half of the collision is gradually higher than the deformation load in the first half of the collision after the maximum load is generated. The fluctuation is large and the energy absorption efficiency is relatively low.

It is an object of the present invention to provide an energy absorbing member and an energy absorbing assembly capable of reducing the maximum load at the initial stage of a collision and suppressing the load fluctuation thereafter.

(1) The present invention is provided in the vehicle in a posture extending in the front-rear direction of the vehicle, and has a tip portion that is an end portion on the collision side and a base end portion that is located on the opposite side of the tip portion in the front-rear direction. It is an energy absorbing member. The energy absorbing member constitutes a closed cross section that surrounds an internal space in a cross section orthogonal to the longitudinal direction of the energy absorbing member, and has an outer wall in which the closed cross section is continuous from the tip end portion to the base end portion, and the cross section. The surface comprises at least one inner wall extending in an orthogonal direction orthogonal to the longitudinal direction and having both ends in the orthogonal direction connected to the outer wall to partition the inner space. The tip edge of the inner wall at the tip portion retracts toward the proximal end portion with respect to the peripheral edge so as to be located on the proximal end portion side in the longitudinal direction with respect to the peripheral edge of the outer wall at the tip portion. Including the receding part. The inner wall is continuous in the longitudinal direction on the proximal end side of the retracted portion. The tip edge of the inner wall includes a continuous portion continuous with the peripheral edge of the outer wall, and the continuous portion is formed so as to extend inward from the peripheral edge in a plane including the peripheral edge. The retracted portion is located closer to the base end portion in the longitudinal direction than the continuous portion.

In the energy absorbing member of the present invention, since the tip edge of the inner wall includes a retracted portion at the tip portion which is the end portion on the collision side, the pressure receiving area at the tip portion at the time of collision becomes small. As a result, the deformation load at the initial stage of the collision can be reduced, and as a result, the maximum load at the initial stage of the collision can be reduced. Then, the tip portion on the collision side where the deformation load is reduced is crushed relatively easily, and the crushed tip portion serves as the starting point, so that the portion on the base end portion side of the tip portion is crushed smoothly. Can be done. Moreover, since not only the outer wall but also the inner wall is continuous in the longitudinal direction on the base end side of the receding portion of the inner wall, the buckling wavelength at the time of crush deformation is shortened and the load fluctuation is suppressed. .. Therefore, in the present invention, it is possible to reduce the maximum load at the initial stage of collision and suppress the load fluctuation after that. Moreover, since the tip edge of the inner wall includes not only the receding part but also the continuous part, the load at the initial stage of the collision is partially transmitted to the continuous part of the inner wall, and the buckling deformation of the inner wall starts from the initial stage of the collision. It is easier to get started partially. As a result, the portion of the inner wall located closer to the base end portion than the continuous portion can be smoothly crushed. Further, since this continuous portion is continuous with the peripheral edge of the outer wall, it is constrained to some extent by the outer wall. Therefore, the crushing of the inner wall in the vicinity of the continuous portion proceeds more stably. From these facts, the crushing at the initial stage of the collision and the subsequent crushing are stable, and the deformation load is more stable. This makes it possible to more effectively suppress load fluctuations during a collision.

(2) In the energy absorbing member, the at least one inner wall extends in a first direction orthogonal to the longitudinal direction in the cross section, and both ends of the first direction are connected to the outer wall, respectively. In a portion of the cross section that is orthogonal to the longitudinal direction and extends in a second direction intersecting the first direction and both ends of the second direction are different from the first inner wall. A portion including a second inner wall connected to each of the outer walls and intersecting the first inner wall in the inner space, and a portion where the first inner wall and the second inner wall intersect. In the above, the retracted portion may be provided in each of the first inner wall and the second inner wall.

When the first inner wall and the second inner wall intersect as in this embodiment, the length of each side constituting the closed cross section can be significantly shortened, so that the buckling wavelength at the time of crush deformation can be set. Can be shortened. When the buckling wavelength is shortened, the cycle of the load fluctuation is also shortened, and it is possible to suppress the increase in the amplitude of the load fluctuation. This makes it possible to effectively suppress load fluctuations during a collision. The length of each side constituting the closed cross section here means the length of the cross section element connecting the connecting points of the members. When the first inner wall and the second inner wall intersect in this way, the deformation resistance at the intersection of these increases, so that the deformation load at the initial stage of the collision increases, but the first at the intersection. By providing the retracted portion on each of the inner wall and the second inner wall, the deformation of the tip portion of the energy absorbing member can be facilitated. As a result, it is possible to effectively suppress the load fluctuation after that while suppressing the increase in the maximum load at the initial stage of the collision.

(3) In the energy absorbing member, the at least one inner wall is a first inner wall whose both ends are connected to the outer wall in the cross section and the first inner wall whose both ends are connected to the outer wall in the cross section. The first interior including a second inner wall connected to the outer wall at different portions and arranged at intervals in a direction orthogonal to the longitudinal direction with respect to the first inner wall. The recessed portion may be provided on each of the wall and the second inner wall.

When the first inner wall and the second inner wall arranged at intervals from each other are provided as in this embodiment, the length of the side constituting the closed cross section is shortened to suppress the load fluctuation at the time of collision. Can enhance the effect of On the other hand, when the first inner wall and the second inner wall as described above are provided, the deformation load at the initial stage of the collision is compared with the case where only a single inner wall is provided. Becomes larger. Therefore, in this embodiment, the recessed portion is provided on each of the first inner wall and the second inner wall, thereby facilitating the deformation of the tip portion of the energy absorbing member. As a result, it is possible to effectively suppress the load fluctuation after that while suppressing the increase in the maximum load at the initial stage of the collision.

( 4 ) In the energy absorbing member, it is preferable that the continuous portion is provided on both outer sides of the retracted portion when viewed in the longitudinal direction.

