JP2009154587A - Shock absorption structure - Google Patents

Abstract

An impact absorbing member can be efficiently compressed and deformed even when a collision load is input to one end side of the load input member.
In this shock absorbing structure, when a collision load is input to the end of the bumper reinforcement 12 in the vehicle width direction, a bending moment is generated in the crash box 16. Here, when the collision load is equal to or greater than a predetermined value, the fracture portion 40 provided in the crash box 16 is fractured, and the front end portion of the crash box 16 is partially deformed by the impact load. Thereby, since the moment arm of the bending moment generated in the crash box 16 is shortened, the crash box 16 can be efficiently compressed and deformed by the collision load.
[Selection] Figure 1

Description

  The present invention relates to a shock absorbing structure that absorbs energy at the time of a collision by compressively deforming a shock absorbing member interposed between a load input member to which a collision load is input and a load transmission member to which the collision load is transmitted. .

Conventionally, there is a vehicle such as an automobile in which an impact absorbing member called a crash box (see, for example, Patent Document 1) is interposed between a bumper reinforcement and a front side member. Such an impact-absorbing member absorbs energy at the time of collision by compressing and deforming in the axial direction when a collision load is input to the bumper reinforcement.
WO2005 / 010397

  By the way, at the time of the oblique collision of the vehicle, the collision load at the start of the collision is concentrated on the end portion in the vehicle width direction of the bumper reinforcement (one end side of the load input member), so between the bumper reinforcement and the front side member, That is, a bending moment is generated in the crash box provided at a position offset inward in the vehicle width direction from the end portion in the vehicle width direction of the bumper reinforcement. For this reason, if the bending moment of the crash box is caused by this bending moment, the crash box does not undergo axial compression deformation as set, and the energy absorption amount of the crash box may be greatly reduced.

  In view of the above facts, an object of the present invention is to obtain an impact absorbing structure capable of efficiently compressing and deforming an impact absorbing member even when a collision load is input to one end side of the load input member.

  The shock absorbing structure according to the first aspect of the present invention interposes between a load input member to which a collision load is input and a load transmission member to which the collision load is transmitted, and compresses and deforms energy at the time of collision. A shock absorbing member that absorbs and generates a bending moment when a collision load is input to one end side of the load input member, and is provided in the shock absorbing member, and has a predetermined value or more on one end side of the load input member. And a breaking portion that shortens the moment arm of the bending moment by breaking when the collision load is input and promoting the partial deformation of the shock absorbing member.

  In the shock absorbing structure according to claim 1, when a collision load is input to the load input member, the collision load is transmitted to the load transmitting member via the shock absorbing member, and the shock absorbing member is caused by the collision load. Compressive deformation. Thereby, the energy at the time of a collision is absorbed.

  Further, in this shock absorbing structure, when a collision load is input to one end side of the load input member, a bending moment is generated in the shock absorbing member. Here, when the collision load is equal to or greater than a predetermined value, the fracture portion provided in the impact absorbing member is fractured, and a partial deformation of the impact absorbing member is promoted. Thereby, since the moment arm of the bending moment generated in the impact absorbing member is shortened, the impact absorbing member can be efficiently compressed and deformed by the collision load.

  A shock absorbing structure according to a second aspect of the present invention is the shock absorbing structure according to the first aspect, wherein the shock absorbing member is formed in a hollow shape and has a coupling wall to which the load input member is coupled. And the fracture portion is a weakened portion provided on the coupling wall.

  In the shock absorbing structure according to claim 2, the shock absorbing member formed in a hollow shape is provided with a connecting wall to which the load input member is connected, and the connecting wall is provided with a fragile portion. . Here, when a collision load of a predetermined value or more is input to one end side of the load input member, the fragile portion is broken and a partial deformation of the shock absorption member is promoted. The moment arm of the generated bending moment is shortened. Thus, since the weak part is provided in the joint wall of the shock absorbing member to which the load input member is joined, the weak part (breaking part) is provided in the shock absorbing member without affecting the compression deformation part of the shock absorbing member. Can be provided.

