JP2012166645A - Die-cast aluminum alloy crash can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a shock received by a vehicle body or an occupant by a crash can 1 when a vehicle is collided.SOLUTION: The crash can 1 is formed of a die-cast aluminum alloy, and arranged between a side frame extending in the longitudinal direction on the right and left of the vehicle and an end of a bumper reinforcement extending in the vehicle width direction. The crash can 1 includes a hollow part 5 of a closed cross-sectional structure extending in the vehicle longitudinal direction, and includes steps 7 and 8 in an intermediate part in its vehicle longitudinal direction. A small diameter part 11, an intermediate diameter part 12 and a large diameter part 13 continue via the steps 7 and 8, the dimensional relationship among a wall thickness A of the small diameter part 11, a wall thickness B of the intermediate part 12 and a wall thickness C of the large diameter part 13 is set to A>B>C, and longitudinal thicknesses Dw and Dw' of the step parts 7 and 8 are formed in a thickness of the wall thickness A or thicker.

Description

  The present invention relates to a crash can for a vehicle.

  The vehicle is provided with an impact absorbing device for the purpose of ensuring the safety of the occupant and reducing vehicle damage when the vehicles collide with each other or when the vehicle collides with a building due to a driving mistake. A typical example is a crash can (also referred to as “crash box”) provided between a bumper reinforcement provided inside a bumper of a vehicle and a side frame end of a vehicle body.

  The crash can is generally formed of a steel material, and absorbs collision energy in the process of collapsing in the vehicle front-rear direction while buckling and deforming in a bellows shape at the time of a normal collision of the vehicle or an offset collision. For this purpose, a conventional crash can made of a steel material is formed in a cylindrical shape in which the inside is hollow by joining both U-shaped members on both the inside and outside of the vehicle. It is also known that the closed cross-sectional shape of the crash can is a cross shape or a dharma shape, and that beads are provided on the inner wall surface and the outer wall surface of the crash can. For example, Patent Document 1 describes a cross-shaped crush can having a closed cross section made of a steel material. Also, a concave portion is provided on the front end surface thereof, and the concave portion extends in the vehicle width direction on the rear surface of the bumper beam. It is described that it is put in a state fitted together.

  An attempt to make the crash can made of an aluminum alloy is also known. For example, Patent Document 2 describes that in a cylindrical die-cast aluminum alloy crush can, the wall thickness thereof is continuously or partially changed in the axial direction. Patent Document 3 describes that a crush can having a hollow rectangular cross section made of an aluminum alloy extruded material is provided with a convex portion having a U-shaped cross section extending in the axial direction with its wall surface protruding outward.

JP 2010-70038 A JP 2002-39245 A JP 2002-12165 A

  The crash cans that make up the car body are not big parts, but if the material for making them is changed from steel to aluminum alloy, the wall thickness needs to be increased slightly to ensure strength. Because it is lighter, it is advantageous for reducing the weight of the vehicle body. However, in the case of an aluminum alloy extruded material, the crush can basically has the same cross-sectional shape over the entire length in the axial direction, so that the cross-sectional shape can be changed in the axial direction to obtain effective shock absorption or both ends. It is difficult to provide a joint flange. On the other hand, in the case of the die-cast aluminum alloy crash can described in Patent Document 2, it is possible to change the wall thickness of the cylindrical portion or to provide a flange or the like, but more effective shock absorption It is desired to obtain.

  In other words, in the case of a conventional crash can, when a collision load is applied, the crash can is stretched against the collision load, so the load received by the vehicle body increases until the first buckling occurs, and then the buckling occurs. A so-called initial peak in which the load decreases with this appears. In a crash can having a high initial load peak until buckling occurs, damage to the vehicle body is likely to increase, and a passenger receives a large impact. When buckling starts, the load received by the vehicle body decreases, but when the buckling deformation stops, the load increases again until the next buckling occurs. Therefore, when further buckling does not occur properly in the crash can, the vehicle body side receives a large load. Even when buckling occurs next time, the portion that is difficult to buckle will be buckled later, so that the load received on the vehicle body side will increase greatly. That is, the damage received by the vehicle body or the impact received by the occupant tends to increase.

