JP2011131647A - Bumper structure of automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure crushing stroke of a bumper stay to be required for energy absorption during a collision, even when a space between a bumper reinforce and a side member is narrow. <P>SOLUTION: The bumper reinforce 2 is made of an aluminum alloy hollow extruded material, both the end parts are crushed in a longitudinal direction and are constituted of a center vertical wall part 12 crushed into a flat planar shape and a pair of lateral wall parts 13 and 14 connected to the upper and lower sides, and a rear side has an opened groove-shaped cross section. A part of a length direction of the bumper stay 3 enters into a groove of a groove-shaped cross section, and a distal end part is mounted on the vertical wall part 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bumper structure for an automobile comprising a bumper reinforcement made of an aluminum alloy hollow extruded material and bumper stays attached to both ends in the vehicle width direction.

In Patent Documents 1 and 2, due to restrictions on vehicle body design, both ends of bumper reinforcement made of aluminum alloy hollow extruded material are crushed from the front side (impact surface side), and the thickness in the front-rear direction is the original thickness. It is further described that the space occupied by the bumper reinforcement is reduced in the vicinity of the bumper stay mounting portion.
In Patent Document 3, when both the bumper reinforcement and the side member cannot secure sufficient space due to restrictions on the vehicle body design, both ends of the bumper reinforcement are crushed from the back side (vehicle body side). It is described that the thickness in the direction is reduced from the original thickness, the space occupied by the bumper reinforcement is reduced in the vicinity of the attachment portion to the side member, and the bumper reinforcement can be installed between the bumper and the side member.

Japanese Patent Laid-Open No. 7-25296 JP 2009-137452 A JP 2003-146156 A

  Bumper stays with bumper stays attached to both ends of the bumper reinforcement in the vehicle width direction are required to absorb more energy when the bumper stays are crushed when a heavy load is applied during a collision. Due to the above restrictions, there may be a case where there is not enough space for a bumper stay between the bumper reinforcement and the side member. At this time, if the length of the bumper stay in the longitudinal direction corresponding to the space is set short, the crushing stroke at the time of the collision is shortened and sufficient energy cannot be absorbed. The initial crushing load at the time becomes excessive and the energy absorption efficiency of the bumper stay is lowered.

In this case, as in Patent Document 3, it is possible to secure the installation space for the bumper stay by crushing both ends of the bumper reinforcement from the back side and reducing the thickness in the front-rear direction from the original thickness. I think for the time being. However, when the cross section after the crushing process is a hollow structure as in Patent Document 3, the increase in the installation space of the bumper stay by the crushing process is not large, and the cross-sectional shape after the crushing process is not stable. There is a problem that it is difficult to ensure the accuracy of the shape of the back surface, which is the joint surface.
On the other hand, the crushing process is not stopped halfway as in Patent Document 3, but the crushing process is performed until the cross-section becomes a flat plate, thereby increasing the increase in the installation space of the bumper stay, and the cross-sectional shape after the crushing process Is also stable. However, in that case, the rigidity against bending of the bumper reinforcement is lowered, and at the time of a collision, a bending deformation easily occurs at a crushed portion, and a predetermined bending strength cannot be obtained.

  Therefore, according to the present invention, the bumper stay crushing required for energy absorption at the time of collision is possible even when the space for providing the bumper stay between the bumper reinforcement and the side member is not sufficient due to restrictions on the vehicle body design. The main purpose is to secure a stroke and to suppress a decrease in rigidity against bending of the bumper reinforcement, and to obtain a predetermined cross-sectional shape stably after crushing.

