JP4035292B2 - Bumper reinforcement with excellent offset impact - Google Patents

Description

【００７７】
【発明の効果】
本発明によれば、湾曲部を両端に有するAl合金製バンパー補強材の場合において、Al合金採用の軽量化の利点を損なわずに、オフセット衝突時の衝突エネルギーの吸収性能を高めたバンパー補強材を提供することができる。
このため、バンパー補強材へのAl合金材の用途を大きく拡大するものであり、工業的な価値が大きい。
【図面の簡単な説明】
【図１】本発明に係るバンパー補強材の一実施態様を示す斜視図である。
【図２】図1 の本発明に係るバンパー補強材の平面図である。
【図３】本発明に係るバンパー補強材の他の実施態様を示す正面図である。
【図４】本発明に係るバンパー補強材の他の実施態様を示す正面図である。
【図５】本発明に係るバンパー補強材の他の実施態様を示す正面図である。
【図６】本発明に係るバンパー補強材の他の実施態様を示す正面図である。
【図７】本発明バンパー補強材のオフセット衝突後の変形を示す平面図である。
【図８】本発明バンパー補強材のオフセット衝突時の荷重−変位関係を示す説明図である。
【図９】従来のバンパー補強材のを示す正面図である。
【図１０】従来のバンパー補強材のオフセット衝突後の変形を示す平面図である。
【符号の説明】
1:バンパー補強材、2:前面壁、3:後面壁、4 、5:側壁、6:中間壁、7:湾曲部、8:直線部、9:凹部、10、11: 傾斜壁、12: ステイ、[0001]
BACKGROUND 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]
[Prior art]
Bumper reinforcements (also called bumper reinforcements or bumper armatures) as strength reinforcements are provided inside the bumpers attached to the front end (front) and rear end (rear) of automobile bodies. .
[0003]
As is well known, the bumper reinforcing member is disposed between the bumper and the vehicle body so as to extend in a substantially horizontal direction with respect to the vehicle body and in parallel with the vehicle width direction. And as for such a bumper reinforcement, in the shape of the longitudinal direction, various shapes are selected according to the design of an automobile body or a bumper.
[0004]
Typical shapes are (1) a straight bumper reinforcement (straight-line bumper reinforcement) that extends parallel to the vehicle width direction, including the center and ends, and (2) a straight center Broadly divided into bumper reinforcements (curved bumper reinforcements) that have straight or curved curved parts (bent parts) that are bent toward the vehicle body at both ends, or that are entirely curved toward the vehicle body. .
[0005]
These bumper reinforcements are attached to the vehicle body by being connected to vehicle body frames (vehicle body members) of a skeleton member in the longitudinal direction of the vehicle body such as a front side member and a rear side member. Further, the fixing to the vehicle body is performed directly on the front end or rear end of the front or rear side member of the vehicle body or via a vehicle body connecting member such as a bumper stay.
[0006]
As is well known, the bumper reinforcing member constitutes an energy absorbing member for a vehicle body against a collision from the front or rear of the vehicle body or from the front or rear between the bumper and the vehicle body. Therefore, the bumper reinforcement 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 by its own bending deformation and cross-sectional deformation. It has been.
[0007]
In recent years, in order to reduce the weight of these bumper reinforcements and bumper stays, extruded types made of high-strength Al alloys such as 5000 series, 6000 series, and 7000 series according to AA or JIS standards, instead of steel materials that have been used in the past. Materials are beginning to be used.
These aluminum alloy bumper reinforcements and bumper stays have a cross-sectional shape such as a mouth shape and a medium rib, and are reinforced with a daily shape (1 is a bumper reinforcement, 20 is a middle rib) Basically, it has a substantially rectangular hollow structure.
[0008]
By the way, the bumper reinforcement as an energy absorbing member for the car body is not only used for energy absorption performance at the time of the conventional frontal collision (barrier collision, full-clap frontal collision), but recently, the car body has been separated from oncoming vehicles and obstacles. It is required to exhibit excellent energy absorption performance at the time of offset collision, such as a frontal collision.