  Therefore, according to the present invention, when the load peak at the initial stage of the collision is lowered to reduce the impact received on the vehicle body side, the collision energy is efficiently absorbed thereafter so that the load received on the vehicle body side is not excessively increased.

  In order to solve the above-mentioned problems, the present invention adopts a die-cast aluminum alloy crash can and partitions buckling deformation places in the middle portion of the crash can so that buckling that effectively absorbs collision energy occurs sequentially. A step is provided to serve as a knot.

In other words, the die-cast aluminum alloy crash can disclosed herein is provided between the side frame extending in the front-rear direction and the end of the bumper reinforcement extending in the vehicle width direction, respectively,
A cylindrical portion extending in the longitudinal direction of the vehicle,
The cylindrical portion includes at least one step portion at an intermediate portion in the vehicle front-rear direction, and the peripheral wall of the cylindrical portion is bent in a step shape at the step portion, and the bumper reinforcement side from the step portion is the side frame side. Formed with a smaller diameter than
The wall thickness of the small diameter portion on the bumper reinforcement side than the stepped portion is larger than the wall thickness of the large diameter portion on the side frame side than the stepped portion,
The front and rear thickness of the stepped portion is equal to or greater than the maximum wall thickness of the portion of the peripheral wall excluding the stepped portion,
The front and rear thicknesses of the stepped portions are a surface facing the bumper reinforcement side of the stepped portion on the outer peripheral side of the cylindrical portion and a surface facing the side frame side of the stepped portion on the inner peripheral side of the cylindrical portion. It is the distance to.

  Here, the front and rear thickness of the stepped portion is equal to or greater than the maximum wall thickness of the peripheral wall excluding the stepped portion, which means that the stepped portion has high strength and a collision load is applied to the cylindrical portion. This means that it does not become a starting point for causing buckling, but becomes a so-called node that defines a buckling deformation place in the cylindrical portion. Therefore, when a collision load is applied to the cylindrical portion, it is advantageous for reliably generating buckling in each of the small diameter portion on the front side and the large diameter portion on the rear side across the stepped portion.

  Then, when the bumper reinforcement side (small diameter part) and the side frame side (large diameter part) are compared with the stepped part, the bumper reinforcement side has a smaller diameter. Since the wall thickness on the bumper reinforcement side is larger, it is possible to prevent a large difference between a load causing buckling in the small diameter portion and a load causing buckling in the large diameter portion. That is, the small diameter portion and the large diameter portion can be buckled and deformed in order from either one with a slight load difference.

  Therefore, when one of the small-diameter portion and the large-diameter portion buckles with a relatively low input load (when the load peak at the initial stage of collision is lowered), the other then buckles with a relatively low input load. Thus, an excessive increase in the collision load received on the vehicle body side can be avoided. Therefore, it is possible to efficiently absorb the energy at the time of collision while minimizing the damage received by the vehicle body and the impact received by the occupant.

  Moreover, the cylindrical portion has a simple step shape in which the small diameter portion, the step portion, and the large diameter portion are arranged in order in the vehicle front-rear direction, and no undercut occurs, so the lower die and the upper die are coaxially relative to each other. The crush can can be manufactured with a moving die with a simple two-way, and the die casting mold structure is not complicated.

  In a preferred embodiment, the wall thickness from the inner peripheral surface to the outer peripheral surface of the stepped portion is not more than the total thickness of the wall thickness of the small diameter portion and the wall thickness of the large diameter portion. In other words, although the small diameter portion and the large diameter portion are offset inward and outward through the stepped portion, the outer surface of the small diameter portion and the inner surface of the large diameter portion are on the same plane, Or it means that the outer surface of a small diameter part exists in the outer side rather than the inner surface of a large diameter part. Accordingly, the vehicle longitudinal load applied to the small-diameter portion is easily transmitted to the large-diameter portion as it is through the step as the vehicle longitudinal load, and the moment at which the small-diameter portion bends inward from the step is reduced. Therefore, it is advantageous for surely manifesting the effect as a node of the stepped portion (the effect of separately buckling and deforming each of the small diameter portion and the large diameter portion).