The present invention relates to a bumper reinforcement for a vehicle comprising a bumper reinforcement and bumper stays attached to both ends of the vehicle in the vehicle width direction. The bumper reinforcement includes a front wall on a collision surface and a rear wall on a vehicle body side as cross-sectional contours. It is made of an aluminum alloy hollow extruded material having upper and lower walls connecting them, and both ends thereof are crushed in the front-rear direction, and a central vertical wall portion crushed into a flat plate shape and a pair of horizontal wall portions connected to the upper and lower sides. The vertical wall portion and the pair of horizontal wall portions form a groove that opens to the rear side, a part of the bumper stay in the longitudinal direction enters the groove, and a tip portion is attached to the vertical wall portion. It has been.
The central vertical wall portion includes the front wall and the rear wall, and the horizontal wall portion mainly includes upper and lower walls. The vertical wall portion is completely crushed into a flat plate shape and is not substantially a hollow cross section, but the horizontal wall portion may be a hollow cross section.

More specifically, both ends to which the bumper stay of the bumper reinforcement is attached have a substantially C-shaped (groove shape) or a substantially H-shaped cross section due to the vertical wall portion and the pair of horizontal wall portions. In the case of a substantially C-shaped cross section, there is one groove that opens to the rear side, and in the case of a substantially H-shaped cross section, there are a groove that opens to the front side and a groove that opens to the rear side. The front end of From the viewpoint of securing the installation space for the bumper stay, a substantially C-shaped cross section is desirable. In the case of the substantially C-shaped cross section, the crushing process is performed from the rear wall side toward the front wall side.
In the present invention, regardless of the front side and rear side of the vehicle, the collision surface side is expressed as front, front, and front, and the vehicle body side is expressed as rear, back, and rear.

  According to the present invention, both ends to which the bumper stay of the bumper reinforcement is attached are crushed even when the space for providing the bumper stay between the bumper reinforcement and the side member is not sufficient due to restrictions on the vehicle body design. By processing, the cross-sectional shape of both ends is made into a substantially C-shaped (groove shape) or a substantially H-shaped cross section, and in particular, the vertical wall is flattened by crushing, and bumper stays are attached to it, The crushing stroke of the bumper stay necessary for energy absorption at the time can be secured. Moreover, since a pair of horizontal wall part is formed in the upper and lower sides of a vertical wall part, the fall of the rigidity accompanying crushing the cross section can be suppressed, and the fall of bending strength can be suppressed.

In the present invention, a predetermined cross-sectional shape can be stably obtained after crushing by crushing the vertical wall portion until it becomes a flat plate shape. When the crushing process is stopped halfway as in Patent Document 3, it is difficult to stably obtain a predetermined cross-sectional shape, and in particular, there is a problem that it is difficult to ensure the shape accuracy of the mounting surface of the bumper stay. The problem is solved by crushing the vertical wall part until it becomes a flat plate.
And since the vertical wall portion is like a flat plate, the vertical wall portion can be processed, for example, by punching with a press without a core or the like from one side, as with a normal plate. For example, when the front end of the bumper stay is bolted to the vertical wall portion, the fastening portion can be prevented from being crushed and the fastening state is stabilized.

It is a top view of the bumper structure concerning the present invention. It is AA sectional drawing of FIG. It is a BB end view of FIG. It is CC sectional drawing of FIG. It is a figure which shows an example of the crushing method of the edge part of the bumper reinforcement which concerns on this invention. It is a figure which shows the other example of the crushing processing method of the edge part of the bumper reinforcement which concerns on this invention. It is sectional drawing explaining the other example of the crushing form of the edge part of the bumper reinforcement which concerns on this invention. It is a figure which shows the preferable example of the cross-sectional shape of the bumper reinforcement which concerns on this invention. It is a figure which shows the other preferable example of the cross-sectional shape of the bumper reinforcement which concerns on this invention. It is a figure which shows the other example of the attachment form of the bumper reinforcement and bumper stay in the bumper structure which concerns on this invention. It is a figure which shows the means to obtain the attachment form of FIG. It is a figure which shows the other means to obtain the attachment form of FIG. It is a figure which shows the other example of the cross-sectional shape of the bumper reinforcement which concerns on this invention.

