JP2002225652A - Bumper reinforcing material superior in offset collision performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al alloy bumper reinforcing material having improved collision energy absorbing performance in offset collision without marring the advantage of a lighter weight due to the adoption of an Al alloy. SOLUTION: The bumper reinforcing material 1a is formed of an aluminum alloy hollow section with portions curved toward a body side at both ends so as to be supported at the backs of the curved portions by a bumper stay. The hollow section is formed in an approximately rectangular cross section by a front wall facing in the direction of collision, a rear wall 3 located at the rear part and side walls 4, 5 connected perpendicular to these walls. An intermediate wall 6 is provided in parallel to the side walls to form a plurality of hollow portions in the cross section. The intermediate wall 6, the side walls 4, 5 and the front wall 2 are connected together in such a manner as to reduce the wall width of the front wall, and a recessed portion 9 is formed at a connection between the front wall 2 and the intermediate wall 6 throughout the length of the hollow section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight bumper reinforcing material (hereinafter, aluminum is simply referred to as Al) made of an aluminum alloy having excellent offset collision properties.

[0002]

2. Description of the Related Art Inside a bumper attached to a front end (front) and a rear end (rear) of a vehicle body such as an automobile, a bumper reinforcing material (also referred to as a bumper reinforcement or a bumper armature) as a strength reinforcing material is provided. Is provided.

As is well known, the bumper reinforcing member is disposed between the bumper and the vehicle body so as to extend substantially horizontally with respect to the vehicle body and parallel to the vehicle width direction. As the shape of the bumper reinforcing material in the longitudinal direction, various shapes are selected according to the design of the vehicle body or the bumper.

[0004] A typical shape is a straight bumper reinforcing material (straight bumper reinforcing material) extending parallel to the vehicle width direction including the center portion and the end portion, and a vehicle body at both ends of the straight center portion. Straight or curved curves bent to the side
(Bending portion) or a bumper reinforcing material (curved bumper reinforcing material) that is curved toward the vehicle body as a whole.

[0005] The mounting of these bumper reinforcements to the vehicle body is performed by using a vehicle body frame (body members) of a frame member in the vehicle front-rear direction such as a front side member or a rear side member.
The connection is made. Further, the vehicle body is fixed to the front or rear side members of the vehicle body directly at the front end or rear end thereof or via a vehicle body connecting member such as a bumper stay.

As is well known, the bumper reinforcing member constitutes an energy absorbing member for the vehicle body between the bumper and the vehicle body in the event of a collision from the front or rear of the vehicle body, or from the front or rear. Therefore, the bumper reinforcing material as an energy absorbing member for the vehicle body must have the ability to protect the vehicle body by absorbing the external force energy (collision energy) applied by the vehicle body collision through its own bending deformation and cross-sectional deformation. Have been.

In recent years, these bumper reinforcements and bumper stays have been replaced by steels of high strength, such as 5000 series, 6000 series, 7000 series, etc. according to AA or JIS standards, in order to reduce the weight, instead of steel materials conventionally used. Extruded shapes are being used. This aluminum alloy bumper reinforcement and bumper stay
The cross-sectional shape is a mouth shape, a day shape (1 is a bumper reinforcing material, 20 is a middle rib) or a rice shape shown in FIG.
It is basically made up of a substantially rectangular hollow structure such as an eye shape.

[0008] By the way, the bumper reinforcing material as an energy absorbing member for a vehicle body not only has the energy absorbing performance at the time of a conventional head-on collision (barrier collision, full-lap frontal collision), but also recently, the vehicle body has an oncoming vehicle or an obstacle. It is required to exhibit excellent energy absorption performance at the time of offset collision, which partially collisions with the head.

However, at the time of this offset collision, since the end of the offset barrier (or oncoming vehicle) comes closer to the center of the collision vehicle, a collision load is inevitably applied to the center of the collision vehicle bumper reinforcement. Easy to concentrate on. For this reason, in the curved bumper reinforcing material, the deformation concentrates particularly on a portion from the center of the bumper reinforcing material. There is a problem that it cannot be sufficiently performed, and furthermore, the vehicle body is damaged.