[0009]
However, during this offset collision, the end of the offset barrier (or oncoming vehicle) comes closer to the center of the impacted vehicle, so the collision load is inevitably concentrated on the center of the impacted vehicle bumper reinforcement. Cheap. For this reason, in the curved bumper reinforcing material, the deformation concentrates particularly on the portion from the central portion of the bumper reinforcing material, and in some cases, the bumper reinforcing material bends in the longitudinal direction in a U-shape and absorbs collision energy. This is not sufficient, and further causes damage to the vehicle body.
[0010]
This problem is relatively unlikely to occur with the linear bumper reinforcement. In the case of a linear bumper reinforcement, the collision load at the time of offset collision is distributed over the entire barrier contact portion of the bumper reinforcement, and the collision load is less likely to be concentrated on the central side of the bumper reinforcement. For this reason, in the case of a linear bumper reinforcement, deformation from the central part of the bumper reinforcement is unlikely to occur, but a cross-sectional deformation in which the bumper reinforcement is crushed between the stay on the back of the reinforcement and the barrier (originally expected) Deformation) is likely to occur. As a result, the deformation region of the bumper reinforcing material is widened, and the amount of collision energy absorbed can be increased.
[0011]
On the other hand, the curved bumper reinforcing material is normally supported by a stay or the like on the back surface of the curved portion, and the amount of the curved portion is closer to the collision side than the stay or the like from the central portion of the bumper reinforcing material. It will protrude to the front. 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.
[0012]
As a result, in the case of a curved bumper reinforcement, at the time of an offset collision, the deformation of the entire cross section near the stay is crushed (originally expected deformation) and the side closer to the center of the bumper reinforcement is locally buckled. , It tends to be bent in the shape of a circle in the longitudinal direction.
[0013]
Actually, even when the bumper reinforcement 1 partially collides with the partial offset barrier 19 even in the offset collision test condition of 15 km / hr shown in the plan view of FIG. 10, the portion 21 closer to the center of the bumper reinforcement 1 However, as shown in FIG. 10, there are many cases where the collision energy cannot be sufficiently absorbed due to buckling and bending in the shape of a dogleg in the longitudinal direction. 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).
[0014]
Therefore, in the case of a bumper reinforcement made of an Al alloy having a rectangular section and having a curved portion at both ends and supported by a bumper stay at the back of the curved portion, even if it has excellent barrier collision performance, it has excellent offset collision performance. However, the offset collision performance may be inferior.
[0015]
For this reason, the bumper reinforcement, stay, and side member connection and joint structure have been strengthened and improved by providing a cross member between stays, so that the collision load during offset collision is limited to one side of the bumper reinforcement. Various techniques have been proposed in Japanese Patent Laid-Open Nos. 10-203411, 10-250505, 10-203403, and the like.
[0016]
Further, in order to reduce the amount of deformation of the curved portion (projecting portion) when the vehicle collides with the wall in the oblique direction (oblique collision) with respect to the vehicle, Japanese Laid-Open Utility Model Publication No. 3-42452 proposes that the intersection between the central portion and the curved portion is positioned within the width in the vehicle width direction.
[0017]
Furthermore, in the bumper reinforcement made of Al alloy with a rectangular section at both ends, the bending angle of the bending portion in the vehicle body direction and the protruding amount of the bending portion are also reduced in order to reduce the deformation amount of the bending portion at the time of oblique collision. Japanese Patent Laid-Open No. 8-2350 proposes to control the value within the optimum range.
[0018]
[Problems to be solved by the invention]
However, the connection of the bumper reinforcing material, the stay, and the side member and the strengthening of the joint structure inevitably lead to a complicated connection and a joint structure and an increase in weight. This also leads to an increase in the complexity of the work for assembling or repairing the vehicle body.