Hereinafter, the present invention will be specifically described with reference to FIGS.
A bumper structure 1 shown in FIG. 1 includes a bumper reinforcement 2 made of an aluminum alloy hollow extruded material having a rectangular cross section shown in FIG. As shown in FIG. 2, the cross section of the aluminum alloy extruded material constituting the bumper reinforcement 2 is a front wall 4 on the collision surface side, a rear wall 5 on the vehicle body side, and an upper wall connecting the front wall 4 and the rear wall 5. 6 and the lower wall 7. As shown in FIG. 4, the bumper stay 3 is made of a cylindrical aluminum alloy extruded material, has a flange 9 for mounting on the back side of the bumper reinforcement 1 at the front end of the shaft portion 8, and a side member (not shown) at the rear end. The mounting flange 11 is integrally formed.

  The bumper reinforcement 2 has a central portion in the vehicle width direction that is parallel to the vehicle width direction, and both end portions are bent rearward (vehicle body side) and inclined, and most of the inclined end portions are crushed in the front-rear direction by pressing. Has been processed. This crushing process is performed from the rear side toward the front side, and the front wall 4 side is pushed to the front side by the crushing process without changing the position before the crushing process. As shown in FIG. 4, the stay attaching portion and its vicinity region among the both ends subjected to the crushing processing are subjected to crushing processing (so-called full crushing processing) until the rear wall 5 comes into contact with the back surface of the front wall 4. There is a transition region in which the degree of the crushing process gradually increases from the non-crushing area to the area where the full crushing process is performed (see FIG. 3).

  As shown in the cross-sectional view of FIG. 4, the front wall 4 and the rear wall 5 are stacked in contact with each other, and are crushed into a flat plate shape, as shown in FIG. 4. The bumper reinforcement 2 as a whole has a substantially C-shaped (groove-shaped) cross section opened to the rear side. The substantially C-shaped cross section is composed of a central vertical wall portion 12 crushed flat and a pair of horizontal wall portions 13 and 14 (also crushed flat) vertically above and below the vertical wall portion 12. It consists of the original front wall 4 and the rear wall 5, and the lateral wall portions 13, 14 are composed of the original upper and lower walls 6, 7. The bumper stay 3 has a front end portion inside the groove having a substantially C-shaped cross section, a flange 9 at the front end is in contact with the back surface of the vertical wall portion 12, and both are bolted (not shown), for example.

  In the transition region, as shown in the cross-sectional view of FIG. 3, the bumper reinforcement 2 includes a substantially rectangular hollow portion 15 and outer rib-shaped protruding portions 16 and 17 protruding rearward from both upper and lower ends of the hollow portion 15. . The hollow portion 15 includes a part of the front wall 4 and the rear wall 5, and the upper wall 6 and the lower wall 7, and the thickness of the hollow portion 15 in the front-rear direction (the gap between the front wall 4 and the rear wall 5) is in the vehicle width direction. It gradually becomes smaller toward the outside and continues to the vertical wall portion 12. The projecting portions 16 and 17 are formed by folding a part of the upper wall 6 and the lower wall 7, and the height in the front-rear direction gradually increases toward the outside in the vehicle width direction. It is lined up.

  As shown in FIG. 5, for example, as shown in FIG. 5, the crushing process of both ends of the bumper reinforcement 2 is performed by placing the front wall 4 side down on the lower mold 18 having a recess 18a that can accommodate approximately half of the cross section of the aluminum alloy hollow extruded material. The aluminum alloy hollow extruded material (end of bumper reinforcement 2) is placed toward the mold 18 side, and the rear wall 5 is brought into close contact with the front wall 4 with a width slightly narrower than the vertical width of the front wall 4 and the rear wall 5. The upper die 19 having a stamping surface corresponding to the shape of the back side of the rear wall 5 is advanced (see the white arrow), and the rear wall 5 is pushed between the upper wall 6 and the lower wall 7. be able to. By this crushing process, the upper and lower walls 6 and 7 are bent by 180 ° at substantially the center, and the corners of the rear wall 5 and the upper and lower walls 6 and 7 are also bent by 180 °.