  The cross-sectional shape of the cylindrical portion can be either a circular shape or a non-circular shape, but is preferably a non-circular shape, particularly a convex polygon shape, a cross shape, other concave polygon shapes, or a dharma shape. As a result, not only when receiving a collision load from the front, but also when receiving an offset load (when the collision load is applied to the crash can obliquely from the top or bottom or from the left and right) It is advantageous for buckling deformation and absorbing collision energy.

  As described above, the crash can according to the present invention includes a step portion in the middle portion of the cylindrical portion extending in the vehicle front-rear direction, and the bumper reinforcement side is formed with a smaller diameter than the side frame side from the step portion. The wall thickness of the cylindrical portion peripheral wall is larger in the small diameter portion on the bumper reinforcement side than the large diameter portion on the side frame side, and the front and rear thickness of the step portion is the portion of the peripheral wall excluding the step portion. Since the thickness is equal to or greater than the maximum wall thickness, the step portion becomes a node that defines the buckling deformation place in the cylindrical portion, and the small diameter portion and the large diameter portion are separately buckled and deformed with substantially the same load. Will be able to. Therefore, according to the present invention, it is possible to prevent the load peak at the initial stage of the collision from becoming high and prevent the load applied to the vehicle body side from increasing excessively thereafter, that is, not to apply a large impact to the vehicle body or the occupant. It becomes easy to make. Moreover, it is easy to die-crush a crash can.

It is a disassembled perspective view which shows the vehicle body structure of the vehicle front part which concerns on embodiment of this invention. It is a perspective view of the crush can concerning the embodiment of the present invention. It is a longitudinal cross-sectional view which shows a part of the crash can. It is explanatory drawing which shows that the wall of the small diameter part and the wall of a medium diameter part of the crash can overlap. It is sectional drawing which shows the metal mold | die for crash can manufacturing typically. It is a front view showing typically the state where the crash can buckled and deformed. It is a graph which shows the load-displacement characteristic of the crash can of an Example and each comparative example. It is a perspective view of the crash can which concerns on another embodiment. It is a cross-sectional view of the crash can. It is a figure which shows the 1st deformation pattern of the crash can cylinder part. It is a figure which shows the 2nd deformation pattern of the crash can cylinder part. It is a perspective view which shows the deformation | transformation state of the crash can cylinder part.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

  FIG. 1 is an exploded perspective view showing the vehicle body structure at the front of the vehicle. In the figure, 1 is a crash can made of die-cast aluminum alloy, 2 is a front side frame extending in the front-rear direction on the left and right sides of the vehicle, and 3 is a bumper reinforcement (bumper beam) extending in the vehicle width direction. The crash can 1 is provided so as to connect the front ends of the left and right front side frames 2 to both ends of the bumper reinforcement 3.

  The front side frame 2 is a closed cross-section structure that extends in the vehicle front-rear direction, and is configured by joining a cross-section hat-shaped inner member 2a on the inner side in the vehicle width direction and a flat plate outer member 2b on the outer side in the vehicle width direction. A mounting plate 4 with the plate surface facing forward is fixed to the front end surface of the front side frame 2. The bumper reinforcement 3 is configured by joining a flat front member 3a and a rear member 3b having a hat-shaped cross section. A bumper face (not shown) is attached to the bumper reinforcement 3.