In this aspect, since the above-mentioned effects of stabilizing the crushing and stabilizing the deformed load can be obtained on both outer sides of the retracted portion, the load fluctuation at the time of collision can be suppressed more effectively.

( 5 ) In the energy absorbing member, the longitudinal distance from the peripheral edge of the outer wall to the retracted portion of the tip edge of the inner wall is a length corresponding to the stroke in which the maximum load is generated at the time of collision. It is preferable that the value exceeds.

In order to reduce the maximum load, it is desirable that after the maximum load is generated at the initial stage of the collision, crushing deformation of the portion on the proximal end side in the longitudinal direction rather than the receding portion of the tip edge of the inner wall begins. When the distance is set to a value exceeding the length corresponding to the stroke, crush deformation of the portion on the proximal end side of the receding portion of the distal edge of the inner wall after the maximum load is generated at the initial stage of the collision. Can be made to occur, whereby the maximum load at the initial stage of the collision can be reduced more effectively.

( 6 ) The energy absorbing member is preferably any one of a bumper stay, a crash box, a front side member, a rear side member, a side sill, and a front subframe. These members are energy absorbing members arranged substantially parallel to the front-rear direction of the vehicle, and are required to have a function of absorbing energy at the time of a collision from the front or the rear.

( 7 ) The energy absorbing member is preferably made of a 7000 series aluminum alloy having a relatively high strength among aluminum alloys.

( 8 ) The energy absorption assembly of the present invention comprises a facing member having a facing surface that abuts or is close to the peripheral edge of the outer wall of the energy absorbing member, and is between the facing surface and the retracted portion. A gap is formed in.

In this aspect, since a gap is formed between the retracted portion of the inner wall of the energy absorbing member and the facing surface of the facing member, when the pressure input to the facing member at the time of collision is transmitted to the energy absorbing member, The pressure receiving area at the tip of the energy absorbing member can be reduced. As a result, the deformation load at the initial stage of the collision can be reduced, and as a result, the maximum load at the initial stage of the collision can be reduced.

As described above, according to the present invention, it is possible to provide an energy absorbing member, a manufacturing method thereof, and an energy absorbing assembly capable of reducing the maximum load at the initial stage of a collision and suppressing the load fluctuation thereafter.

It is a perspective view which shows the example of the member to which the energy absorption member which concerns on each embodiment of this invention can apply. It is a side view which shows the example of the member to which the energy absorption member which concerns on each embodiment of this invention can apply. It is a side view which shows the schematic structure of the energy absorption member which concerns on each embodiment of this invention. It is a perspective view which shows the structure near the tip part of the energy absorption member which concerns on 1st Embodiment of this invention. It is a figure which shows the cross section in the VV line of FIG. 3 of the energy absorption member which concerns on 1st Embodiment. It is a figure which shows the cross section in the VI-VI line of FIG. 3 of the energy absorption member which concerns on 1st Embodiment. It is a figure which shows the cross section in the VII-VII line of FIG. 4 of the energy absorption member which concerns on 1st Embodiment. It is a graph which shows the relationship between the displacement at the time of a collision and a load schematically. It is sectional drawing which shows the energy absorption assembly which concerns on embodiment of this invention. It is a perspective view which shows the structure near the tip part of the energy absorption member which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the structure near the tip part of the energy absorption member which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the structure near the tip part of the energy absorption member which concerns on 4th Embodiment of this invention. It is a top view which shows the energy absorption assembly which concerns on embodiment of this invention.

Preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of a member to which the energy absorbing member according to each embodiment of the present invention can be applied. FIG. 2 is a side view showing an example of a member to which the energy absorbing member according to each embodiment of the present invention can be applied.

The energy absorbing member according to the embodiment is provided on the vehicle in a posture extending in the front-rear direction of a vehicle such as an automobile, and is a member for absorbing energy at the time of a collision. As shown in FIGS. 1 and 2, the energy absorbing members include, for example, a side sill 1A, a front side member 1B, a crash box 1C (front bumper paste 1C), a front subframe 1D, a lower crash box 1E, a rear side member 1F, and a rear bumper stay. It can be applied to 1G and the like.

The side sill 1A is one of the strength members constituting the side opening of the automobile, and is a member located under the door. The front side member 1B is a member that transmits the collision load transmitted from the bumper reinforcing material 101 through the crash box 1C to the vehicle body and absorbs energy by crushing itself. The crash box 1C and the lower crash box 1E are energy absorbing members provided on the bumper reinforcing material 101 or the collision back surface side of the bumper reinforcing material provided below the bumper reinforcing material 101. The front subframe 1D is a member that forms a skeleton for assembling the engine, front suspension, steering, and the like to the body. The rear side member 1F is a member attached to both sides of the lower surface of the trunk floor, transmitting the collision load transmitted from the bumper reinforcing material 102 via the rear bumper stay 1G to the vehicle body, and absorbing energy by crushing itself. The rear bumper stay 1G is an energy absorbing member provided on the collision back surface side of the bumper reinforcing material 102.

FIG. 3 is a side view showing a schematic structure of the energy absorbing member 1 according to each embodiment of the present invention. As shown in FIG. 3, the energy absorbing member 1 has a tip portion 3 which is an end portion on the collision side and a base end portion 2 located on the opposite side of the tip portion 3 in the front-rear direction.

The tip portion 3 is an end portion that receives a load in the axial direction due to a assumed collision, and is specified by a place where the energy absorbing member 1 is arranged. In the case of a member that is expected to have a head-on collision, for example, in the case of a member such as a side sill 1A, a front side member 1B, a crash box 1C, a front subframe 1D, and a lower crash box 1E, the energy absorbing member 1 is the tip portion 3 thereof. Is attached to the automobile frame 100 so as to be located in front of the base end portion 2. Then, at the time of a head-on collision, as shown by an arrow F in FIG. 3, a large backward axial compression load is applied to the tip portion 3 of the energy absorbing member 1.