This problem is relatively unlikely to occur with the straight bumper reinforcing material. In the case of a straight bumper reinforcement, the collision load at the time of an offset collision is dispersed over the entire barrier contact portion of the bumper reinforcement, and the collision load is less likely to concentrate on the center side of the bumper reinforcement. For this reason, in the case of the linear bumper reinforcement, the deformation from the center of the bumper reinforcement is unlikely to occur, while the cross-sectional deformation in which the bumper reinforcement is crushed between the stay on the back of the reinforcement and the barrier (which is originally expected). Deformation) is likely to occur. As a result, the deformation region of the bumper reinforcing member is widened, and the amount of collision energy absorption can be increased.

On the other hand, in the case of the curved bumper reinforcing member, the stay is generally supported by a stay or the like on the back surface of the curved portion. That is, it protrudes from the front surface on the collision side. As a result, at the time of an offset collision, the initial collision load is supported by bending deformation centered on the side closer to the center of the bumper reinforcement.

As a result, in the case of the curved bumper reinforcing material, at the time of the offset collision, the deformation (the originally expected deformation) in which the entire cross section near the stay is crushed occurs.
The side closer to the center of the bumper reinforcing material is locally buckled, and is likely to bend in the shape of a letter in the longitudinal direction.

In fact, even when the bumper reinforcement 1 partially collides with the partial offset barrier 19 under the offset collision test condition of 15 km / hr shown in the plan view of FIG. In many cases, as shown in FIG. 10, the portion 21 is bent in the longitudinal direction in a buckling and C-shape, and the collision energy cannot be sufficiently absorbed. In FIG. 10, 7 is a curved portion at both ends of the bumper reinforcing material, and 12 is a stay provided on the back surface of the curved portion and connected to a side arm of a vehicle body (not shown).

Therefore, in the case of a bumper reinforcing member made of an Al alloy having a rectangular cross section, which has a curved portion at both ends and is supported by a bumper stay on the back surface of the curved portion, even if the barrier collision performance is excellent, the offset collision performance can be improved. Is not always excellent, and the offset collision performance may be inferior.

For this reason, conventionally, the connection and joining structure of the bumper reinforcing member, the stay, and the side member have been strengthened and improved by providing a cross member between the stays, so that the collision load at the time of an offset collision can be reduced. Japanese Patent Laid-Open Publication No. 10-203411
And various publications such as JP-A-10-250505 and JP-A-10-203403.

Further, in order to reduce the amount of deformation of the curved portion (projection portion) when the vehicle collides with a wall obliquely to the vehicle (oblique collision), a bumper with a rectangular cross section having curved portions at both ends is provided. It has been proposed in Japanese Unexamined Utility Model Publication No. 3-42452 that the intersection of the central portion and the curved portion is located within the width in the vehicle width direction.

Furthermore, Al having a rectangular cross section having curved portions at both ends.
In order to reduce the amount of deformation of the curved portion at the time of an oblique collision, it is also necessary to control the bending angle of the curved portion in the vehicle body direction and the amount of overhang of the curved portion in the alloy bumper reinforcing material within an optimum range. -2350.

[0018]

However, the strengthening of the connection and joining structure of the bumper reinforcing material, the stay, and the side members inevitably leads to the complexity and weight increase of the connection and joining structure. This also leads to an increase in the complexity of the work for assembling or repairing the vehicle body.

On the other hand, measures have been taken to increase the crushing strength of these members by increasing the thickness of a bumper reinforcing material or stay, or by attaching and reinforcing steel members such as high tensile steel. . However, even in this case, in order to prevent the bending of the bumper reinforcing material, it is necessary to considerably increase the thickness and to reinforce, and the advantage itself of using the Al alloy material for weight reduction is impaired. .

