WO2010113894A1

WO2010113894A1 - Vehicle bumper beam

Info

Publication number: WO2010113894A1
Application number: PCT/JP2010/055603
Authority: WO
Inventors: 拓則山口; 知和中川; 雅男杵渕; 徹橋村; 美枝橘
Original assignee: 株式会社神戸製鋼所
Priority date: 2009-03-30
Filing date: 2010-03-29
Publication date: 2010-10-07
Also published as: JP2010228685A

Abstract

A vehicle bumper beam which is lightweight and can more reliably transmit an impact load to side members. A bumper beam (1) is configured in such a manner that a cross-section thereof perpendicular to the longitudinal direction thereof is closed by a front flange (2), a rear flange (3), and webs (4, 5). Webs (4-6) are formed in such a manner that the plate thickness thereof is gradually reduced from the portions at which the webs are connected to the front flange (2) up to the intermediate portions of the webs between the front flange (2) and the rear flange (3) and that the plate thickness is constant from the intermediate portions up to the portions at which the webs are connected to the rear flange (3). The plate thickness of the front flange (2) is greater than the plate thickness of the webs (4-6) at portions at which the webs are connected to the rear flange (3).

Description

Bumper beam for vehicles

The present invention relates to a vehicle bumper beam attached to a vehicle such as an automobile.

As schematically shown in FIG. 1, the main role of the bumper beam 101 attached to the vehicle 100 is to deform itself and absorb energy when it collides with the obstacle 200, and transmit the collision load to the left and right side members 102. Then, the energy at the time of collision is absorbed by deforming the side member 102. That is, the bumper beam itself is deformed at the time of collision, and the deformation of the cabin 103 is suppressed by deforming the side member 102, so that the occupant can be protected from impact. From such a viewpoint, a bumper beam capable of more effectively absorbing shock is demanded.
On the other hand, it is desired to reduce the weight of the bumper beam from the viewpoint of reducing the weight of the vehicle and improving the controllability of the vehicle. That is, improvement in fuel efficiency of vehicles is desired due to stricter regulations on exhaust gas, and demands for weight reduction of vehicles are becoming strict. Further, since the bumper beam is mounted at a position far away from the center of gravity of the vehicle body, when the weight of the bumper beam increases, the inertia moment of the vehicle increases, which adversely affects the maneuverability.

From the viewpoints of impact absorption at the time of collision and weight reduction as described above, those described in Patent Documents 1 to 4 are known as bumper beams in which the cross-sectional shape is devised.

In Patent Document 1, a connecting wall portion that connects the front wall portion and the rear wall portion is formed so that the second moment of section gradually decreases from the front wall portion toward the rear wall portion, and the rear portion is bent via the bent portion. A bumper reinforce connected to the wall is disclosed. According to this configuration, it is possible to absorb an impact acting on the bumper lean force without providing an impact absorbing member between the bumper lean force and the vehicle body frame.

In Patent Document 2, a bumper reinforcement for a vehicle (bumper reinforcement) in which the thickness of the connecting portion of the front flange, the upper web, the intermediate web, and the lower web is made thicker than the thickness of the portion other than the connecting portion. ) Is disclosed. According to this configuration, a lightweight configuration and a large energy absorption amount can be achieved.

In bumper reinforcement which is disclosed in Patent Document 3, an upper thick portion protrudes upward from the vehicle body at the front end portion of the upper wall portion which is the upper end portion of the front wall portion. The wall thickness is greater than the wall thickness of the front wall. In addition, a lower thick portion protrudes from the front end of the lower wall portion, which is the lower end portion of the front wall portion, toward the lower side of the vehicle body, and the thickness of the lower thick portion is larger than the thickness of the front wall portion. . According to this configuration, the side member can be reliably axially compressed and deformed at the time of an offset collision.

In the vehicle bumper beam disclosed in Patent Document 4, the lateral wall portion that connects the front wall portion and the rear wall portion has a wall thickness in the vicinity of the central portion of the bumper beam that is connected to the front wall portion or the rear wall portion. It is formed to be thinner than the wall thickness in the vicinity. According to this configuration, the buckling deformation of the bumper beam can be stably generated.

Japanese Unexamined Patent Publication No. 2005-306294 Japanese Unexamined Patent Publication No. 2003-182481 Japanese Unexamined Patent Publication No. 2005-212587 Japanese Unexamined Patent Publication No. 2000-318549

As described above, although a bumper beam having a light weight and high shock absorption has been proposed, its characteristics are not sufficient, and further reduction in weight of the bumper beam and improvement in shock absorption are desired. In particular, if the bumper beam bends or breaks at the time of a collision, there is a fear that the transmission of impact load from the bumper beam to the side member may be insufficient. In this case, the side member is not sufficiently deformed, and the impact energy cannot be sufficiently absorbed.