[0019]
On the other hand, measures have been taken to increase the crushing strength of these members by increasing the thickness of bumper reinforcements or stays, or attaching and reinforcing steel members such as high tension.
However, even in this case, in order to prevent the bumper reinforcing material from being bent, a considerable increase in thickness and reinforcement are required, and the advantages of using an Al alloy material for weight reduction are impaired. .
[0020]
Further, in order to reduce the amount of deformation of the bending portion with respect to the oblique collision, a technique for positioning the intersection portion between the central portion of the bumper reinforcing member and the bending portion within the width in the vehicle width direction, or bending the bending portion in the vehicle body direction. The technique for controlling the angle and the protruding amount of the curved portion within the optimum range has no effect on the offset collision performance which is a problem of the present invention. This is because at the time of an offset collision that is a problem of the present invention, as described above, deformation concentrates on a portion from the central portion of the bumper reinforcement.
[0021]
For this reason, in the case of an Al alloy bumper reinforcement that has a curved part at both ends and is supported by a bumper stay on the back of the curved part, it prevents the bending of a dogleg shape at the time of an offset collision and improves the collision energy absorption performance. The only way to increase the thickness is to increase the thickness of the reinforcing material, and the fact that the weight reduction, which is the advantage of adopting the bumper reinforcing material made of Al alloy, has been greatly impaired.
[0022]
Therefore, the object of the present invention is to improve the collision energy absorption performance at the time of offset collision without impairing the light weight advantage of adopting Al alloy in the case of a bumper reinforcing material having curved portions that bend to the vehicle body at both ends. It intends to provide bumper reinforcement made of Al alloy.
[0023]
[Means for Solving the Problems]
  In order to achieve this object, the gist of the bumper reinforcing material excellent in offset collision property according to claim 1 of the present invention is made of an aluminum alloy hollow shape, and has curved portions toward the vehicle body at both ends. The bumper reinforcement is supported by a bumper stay on the back of the curved portion, and the hollow shape member includes a front wall facing the collision direction, a rear wall positioned rearward, and side walls connected orthogonally to these walls. An intermediate wall is provided in parallel with the side wall so as to have a plurality of hollow portions in the cross section, and the intermediate wall and the connection between the side wall and the front wall are connected to the front wall by an inclined wall. The wall width is reduced so that a concave portion is formed in the connecting portion between the front wall and the intermediate wall and extends in the longitudinal direction of the hollow shape member.Bending buckling strength closer to the center of the bumper reinforcement when subjected to bending deformation load during offset collision by increasing the width-thickness ratio of the front wall and increasing the bending buckling strength of the front wall Is made larger than the crushing strength on the side of the bumper reinforcement curved portion supported by the stay.That is.
[0024]
  According to the configuration of the present invention, the wall width of the front wall facing the collision direction is reduced, and the width-thickness ratio (wall width / wall thickness) is reduced.DecreaseBy doing so, the bending buckling strength of the front wall of the bumper reinforcement is increased. Moreover, since the said recessed part and intermediate | middle wall which oppose a collision direction resist with respect to a collision load, a bumper reinforcement material becomes difficult to buckle.
[0025]
As a result, for example, as shown in FIGS. 1 and 2, when the bumper reinforcing material 1a of the present invention receives a bending deformation load F at the time of offset collision, the bending buckling strength on the side closer to the center is reduced by stays 12a and 12b. The crushing strength on the side of the supported curved portions 7a, 7b (crushing strength in the cross section direction of the reinforcing material) is set larger. In other words, when subjected to bending deformation at the time of an offset collision, the bumper reinforcement curved portions 7a, 7b to the stays 12a, 12b are crushed (absorption of collision energy) by bending buckling ( Let it be done before the bend).
[0026]
As a result, the crushing strength in the cross-sectional direction of the bumper reinforcement (the ability to absorb the collision energy by deformation in its own cross-section) even when subjected to bending deformation around the center of the bumper reinforcement during offset collision ) Can be maintained, and the bending strength of the central part of the bumper reinforcement can be improved.