  As shown in FIG. 2, the crash can 1 includes a cylindrical portion 5 having a closed cross-sectional structure (hollow) that extends in the vehicle front-rear direction and is tapered stepwise toward the front. A joint flange 6 projecting outward is provided at the end. The cylindrical portion 5 has a rectangular cross-sectional shape, and includes a small diameter portion 11, a medium diameter portion 12, and a large diameter that are stepped by including a front step portion 7 and a rear step portion 8 in an intermediate portion in the axial direction (vehicle longitudinal direction). Part 13.

  Lightweight holes 15 provided to reduce the weight of the crash can 1 are opened at the center of the front wall 14 that closes the front end of the cylindrical portion 5, and bolt holes 16 are opened at four corners of the front wall 14. The front end of the crash can 1 is coupled to the bumper reinforcement 3 by the bolt hole 16. Bolt holes 16 are also formed at four corners of the joint flange 6, and the rear end of the crash can 1 is coupled to the mounting plate 4 at the front end of the front side frame 2 by the bolt holes 16.

  The cylindrical portion 5 will be further described. As shown in FIG. 3, the peripheral wall of the cylindrical portion 5 is bent stepwise at the front step portion 7 and the rear step portion 8, and the vehicle front side from the front step portion 7 is a small diameter portion 11, and the front step portion 7 and the rear step portion 8. The middle diameter part 12 is formed between the rear part 8 and the rear side part 8 is formed on the large diameter part 13.

  Thus, the dimensional relationship among the wall thickness A of the small diameter portion 11, the wall thickness B of the medium diameter portion 12, and the wall thickness C of the large diameter portion 13 is A> B> C. The front-rear thickness (the distance between the surface 7a facing the front of the vehicle on the outer peripheral side of the cylindrical portion 5 and the surface 7b facing the rear of the vehicle on the inner peripheral side of the cylindrical portion 5) Dw is the cylindrical portion The peripheral wall has a thickness equal to or greater than the maximum wall thickness (wall thickness A of the small diameter portion 11) of the portion excluding the stepped portion (Dw ≧ A). The wall thickness Dt from the inner peripheral surface to the outer peripheral surface of the front step portion 7 is equal to or less than the total thickness of the wall thickness A of the small-diameter portion 11 on the front side and the wall thickness B of the middle-diameter portion 12 on the rear side. (A <Dt ≦ (A + B)).

  The rear portion 8 also has a front and rear thickness Dw ′ equal to or greater than the maximum wall thickness (wall thickness A of the small diameter portion 11) (Dw ′ ≧ A), and the wall thickness Dt ′ is The wall thickness B of the middle diameter portion 12 on the side and the wall thickness C of the large diameter portion 13 on the rear side are equal to or less than the total thickness (B <Dt ′ ≦ (B + C)).

  For example, when the wall thickness A = 3.0 mm, the wall thickness B = 2.5 mm, and the wall thickness C = 2.0 mm, the front and rear thicknesses Dw and Dw ′ of the front step portion 7 and the rear step portion 8 are 3.0 mm or more and 5 0.04 mm or less, the wall thickness Dt of the front step portion 7 may be 4.5 mm or more and 5.5 mm or less, and the wall thickness Dt ′ of the rear step portion 8 may be 3.5 mm or more and 4.5 mm or less. In this case, as shown in FIG. 4, the peripheral wall of the small-diameter portion 11 and the peripheral wall of the medium-diameter portion 12 have an overlap amount X of 0 to 1 mm when viewed in the vehicle front-rear direction. With respect to the peripheral wall of the portion 13, the overlap amount in the vehicle front-rear direction view is 0 to 1 mm. What is preferable is not to make the overlap amount X zero, but to make a certain amount of overlap.

  Further, regarding the wall thicknesses A, B, and C, when the total circumference of the small diameter portion 11 is L1, the total circumference of the medium diameter portion 12 is L2, and the total circumference of the large diameter portion 13 is L3, A × L1≈B × L2≈C × L3, that is, the product of the wall thickness and the total circumference is substantially constant. Thereby, when a collision load is applied to the crash can 1, there is no great difference in the load that causes the small diameter portion 11, the medium diameter portion 12, and the large diameter portion 13 to buckle. However, in the present embodiment, the magnitude of the load leading to buckling is adjusted by adjusting the diameters (total circumferential lengths) and wall thicknesses A to C of the small diameter part 11, the medium diameter part 12, and the large diameter part 13. The medium diameter portion 12 and the large diameter portion 13 are set so as to increase gradually.