In order to reduce the amount of deformation of the curved portion due to the oblique collision, a technique of positioning the intersection of the central portion of the bumper reinforcement and the curved portion within the width in the vehicle width direction, The technique of controlling the bending angle and the amount of protrusion of the curved portion to the optimum range has no effect on the offset collision performance which is the subject of the present invention. This is because, at the time of the offset collision, which is an object of the present invention, as described above, the deformation concentrates on a portion of the bumper reinforcing member from the center.

For this reason, in the case of an aluminum alloy bumper reinforcing material having a curved portion at both ends and supported by a bumper stay on the back surface of the curved portion, a U-shaped bending at the time of an offset collision is prevented, and the collision energy is reduced. The only way to increase the absorption performance is to increase the thickness of the reinforcing material.
The fact is that the weight reduction, which is an advantage of using alloy bumper reinforcement, has been greatly impaired.

Accordingly, an object of the present invention is to provide a bumper reinforcing material having a curved portion which bends toward the vehicle body at both ends, without impairing the advantage of weight reduction by employing an Al alloy, and absorbing the collision energy at the time of an offset collision. It is an object of the present invention to provide an Al alloy bumper reinforcing material having an increased hardness.

[0023]

In order to achieve this object, the gist of the bumper reinforcing material excellent in offset collision property according to the first aspect of the present invention is that the bumper reinforcing material is made of an aluminum alloy hollow shape and is provided at both ends toward the vehicle body. A bumper reinforcing member supported by a bumper stay at the back of the curved portion, wherein the hollow shape member includes a front wall facing a collision direction, a rear wall located rearward, and these walls. Are formed in a substantially rectangular cross section by a side wall which is connected perpendicularly to the side wall, and an intermediate wall is provided in parallel with the side wall so as to have a plurality of hollow portions in this cross section. Is performed so as to reduce the width of the front wall, and a concave portion is formed in the connecting portion between the front wall and the intermediate wall in the longitudinal direction of the hollow profile.

According to the configuration of the present invention, the width of the front wall facing the collision direction is reduced, and the width-to-thickness ratio (wall width / wall thickness) is increased, so that the bending buckling of the front wall of the bumper reinforcing material is achieved. Increase strength. Further, since the concave portion and the intermediate wall facing the collision direction resist the collision load, the bumper reinforcing material is less likely to buckle.

Thus, as shown in FIGS. 1 and 2, for example, when the bumper reinforcing material 1a of the present invention receives a bending deformation load F at the time of an offset collision, the bending buckling strength on the side closer to the center is reduced by the stay 12a. , 12b supported by the curved portion 7a,
The crushing strength on the 7b side (crushing strength in the cross section direction of the reinforcing material) should be larger. In other words, when subjected to bending deformation at the time of an offset collision, the crushing (absorption of collision energy) of the curved portions 7a and 7b side of the bumper reinforcing material or the stays 12a and 12b side is caused by bending buckling (central side side). (Bending).

As a result, even when the bumper reinforcement undergoes bending deformation centered on the side closer to the center of the bumper at the time of the offset collision, the crushing strength of the bumper reinforcement in the cross-sectional direction (the collision energy is reduced by its own cross-sectional deformation). The bending strength of the central portion of the bumper reinforcement can be improved while maintaining the performance of absorbing.

Therefore, even if the wall thickness of the bumper reinforcing member is made thinner than before and the load of the offset collision is large, the bending of the bumper reinforcing member is prevented, and the collision energy at the time of the offset collision is reduced by itself. Can be absorbed by deformation in the cross-sectional direction.

Incidentally, the present applicant has previously disclosed in Japanese Patent Laid-Open No.
No. 34 proposes a hollow profile having increased deformation resistance against an external load as a hollow profile for a strength member of a structure such as a vehicle or an aircraft. This hollow profile is a hollow profile in which an intermediate wall is provided inside an outer wall having a horizontal wall and a vertical wall so as to have a plurality of hollow sections having a rectangular cross section. And / or the connection between the outer wall and the intermediate wall is made by an inclined wall so as to reduce the wall width.