On the other hand, in the case of a member that is expected to collide with the rear surface (for example, a rear-end collision), for example, in the case of a member such as a rear side member 1F and a rear bumper stay 1G, the energy absorbing member 1 has a tip portion 3 thereof rather than a base end portion 2. It is attached to the automobile frame 100 so as to be located at the rear. Then, at the time of a rear surface collision, as shown by an arrow F in FIG. 3, a large forward-looking axial compressive load is applied to the tip portion 3 of the energy absorbing member 1.

[First Embodiment]
FIG. 4 is a perspective view showing a structure in the vicinity of the tip portion 3 of the energy absorbing member 1 according to the first embodiment of the present invention. FIG. 5 is a diagram showing a cross section of the energy absorbing member 1 according to the first embodiment in the VV line of FIG. FIG. 6 is a diagram showing a cross section of the energy absorbing member 1 according to the first embodiment in the VI-VI line of FIG. FIG. 7 is a diagram showing a cross section of the energy absorbing member 1 according to the first embodiment in the line VII-VII of FIG. The cross section shown in FIGS. 5 and 6 is a cross section orthogonal to the longitudinal direction of the energy absorbing member 1, in other words, a cross section of the energy absorbing member 1 viewed along the longitudinal direction.

As shown in FIGS. 3 to 7, the energy absorbing member 1 according to the first embodiment is a member whose cross section is substantially uniform in the longitudinal direction of the energy absorbing member 1 except for the tip portion 3, and the outer wall 10 is formed. And a plurality of internal walls. The outer wall 10 has a shape extending in the longitudinal direction. Each of the plurality of internal walls has a shape extending in the longitudinal direction.

The outer wall 10 includes a first vertical wall 11, a second vertical wall 12, a first horizontal wall 13, and a second horizontal wall 14. The first vertical wall 11, the second vertical wall 12, the first horizontal wall 13, and the second horizontal wall 14 form a closed cross section that surrounds a rectangular internal space in a cross section orthogonal to the longitudinal direction. The closed cross section formed by the outer wall 10 is continuous from the tip portion 3 to the base end portion 2.

The first vertical wall 11 extends in the vertical direction in the cross section, and the second vertical wall 12 is vertically located at a position separated from the first vertical wall 11 in the vehicle width direction (horizontal direction) in the cross section. Extend in the direction. The first horizontal wall 13 extends in the vehicle width direction in the cross section and is connected to the upper end portion of the first vertical wall 11 and the upper end portion of the second vertical wall 12. The second horizontal wall 14 extends in the vehicle width direction at a position vertically separated from the first horizontal wall 13 in the cross section and is connected to the lower end portion of the first vertical wall 11 and the lower end portion of the second vertical wall 12.

The plurality of inner walls include an inner vertical wall 21 (first inner wall) and an inner horizontal wall 22 (second inner wall).

The internal vertical wall 21 extends in the vertical direction (first direction orthogonal to the longitudinal direction) in the cross section, and the upper end is connected to the first horizontal wall 13 and the lower end is connected to the second horizontal wall 14. The internal horizontal wall 22 extends in the vehicle width direction (a second direction orthogonal to the longitudinal direction and intersects the first direction) in the cross section, and one end in the vehicle width direction is connected to the first vertical wall 11. The other end in the vehicle width direction is connected to the second vertical wall 12. The inner vertical wall 21 and the inner horizontal wall 22 have an intersecting portion C that intersects with each other in the internal space surrounded by the outer wall 10. The intersection C is a portion shared by two internal walls (internal vertical wall 21 and internal horizontal wall 22). The intersecting portion C is continuous in the longitudinal direction.

As shown in FIGS. 5 and 7, the internal vertical wall 21 has a main body portion 26 and a pair of projecting portions 27, 27. The main body portion 26 is a portion of the internal vertical wall 21 from the portion of the cross section including the receding portion 24 described later to the base end portion 2. When the direction orthogonal to the longitudinal direction of the energy absorbing member 1 and parallel to the inner vertical wall 21 is the width direction of the inner vertical wall 21, the pair of protrusions 27, 27 are spaced apart from each other in the width direction. Each of the main body portion 26 projects in the longitudinal direction from the end portion in the longitudinal direction (the end portion on the tip portion 3 side) to the pair of continuous portions 25.

As shown in FIGS. 4, 5 and 7, in the tip portion 3 of the energy absorbing member 1, the tip edge 23 of the internal vertical wall 21 has a retracted portion 24, a pair of upper and lower continuous portions 25 and 25, and a pair of upper and lower portions. Including the connection portions 28, 28 and. The tip edge 23 is composed of an edge of a pair of protruding portions 27 and an edge of a main body portion 26 connecting between these edges.

The retracted portion 24 of the inner vertical wall 21 is a portion recessed toward the proximal end portion 2 with respect to the peripheral edge 15 so as to be located on the proximal end portion 2 side in the longitudinal direction with respect to the peripheral edge 15 of the outer wall 10, and is a portion retracted toward the proximal end portion 2 in the vertical direction. Extends to. The portion of the internal vertical wall 21 from the portion of the cross section including the retracted portion 24 to the proximal end portion 2, that is, the main body portion 26 is continuous in the longitudinal direction. The retracted portion 24 of the inner vertical wall 21 extends from the intersecting portion C to both sides in a direction orthogonal to the longitudinal direction (vertical direction) in the cross section. When the energy absorbing member 1 is viewed in the longitudinal direction, the retracted portion 24 is located between the pair of protruding portions 27, 27.

Each of the pair of continuous portions 25 of the inner vertical wall 21 is a portion extending in a plane including the peripheral edge 15 of the outer wall 10 and continuous with the peripheral edge 15, and extends in the vertical direction. The upper continuous portion 25 is located above the retracted portion 24 when viewed longitudinally, and the lower continuous portion 25 is located below the retracted portion 24 when viewed longitudinally. is doing.