Alternatively, for example, as shown in FIG. 6, the end of the bumper reinforcement 2 is placed on a flat lower mold 19 with the front wall 4 side facing the lower mold 19, and an upper mold having a flat stamping surface. 18 can be moved forward (see the white arrow), and the entire cross-section is once flattened (the upper and lower walls 6 and 7 are bent to the outside of the cross-section), and then both sides are bent to form a substantially C-shaped cross-section. .
Such crushing by pressing (FIGS. 5 and 6) can be performed simultaneously with the bending of both ends of the bumper reinforcement 2. If necessary, drilling such as bolt holes and work holes can be performed simultaneously with the crushing process.

  As described above, the vertical wall portion 12 is completely crushed (crushing that does not intentionally form a space between the front wall 4 and the rear wall 5), thereby obtaining a predetermined cross-sectional shape stably after the crushed processing. Can do. For this reason, the shape accuracy of the mounting surface of the bumper stay (the back side of the vertical wall portion 12) is ensured, and since the vertical wall portion 12 can be handled as a single plate, processing such as drilling is easy. In addition, when the bumper stay is joined (for example, bolt fastening), a stable joined state can be obtained.

In addition, in the vertical wall portion 12 having a substantially C-shaped cross section, it is desirable that the front wall 4 and the rear wall 5 are in close contact as shown in FIG. A gap may be created by the springback after processing). If the aluminum alloy hollow extruded material has an example of a rectangular cross section as shown in FIG. 2, the thickness of the vertical wall portion 12 is as follows when the thickness of the front wall 4 is t ₁ and the thickness of the rear wall 5 is t _2. If it is about 1.1 × (t ₁ + t ₂ ) or less, the bumper structure is allowed with no problem in practice. In the present invention, even when there is such a gap between the front wall 4 and the rear wall 5 after the complete crushing process, it is expressed as a flat plate shape.

FIGS. 7A and 7B show another example of the crushing form of the end portion of the bumper reinforcement 2 (a completely crushed region).
The cross-sectional shape shown in FIG. 7A is the same as the cross-sectional shape shown in FIG. 4. The central vertical wall portion 12 crushed flat and a pair of horizontal wall portions 13, 14 connected vertically above and below (also flat) However, it has a substantially H-shaped cross section, and has a groove opening on the front side and a groove opening on the rear side, and the front end of the bumper stay 3 is formed in the groove opening on the rear side. Get in. Also in this cross section, the vertical wall portion 12 includes the original front wall 4 and the rear wall 5, and the horizontal wall portions 13 and 14 include the original upper and lower walls 6 and 7. In order to crush the aluminum alloy hollow extruded material having the cross section shown in FIG. 2 and form it into this cross section, crushing is performed from both the front wall 4 side and the rear wall 5 side.

  The cross-sectional shape shown in FIG. 7 (b) is a substantially C-shaped cross-section as in the cross-sectional shape shown in FIG. 4, but the cross-sectional shape shown in FIG. Is different. By making the horizontal wall portions 13 and 14 have a hollow cross section, the torsional rigidity is improved. In order to crush the aluminum alloy hollow extruded material having the cross section shown in FIG. 2 and form the cross section into this cross section, for example, a lower mold having a shallow recess (see the lower mold 18 shown by the phantom line in FIG. 8) is used. Is possible.