The cross-sectional structure of the hollow profile disclosed in this publication is similar to the cross-sectional structure of the hollow profile of the present invention. However, this publication does not disclose a bumper reinforcing material made of an Al alloy having a rectangular cross section, which has a curved portion at both ends and is supported by a bumper stay on the back surface of the curved portion. Further, there is no disclosure of the offset collision property or the collision mechanism, which is the subject of the present invention. Furthermore, there is no suggestion that the cross-sectional structure of the hollow profile contributes to the offset collision property due to its collision mechanism.

Further, the load-deformation mechanism of the Al alloy bumper reinforcement supported by the stay of the present invention at the time of an offset collision, that is, the bending buckling strength on the side closer to the center of the bumper reinforcement, is determined by the following formula. The crush strength on the side of the reinforcing material curved portion is made larger, and when a bending deformation load is applied at the time of an offset collision, the crush on the curved portion side and the stay side of the bumper reinforcing material is reduced by the bending seat near the center portion. There is no disclosure of leading ahead of bending, and the mechanism of load-deformation at the time of collision is completely different.

According to the structure of the present invention, the above-mentioned excellent effects are obtained, and the effect of the first aspect is that the bumper reinforcing member and the stay can be used under various collision conditions (degree of impact) of offset collision. There is also an advantage that the design can be freely and easily selected, and the vehicle body design for the required crash safety is significantly facilitated.

The connection and joining structure of the bumper reinforcement, the stay, and the side members are basically the same as before, so that the work of assembling and repairing the car body can be performed as before, and the work is complicated. There is also an advantage that does not increase.

Further, the bumper reinforcing material of the present invention is provided in the form of claim 2
As described in the above, by integrating with the stay in advance, and as a bumper reinforcing material with a stay, through the stay,
It is extremely easy and simple to attach to the side members.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the bumper reinforcing material of the present invention will be described in detail.

(Overall Shape and Structure of Bumper Reinforcement) One embodiment of the basic form of the Al alloy bumper reinforcement of the present invention is shown in FIG.
1 is a perspective view, and FIG. 2 is a plan view. FIGS. 1 and 2 show a state in which the bumper reinforcing member 1a extends substantially horizontally in the vehicle width direction. The overall shape of the bumper reinforcement 1a is linearly bent at both ends in the vehicle body direction (in the case of a vehicle body front, in the case of a vehicle body rear, it is bent forward of the vehicle body).
a, 7b and a central straight portion 8.

The curved bumper reinforcing material of the present invention is
Both ends may have a straight or curved portion (bent portion), or the entire portion may be curved.

Then, as shown in FIG. 2, the curved portions 7a,
7b On the back side (back side), a hollow cylindrical steel stay 12a,
The bumper reinforcing member 1a is connected to the vehicle body side member (not shown) via the base member 12b, and is supported on the vehicle body side.

In FIG. 2, flanges 14a, 14b are joined to the rear surfaces of the stays 12a, 12b, and are welded or mechanically joined to and supported by the front surfaces of the side members.

(Cross-sectional Shape and Structure of Bumper Reinforcing Material) The cross-sectional shape and structure of the bumper reinforcing material 1a (hollow shaped member) are, as shown in FIG. (Front side flange) 2a, 2b and rear wall located behind
(Rear side flange) 3 and horizontal side walls (webs) 4 and 5 connecting these at right angles to each other to form a substantially rectangular cross section. Here, the cross-sectional shape in the longitudinal direction of the bumper reinforcing material is not necessarily the same, but a hollow shape in which the cross-sectional shape changes partially or sequentially can be freely selected from the design side of the vehicle body.

In the bumper reinforcing member 1a shown in FIG. 1, a horizontal intermediate wall (middle rib) 6 is provided in this substantially rectangular hollow section so as to have two hollow sections in parallel with the side walls 4, 5. Have been. Then, the intermediate wall 6 and the side walls 4, 5
And the front walls 2a and 2b are connected to the front walls 2a and 2b by the inclined walls 10a and 10b so as to reduce the original wall widths W _a and W _b of the front walls 2a and 2b. At the connection part of
A concave portion 9 facing the collision direction F is formed in the longitudinal direction of the hollow profile 1a (continuously formed on the surface of the front wall in the longitudinal direction).