Each of the pair of connecting portions 28 of the internal vertical wall 21 is a portion connecting the retracted portion 24 and the corresponding continuous portion 25, and extends in the longitudinal direction of the energy absorbing member 1. Specifically, the upper connecting portion 28 connects the upper end of the retracted portion 24 and the lower end of the upper continuous portion 25. The lower connecting portion 28 connects the lower end of the retracted portion 24 and the upper end of the lower continuous portion 25. In the first embodiment, the retracted portion 24 and the pair of connecting portions 28, 28 are located closer to the base end portion 2 in the longitudinal direction than the pair of continuous portions 25, 25.

As shown in FIGS. 5 and 7, the internal horizontal wall 22 has a main body portion 26 and a pair of protruding portions 27, 27, similarly to the internal vertical wall 21. The main body portion 26 is a portion of the internal lateral wall 22 from the portion of the cross section including the retracted portion 24 to the base end portion 2. When the direction orthogonal to the longitudinal direction of the energy absorbing member 1 and parallel to the inner side wall 22 is the width direction of the inner side wall 22, the pair of projecting portions 27, 27 are spaced apart from each other in the width direction, and the main body portion. 26 protrudes in the longitudinal direction from the end portion in the longitudinal direction (the end portion on the tip 3 side) to the pair of continuous portions 25.

In the tip portion 3 of the energy absorbing member 1, the tip edge 23 of the inner side wall 22 includes a retracting portion 24, a pair of left and right continuous portions 25, 25, and a pair of left and right connecting portions 28, 28. The tip edge 23 is composed of an edge of a pair of protruding portions 27 and an edge of a main body portion 26 connecting between these edges.

The retracted portion 24 of the inner side wall 22 is a portion retracted to the proximal end portion 2 side with respect to the peripheral edge 15 so as to be located on the proximal end portion 2 side in the longitudinal direction with respect to the peripheral edge 15 of the outer wall 10, and is a portion retracted to the proximal end portion 2 side in the vehicle width direction. It extends in the (left-right direction) direction. The portion of the inner lateral wall 22 from the portion of the cross section including the retracted portion 24 to the proximal end portion 2, that is, the main body portion 26 is continuous in the longitudinal direction. The retracted portion 24 of the inner lateral wall 22 extends from the intersecting portion C to both sides in a direction orthogonal to the longitudinal direction (vehicle width direction) in the cross section. When the energy absorbing member 1 is viewed in the longitudinal direction, the retracted portion 24 is located between the pair of protruding portions 27, 27.

Each of the pair of continuous portions 25 of the inner side wall 22 is a portion extending in a plane including the peripheral edge 15 of the outer wall 10 and continuous with the peripheral edge 15, and extends in the vehicle width direction. The continuous portion 25 on the right side is located on the right side with respect to the retracted portion 24 when viewed in the longitudinal direction, and the continuous portion 25 on the left side is located on the left side with respect to the retracted portion 24 when viewed in the longitudinal direction. There is.

Each of the pair of connecting portions 28 of the inner side wall 22 is a portion connecting the retracted portion 24 and the corresponding continuous portion 25, and extends in the longitudinal direction of the energy absorbing member 1. Specifically, the connecting portion 28 on the right side connects the right end of the retracted portion 24 and the left end of the continuous portion 25 on the right side. The connection portion 28 on the left side connects the left end of the retracted portion 24 and the right end of the continuous portion 25 on the left side. In the first embodiment, the retracted portion 24 and the pair of connecting portions 28, 28 are located closer to the base end portion 2 in the longitudinal direction than the pair of continuous portions 25, 25.

As shown in FIG. 7, in the first embodiment, the longitudinal distance D from the peripheral edge 15 of the outer wall 10 to the retracted portion 24 of the inner vertical wall 21 is the receding of the inner horizontal wall 22 from the peripheral edge 15 of the outer wall 10. It is the same as the longitudinal distance D to the portion 24. The distance D is set to a value exceeding the length corresponding to the stroke in which the maximum load is generated at the time of collision. However, the distance D from the peripheral edge 15 to the retracted portion 24 of the internal vertical wall 21 may be different from the distance D from the peripheral edge 15 to the retracted portion 24 of the internal horizontal wall 22.

In order to reduce the maximum load at the time of a collision, after the maximum load is generated at the initial stage of the collision, the main body portion 26 of the inner walls 21 and 22 (the base end portion 2 in the longitudinal direction from the receding portion 24 of the inner walls 21 and 22). It is desirable that the crushing deformation of the side part) begins. When the distance D is set to a value exceeding the length corresponding to the stroke, the main body 26 of the inner walls 21 and 22 is crushed and deformed after the maximum load is generated at the initial stage of the collision. This makes it possible to more effectively reduce the maximum load at the initial stage of a collision.

Assuming that elastic buckling does not occur in the energy absorbing member 1 at the time of collision, the stroke in which the maximum load at the initial stage of collision is generated generally occurs when the material reaches the proof stress. Assuming that the proof stress σy of the aluminum material is about 500 MPa at the maximum, the elastic modulus is E, and the material length is L, the stroke S at which the maximum load at the initial stage of collision is generated is S = σy × L / E. Assuming that the maximum length L of the compression deformation portion of the energy absorbing member 1 which is the target automobile component is about 500 mm, the stroke S is 5 mm or less. To give a specific example, when the proof stress σy of the aluminum material is 500 MPa, the elastic modulus E of the aluminum material is 68600 N / mm ² , and the length L of the energy absorbing member 1 is 500 mm, the stroke S is It will be 3.6 mm. In order to reduce the maximum load, it is desirable that the portion where the notch portion 30 is not provided, that is, the main body portion 26 is crushed and deformed at the stage where the load is reduced after the maximum load is generated. Therefore, the distance D (cutout depth D) is preferably 3.6 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more. Further, in general, the load fluctuation depends on the buckling wavelength, and the buckling wavelength is generally proportional to the average length of each side constituting the cross section. Therefore, the distance D (cutout depth D) is obtained. Second, it is desirable that the length is equal to or less than the average length of each side constituting the cross section where the second and subsequent buckling deformations start. Explaining using an example of the relationship between the displacement at the time of collision and the load shown in FIG. 8, the time point at which the second and subsequent buckling deformations start is the arrow indicating “the load increase due to the second buckling deformation” in FIG. Points to, that is, at the time of the peak of the second load. The distance D can be, for example, in the range of 10 to 30 mm.