In FIG. 8, the example of the cross-sectional shape of the aluminum alloy hollow extrusion material suitable for carrying out a full crushing process to a substantially C-shaped cross section is shown.
The cross-sectional shape shown in FIG. 8 is that the front half of the front wall 4 and the upper and lower walls 6 and 7 is thicker than the rear wall 5 and the rear half of the upper and lower walls 6 and 7. The cross-sectional shape shown in FIG. As indicated by phantom lines in FIG. 8, an aluminum alloy hollow extruded material with the front wall 4 side facing the lower mold 18 side on the lower mold 18 having a shallow recess 18 a corresponding to the front side shape of the bumper reinforcement 2. (The end of the bumper reinforcement 2) is placed, and is slightly narrower than the vertical width of the front wall 4 and the rear wall 5, and corresponds to the rear side shape of the rear wall 5 when the rear wall 5 is brought into close contact with the front wall 4. By crushing the upper mold 19 having the punching surface and pushing the rear wall 5 between the upper wall 6 and the lower wall 7, crushing can be performed.

  The cross-sectional shape shown in FIG. 8 has the above-described thickness structure, so that the rear side portion of the thin wall undergoes a large bending deformation in the crushing process, and there is an advantage that the full crushing process is easy to perform. As shown by the phantom line in FIG. 8, the crushing process is performed from the rear wall 5 side toward the front wall 4 side, and the cross-sectional shape after the crushing process is a substantially C-shaped cross section that opens to the rear, The thick portions of the upper and lower walls 6 and 7 are located outside the substantially C-shaped cross section, and the thin portions of the rear wall 5 and the upper and lower walls 6 and 7 are located inside the C-shaped cross section. It can also be said that the average thickness of the portion located outside the C-shaped cross section is larger than the average thickness of the portion located inside.

FIG. 9 shows another example of the cross-sectional shape of an aluminum alloy hollow extruded material suitable for being completely crushed into a substantially C-shaped cross section.
The cross-sectional shape shown in FIG. 9 is different from the cross-sectional shape shown in FIG. 2 in that the corners R of the rear wall 5 and the upper and lower walls 6 and 7 are formed larger than others. As shown by phantom lines in FIG. 9, an aluminum alloy hollow extruded material (an end portion of the bumper reinforcement 2) is placed on the lower mold 18, the upper mold 19 is advanced, and the rear wall 5 is connected to the upper wall 6 and the lower wall. By pushing between the walls 7, crushing can be performed.

  The cross-sectional shape shown in FIG. 9 is easy to bend 180 ° at the corners of the rear wall 5 and the upper and lower walls 6 and 7 in the crushing process by increasing the corner R of the rear wall 5 and the upper and lower walls 6 and 7 as an initial irregularity. Thus, there is an advantage that the entire crushing process is easy to perform. As shown in phantom lines in FIG. 9, the crushing process is performed from the rear wall 5 side toward the front wall 4 side, and the cross-sectional shape after the crushing process is a substantially C-shaped cross section that opens rearward.

  In the bumper structure described above, the bumper stay 3 is assumed to be integrally formed from an aluminum alloy hollow extruded material including the flanges 9 and 11 (see, for example, Japanese Patent Laid-Open No. 2004-189062). As for one or both of the flanges 9 and 11, a separate member may be joined to the shaft portion 8 by means such as welding or electromagnetic forming (see, for example, JP-A-2005-152920). Further, instead of the bumper stay 3 made of the aluminum alloy hollow extruded material, a steel bumper stay can be used, and a lateral crush type bumper stay can be used instead of the vertical crush type (vertical crush type and lateral crush type). For the bumper stay, see, for example, JP-A-2005-14836).

FIG. 10 shows another example of a bumper reinforcement and bumper stay mounting form in the bumper structure according to the present invention. The bumper structure 1 has a hole (burring hole) 21 formed in the end of the bumper reinforcement 2 that has been crushed, and the front end of the bumper stay 3 is caulked and joined to the inner periphery of the hole 21. Different from the bumper structure shown in FIG.
As shown in FIG. 10, the front portion (portion involved in joining) of the shaft portion 8 of the bumper stay 3 is inserted into the hole 21 so as to be in close contact with the inner peripheral surface of the hole 21 and along the inner peripheral surface of the hole 21. It spreads out to the front side (close contact portion 22) and protrudes in the outer diameter direction on the rear side of the hole 21 (overhang portion 23). As described above, the front portion of the shaft portion 8 of the bumper stay 3 is in close contact with the inner peripheral surface of the hole 21, projects in the outer diameter direction before and after the hole 21, and is firmly joined to the end portion of the bumper reinforcement 2. ing.