  A shock absorbing structure according to a third aspect of the present invention is the shock absorbing structure according to the second aspect, wherein the load input member is a bumper reinforcement of a vehicle, and the load transmitting member is a side member of the vehicle. The impact absorbing member generates the bending moment when a collision load is input to the end of the bumper reinforcement in the vehicle width direction, and the fragile portion extends along the vehicle body in the vertical direction of the vehicle body. It is characterized by being provided.

  In the shock absorbing structure according to the third aspect, the weakened portion is provided along the vertical direction of the vehicle body on the connecting wall of the shock absorbing member to which the bumper reinforcement is connected. Here, when a collision load of a predetermined value or more is input to the end portion of the bumper reinforcement in the vehicle width direction, the weak portion along the vertical direction of the vehicle body is broken to promote partial deformation of the shock absorbing member. As a result, the moment arm of the bending moment generated in the shock absorbing member is shortened. As described above, since the fragile portion is provided on the joint wall of the shock absorbing member along the vertical direction of the vehicle body, the fragile portion can be efficiently broken by the collision load input to the vehicle width direction end portion of the bumper reinforcement. it can.

  As described above, in the impact absorbing structure according to the first aspect of the present invention, even when a collision load is input to one end side of the load input member, the impact absorbing member can be efficiently compressed and deformed.

  In the impact absorbing structure according to the second aspect of the present invention, the impact absorbing member can be provided with a fragile portion (broken portion) without affecting the compression deformation portion of the impact absorbing member.

  In the shock absorbing structure according to the third aspect of the present invention, the fragile portion can be efficiently broken by the collision load acting on the end portion in the vehicle width direction of the bumper reinforcement.

  FIG. 1 is a perspective view showing a partial configuration of a vehicle body front portion of a vehicle configured by applying an impact absorbing structure 10 according to an embodiment of the present invention. In the figure, the arrow FR indicates the vehicle body front side, the arrow UP indicates the vehicle body upper side, and the arrow IN indicates the vehicle body width direction inner side.

  As shown in FIG. 1, in the shock absorbing structure 10 according to the present embodiment, a shock absorbing member as a shock absorbing member is provided between a front bumper reinforcement 12 as a load input member and a front side member 14 as a load transmitting member. A crash box 16 is provided.

  The front bumper reinforcement 12 is a strength member formed in a long shape, and is arranged with the vehicle width direction as a longitudinal direction at the front end portion of the vehicle. The front side member 14 is a long strength member, and is disposed on the vehicle rear side of the front bumper reinforcement 12 with the longitudinal direction of the vehicle body as the longitudinal direction. An end in the vehicle width direction of the front bumper reinforcement 12 protrudes outward in the vehicle width direction from the front side member 14, and the protruding portion is gently curved toward the rear side of the vehicle body.

  Further, the front end portion of the front side member 14 is arranged to be separated from the rear end surface of the front bumper reinforcement 12 by a predetermined distance toward the vehicle rear side, and via a crash box 16 interposed therebetween. The front bumper reinforcement 12 is connected to the front end portion of the front side member 14.

  Here, FIG. 2 shows an overall perspective view of the crash box 16. 3 and 4 are sectional views of the crash box 16 as appropriate.

  As shown in these drawings, the crash box 16 according to the present embodiment is formed in a hollow shape, and has two upper and lower upper cylindrical portions 22 and a lower cylindrical shape whose axial direction is along the longitudinal direction of the vehicle body. The unit 24 is provided. The upper cylindrical portion 22 and the lower cylindrical portion 24 are arranged in parallel in the direction perpendicular to the axis (the vertical direction of the vehicle body), and the crash box 16 is configured as a composite of cylindrical portions. As shown in FIG. 3, the upper cylindrical portion 22 and the lower cylindrical portion 24 are each formed in a regular octagon, and exhibit high energy absorption performance as a whole by sharing the bottom wall and the top wall. It is formed in an approximately 8 shape.