<Crush can manufacturing method>
For the manufacture of the crash can 1, it is preferable to use a high vacuum die casting apparatus having a clamping force of 500 tons. FIG. 5 schematically shows a mold for that purpose. In the figure, 21 is a lower mold and 22 is an upper mold. A crush can molding cavity 23 is formed by both molds 21 and 22. Reference numeral 24 denotes a core movable plate, which is provided with a core 25 for forming the lightweight hole 15 and a core (not shown) for forming the bolt hole 16. Reference numeral 27 denotes a plunger hole through which the molten metal injection plunger advances and retracts, and reference numeral 28 denotes a runner.

  Since the cylindrical portion 5 itself of the crash can 1 has a simple step-shaped taper shape, as is clear from FIG. 5, neither the lower mold 21 nor the upper mold 22 is split. The crash can 1 can be formed as a die without direction.

  As an aluminum alloy for casting, Mn: 1.4% or more and 1.6% or less, Si: 0.2% or more and 5.0% or less, Cu: 0.05% or more and 0.35% or less, Mg: 0.1% or more and 0.3% or less, Fe: 0.5% or more and 0.7% or less, Ti: 0.1% or more and 0.3% or less, and the balance from Al and inevitable impurities It is preferable to adopt the following. Thereby, the crash can 1 having a 0.2% proof stress of 70 MPa or more, a tensile strength of 120 MPa or more, and an elongation of 10% or more can be obtained.

  For example, Mn: 1.56%, Si: 0.22%, Cu: 0.05%, Mg: 0.16%, Fe: 0.65%, Ti: 0.15%, the balance being Al In addition, when die casting is performed under the conditions of an aluminum alloy composed of unavoidable impurities, plunger speed: 1.50 m / sec, vacuum in cavity: 98 kPa, mold temperature: 150 to 160 ° C., 0.2% proof stress is 100 MPa. In addition, the crash can 1 having mechanical properties with a tensile strength of 200 MPa and an elongation of about 18% can be obtained.

<Compression deformation of crash can>
When a collision load is applied to the crash can 1 via the bumper reinforcement 3, in the case of this embodiment, the small diameter portion 11 is buckled, then the medium diameter portion 12 is buckled, and finally the large diameter portion 13 is formed. Cause buckling. FIG. 6 schematically shows a state in which each of the small diameter portion 11, the medium diameter portion 12, and the large diameter portion 13 is buckled.

  In this case, the front-stage portion 7 and the rear-stage portion 8 have the front and rear thicknesses Dw and Dw ′ that are equal to or greater than the wall thickness A of the small-diameter portion 11, and the strength thereof is high. The section 11, the medium diameter section 12, and the large diameter section 13 each function as a node that separates the buckling occurrence place. Therefore, as shown in FIG. 6, the small diameter portion 11, the medium diameter portion 12 and the large diameter portion 13 are surely buckled.

  Moreover, the wall thicknesses Dt and Dt ′ of the front-stage part 7 and the rear-stage part 8 respectively satisfy A <Dt ≦ (A + B) and B <Dt ′ ≦ (B + C). That is, as shown in FIG. 4, the front small-diameter wall sandwiching the stepped portions 7 and 8 overlaps the rear large-diameter wall in the vehicle front-rear direction view, or the outer surface of the small-diameter side wall. And the inner surface of the large-diameter wall are flush with each other when viewed in the vehicle longitudinal direction. For this reason, the vehicle front-rear direction load applied to the small-diameter side wall is easily transmitted to the large-diameter side wall as the vehicle front-rear direction load via the step portions 7 and 8 as they are. Therefore, the moment that acts so that the small-diameter side wall is bent inward starting from the stepped portions 7 and 8 is small. That is, the step portions 7 and 8 effectively function as nodes, and the cylindrical portion 5 is prevented from buckling at the step portions 7 and 8.