The bumper reinforcement 2 and the bumper stay 3 shown in FIG. 10 can be preferably joined by electromagnetic forming (see, for example, Japanese Patent Application Laid-Open No. 2004-237818). FIG. 11 is a diagram for explaining the electromagnetic forming method.
As shown in FIG. 11, the stay material 24 whose front end is inclined at the same angle as the end of the bumper reinforcement 2 and whose rear end is perpendicular to the axial direction is fitted into the hole 21 from the front side. A shallow flange 25 formed at the front end is in contact with the shoulder of the hole 21. The stay material 24 is made of a cylindrical aluminum alloy extruded material, and the front end flange can be formed by, for example, electromagnetic forming (see, for example, JP-A-2004-42066).

  The periphery of the portion of the stay material 24 that protrudes rearward from the hole 21 is surrounded by an electromagnetic forming mold 26 that is a split mold. The electromagnetic forming mold 26 has a through hole 27, the inner diameter of the through hole 27 is larger than the outer diameter of the stay material 24, and the rear end of the stay material 24 protrudes from the end face 28 of the electromagnetic forming mold 26 by a predetermined length. ing. In this state, the bumper reinforcement 2, the stay material 24 and the electromagnetic molding die 26 are positioned, an electromagnetic molding coil (not shown) is inserted into the hollow of the stay material 24, and an instantaneous large current is passed through the electromagnetic molding coil. Tube expansion by electromagnetic forming is performed on the entire length of the stay material.

  Due to this electromagnetic forming, the diameter of the stay material 24 is expanded, and as shown in FIG. 10, the front end is in close contact with the inner peripheral surface of the hole 21 to form the expanded portion 22, and the rear portion is projected in the outer diameter direction. The protruding portion 23 is formed, and the rear portion thereof hits the inner peripheral surface of the through hole 27 of the electromagnetic molding die 26. At the same time, the rear end portion is expanded, and the end surface (molding surface) of the electromagnetic molding die 26 is formed. The flange 11 is formed by striking 28. As a result, the stay material 24 is bonded to the bumper reinforcement 2 and the bumper stay 3 is formed. If necessary, the molded flange 11 can be pressed to be shaped into a desired shape (for example, the rear side (attachment side to the side member) is planarized).

  In this example, the shallow flange 25 is formed at the front end of the stay material 24 in order to improve the bondability and positioning. However, an aluminum alloy extruded material simply cut may be used as the stay material. Further, instead of integrally molding the flange 11, a separate member can be joined by electromagnetic molding (see JP-A-2005-152920).

FIG. 12 is a diagram for explaining another electromagnetic forming method for obtaining the bumper reinforcement and bumper stay mounting form shown in FIG.
As shown in FIG. 12, a stay material 24 having a small-diameter portion 29 at the front end and a large-diameter portion 31 through a transition region whose diameter changes on the rear side and the flange 11 formed at the rear end is formed in the hole 21. It is inserted in the rear side. The small diameter portion 29 of the stay material 24 fits into the hole 21, and the transition region starts from the vicinity of the lower end of the hole 21. The stay material 24 is made of a cylindrical aluminum alloy extruded material having the same diameter as the small diameter portion 29, and the large diameter portion 31 and the rear end flange 11 can be simultaneously formed by, for example, electromagnetic forming (for example, JP-A-2004-189062). No. publication).