In view of the above circumstances, an object of the present invention is to provide a vehicle bumper beam that is lightweight and capable of more reliably transmitting an impact load to a side member.

The vehicle bumper beam according to the present invention has the following features in order to achieve the above object. That is, the vehicular bumper beam of the present invention includes the following features alone or in combination.

In order to achieve the above object, the first feature of the vehicle bumper beam according to the present invention is a plate-like front flange, a plate-like flange that is disposed opposite the front flange and connected to the front end of the side member. A longitudinal flange closed by the front flange, the rear flange, and the plurality of webs, the rear flange, and a plurality of plate-shaped webs connecting the front flange and the rear flange. A vehicular bumper beam configured to have a cross section, wherein the thickness of the web gradually decreases from a connection portion between the web and the front flange to an intermediate portion between the front flange and the rear flange. In addition, the intermediate portion is constant from the connecting portion to the rear flange, and the plate thickness of the front flange is the web and the rear flange. Wherein is greater than the plate thickness of the web at the connecting portion between.

According to this configuration, the buckling load in the vicinity of the front flange of the web can be increased. Thereby, when an impact load acts on the front flange, the buckling of the web in the vicinity of the front flange can be suppressed.
Here, it has been found by the present inventor that the stress generated in the web at the time of the collision becomes the largest at the connection portion with the front flange after the collision and becomes smaller as it approaches the rear flange. For this reason, as described above, the thickness of the web is gradually decreased from the connecting portion with the front flange toward the intermediate portion, thereby preventing the occurrence of buckling while suppressing an increase in weight.
Thus, the buckling of the web is prevented, so that the compressive deformation of the bumper beam in its cross-sectional shape is suppressed. Thereby, the bending strength of the bumper beam can be maintained at the time of collision. As a result, the bending deformation of the bumper beam at the time of collision is suppressed, and the impact load can be more reliably transmitted to the side member.
Further, the inventor of the present application has found that in the initial buckling after the collision, the entire front flange is deformed so as to bend. Therefore, it is possible to effectively suppress the deformation of the cross-sectional shape of the bumper beam by making the plate thickness of the front flange larger than the plate thickness of the web at the connection portion with the rear flange as in the above configuration. Become.

A second feature of the bumper beam for a vehicle according to the present invention is that the length of the portion where the thickness of the web gradually decreases in the direction from the front flange to the rear flange is the web in the same direction. 30 to 50% of the total length.

According to this configuration, the length of the portion where the web thickness is gradually reduced is set to 30% or more of the total length of the web, thereby ensuring the occurrence of buckling in the portion where the web thickness is constant. Can be prevented.
Moreover, the increase in the weight of a bumper beam can be suppressed by making the length of the part where the plate | board thickness of a web reduces gradually into 50% or less of the full length of a web.

The third feature of the vehicle bumper beam according to the present invention is that the thickness of the web at the connection portion between the web and the front flange is such that the web plate at the connection portion between the web and the rear flange. It is 120 to 200% of the thickness.

According to this configuration, the thickness of the web at the connecting portion between the web and the front flange is set to 120% or more of the thickness of the web at the connecting portion between the web and the rear flange, so that in the vicinity of the front flange of the web. The occurrence of buckling can be prevented.
Moreover, the increase in the weight of the bumper beam can be suppressed by setting the thickness of the web at the connecting portion between the web and the front flange to 200% or less of the thickness of the web at the connecting portion between the web and the rear flange. .

According to a fourth aspect of the vehicle bumper beam of the present invention, the web includes an upper end web connecting the upper end of the front flange and the upper end of the rear flange, the lower end of the front flange, and the rear flange. A lower end web that connects the lower end of the front flange, and an intermediate web that connects the vertical intermediate portion of the front flange and the vertical intermediate portion of the rear flange, the plate thickness of the upper end web and the lower end web being And gradually decreasing from the connecting portion with the front flange to the intermediate portion between the front flange and the rear flange, and constant from the intermediate portion to the connecting portion with the rear flange, The plate thickness of the upper end web in the connecting portion is equal to the plate thickness of the lower end web, and the plate thickness of the upper end web in the connecting portion with the rear flange and the Equal to the thickness of the end web and the upper end is that equal the web and the length from the front flange in a direction toward the rear flange of the lower end portion of the thickness of the web gradually decreases.

According to this configuration, when an impact load is applied to the front flange, the buckling of the upper end web and the lower end web in the vicinity of the front flange can be delayed, and the load bearing capacity of the bumper beam can be further increased.

According to the present invention, the bumper beam capable of more reliably transmitting the impact load to the side member can be configured with a light weight.