  The left and right upper walls 22A and side walls 22C of the upper cylindrical portion 22 and the left and right lower walls 24A and side walls 24C of the lower cylindrical portion 24 have beads 26 for specifying the compression buckling start points. Are formed at predetermined intervals. The beads 26 formed on the upper wall 22A and the beads 26 formed on the side wall 22C are alternately arranged. Similarly, the beads 26 formed on the lower wall 24C and the beads 26 formed on the side wall 24C are alternately arranged.

  One end portion (rear end portion) of the crash box 16 in the axial direction is open, and a rectangular flat plate flange portion 30 coupled to the front end portion of the front side member 14 is integrally formed around the periphery. Bolt insertion holes 32 are formed at the four corners of the flange portion 30, and bolts (not shown) inserted through these bolt insertion holes 32 are screwed into female screws formed at the front end portion of the front side member 14. The crash box 16 is coupled to the front end portion of the front side member 14. The plate thickness of the flange portion 30 is set to be thicker than the plate thickness of the upper cylindrical portion 22 and the lower cylindrical portion 24 in order to ensure the coupling rigidity to the front end portion of the front side member 14.

  On the other hand, the other end portion (front end portion) in the axial direction of the crash box 16 is closed and serves as a coupling wall 28 coupled to the front bumper reinforcement 12. The coupling wall 28 includes a vertically long thick portion 28A formed in an approximately eight-letter shape, and a pair of thin portions 28B formed so as to cover both the left and right sides of the middle portion in the height direction of the thick portion 28A. , Is composed of. The plate thickness of the thick wall portion 28A is set to be thicker than the plate thicknesses of the upper cylindrical portion 22 and the lower cylindrical portion 24 in order to ensure the coupling rigidity to the front end portion of the front side member 14.

  The thin-walled portion 28B includes three parts: a lower wall 22B of the upper cylindrical portion 22, an upper wall 24B of the lower cylindrical portion 24, and an intermediate rib (shared wall) 23 of the upper cylindrical portion 22 and the lower cylindrical portion 24. It is set to the range surrounding the part where the walls intersect. On the other hand, the thick portion 28 </ b> A is set in a range obtained by removing the pair of left and right thin portions 28 </ b> B from the outer shape of the figure 8 shape of the crash box 16. A step 34 is formed between the thick portion 28A and the thin portion 28B, and the height of the step 34 is set to a predetermined height (about several millimeters) corresponding to the stroke at which the peak load at the initial stage of the collision occurs. Has been.

  Further, the upper and lower four portions of the thick portion 28 </ b> A (two locations on both sides of the upper tubular portion 22 and two locations on the middle portions of the lower tubular portion 24) are attachment portions to the front bumper reinforcement 12. A mounting hole 36 is formed. A female screw is formed on the inner peripheral surface of the mounting hole 36, and a bolt (not shown) is screwed from the front bumper reinforcement 12 side. Note that the fastening direction of the crash box 16 to the front bumper reinforcement 12 side and the fastening direction of the front side member 14 to the front end side are both the vehicle body front-rear direction.

  Further, a straight bent bead 38 (groove) is formed on the front end surface (the surface contacting the front bumper reinforcement 12) of the thick portion 28A from the upper end portion to the lower end portion along the vertical direction of the vehicle body. . In the present embodiment, the folded bead 38 is formed in a semicircular cross section, and is disposed on the inner side in the vehicle width direction than the central portion in the vehicle width direction of the thick portion 28A. For this reason, the thick portion 28A is a thin fragile portion 40 where the folded bead 38 is formed, and the fragile portion 40 is thick along the vertical direction of the vehicle body corresponding to the folded bead 38. It is provided in the portion 28A.

  In addition, the crash box 16 having the above-described configuration is constituted by one part and is manufactured by forging an aluminum alloy. Schematically, the crush box 16 is manufactured by forging an aluminum alloy utilizing (combining) two steps of a forward extrusion method and a backward extrusion method.

(Action / Effect)
Next, the operation and effect of this embodiment will be described.