[0027]
For this reason, even if the wall thickness of the bumper reinforcement is thinner than before and the offset collision load is large, the bumper reinforcement is prevented from bending, and the collision energy at the time of the offset collision It can be absorbed by deformation.
[0028]
The applicant previously proposed a hollow profile with 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 according to Japanese Patent Laid-Open No. 8-155534. did. This hollow shape member is a hollow shape member in which an intermediate wall is provided in an outer wall provided with 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 performed by an inclined wall so as to reduce the wall width.
[0029]
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 an Al alloy bumper reinforcing material having a rectangular section and having a curved portion at both ends and supported by a bumper stay on the back surface of the curved portion, which is the subject of the present invention. Also, there is no disclosure of the offset collision property and the collision mechanism, which is the subject of the present invention. Furthermore, there is no suggestion that the cross-sectional structure of the hollow shape material contributes to the offset collision property from the collision mechanism.
[0030]
In addition, the load-deformation mechanism of the bumper reinforcement made of an Al alloy supported by the stay of the present invention at the time of an offset collision, that is, the bending buckling strength closer to the center of the bumper reinforcement, When the bending strength of the bumper reinforcement is applied to the crushing side of the bumper reinforcement and the stay side, the bending buckling (bending ) There is no disclosure about preceding, and the load-deformation mechanism at the time of collision is completely different.
[0031]
According to the configuration of the present invention, the above-described excellent effect is obtained. Further, as the effect of claim 1, the design selection of the bumper reinforcing material and the stay can be selected for various collision conditions (impact level) of the offset collision. There is also the advantage that it can be done freely and easily, making the body design for the required crash safety significantly easier.
[0032]
In addition, since the bumper reinforcement, stay, and side member connection and joining structure are basically the same as before, the assembly of the vehicle body and the repair of the vehicle body can be performed as usual, which increases the complexity of the operation. There are also no advantages.
[0033]
Furthermore, as described in claim 2, the bumper reinforcing material of the present invention is integrated with the stay in advance and used as a bumper reinforcing material with a stay, so that it is extremely easy to attach to the side member via the stay. It becomes simple.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the bumper reinforcing material of the present invention will be described in detail.
[0035]
(Overall shape and structure of bumper reinforcement)
One embodiment of the basic form of the Al alloy bumper reinforcing material of the present invention is illustrated in a perspective view in FIG. 1 and a plan view in FIG. 1 and 2 show a state in which the bumper reinforcing material 1a extends in a substantially horizontal direction in the vehicle width direction. The overall shape of the bumper reinforcement 1a is linearly bent in the vehicle body direction at both ends (in the case of the front of the vehicle, it is bent in the front of the vehicle in the case of the rear of the vehicle) and the curved portions 7a, 7b and the central straight portion 8 are formed. Have.
[0036]
Note that the curved bumper reinforcing material of the present invention may have linear or curved curved portions (bent portions) at both ends, or may be entirely curved.
[0037]
Then, as shown in FIG. 2, the curved portions 7a and 7b are back (rear) and joined to a vehicle body side member (not shown) via hollow cylindrical steel stays 12a and 12b, so that the bumper reinforcement 1a is mounted on the vehicle body side. Supported by
[0038]
In FIG. 2, flanges 14a and 14b are joined to the rear surfaces of the stays 12a and 12b, and are supported by being welded or mechanically joined to the front surfaces of the side members.
[0039]
(Cross-sectional shape and structure of bumper reinforcement)
The cross-sectional shape and structure of the bumper reinforcement 1a (hollow profile) is as shown in Fig. 1, with front walls (front side flanges) 2a and 2b erected against the impact direction or impact load F, The rear side wall (rear side flange) 3 and the horizontal side walls (webs) 4 and 5 that connect them in a right angle direction 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 whose cross-sectional shape changes partially or sequentially can be freely selected from the design side of the vehicle body.