FIG. 8 is a graph schematically showing the relationship between the displacement at the time of a collision and the load. As shown in FIG. 8, in the comparative example in which the notch portion 30 is not provided, a large maximum load is generated within the range where the displacement amount S due to the crushing of the energy absorbing member caused by the collision is 5 mm or less. In the embodiment, the maximum load is generated within the range where the displacement amount S due to the crushing of the energy absorbing member 1 caused by the collision is 5 mm or less as in the comparative example, but the maximum load is greatly reduced as compared with the comparative example. Has been done.

As shown in FIG. 7, in the tip portion 3 of the energy absorbing member 1, the notch width W of the notch portion 30 provided at the tip edge 23 of the inner walls 21 and 22 corresponds to the target value of the maximum load at the initial stage of collision. Is set as appropriate. An example of a guideline for setting the notch width W is as follows. The ratio (L1 / L0) of the maximum load L1 at the initial stage of collision and the target value L0 of the maximum load at the initial stage of collision when the notch 30 is not provided is the energy in the cross section of the region where the notch 30 is not provided. The cross-sectional area S1 of the absorbing member 1 (the cross-sectional area of the energy absorbing member 1 in the cross section shown in FIG. 6) and the cross-sectional area S0 of the energy absorbing member 1 in the cross section of the region where the notch 30 is provided (in FIG. 5). By setting the notch width W so as to be the ratio (S1 / S0) to the cross-sectional area of the energy absorbing member 1 in the cross section shown, the maximum load at the initial stage of collision is approximately set to the target value L0 (target load). You can get closer.

FIG. 9 is a cross-sectional view showing an energy absorbing assembly according to an embodiment of the present invention. The energy absorbing assembly according to the present embodiment includes the above-mentioned energy absorbing member 1 and a facing member 40 having a facing surface 41 that abuts or is close to the peripheral edge 15 of the outer wall 10 of the energy absorbing member 1.

The facing member 40 is a member provided so as to abut or approach the tip portion 3 which is the end portion on the collision side of the energy absorbing member 1. For example, when the energy absorbing member 1 is the crash box 1C (front bumper stay 1C) shown in FIGS. 1 and 2, the facing member 40 is a bumper reinforcing member arranged to face the tip portion 3 of the crash box 1C. It is a member such as 101. Further, when the energy absorbing member 1 is the rear bumper stay 1G shown in FIGS. 1 and 2, the facing member 40 is a member such as a bumper reinforcing member 102 arranged to face the tip portion 3 of the rear bump pasty 1G. be.

As shown in FIG. 9, a gap is formed between the facing surface 41 of the facing member 40 and the retracted portion 24 of the inner walls 21 and 22 of the energy absorbing member 1. Therefore, when the pressure input to the facing member 40 at the time of collision is transmitted to the energy absorbing member 1, the pressure receiving area at the tip portion 3 of the energy absorbing member 1 can be reduced. As a result, the deformation load at the initial stage of the collision can be reduced, and as a result, the maximum load at the initial stage of the collision can be reduced.

The energy absorbing member 1 according to the first embodiment is made of a 7000 series aluminum alloy having a relatively high strength among aluminum alloys.

The energy absorbing member 1 according to the first embodiment described above can be manufactured by using, for example, the following manufacturing method.

The manufacturing method includes an extrusion molding step and a recessed portion forming step. In the extrusion molding step, a closed cross section surrounding the internal space is formed in a cross section orthogonal to the longitudinal direction, and the outer wall 10 in which the closed cross section is continuous from the tip portion 3 to the proximal end portion 2 and the longitudinal direction in the cross section. It is a step of forming a member provided with at least one inner wall extending in an orthogonal direction orthogonal to the above and having both ends in the orthogonal direction connected to the outer wall 10 to partition the internal space by extrusion molding of an aluminum alloy.

The receding portion forming step is a step of forming the receding portion 24 by removing a portion of the member including at least a part of the tip edge 23 of the inner wall of the tip portion 3. As described above, the retracted portion 24 is a portion recessed toward the proximal end portion 2 with respect to the peripheral edge 15 so as to be located on the proximal end portion 2 side in the longitudinal direction with respect to the peripheral edge 15 of the outer wall 10 in the tip portion 3. be. The trim processing in the receding portion forming step may be performed by using a cutting machine (pressing machine) such as a shear, or may be performed by machining such as cutting.

According to the manufacturing method, the energy absorbing member 1 provided with the retracted portion 24 can be obtained only by removing a part of the inner wall after producing the member as a whole by extrusion molding. There is no need to weld the members of the above wall or remove a part of the outer wall 10. Therefore, it is possible to suppress the decrease in the rigidity of the energy absorbing member 1, and it is possible to prevent water or the like from entering the internal space from the outer wall 10. Further, according to the manufacturing method, since the retracted portion 24 can be formed in at least a part of the tip edge 23 of the inner wall, the maximum load at the initial stage of the collision can be reduced and the load fluctuation after that can be suppressed. Moreover, a lightweight energy absorbing member 1 made of an aluminum alloy can be efficiently manufactured. By using this energy absorbing member 1, the weight of the vehicle can be reduced.