It is a schematic diagram which shows the deformation | transformation state of the motor vehicle front part at the time of a motor vehicle collision. 1 is a schematic perspective view showing a bumper beam 1 according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line AA of the bumper beam shown in FIG. 2. It is a figure which shows the analysis result about the relationship between the weight and load-bearing force in the bumper beam of embodiment of this invention and a conventional structure. (A)-(c) is a schematic diagram which shows the cross-sectional deformation | transformation aspect at the time of the collision in a conventional structure in time series. (A) is a schematic diagram which shows the cross-sectional deformation | transformation aspect at the time of the collision in a conventional structure, (b) is a schematic diagram which shows the cross-sectional deformation | transformation aspect at the time of the collision in embodiment of this invention. (A) is a figure for demonstrating a 3 point | piece bending analysis method, (b) is a figure for demonstrating the relationship between an indenter pushing amount and reaction force.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 2 is a schematic perspective view showing the bumper beam 1 according to the embodiment of the present invention. FIG. 3 is a schematic cross-sectional view taken along the line AA of the bumper beam 1 shown in FIG. 2. The AA cross section is a cross section taken along a plane perpendicular to the longitudinal direction of the bumper beam 1.
In the following, the direction indicated by arrow X in FIG. 2 is the vehicle width direction, the direction indicated by arrow Y is the front-rear direction (Y1: forward, Y2: rearward), and the direction indicated by arrow Z is the vertical direction (Z1: upward, Z2: downward) ).

(Outline of bumper beam 1)
As shown in FIG. 2, the bumper beam 1 according to the embodiment of the present invention is attached to the front end portion of the side member 10 extending in the front-rear direction of the vehicle so as to extend in the width direction of the vehicle. The bumper beam 1 is formed by extruding an aluminum alloy.

As shown in FIGS. 2 and 3, the bumper beam 1 includes a front flange 2 positioned in front of the vehicle, a rear flange 3 positioned in the rear of the vehicle relative to the front flange 2, a front flange 2 and a rear flange 3. 3 webs to be connected (upper end web 4, lower end web 5, intermediate web 6). These flanges and webs are each formed in a plate shape.

(Configuration of each part)
The front flange 2 is a plate-like portion that forms the front surface (a surface that receives an impact load) of the bumper beam 1.
The rear flange 3 is a plate-like portion that forms the rear surface of the bumper beam 1, and is disposed substantially parallel to the front flange 2 so as to face the front flange 2. The rear flange 3 is fixed to the front end of the side member 10.
In the present embodiment, as shown in FIG. 2, the front flange 2 and the rear flange 3 are formed as slightly curved plates, but are not limited to this case, and may be flat plates or the like.

The upper end web 4 is a plate-like portion that forms the upper surface of the bumper beam 1, and connects the upper end of the front flange 2 and the upper end of the rear flange 3.
The lower end web 5 is a plate-like portion that forms the lower surface of the bumper beam 1, and connects the lower end of the front flange 2 and the lower end of the rear flange 3.
The intermediate web 6 is a plate-like portion provided in a closed space surrounded by the front flange 2, the rear flange 3, the upper end web 4, and the lower end web 5. The vertical center of the flange 3 is connected.

These upper end web 4, lower end web 5, and intermediate web 6 are all arranged so as to be substantially orthogonal to the front flange 2 and the rear flange 3. The upper end web 4, the lower end web 5, and the intermediate web 6 are proportionally reduced in thickness from the connecting portion with the front flange 2 to a predetermined position in the front-rear direction toward the rear, and from the predetermined position to the rear flange. 3 is formed so that the plate thickness is constant up to the connection part.

Specifically, the upper end web 4, the lower end web 5, and the intermediate web 6 are configured as follows.
In the cross section perpendicular to the longitudinal direction of the bumper beam 1 (the cross section shown in FIG. 3), the upper surface 4 a of the upper end web 4 (the upper end surface of the bumper beam 1) extends linearly in a direction substantially perpendicular to the front flange 2. ing. On the other hand, the lower surface 4b of the upper end web 4 is inclined so as to be positioned upward as it goes rearward to a predetermined position P1 that is a predetermined length (Lv1) away from the front flange 2. The lower surface 4b of the upper end web 4 is bent at the predetermined position P1 and extends substantially parallel to the upper surface 4a of the upper end web 4 from the predetermined position P1 to the rear flange 3.
In the cross section perpendicular to the longitudinal direction of the bumper beam 1 (the cross section shown in FIG. 3), the lower surface 5 b of the lower end web 5 (the lower end surface of the bumper beam 1) is linear in a direction substantially perpendicular to the front flange 2. It extends to. On the other hand, the upper surface 5a of the lower end web 5 is inclined so as to be positioned downward as it goes backward to a predetermined position P2 that is a predetermined length (Lv2) away from the front flange 2. The upper surface 5a of the lower end web 5 is bent at the predetermined position P2 and extends substantially parallel to the lower surface 5b of the lower end web 5 from the predetermined position P2 to the rear flange 3.
In the cross section perpendicular to the longitudinal direction of the bumper beam 1 (the cross section shown in FIG. 3), the intermediate web 6 is substantially perpendicular to the front flange 2 and passes through the plane S ( Hereinafter, it has a symmetrical shape with respect to the symmetry plane S). Then, the upper surface 6a of the intermediate web 6 is inclined so as to be positioned downward as it goes rearward to a predetermined position P3 that is a predetermined length (Lv3) away from the front flange 2. The upper surface 6a of the intermediate web 6 is bent at the predetermined position P3 and extends from the predetermined position P3 to the rear flange 3 substantially in parallel with the symmetry plane S. Further, the lower surface 6b of the intermediate web 6 is inclined so as to be located upward as it goes rearward to a predetermined position P3 that is a predetermined length (Lv3) away from the front flange 2. The lower surface 6b of the intermediate web 6 is bent at the predetermined position P3 and extends substantially parallel to the symmetry plane S from the predetermined position P3 to the rear flange 3.
In the present embodiment, the bumper beam 1 has a symmetrical shape with respect to the symmetry plane S.