[0040]
  In the bumper reinforcing member 1a of FIG. 1, a horizontal intermediate wall (medium rib) 6 is provided in parallel with the side walls 4 and 5 so as to further include two hollow section sections in the substantially rectangular hollow cross section. . The intermediate wall 6 and the side walls 4, 5 and the front walls 2a, 2b are connected to the inclined walls 10a, 10b.and 11a , 11bDepending on the original wall width W of the front walls 2a, 2b_a, W_bIn the connecting portion between the front walls 2a, 2b and the intermediate wall 6, a recess 9 facing the collision direction F is formed in the longitudinal direction of the hollow profile 1a (the length of the front wall Continuously formed on the surface of the direction).
[0041]
The concave portion 9 facing the collision direction F needs to be provided at least on the front walls 2a and 2b, but is not only provided on the front walls 2a and 2b, but also on the connection portion between the rear wall 3 and the intermediate wall 6. A recess similar to the recess 9 may be formed.
[0042]
Further, the cross-sectional shape of the recess 9 (the shape of the inclined walls 10a and 10b) is the wall width W._a, W_b1 is not limited to the triangular cross-sectional shape shown in FIG. 1, but squares (inclined walls 10a and 10b are L-shaped), semicircles (inclined walls 10a and 10b are connected in an arc), etc. The shape is appropriately selected.
[0043]
  According to such a configuration of the present invention, as described above, the wall width W of the front walls 2a and 2b facing the collision direction F 1._a, W_bTo reduce the width-thickness ratio (W wall thickness t)DecreaseTo increase the bending buckling strength of the front walls 2a and 2b. Further, since the concave portion 9 and the intermediate wall 6 facing each other in the collision direction resist the collision load F, the bumper reinforcing material is less likely to buckle.
[0045]
Therefore, the bending strength of the entire bumper reinforcing material 1a is maintained while maintaining the crushing strength in the cross-sectional direction of the bumper reinforcing material 1a even when subjected to bending deformation around the central portion 8 side of the bumper reinforcing material at the time of offset collision. Can be improved.
[0046]
And even if the wall thickness of the bumper reinforcement is smaller than before (even if it is made thinner), and even if the offset collision load is large, the bumper reinforcement is prevented from bending and the collision energy at the time of offset collision Can be absorbed by deformation in its own cross-sectional direction.
[0047]
In the case of an aluminum alloy bumper reinforcement, in order to achieve the advantage or purpose of adopting an aluminum alloy material for weight reduction, it is preferably made of a thin aluminum alloy hollow material having a wall thickness of 5 mm or less. If this wall thickness exceeds 5 mm, even if it is a hollow shape, the relationship between weight and strength is not much different from steel, and the advantages of using an Al alloy material for weight reduction may be impaired. There is sex.
Therefore, in the present invention, when the thickness of the bumper reinforcing material wall is referred to as being thin, the wall thickness is 5 mm or less, which is an indication of the thinning.
[0048]
The cross-sectional shape and structure of the bumper reinforcing material (hollow profile) of the present invention has the intermediate wall, so the size (height) of the cross-section of the bumper reinforcing material according to the vehicle body design, the strength or the impact energy absorption amount. The cross-sectional shape is basically selected from a daily shape and an eye shape according to the required characteristics.
[0049]
(Cross-sectional shape and structure of other bumper reinforcements)
3, 4, 5, and 6 are side views showing another aspect of the cross-sectional shape and structure of the bumper reinforcing material (hollow profile) of the present invention.
[0050]
In the bumper reinforcing member 1b of FIG. 3, the front walls 2c and 2d are curved in an arc shape protruding (expanding) in the collision direction (outer side, front side). The front wall can be curved in a circular arc shape, and can also be applied to bumper reinforcements such as those shown in FIGS.