The concave portion 9 facing the collision direction F needs to be provided at least on the front walls 2a and 2b.
In addition to the concave portion 2b only, a concave portion similar to the concave portion 9 may be formed at a connection portion between the rear wall 3 and the intermediate wall 6.

The cross-sectional shape of the recess 9 (inclined walls 10a, 10a)
b shape), the wall width W _a, have a shape such as W _b is decreased is not limited to a triangular shape in cross section in FIG. 1, square (the inclined wall 10a, 10b is L-shaped), semi-circular (The inclined walls 10a and 10b are connected in an arc shape).

According to such a configuration of the present invention, as described above, the wall width W _a of the front walls 2a, 2b facing the collision direction F,
Decrease W _b to increase width-to-thickness ratio (W wall thickness t),
Increase the bending buckling strength of 2a, 2b. In addition, since the concave portion 9 and the intermediate wall 6 that face each other in the collision direction resist the collision load F, the buckling of the bumper reinforcing material becomes difficult.

Accordingly, when receiving the bending deformation load F at the time of the offset collision, the crushing load applied to the curved portions 7a and 7b supported by the stay is reduced by the bending buckling on the side closer to the center portion 8. Make it larger than the strength. As a result, even when subjected to bending deformation at the time of an offset collision, the crushing of the curved portions 7a and 7b of the bumper reinforcing material or the stays 12a and 12b is performed before the bending buckling on the side closer to the center. Can be.

Therefore, even if the bumper reinforcing member is subjected to bending deformation centered on the side closer to the central portion 8 at the time of an offset collision, the overall strength of the bumper reinforcing member 1a is maintained while maintaining the crushing strength in the sectional direction of the bumper reinforcing member 1a. Can be improved in bending strength.

Even if the wall thickness of the bumper reinforcing member is set to a value smaller than that of the conventional one (even if the wall thickness is reduced), and even if the offset collision load is large, the bumper reinforcing member can be prevented from bending, and Can be absorbed by its own cross-sectional deformation.

In the case of the Al alloy bumper reinforcing material, it is necessary to use a thin aluminum alloy hollow shape having a wall thickness of 5 mm or less in order to achieve the advantages and advantages of using the Al alloy material for weight reduction. Is preferred. If the wall thickness exceeds 5 mm, even if it is a hollow shape, it will not be much different from steel in terms of weight and strength, and the advantage of using Al alloy material for weight reduction may be impaired. There is. Therefore, when the thickness of the bumper reinforcing material wall is reduced in the present invention, the thickness of the wall is 5 mm or less, which is a measure of the reduction in thickness.

The cross-sectional shape and structure of the bumper reinforcing member (hollow shaped member) of the present invention have the above-mentioned intermediate wall. The cross-sectional shape is basically selected from a daily shape and an eye shape according to required characteristics such as energy absorption.

(Other Sectional Shapes and Structures of Bumper Reinforcing Material) FIGS. 3, 4, 5 and 6 show other aspects of the sectional shape and structure of the bumper reinforcing material (hollow shaped member) of the present invention in a side view.

The bumper reinforcement 1b shown in FIG. 3 includes front walls 2c and 2d.
Are protruding (bulging) in the direction of collision (outside, front), and are curved. The front wall can be curved in an arc shape, and can also be applied to a bumper reinforcing material shown in FIGS. As described above, since the front walls 2c and 2d are each curved, the bending buckling strength of the front walls 2c and 2d is obtained.
(Bending stiffness) is larger than the straight front walls 2a and 2b in FIG. 1 and is less likely to buckle, so that the bumper reinforcing material can be prevented from bending when a larger offset collision load is applied, and the bumper reinforcing material Energy can be increased.