As described above, in the energy absorbing member 1 according to the first embodiment, in the tip portion 3 which is the end portion on the collision side, the tip edge 23 of the inner walls 21 and 22 includes the retracted portion 24, so that the tip portion thereof. The pressure receiving area at the time of collision in No. 3 becomes smaller. As a result, the deformation load at the initial stage of the collision can be reduced, and as a result, the maximum load at the initial stage of the collision can be reduced. Then, the tip portion 3 on the collision side where the deformation load is reduced is crushed relatively easily, and the crushed tip portion 3 serves as a starting point, so that the portion on the base end portion 2 side of the tip portion 3 is smoothed. Can be crushed. Moreover, since not only the outer wall 10 but also the inner walls 21 and 22 are continuous in the longitudinal direction on the base end portion 2 side of the receding portion 24 of the inner walls 21 and 22, the buckling wavelength at the time of crush deformation is increased. It becomes shorter and load fluctuation is suppressed.

Further, in the first embodiment, since the internal vertical wall 21 as the internal wall and the internal horizontal wall 22 intersect with each other, the length of each side constituting the closed cross section can be significantly shortened. As a result, the buckling wavelength at the time of crush deformation can be shortened. When the buckling wavelength is shortened, the cycle of the load fluctuation is also shortened, and it is possible to suppress the increase in the amplitude of the load fluctuation. This makes it possible to effectively suppress load fluctuations during a collision. When the internal vertical wall 21 and the internal horizontal wall 22 intersect in this way, the deformation resistance at the intersecting portion C becomes high, so that the deformation load at the initial stage of the collision increases. However, in the first embodiment, the intersecting portion By providing the retracting portion 24 on each of the internal vertical wall 21 and the internal horizontal wall 22 in C, the deformation of the tip portion 3 of the energy absorbing member 1 can be facilitated. As a result, it is possible to effectively suppress the load fluctuation after that while suppressing the increase in the maximum load at the initial stage of the collision.

In the first embodiment, the tip edge 23 of the inner walls 21 and 22 includes not only the receding portion 24 but also the continuous portion 25, so that the load at the initial stage of the collision is partially transmitted to the continuous portion 25 of the inner walls 21 and 22. , The buckling deformation of the inner walls 21 and 22 is likely to be partially started from the initial stage of the collision. As a result, the portion of the inner walls 21 and 22 located closer to the base end portion 2 than the continuous portion 25 can be smoothly crushed. Further, since the continuous portion 25 is continuous with the peripheral edge 15 of the outer wall 10, it is constrained to some extent by the outer wall 10. Therefore, the crushing of the inner walls 21 and 22 in the vicinity of the continuous portion 25 proceeds more stably. From these facts, the crushing at the initial stage of the collision and the subsequent crushing are stable, and the deformation load is more stable. This makes it possible to more effectively suppress load fluctuations during a collision. Moreover, in the first embodiment, the continuous portion 25 is provided on both sides of the retracted portion 24 when viewed in the longitudinal direction. Therefore, since the above-mentioned effects of stabilizing the crushing and stabilizing the deformation load can be obtained on both sides of the retracting portion 24, the load fluctuation at the time of collision can be suppressed more effectively.

Further, in the first embodiment, the energy absorption efficiency is enhanced by cutting a part of the inner walls 21 and 22 to form the retracted portion 24 without partially cutting the outer wall 10. Therefore, since holes and the like are not formed in the outer wall 10, it is possible to suppress a decrease in rigidity such as bending rigidity of the outer wall 10, and water or the like infiltrates from the outer wall 10 into the internal space thereof. You can avoid that.

The energy absorbing member 1 preferably has an outer shape having a flat surface. The energy absorbing member 1 may be attached to another component or may be attached to another component. Considering this point, a flat surface having a certain area may be required on the outer surface of the outer wall 10. In order to secure such a flat surface, the outer shape of the outer wall 10 is preferably rectangular in the cross section of the outer wall 10. In the first embodiment, the outer wall 10 has a substantially rectangular closed cross section in the cross section, and has a flat surface on the outer surface of the outer wall 10.

Further, in consideration of weight reduction, it is preferable that the length of the inner wall is reduced in the cross section. Considering this point, in the cross section, portions of the outer wall 10 extending in parallel directions (for example, the first vertical wall 11 and the second vertical wall 12) are connected by an inner wall extending in a direction orthogonal to the first vertical wall 11. Is preferable.

Further, the energy absorbing member 1 can be easily obtained by the above-mentioned manufacturing method. Therefore, even when manufacturing an energy absorbing member 1 such as a side member or a side sill which is a long member, it is only necessary to remove a portion including at least a part of the tip edge 23 of the inner wall after extrusion molding. Therefore, as compared with the case where unevenness is formed on a part of the outer wall 10 by press molding or the like for the purpose of reducing the maximum load, problems such as breakage of members and deformation of peripheral parts do not occur, and it is relatively stable. Productivity is obtained.

[Second Embodiment]
FIG. 10 is a perspective view showing a structure in the vicinity of the tip portion 3 of the energy absorbing member 1 according to the second embodiment of the present invention. The energy absorbing member 1 according to the second embodiment has an internal wall configuration different from that of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, in the following, only the parts different from the first embodiment will be described.

In the energy absorbing member 1 according to the second embodiment, the first inner wall 21 (inner side wall 21) and the second inner wall 22 (inner side wall 22) are in the vertical direction orthogonal to the longitudinal direction of the energy absorbing member 1. They are lined up in parallel with each other at intervals. The first internal wall 21 extends in the vehicle width direction in the cross section, one end in the vehicle width direction is connected to the first vertical wall 11, and the other end in the vehicle width direction is connected to the second vertical wall 12. The second inner wall 22 extends in the vehicle width direction in the cross section, one end in the vehicle width direction is connected to the first vertical wall 11, and the other end in the vehicle width direction is connected to the second vertical wall 12. Each of the first inner wall 21 and the second inner wall 22 is provided with the retracted portion 24.