Since the front walls 2c and 2d are curved in this way, the bending buckling strength (bending rigidity) of the front walls 2c and 2d is larger than that of the straight front walls 2a and 2b in FIG. Since it becomes difficult to buckle, it is possible to prevent the bumper reinforcing material from being bent at the time of a larger offset collision load and to increase the energy absorption amount of the bumper reinforcing material.
[0051]
Further, the bumper reinforcing member 1c of FIG. 4 is provided with two intermediate walls 6a and 6b in parallel with the side walls 4 and 5 so as to further have three hollow section sections in the hollow cross section, and the front wall 2e. , 2f and intermediate walls 6a, 6b are formed with two recesses 9a, 9b facing the collision direction F over the longitudinal direction of the hollow profile 1c.
Of course, the means for increasing the number of the intermediate wall, the hollow section, and the number of recesses facing the collision direction F 1 can also be applied to the bumper reinforcing material shown in FIGS. 1 and 3 or FIG.
[0052]
  In this way, if the number of intermediate walls is increased to increase the number of hollow sections and the number of recesses facing the collision direction F, the wall thickness of the front wall facing the collision direction F is further reduced, and the width-thickness ratio is increased.DecreaseThus, the bending buckling strength of the front wall can be increased and the buckling stress can be further increased. In addition, since the amount of collision load absorption between the concave portion facing the collision direction F and the intermediate wall is increased and buckling is difficult, the bumper reinforcement is prevented from bending during a larger offset collision load, and the bumper reinforcement The amount of energy absorption can be increased.
[0053]
Further, like the bumper reinforcement 1d in FIG. 5, the front walls 2h, 2i (which may be provided on the rear wall) are flush with the front walls 2h, 2i and have flange portions 13a protruding sideways. 13b may be included. The means for providing the flange portion can be applied to the bumper reinforcing material shown in FIGS.
[0054]
Since the flange portions 13a and 13b are provided in this way, the bending buckling strength of the front walls 2h and 2i is higher than that in the case of FIGS. 1 to 4 in which the front wall is connected to the side wall at the end. As a result, the bumper reinforcing material is prevented from being bent at the time of a larger offset collision load, and the energy absorption amount of the bumper reinforcing material can be increased. Note that the flange portion does not necessarily protrude to both sides, and may be provided to protrude only on one side.
[0055]
6 has the same basic structure as that of FIG. 1, but has flange portions 17a and 17b that are flush with the rear wall 3 and project laterally, and the side walls 4 and 5 and the rear wall. 3 are orthogonal to each other so as to have bent portions 16a and 16b which are bent in the inner direction of the cross section.
[0056]
If the side wall and the rear wall are simply perpendicular to each other as shown in Fig. 1, the side wall may be bent in the shape of a circle in the outer direction of the cross section when the impact load during offset collision is extremely large. As a result, the amount of energy absorption may be reduced, or the bumper reinforcement may be bent easily.
[0057]
On the other hand, when the bent portions 15a and 15b that bend inward of the cross section are provided at the connection portion between the side walls 4 and 5 and the rear wall 3, the side walls 4 and 5 are cross-sectioned when a collision load is applied. In order to suppress crushing by bending inwardly, there is an advantage that the amount of energy absorption is increased and bending of the bumper reinforcing material is not generated as compared with the case where they are simply orthogonal.
[0058]
(stay)
The stay used in the present invention is joined to a bumper reinforcing material having curved portions whose both ends are linearly bent rearward of the vehicle body. For this reason, the front wall in the case of a cylinder and the front wall in the case of a front wall, as shown in FIG. 2, are linear or curved slopes corresponding to the rear surface of the curved portion of the bumper reinforcement. It is desirable that it is a shape or an inclined wall.
[0059]
In order to reduce the weight of the stay, it is preferable that the stay itself is also a hollow cylinder or shape member. As for the material, steel materials such as ordinary steel and high tensile steel, and aluminum alloy extruded shapes are appropriately selected.
[0060]
Furthermore, the bumper reinforcing material of the present invention is integrated with the stay in advance and used as a bumper reinforcing material with a stay, so that it is extremely easy and simple to attach to the side member via the stay.