Further, the bumper reinforcing member 1c shown in FIG. 4 has the side wall so as to have three hollow sections in the hollow cross section.
Two intermediate walls 6a, 6b are provided in parallel with 4, 5 and the front wall
Two concave portions 9a, 9b facing the collision direction F are formed in the connecting portion between 2e, 2f and the intermediate walls 6a, 6b in the longitudinal direction of the hollow profile 1c. This means for increasing the number of intermediate walls, hollow sections and concave portions facing the collision direction F can of course be applied to the bumper reinforcing material shown in FIGS. 1 and 3 or FIG. 5 described later.

As described above, by increasing the number of intermediate walls and the number of hollow sections and concave portions facing the collision direction F,
It is possible to further decrease the width of the front wall facing the collision direction F, increase the width-to-thickness ratio, increase the bending buckling strength of the front wall, and further increase the buckling stress. Also, the collision direction F
In addition, the absorption of the collision load between the recess and the intermediate wall, which is opposite to, also increases, making it difficult to buckle, so that the bumper reinforcement can be prevented from bending at the time of a larger offset collision load, and the energy absorption of the bumper reinforcement can be reduced. Can be bigger.

Further, as shown in a bumper reinforcing member 1d in FIG.
The front wall 2h, 2i (which may be provided on the rear wall) has a flange 13 which is flush with the front wall 2h, 2i and which projects laterally.
a, 13b and the like. The means for providing the flange portion is, of course, applicable to the bumper reinforcing material shown in FIGS.

Then, as described above, the flange portions 13a, 13b
The figure shows that the bending buckling strength of the front walls 2h and 2i is
As compared with the case of 1-4, it becomes large and it is difficult to buckle, so it is possible to prevent the bending of the bumper reinforcement at the time of a larger offset collision load and to increase the energy absorption amount of the bumper reinforcement. . In addition, this flange part may be provided so as not to protrude to both sides but to protrude to only one side.

FIG. 6 has the same basic structure as that of FIG. 1, but has flange portions 17a and 17b which are flush with the rear wall 3 and project laterally, and have side walls 4 and 5 respectively.
The connection between the rear wall 3 and the rear wall 3 are perpendicular to each other so as to have bent portions 16a and 16b bent inward in the cross section.

When the side wall and the rear wall are simply made perpendicular to each other as shown in FIG. 1, when the collision load at the time of the offset collision is extremely large, the side wall may be bent in a U-shape outward in the cross section. There is a possibility that the crushing is accelerated, the energy absorption amount is reduced, or the bumper reinforcing material is easily bent.

On the other hand, the connecting portions between the side walls 4, 5 and the rear wall 3 have bent portions 15a, 15b bent inward in the cross section.
When the collision load is applied, the side walls 4 and 5 bend inward in the cross section to suppress crushing, so that the amount of energy absorption becomes larger as compared with the case where they are simply orthogonal. In addition, there is an advantage that bending of the bumper reinforcing material does not occur.

(Stay) The stay used in the present invention is joined to a bumper reinforcing material having a curved portion which is straightly bent rearward of the vehicle body. Therefore, as shown in FIG. 2, the front surface of the cylindrical member and the front surface of the front member, if any, have a linear or curved slope corresponding to the rear surface of the curved portion of the bumper reinforcement. It is desirable to have a shape or an inclined wall.

In order to reduce the weight of the stay, it is preferable that the stay itself is also a hollow cylinder or a shaped member. As for the material, a steel material such as ordinary steel or high tensile steel or an extruded aluminum alloy material is appropriately selected.

Furthermore, by integrating the bumper reinforcing material of the present invention with the stay in advance to form a bumper reinforcing material with a stay, it is extremely easy and simple to attach the bumper reinforcing material to the side member via the stay.

In the case of the conventional integrated stay, two steps of attaching the stay to the bumper reinforcing member and attaching the stay to the side member have been required on the automobile manufacturing or repair side. Also, the connection and fixation of the bumper reinforcing material and the side member to the stay are also very complicated because welding and joining mainly using rivets are required.