  FIG. 7 shows compression test results (load-compression displacement data) of three types of die-cast aluminum alloy crush cans. S1 in the figure is a crash can according to the embodiment shown in FIG. 2 (wall thickness A = 3.0 mm, wall thickness B = 2.5 mm, wall thickness C = 2.0 mm, front and rear thicknesses Dw, Dw ′ = 3. 0 mm, wall thickness Dt = 4.5 mm, wall thickness Dt ′ = 3.5 mm). S2 is a characteristic of Comparative Example 1 (the wall thickness = 3.0 mm constant, other steps are the same as in the embodiment) in which the cylindrical portion is formed in a rectangular cross section having the same outer diameter as the large diameter portion 13 over the entire length. It is. S3 is a characteristic of Comparative Example 2 (the other configurations are the same as those of the example, with stepped portions 7 and 8) in which the wall thicknesses A, B, and C are all 3.0 mm.

  Looking at S2 (Comparative Example 1), it can be seen that the initial load peak value is large, and then the buckle deformation is irregular and the load value gradually increases. Looking at S3 (Comparative Example 2), the initial load peak is lower than S2 (Comparative Example 1). This initial load peak is related to buckling of the small diameter portion, but the wall thickness of this small diameter portion is 3.0 mm, which is the same as S2 (Comparative Example 1), but unlike S1, it has a small diameter. Therefore, the initial load peak is low.

  Then, in the case of this S3 (Comparative Example 2), after the initial load peak appears, the load peaks appear in two more places, so buckling occurs in the order of the small diameter part, medium diameter part and large diameter part. You can see that it happened. This is a node effect at the front and rear stages. However, the next load peak is higher than the initial load peak, and the last load peak is even higher. This is because the wall thickness of the medium-diameter portion and the large-diameter portion is the same as the wall thickness of the small-diameter portion, so that the load value that leads to buckling increases as the diameter increases.

  On the other hand, in S1 (Example), the initial load peak is low as in S3 (Comparative Example 2), and the load peaks appear in two places, so the order of the small diameter portion, the medium diameter portion, and the large diameter portion is the order. It can be seen that buckling occurred. However, unlike S3 (Comparative Example 2), the second and third load peaks are low in S1 (Example). This is an effect in which the wall thicknesses of the small diameter portion, the medium diameter portion, and the large diameter portion are set such that A> B> C.

  From the above, in the case of the embodiment, when the initial load peak is kept low, the load applied to the vehicle body side thereafter does not increase greatly, the collision energy is absorbed efficiently, and the vehicle body and the occupant receive the impact during the collision. It turns out that it becomes small.

<Another embodiment>
FIG. 8 shows a crash can 1 according to another embodiment of the present invention. The difference from the previous embodiment is that the cylindrical portion 5 has a cross-shaped concave polygon having a cross section having eight convex corner portions 5a and four concave corner portions 5b. This is the same as the embodiment. As shown in FIG. 9, each convex corner portion 5a and each concave corner portion 5b of the cylindrical portion 5 have a wall thickness that is larger than that of the flat portion in order to facilitate deformation of first and second deformation patterns described later. Is thinner.

  In the case of the present embodiment, as in the previous embodiment, not only does the small diameter portion 11, the medium diameter portion 12 and the large diameter portion 13 buckle in the order of collision, but also the small diameter portion 11, the medium diameter portion 12 and the large diameter portion. In each part 13, it becomes easy to produce several buckling which is folded in the shape of a bellows. That is, the cylindrical portion 5 has a first deformation pattern T1 that is deformed as shown by a solid line in FIG. 10 from a basic cross-sectional shape “regular cross shape” BF shown by a chain line in FIG. 10 and a solid line in FIG. The buckling deformation is performed while alternately repeating the second deformation pattern T2 that is deformed in the vehicle longitudinal direction.