In this second embodiment, the length of the side constituting the closed cross section can be shortened to enhance the effect of suppressing the load fluctuation at the time of collision. On the other hand, when the first inner wall 21 and the second inner wall 22 as described above are provided, the initial collision stage is compared with the case where only a single inner wall is provided. The deformation load increases. Therefore, in this embodiment, the retracted portion 24 is provided on each of the first inner wall 21 and the second inner wall 22, thereby facilitating the deformation of the tip portion 3 of the energy absorbing member 1. As a result, it is possible to effectively suppress the load fluctuation after that while suppressing the increase in the maximum load at the initial stage of the collision.

[Third Embodiment]
FIG. 11 is a perspective view showing a structure in the vicinity of the tip portion 3 of the energy absorbing member 1 according to the third embodiment of the present invention. The energy absorbing member 1 according to the third embodiment has an internal wall configuration different from that of the first embodiment and is the same as that of the first embodiment except for that. Therefore, in the following, only the parts different from the first embodiment are described. explain.

In the energy absorbing member 1 according to the third embodiment, only a single inner wall 20 is provided, and the configuration of the pair of connecting portions 28, 28 is different from that of the first embodiment. As shown in FIG. 11, the pair of connecting portions 28, 28 are inclined with respect to the longitudinal direction so that the distance between the pair of connecting portions 28, 28 becomes closer to each other toward the proximal end portion 2 side in the longitudinal direction. That is, the shape of the notch portion 30 may not be substantially rectangular as in the first embodiment, may be trapezoidal as shown in FIG. 11, or may be another shape.

[Fourth Embodiment]
FIG. 12 is a perspective view showing a structure in the vicinity of the tip portion 3 of the energy absorbing member according to the fourth embodiment of the present invention. FIG. 13 is a plan view showing an energy absorption assembly according to an embodiment of the present invention.

In the fourth embodiment shown in FIG. 12, only a single inner wall 20 is provided, and the shapes of the outer wall 10 and the inner wall 20 at the tip portion 3 of the energy absorbing member are different from those of the first embodiment. Since the other parts are the same as those of the first embodiment, only the parts different from the first embodiment will be described below.

In the fourth embodiment shown in FIG. 12, the energy absorbing member is applied to the front bumper stay 1C. FIG. 12 shows a bumper stay 1C mounted on the front left side of the vehicle. FIG. 13 shows a portion on the right side of the front part of the vehicle. As shown in FIG. 13, as the facing member 40 having the facing surface 41 in contact with or close to the tip portion 3 of the bumper stay 1C, for example, the bumper reinforcing material 101 can be mentioned. The bumper reinforcing material 101 shown in FIG. 13 is not a horizontal direction orthogonal to the direction (longitudinal direction) from the base end portion 2 to the tip end portion 3 of the bumper stay 1C, but an inclination extending in the horizontal direction inclined with respect to the longitudinal direction. Has a part. The inclined portion is in contact with or in close proximity to the tip portion 3 of the bump pasty 1C. Therefore, the tip portion 3 of the bumper stay 1C is inclined with respect to the horizontal direction orthogonal to the longitudinal direction of the bumper stay 1C so as to be along the inclined portion of the bumper reinforcing member 101. The base end portion 2 of the bump pasty 1C is in contact with another member 42.

Specifically, the bumper stay 1C includes an outer wall 10 and an inner wall 20. The outer wall 10 includes an outer vertical wall 11, an inner vertical wall 12, an upper horizontal wall 13, and a lower horizontal wall 14. The outer vertical wall 11 extends in the vertical direction in the cross section, and the inner vertical wall 12 extends in the vertical direction at a position separated inward in the vehicle width direction from the outer vertical wall 11 in the cross section. The upper horizontal wall 13 extends in the vehicle width direction in the cross section and is connected to the upper end portion of the outer vertical wall 11 and the upper end portion of the inner vertical wall 12. The lower horizontal wall 14 extends in the vehicle width direction at a position downward from the upper horizontal wall 13 in the cross section and is connected to the lower end portion of the outer vertical wall 11 and the lower end portion of the inner vertical wall 12. The inner wall 20 extends in the vehicle width direction in the cross section, one end in the vehicle width direction is connected to the outer vertical wall 11, and the other end in the vehicle width direction is connected to the inner vertical wall 12.

The portion of the peripheral edge 15 of the outer wall 10 corresponding to the tip edge of the inner vertical wall 12 is located in front of the portion of the peripheral edge 15 of the outer wall 10 corresponding to the tip edge of the outer vertical wall 11. The tip edge of the upper horizontal wall 13 connects the upper end of the tip edge of the inner vertical wall 12 and the upper end of the tip edge of the outer vertical wall 11. The tip edge of the lower horizontal wall 14 connects the lower end of the tip edge of the inner vertical wall 12 and the lower end of the tip edge of the outer vertical wall 11. As a result, the plane including the peripheral edge 15 of the outer wall 10 is inclined with respect to the plane orthogonal to the longitudinal direction of the bumper stay 1C.

As shown in FIGS. 12 and 13, in the tip portion 3 of the bump pasty 1C, the tip edge 23 of the inner wall 20 has a retracted portion 24, a pair of left and right continuous portions 25, 25, and a pair of left and right connecting portions 28, 28. And, including.

The retracted portion 24 is a portion recessed toward the proximal end portion 2 with respect to the peripheral edge 15 so as to be located on the proximal end portion 2 side in the longitudinal direction with respect to the peripheral edge 15 of the outer wall 10, and extends in the left-right direction. Each of the pair of continuous portions 25 is a portion extending in a plane including the peripheral edge 15 of the outer wall 10 and continuous with the peripheral edge 15, and extends in a direction inclined with respect to the left-right direction. Each of the pair of connecting portions 28 is a portion connecting the retracted portion 24 and the corresponding continuous portion 25, and extends in the longitudinal direction of the energy absorbing member 1.