On the other hand, in the case of the bumper reinforcing material with a stay of the present invention, the bumper reinforcing material and the stay can be integrated in advance. It can be set only with. In addition, there is an advantage that connection and fixation of the bumper reinforcing material and the side member to the stay can be simplified.

(Al Alloy for Bumper Reinforcement Material) As described above, the bumper reinforcement material of the present invention preferably has a wall thickness of 5 mm or less in order to achieve the advantages and advantages of employing an Al alloy material for weight reduction. For this reason, Al used in the bumper reinforcing material of the present invention
The alloy, which satisfies the conditions for weight reduction, has a long hollow profile of 5 mm or less in thickness for the purpose of excellent offset collision performance. In view of the relationship with the members, it is preferable that the proof stress of the Al alloy be 280 MPa or more and be larger than the proof stress of the Al alloy constituting the later-described bumper stay.

When the proof stress of the Al alloy for bumper reinforcement is less than 280 MPa, the bumper reinforcement cross-sectional structure of the present invention has a large offset collision load. It is difficult to be superior to the above, and there is a possibility that the bending may occur due to a collision load at the time of an offset collision. Also, when the proof stress of the Al alloy for bumper reinforcement is smaller than the proof stress of the Al alloy for stays, similarly to the above, it is difficult to have excellent offset collision properties, and at the time of offset collision, the bending may occur. is there.

On the other hand, when the proof stress of the Al alloy for the bumper reinforcing material is greater than the proof stress of the Al alloy for the stay, one of the stays on the side to which the collision load is applied is more intense than the collision load at the time of the offset collision. It begins to collapse quickly, creating a kind of cushioning role for the side of the bumper reinforcement where the impact load is applied. The role of the cushioning member is to reduce the collision load at the time of an offset collision by causing the stay to make a certain small displacement (crushing deformation, buckling), and to significantly reduce the above-mentioned deviation of the collision load against the bumper reinforcement. The bumper reinforcement is relaxed, and the bumper reinforcement is prevented from being bent, and the bumper reinforcement is received.

As a result, in combination with the cross-sectional structure of the bumper reinforcing material of the present invention, even in the case of a hollow aluminum alloy material having a thickness of 5 mm or less, the collision load at the time of an offset collision can be reduced on one side of the bumper reinforcing material. Even if you are biased only to
The bumper reinforcing member is deformed in the cross-sectional direction without bending, and a large amount of energy absorption is secured.

Al alloys satisfying the required characteristics as a bumper reinforcing material include those generally used for structural members of this kind, such as 5000 series, 6000 series, and 7000 series, which have relatively high proof stresses. ) Al alloy used for selection. However, among these, an 7000 series Al alloy extruded material such as A7003S, A7N01S, etc., and an aged Al alloy material is preferable.

(Example) (Offset collision test) Bumper reinforcing material having a cross-sectional structure of the present invention shown in FIG. 1 (rectangular hollow shape, thickness 4 mm, length 1300 mm,
Center straight part 560mm, Displacement of curved part end 100mm (body rear side)
, Height 70 mm, the front wall width 50 mm, wall width W _a + W _b 80mm)
And a welded steel rectangular hollow stay (thickness 1 mm, length 15
0 mm, width 70 mm, height 70 mm) and an offset collision test (15 km / hr) was performed. In addition, proof strength is used for bumper reinforcement
An A7003SAl alloy extruded member subjected to aging treatment at 305 MPa was used.

For comparison, the conventional bumper reinforcement having a Japanese cross section shown in FIG. 9 (the connection between the intermediate wall and the side wall and the front wall is made orthogonal, the width of the front wall is not reduced, and An offset collision test was also performed on an example in which a concave section was not formed at the connection portion between the inner wall and the intermediate wall, and a simple cross section was formed, except that the other conditions were the same as those of the invention example.

FIG. 7 or FIG. 10 shows an outline of the static offset collision test at 15 km / hr. In FIG. 7 or FIG. 10, 1 is a bumper reinforcing material as a specimen, 7 is a curved portion at both ends of the bumper reinforcing material, and 12 is a stay provided on the back surface of the curved portion.
Reference numeral 19 denotes an offset barrier provided on the front surface of the bumper reinforcement 1 and a portion (40%) that collides with the bumper reinforcement 1.