  In this embodiment, when the vehicle collides head-on, the collision load at that time is input to the front bumper reinforcement 12. The input collision load is transmitted to the front side member 14 via the crash box 16. At this time, the upper cylindrical portion 22 and the lower cylindrical portion 24 of the crash box 16 are compressed in the axial direction and sequentially deformed (collapsed) in a bellows shape starting from each bead 26, whereby predetermined energy absorption is performed. The

  Further, in the present embodiment, as shown in FIG. 5, when the vehicle collides obliquely with the collision object 42, the collision load F at the start of the collision is concentrated on the end of the bumper reinforcement in the vehicle width direction. To do. In this case, since the load center S1 of the collision load F and the center axis S2 of the crash box 16 are offset in the vehicle width direction (see symbol L in FIG. 5), a bending moment is generated in the crash box 16 ( (See arrow M in FIG. 5).

  Here, in this embodiment, when the collision load F at the time of the oblique collision is a predetermined value or more, as shown in FIG. 6, the fragile portion 40 provided on the coupling wall 28 of the crash box 16 breaks. The front end portion of the crash box 16 is partially deformed by the collision load F (that is, the deformation of the front end portion of the crash box 16 is promoted by the breakage of the fragile portion 40). As a result, the load center S1 of the collision load F moves inward in the vehicle width direction, and the moment arm of the bending moment is shortened. Therefore, at the initial stage of the oblique collision (the state shown in FIG. 6), the influence of the bending moment is reduced, and the crash box 16 is compressed in the axial direction by the collision load F. For this reason, the crash box 16 is sequentially deformed (collapsed) in a bellows shape starting from each bead 26 as in the case of the frontal collision of the vehicle, and absorbs predetermined energy.

  That is, in the present embodiment, the load center S1 of the collision load F is moved inward in the vehicle width direction by intentionally deforming the front end portion of the crash box 16 in the initial stage of the oblique collision, and the crash box 16 is generated. Cancel the bending moment. As a result, the crash box 16 can be guided to the original axial compression form, and the crash box 16 can be efficiently axially compressed and deformed.

  By the way, if the crash box 16 is connected to the front end portion of the front side member 14 so as to be rotatable, the bending moment as described above can be canceled. However, in the case of such a configuration, a structure (such as a support shaft) for rotatably connecting the crash box 16 to the front end portion of the front side member 14 is required, which increases the number of parts. Occurs. Moreover, the length dimension (crash stroke) of the effective deformable part of the crash box 16 is reduced by the rotating structure, and in order to compensate for this, the length dimension of the reduced effective deformable part must be extended. The problem that it becomes necessary also arises.

  On the other hand, it is also conceivable to increase the strength of the crash box to counter the bending moment as described above. However, when the strength of the crash box is excessively increased, the original axial compression deformation for absorbing the collision energy is inhibited, and the crash box cannot be deformed even if the load that should be absorbed by the crash box is exceeded. For this reason, the energy which must be absorbed by other members, such as a front side member, will increase.

  On the other hand, when the strength of the crash box is set so that the crash box is efficiently axially compressed and deformed, as described in the background section, the above bending moment causes the crash box to fall down or bend. In addition, the amount of energy absorbed by the crash box may be significantly reduced.

  In this respect, in the present embodiment, the configuration (fragile portion 40) for canceling the bending moment is provided on the coupling wall 28 of the crash box 16, and therefore the upper cylindrical portion 22 and The strength of the lower cylindrical portion 24 (that is, the strength of the compression deformation portion of the crash box 16) can be set. Accordingly, efficient axial compression deformation of the crash box 16 can be ensured, and the bending moment can be canceled by the fragile portion 40. Therefore, the collision can be efficiently performed both in frontal collision and oblique collision. It can absorb energy.

  Further, in this embodiment, the bending moment at the time of the oblique collision can be canceled simply by providing the fragile portion 40 on the coupling wall 28 of the crash box 16, so that the number of parts can be increased and the effective deformable portion (upper cylindrical shape) Extension of the length dimension of the part 22 and the lower cylindrical part 24) becomes unnecessary.