  The portion of the stay material 24 that protrudes rearward from the hole 21 (the large-diameter portion 31 and the transition region) is surrounded by an electromagnetic forming die 26 that is a split die with almost no gap, and the flange 11 is electromagnetically formed. It abuts against the end face 28 of the mold 26 for use. In this state, the bumper reinforcement 2, the stay material 24 and the electromagnetic molding die 26 are positioned, an electromagnetic molding coil (not shown) is inserted into the hollow of the stay material 24, and an instantaneous large current is passed through the electromagnetic molding coil. Pipe expansion by electromagnetic forming is performed mainly on the small diameter portion 29 and the transition region of the stay material.

Due to this electromagnetic forming, the diameter of the stay material 24 is expanded, and as shown in FIG. 10, the front end is in close contact with the inner peripheral surface of the hole 21 to form the expanded portion 22, and the rear portion is projected in the outer diameter direction. A protruding portion 23 is formed. As a result, the stay material 24 is bonded to the bumper reinforcement 2 and the bumper stay 3 is formed. In this example, in the electromagnetic forming at the time of joining, since only the front part of the stay material 24 needs to be expanded, the forming force for expanding the tube by electromagnetic forming can be reduced.
In this example, the flange 11 is integrally formed. However, a separate member can be joined by electromagnetic forming (see Japanese Patent Application Laid-Open No. 2005-152920).

In the bumper structure described above, the cross-sectional shape of the aluminum alloy hollow extruded material constituting the bumper reinforcement 2 is a rectangle composed of the front and rear walls 4, 5 and the upper and lower walls 6, 7, but the present invention has various cross-sectional shapes. It can be applied to an aluminum alloy hollow extruded material. FIGS. 13A to 13F are examples of cross-sectional shapes having a rectangular outline and inner ribs. When it has an inner rib, the vertical wall part formed when crushing is performed includes the inner rib in addition to the front and rear walls 4 and 5. In the vertical wall portion, it is desirable that the front and rear walls 4 and 5 and the folded rib wall are in close contact with each other, but each wall is affected by the effect of the fillet thickness at the corner of the connecting portion between the rib wall and the front and rear walls 4 and 5 and spring back. Gaps may be formed between them, and some gaps are allowed. If the thickness of the vertical wall portion is about 1.1 times or less of the total thickness of the front and rear walls 4 and 5 and the thickness of the folded rib wall, no practical problem occurs in the bumper structure.
In addition, the outline of the hollow cross section may not be a simple rectangle as shown in FIG. 13 and may have an outer rib protruding from the cross section outline.

DESCRIPTION OF SYMBOLS 1 Bumper structure 2 Bumper reinforcement 3 Bumper stay 4 Front wall 5 Rear wall 6 Upper wall 7 Lower wall 12 Vertical wall part 13,14 Horizontal wall part

Claims (4)

A bumper structure of an automobile comprising a bumper reinforcement and bumper stays attached to both ends of the vehicle in the vehicle width direction. The bumper reinforcement includes a front wall on the collision surface side, a rear wall on the vehicle body side, and an upper and lower side connecting these as a cross-sectional contour. It consists of an aluminum alloy hollow extruded material with walls, and both ends of the bumper reinforcement are crushed in the front-rear direction, and consisted of a central vertical wall portion crushed into a flat plate shape and a pair of horizontal wall portions connected to the upper and lower sides. The vertical wall portion and the pair of horizontal wall portions constitute a groove that opens to the rear side, and a part of the bumper stay in the length direction enters the inside of the groove, and a tip portion is attached to the vertical wall portion. A bumper structure for an automobile. 2. The automobile bumper structure according to claim 1, wherein the crushing process is performed from the rear wall side toward the front wall side, and the both end portions have a groove-shaped cross section that opens to the rear side. The automobile bumper structure according to claim 2, wherein an average thickness of a portion located outside the groove-shaped cross section is larger than an average thickness of a portion located inside. The automobile bumper structure according to claim 1, wherein the lateral wall portion has a hollow cross section.

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