[0061]
In the case of the above-mentioned conventional integrated stay, two steps of (1) mounting the stay on the bumper reinforcement and (2) mounting the stay on the side member are necessary so far in the automobile manufacturing or repair side. It is said. Further, the connection and fixing of the bumper reinforcing member and the side member and the stay are also very complicated because joining mainly by welding or rivets is required.
[0062]
On the other hand, in the bumper reinforcing material with a stay according to the present invention, the bumper reinforcing material and the stay can be integrated in advance. Therefore, in the automobile manufacturing or repair side, (2) the step of attaching the stay to the side member. It can be set only with. Further, there is an advantage that the bumper reinforcing material and the side member and the stay can be connected and fixed easily.
[0063]
(Al alloy for bumper reinforcement)
As described above, the bumper reinforcing material of the present invention preferably has a wall thickness of 5 mm or less in order to achieve the advantage and purpose of adopting an Al alloy material for weight reduction.
For this reason, the Al alloy used in the bumper reinforcing material of the present invention is bent as a long hollow material having a thickness of 5 mm or less for the purpose of satisfying this weight reduction condition and excellent offset collision property. In order to prevent as much as possible, it is preferable that the proof stress of the Al alloy is 280 MPa or more in relation to the steel side member of the vehicle body, and is larger than the proof strength of the Al alloy constituting the bumper stay described later.
[0064]
When the proof stress of the Al alloy for bumper reinforcement is less than 280 MPa, even when the bumper reinforcement cross-sectional structure of the present invention increases the offset collision load, it satisfies the weight reduction condition and is excellent in offset collision performance. It is difficult to cause the bending due to the collision load at the time of offset collision.
Also, when the proof stress of the Al alloy for bumper reinforcement becomes smaller than the proof strength of the stay Al alloy, as described above, it is difficult to be excellent in the offset collision property, and the bending may occur during the offset collision. is there.
[0065]
On the other hand, if the strength of the Al alloy for the bumper reinforcement is greater than the strength of the stay Al alloy, one stay on the side where the impact load is applied will collapse faster than the impact load at the time of the offset impact. For the first time, a kind of cushioning member role is produced on the side of the bumper reinforcement where the collision load is applied. The role of this cushioning member is that the stay is subject to a certain small displacement (crushing deformation, buckling) of the collision load at the time of offset collision, and the bias of the collision load against the bumper reinforcement is greatly reduced. The bumper reinforcement material is received while relaxing and preventing the bumper reinforcement material from being bent.
[0066]
As a result, combined with the bumper reinforcing member cross-sectional structure of the present invention, even if it is an Al alloy hollow profile having a thickness of 5 mm or less, the collision load at the time of offset collision is biased to only one side of the bumper reinforcing material. Even if added, the bumper reinforcement does not bend, but deforms in the cross-sectional direction, ensuring a large amount of energy absorption.
[0067]
Al alloys that satisfy the required properties of these bumper reinforcements are usually general purpose (standard) Al alloys with relatively high proof strength such as 5000 series, 6000 series, 7000 series, etc. It is used by selecting from. However, among these, 7000 series Al alloy extruded shapes such as A7003S, A7N01S, etc., and an Al alloy material subjected to aging treatment are preferable.
[0068]
(Example)
(Offset collision test)
Bumper reinforcement with the cross-sectional structure of the present invention shown in FIG. 1 (rectangular hollow shape, wall thickness 4 mm, length 1300 mm, central straight part 560 mm, bending end displacement 100 mm (vehicle rear side), height 70 mm, front wall width 50mm, wall width W_a+ W_b80 mm) and a welded rectangular hollow stay made of steel (wall thickness 1 mm, length 150 mm, width 70 mm, height 70 mm), an offset collision test (15 km / hr) was performed. As the bumper reinforcing material, an A7003SAl alloy extruded shape material subjected to aging treatment with a proof stress of 305 MPa was used.