In the fourth embodiment, the receding portion 24 extends in a direction orthogonal to the collision direction. In the case of such a structure, when a collision occurs in a direction parallel to the front-rear direction, the deformation of the bumper reinforcing material 101 is started, the inclined portion of the bumper reinforcing material 101 is deformed, and the inclined portion is in the collision direction. The shape is almost parallel to. That is, after the inclined portion of the bumper reinforcing material 101 is deformed into a shape substantially parallel to the retracting portion 24 of the bumper stay 1C, the bumper stay 1C can be stably crushed.

[Modification example]
The present invention is not limited to the embodiments described above. The present invention includes, for example, the following forms.

In the first embodiment, the first inner wall 21 extends in the vertical direction in the cross section, the second inner wall 22 extends in the vehicle width direction (horizontal direction) in the cross section, and these inner walls 21 and 22 Illustrated the case where the two intersect at the intersection C, but the present invention is not limited to this. At least one of the first inner wall 21 and the second inner wall 22 extends in a direction inclined with respect to the vertical direction and the horizontal direction in the cross section, and these inner walls 21 and 22 intersect at the intersection portion C. You may.

In the second embodiment, the first inner wall 21 and the second inner wall 22 extend in the vehicle width direction (left-right direction) in the cross section and are arranged in a posture parallel to each other, but the present invention is not limited to this. .. The first inner wall 21 and the second inner wall 22 may extend in a direction inclined with respect to the vehicle width direction in the cross section, or may extend in the vertical direction. Further, the first inner wall 21 and the second inner wall 22 do not have to be parallel to each other in the cross section.

In each embodiment, three or more internal walls may be provided.

In each embodiment, the tip edge 23 of the inner wall may consist of a retracted portion 24, a single continuous portion 25, and a single connecting portion 28 connecting them. Further, the tip edge 23 of the inner wall may include a plurality of receding portions 24 provided at intervals in the cross section.

1 (1A-1G) Energy absorption member 1A Side sill 1B Front side member 1C Crash box (front bumper stay)
1D Front subframe 1E Lower crash box 1F Rear side member 1G Rear bump pasty 2 Base end of energy absorbing member 3 Tip of energy absorbing member 10 External wall 11,12 Vertical wall of external wall 13,14 Horizontal wall of external wall 15 External wall Periphery 20 Inner wall 21 First inner wall 22 Second inner wall 23 Tip edge of inner wall 24 Retreat part at the tip edge of the inner wall 25 Continuous part at the tip edge of the inner wall 30 Retreat part 40 Opposing member 41 Facing surface D Longitudinal distance from the peripheral edge of the outer wall to the receding part of the inner wall (depth of the notch)

Claims (8)

An energy absorbing member provided on the vehicle in a posture extending in the front-rear direction of the vehicle and having a tip portion that is an end portion on the collision side and a base end portion that is located on the opposite side of the front-rear direction. ,
A closed cross section surrounding the internal space in a cross section orthogonal to the longitudinal direction of the energy absorbing member, and an outer wall in which the closed cross section is continuous from the tip end portion to the base end portion.
The cross section comprises at least one internal wall extending in an orthogonal direction orthogonal to the longitudinal direction and having both ends in the orthogonal direction connected to the outer wall to partition the internal space.
The tip edge of the inner wall at the tip portion retracts toward the proximal end portion with respect to the peripheral edge so as to be located on the proximal end portion side in the longitudinal direction with respect to the peripheral edge of the outer wall at the tip portion. Including the recessed part
The inner wall is continuous in the longitudinal direction on the proximal end side of the retracted portion.
The tip edge of the inner wall includes a continuous portion continuous with the peripheral edge of the outer wall, and the continuous portion is formed so as to extend inward from the peripheral edge in a plane including the peripheral edge. An energy absorbing member , wherein the retracted portion is located closer to the base end portion in the longitudinal direction than the continuous portion . The energy absorbing member according to claim 1.
The at least one inner wall
A first inner wall extending in a first direction orthogonal to the longitudinal direction in the cross section and having both ends of the first direction connected to the outer wall, respectively.
In the cross section, it is orthogonal to the longitudinal direction and extends in a second direction intersecting the first direction, and both ends of the second direction are connected to the outer wall at a portion different from the first inner wall. Includes a second interior wall that intersects the first interior wall in the interior space.
An energy absorbing member in which a recessed portion is provided in each of the first inner wall and the second inner wall at a portion where the first inner wall and the second inner wall intersect. The energy absorbing member according to claim 1.
The at least one inner wall
A first inner wall in which both ends are connected to the outer wall in the cross section,
In the cross section, both ends are second inner walls connected to the outer wall at a portion different from the first inner wall, and are spaced in a direction orthogonal to the longitudinal direction with respect to the first inner wall. Including those lined up
An energy absorbing member provided with a recessed portion on each of the first inner wall and the second inner wall. The energy absorbing member according to any one of claims 1 to 3 , wherein the continuous portion is provided on both outer sides of the retracted portion when viewed in the longitudinal direction. The energy absorbing member according to any one of claims 1 to 4 , wherein the distance in the longitudinal direction from the peripheral edge of the outer wall to the retracted portion of the tip edge of the inner wall is the distance at the time of collision. An energy absorbing member that is set to a value that exceeds the length corresponding to the stroke in which the maximum load is generated. The energy absorbing member according to any one of claims 1 to 5 , which is any one of a bumper stay, a crash box, a front side member, a rear side member, a side sill, and a front subframe. The energy absorbing member according to any one of claims 1 to 6 , which is made of a 7000 series aluminum alloy. The energy absorbing member according to any one of claims 1 to 7 .
A facing member having a facing surface that abuts or is close to the peripheral edge of the outer wall of the energy absorbing member.
An energy absorbing assembly in which a gap is formed between the facing surface and the retracted portion.

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