  Furthermore, in this embodiment, since the bead 38 (groove) is formed in the coupling wall 28 of the crash box 16, the fragile portion 40 is provided in the coupling wall 28, so that the fragile portion 40 can be set very easily. can do. In addition, since the fragile portion 40 is linearly formed along the vehicle body vertical direction, the fragile portion is efficiently caused by the vehicle body rearward impact load F acting on the vehicle width direction end portion of the front bumper reinforcement 12. 40 can be broken.

[Supplementary explanation of the embodiment]
In the above-described embodiment, the fragile portion 40 is provided on the coupling wall 28 by forming the fold bead 38 along the vertical direction of the vehicle body on the inner side in the vehicle width direction of the coupling wall 28 of the crash box 16. However, the present invention is not limited to this, and the fragile portion of the crash box 16 (impact absorbing member) is determined by the vehicle-side factor, the position of the end portion of the front bumper reinforcement 12 in the vehicle width direction, the front side member 14 Based on the position and the kinetic energy of the vehicle (the main factor is the vehicle mass / set speed), the arrangement and shape are appropriately set.

  Moreover, in the said embodiment, it was set as the structure by which the weak part 40 was provided in the coupling wall 28 by forming the bead 38 (groove) in the coupling wall 28 of the crash box 16, However, This invention is not limited to this. Instead, the coupling wall 28 may be provided with a weakened portion by forming a hole or a recess in the coupling wall 28 of the crash box 16.

  Moreover, in the said embodiment, although the crush box 16 was manufactured by the forging shaping | molding of aluminum alloy, you may manufacture the crush box 16 not only by this but by extrusion molding.

  Furthermore, in the said embodiment, although the material of the crush box 16 was made into the aluminum alloy material, it is not restricted to this, Various materials, such as iron, carbon, resin, and glass fiber, can be applied.

  Moreover, in the said embodiment, although the crash box 16 was set as the structure provided with the upper side cylindrical part 22 and the lower side cylindrical part 24, this invention is not restricted to this, The shape of the crash box 16 can be changed suitably. it can.

  Furthermore, in the above embodiment, the crash box 16 as an impact absorbing member is configured to be interposed between the front bumper reinforcement (load input member) and the front side member 14 (load transmission member) of the vehicle. However, the present invention is not limited to this. The impact absorbing member is interposed between the load input member and the load transmitting member, and the impact absorbing member is bent when a collision load is input to one end side of the load input member. Any structure that generates a moment is applicable.

1 is a perspective view showing a configuration of a vehicle body front portion of a vehicle configured by applying an impact absorbing structure according to an embodiment of the present invention according to the present embodiment. It is a perspective view of the crush box which is a structural member of the shock absorption structure shown by FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 1 for explaining a state at a moment when the vehicle collides obliquely with a collision object. It is sectional drawing corresponding to FIG. 5, and is a figure for demonstrating the state which the weak part provided in the front wall of the crash box fractured | ruptured and the front-end part of the crash box deform | transformed.

Explanation of symbols

10 Shock absorbing structure 12 Front bumper reinforcement (load input member)
14 Front side member (load transmission member)
16 Crash box (shock absorbing member)
28 Bonding wall 40 Vulnerable part

Claims (3)

It is interposed between a load input member to which a collision load is input and a load transmission member to which a collision load is transmitted, and compresses and deforms to absorb energy at the time of collision, and a collision load is applied to one end side of the load input member. A shock absorbing member that generates a bending moment when
The moment of the bending moment is provided by the shock absorbing member, and breaks when a collision load of a predetermined value or more is input to one end side of the load input member to promote partial deformation of the shock absorbing member. A break to shorten the arm;
Shock absorbing structure having.   The impact absorbing member is formed in a hollow shape, has a coupling wall to which the load input member is coupled, and the fracture portion is a weakened portion provided in the coupling wall. The shock absorbing structure according to claim 1.   The load input member is a bumper reinforcement of the vehicle, the load transmission member is a side member of the vehicle, and the impact absorbing member is input with a collision load at an end in the vehicle width direction of the bumper reinforcement. The shock absorbing structure according to claim 2, wherein the bending moment is generated at the same time, and the fragile portion is provided on the coupling wall along a vertical direction of a vehicle body.

Images