[0069]
For comparison, the bumper reinforcement of the conventional sun-shaped cross section shown in FIG. 9 (the front wall and the intermediate wall are connected without crossing the connection between the intermediate wall and the side wall and the front wall and reducing the wall width of the front wall. In the example in which the concave portion is not formed in the connecting portion with the head and the section is simply a square section, the offset collision test was performed under the same conditions as in the example of the invention.
[0070]
The outline of this 15km / hr static offset collision test is shown in Fig. 7 or Fig. 10. 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, 12 is a stay 19 provided on the back surface of the curved portion, and is provided on the front surface of the bumper reinforcing material 1. The part that collides with the reinforcement 1 (40%) is an offset barrier.
[0071]
(1) Maximum load (KN), (2) Energy absorption (J) at displacement of 100mm, (3) for each bumper reinforcement of the invention and comparative examples measured during the barrier crash test and offset crash test ▼ Table 1 shows the impact velocity (km / hr) and deformation state that can be absorbed at a displacement of 100 mm.
[0072]
Furthermore, FIG. 8 shows the load-displacement relationship at the time of an offset collision (at the time of collapse) between the inventive example and the comparative example. FIG. 7 shows an actual linear deformation state of the invention example, and FIG. 10 shows a deformation state with actual bending of the comparative example.
[0073]
As is clear from these facts, the invention example is prevented from bending as shown in FIG. 10 as shown in FIG. 7, and has a constant displacement as shown in Table 1 and FIG. 8 (the solid line is the invention example and the dotted line is the comparative example). Within this amount, it is possible to increase the collision energy absorption performance (maximum load, energy, and absorbable collision speed) during offset collision. The results of this offset collision test also mean that the barrier collision test shows excellent collision energy absorption performance (maximum load, energy, absorbable collision speed).
[0074]
On the other hand, in the comparative example, a buckling portion 21 and a bend as shown in FIG. 11 occur in the actual deformation state at the time of the offset collision, and as shown in Table 1 and FIG. Is significantly inferior to the inventive examples.
[0075]
Therefore, the effects of the present invention and the significance of the configuration of the present invention are clear from the results of these examples.
[0076]
[Table 1]

[0077]
【The invention's effect】
According to the present invention, in the case of an Al alloy bumper reinforcing material having curved portions at both ends, the bumper reinforcing material having improved collision energy absorption performance at the time of offset collision without impairing the light weight advantage of adopting the Al alloy Can be provided.
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 an embodiment of a bumper reinforcing material according to the present invention.
FIG. 2 is a plan view of the bumper reinforcing material according to the present invention shown in FIG.
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 the deformation of the bumper reinforcing material of the present invention after an offset collision.
FIG. 8 is an explanatory view 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 after offset collision of a conventional bumper reinforcing material.
[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: Recessed part, 10, 11: Inclined wall, 12: stay,

Claims (2)

It is a bumper reinforcement made of an aluminum alloy hollow shape, having curved portions toward the vehicle body at both ends, and supported by a bumper stay on the back of the curved portion, wherein the hollow shape is opposed to the collision direction. The front wall, the rear wall located behind, and the side walls connected perpendicularly to these walls are configured in a substantially rectangular cross section, and an intermediate wall is provided in parallel with the side walls so as to have a plurality of hollow portions in the cross section. The intermediate wall and the side wall and the front wall are connected to each other by an inclined wall so as to reduce the wall width of the front wall. Bending closer to the center of the bumper reinforcement when subjected to bending deformation load at the time of offset collision, increasing the bending buckling strength of the front wall by reducing the width-thickness ratio of the front wall The buckling strength Bumper reinforcement having excellent offset collision properties, characterized in that is larger than the crushing strength of the side of the bumper reinforcement curved portion being more supported.   The bumper reinforcement excellent in offset collision property according to claim 1, wherein the bumper stay and the bumper reinforcement are integrally joined in advance.

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