The maximum load (KN), the amount of energy absorption at a displacement of 100 mm (J), and the absorption at a displacement of 100 mm were measured for the bumper reinforcements of the invention and comparative examples measured during the barrier collision test and the offset collision test. Table 1 shows the various collision velocities (km / hr) and deformation states.

Further, FIG. 8 shows the load-displacement relationship at the time of offset collision (at the time of crushing) of the invention example and the comparative example. FIG. 7 shows an actual linear deformation state of the invention example.
Numeral 10 indicates actual deformed states of the comparative example with bending.

As is apparent from these facts, the invention example prevents the bending as shown in FIG. 10 as shown in FIG.
As shown in Table 1 and FIG. 8 (solid line is the invention example, dotted line is the comparative example), the collision energy absorption performance (maximum load, energy, collision speed that can be absorbed) at the time of offset collision within a certain displacement amount, Both can be increased. Also,
The results of this offset collision test show that even in the barrier collision test, excellent collision energy absorption performance (maximum load,
Energy, collision speed that can be absorbed).

On the other hand, in the comparative example, the buckling portion 21 and the bending as shown in FIG. 11 occurred in the actual deformed state at the time of the offset collision, and as shown in Table 1 and FIG. Is also significantly inferior to the invention examples.

Therefore, the effects of the present invention and the significance of the configuration of the present invention are apparent from the results of these examples.

[0076]

[Table 1]

[0077]

According to the present invention, a curved portion is provided at both ends.
In the case of a bumper reinforcement made of an Al alloy, a bumper reinforcement can be provided that has improved impact energy absorption performance at the time of an offset collision without impairing the advantage of weight reduction by using an Al alloy. For this reason, the use of the Al alloy material for the bumper reinforcement is greatly expanded, and the industrial value is great.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a bumper reinforcing material according to the present invention.

FIG. 2 is a plan view of the bumper reinforcement of FIG. 1 according to the present invention.

FIG. 3 is a front view showing another embodiment of the bumper reinforcing material according to the present invention.

FIG. 4 is a front view showing another embodiment of the bumper reinforcing material according to the present invention.

FIG. 5 is a front view showing another embodiment of the bumper reinforcing material according to the present invention.

FIG. 6 is a front view showing another embodiment of the bumper reinforcing material according to the present invention.

FIG. 7 is a plan view showing a deformation of the bumper reinforcing material of the present invention after an offset collision.

FIG. 8 is an explanatory diagram showing a load-displacement relationship at the time of an offset collision of the bumper reinforcing material of the present invention.

FIG. 9 is a front view showing a conventional bumper reinforcing material.

FIG. 10 is a plan view showing deformation of a conventional bumper reinforcing member after an offset collision.

[Explanation of symbols]

1: Bumper reinforcement, 2: Front wall, 3: Rear wall, 4, 5: Side wall,
6: intermediate wall, 7: curved part, 8: straight part, 9: concave part, 10, 11: inclined wall, 12: stay,

Claims (2)

[Claims] 1. A hollow member made of an aluminum alloy,
A bumper reinforcing member having a curved portion toward the vehicle body at both ends and supported by a bumper stay at the back of the curved portion, wherein the hollow shape member is located rearwardly of a front wall facing a collision direction. A substantially rectangular cross section is formed by the face wall and the side wall which is orthogonally connected to these walls, and an intermediate wall is provided in parallel with the side wall so as to have a plurality of hollow portions in this cross section. Offset collision characterized in that the connection with the front wall is made so as to reduce the width of the front wall, and a concave portion is formed in the connection portion between the front wall and the intermediate wall in the longitudinal direction of the hollow profile. Excellent bumper reinforcement. 2. The bumper reinforcement according to claim 1, wherein the bumper stay and the bumper reinforcement are integrally joined in advance.