   The first deformation pattern T1 shown in FIG. 10 is such that each of the upper and lower convex portions 31 and 32 becomes narrower and protrudes and displaces outward in the vertical direction, while each of the left and right convex portions 33 and 34 becomes wider and laterally inner. It is a deformation pattern displaced in In the second deformation pattern T2 shown in FIG. 11, the upper and lower convex portions 31 and 32 are widened and displaced inward in the vertical direction, while the left and right convex portions 33 and 34 are narrowed and laterally outward. It is a deformation pattern which protrudes and displaces.

  As described above, the first deformation pattern T1 and the second deformation pattern T2 are alternately generated when the metal plate is buckled inward, for example, because a force that deforms outward is applied to a portion adjacent to the buckled portion. It is by working. As a result, the cylindrical portion 5 of the crash can 1 is folded in a bellows shape in the vehicle front-rear direction as shown in FIG.

  Since the cross-sectional shape of the cylindrical portion 5 is a cross shape, not only at the time of a frontal collision, but also when the input direction of the collision load is offset up and down or left and right, the convex portions 31 to 34 projecting in four directions. As a result, the cylindrical portion 5 is prevented from falling and deforming, and the bellows-like folding deformation in which the first deformation pattern T1 and the second deformation pattern T2 are alternately generated is generated.

  In the above embodiment, the cylindrical portion is buckled in order from the small diameter portion, but the wall thickness may be set so that the cylindrical portion is buckled in order from the large diameter portion to the small diameter portion.

  Further, the number of step portions of the cylindrical portion is not limited to two as in the above embodiment, but may be one, or three or more step portions may be provided.

  In addition, the cross-sectional shape of the cylindrical portion 5 is not limited to the above-described rectangular and cross-shaped concave polygons, but may be various cross-sectional shapes such as other concave polygons, convex polygons, or dharma shapes (gourd shapes). be able to.

DESCRIPTION OF SYMBOLS 1 Crash can 2 Side frame 3 Bumper reinforcement 5 Cylindrical part 7, 8 Step part 7a The surface which faced the vehicle front 7b The surface which faced the vehicle rear 11 Small diameter part 12 Medium diameter part 13 Large diameter part

Claims (3)

A die-cast aluminum alloy crash can provided between a side frame extending in the front-rear direction on each side of the vehicle and an end of a bumper reinforcement extending in the vehicle width direction,
A cylindrical portion extending in the longitudinal direction of the vehicle,
The cylindrical portion includes at least one step portion at an intermediate portion in the vehicle front-rear direction, and the peripheral wall of the cylindrical portion is bent in a step shape at the step portion, and the bumper reinforcement side from the step portion is the side frame side. Formed with a smaller diameter than
The wall thickness of the small diameter portion on the bumper reinforcement side than the stepped portion is larger than the wall thickness of the large diameter portion on the side frame side than the stepped portion,
The front and rear thickness of the stepped portion is equal to or greater than the maximum wall thickness of the portion of the peripheral wall excluding the stepped portion,
The front and rear thicknesses of the stepped portions are a surface facing the bumper reinforcement side of the stepped portion on the outer peripheral side of the cylindrical portion and a surface facing the side frame side of the stepped portion on the inner peripheral side of the cylindrical portion. A die-cast aluminum alloy crush can characterized by In claim 1,
The die cast aluminum alloy crash can characterized in that the wall thickness from the inner peripheral surface to the outer peripheral surface of the stepped portion is equal to or less than the total thickness of the wall thickness of the small diameter portion and the wall thickness of the large diameter portion. In claim 1 or claim 2,
The cylinder-shaped crush can made of a die-cast aluminum alloy, wherein the cylindrical portion is formed in a concave polygon having a cross-shaped cross section.

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