Further, in the bumper beam 1 according to this embodiment, the predetermined lengths Lv1, Lv2, and Lv3 in the upper end web 4, the lower end web 5, and the intermediate web 6 are all equal. Here, when Lv1 = Lv2 = Lv3 = Lv, the length Lv is configured to be 40% of the distance Lw between the front flange 2 and the rear flange 3.

Here, the thickness of the connecting portion (the thickest portion) of the upper end web 4 with the front flange 2 is ta1, and the thickness of the connecting portion with the rear flange 3 is tb1. Further, the thickness of the connecting portion (the thickest portion) of the lower end web 5 with the front flange 2 is ta2, and the thickness of the connecting portion with the rear flange 3 is tb2. Further, the thickness of the connecting portion (the thickest portion) of the intermediate web 6 with the front flange 2 is ta3, and the thickness of the connecting portion with the rear flange 3 is tb3.
The front flange 2 is formed so that the plate thickness tf is larger than any of the above-described tb1, tb2, and tb3.
Specifically, in the bumper beam 1 according to the present embodiment, the plate thicknesses tb1, tb2, and tb3 of the connecting portions between the upper end web 4, the lower end web 5, and the intermediate web 6 and the rear flange 3 are all equal. . Here, when tb1 = tb2 = tb3 = tb, the plate thickness tf of the front flange 2 is configured to be about 1.5 times the plate thickness tb.

Further, in the bumper beam 1 according to the present embodiment, the plate thicknesses ta1, ta2, and ta3 of the connecting portions of the upper end web 4, the lower end web 5, and the intermediate web 6 and the front flange 2 are all equal. Has been. Here, when ta1 = ta2 = ta3 = ta, the plate thickness ta is configured to be about 1.9 times the plate thickness tb.

(Comparison analysis with conventional structure)
With respect to the bumper beam 1 according to the present embodiment and the bumper beams having the following three types of conventional structures, the relationship between the weight of the bumper beam and the load bearing capacity was calculated by performing a three-point bending analysis. FIG. 4 shows the analysis result.
The three-point bending analysis is performed as shown in FIG. That is, both ends of the bumper beam α1 are simply supported from the rear flange side by the support portion α2, and the arc surface of the indenter α3 is brought into contact with the bumper beam α1 from the front flange side in the middle of the two support portions α2. Then, the reaction force acting on the indenter when the indenter is moved in the direction perpendicular to the longitudinal direction of the bumper beam (the arrow direction in FIG. 7A) is obtained. The relationship between the amount of movement of the indenter (the amount of pressing into the bumper beam) and the reaction force acting on the indenter is generally as shown in FIG. In this analysis, the maximum reaction force in the graph shown in FIG. 7B is taken as the load bearing capacity of the bumper beam. Here, in FIG. 7B, the reaction force turns from increasing to decreasing as the indenter push-in amount increases, which is due to the buckling of the web. Therefore, it is understood that buckling needs to be delayed in order to increase the maximum value of the reaction force (that is, the load bearing capacity).

The shape of the bumper beam of the conventional structure in this analysis is such that the shapes of the upper end web 4, the lower end web 5 and the intermediate web 6 in the bumper beam 1 according to the present embodiment have a constant plate thickness in the front-rear direction (that is, FIG. 5 (a), a web having a uniform thickness on the entire surface is used). Specifically, the bumper beams having three types of conventional structures are as follows: (a) All webs have a uniform thickness 1.0 times the thickness tb in the vicinity of the rear flanges of the webs 4 to 6 according to this embodiment. (B) having a uniform plate thickness of 1.2 times, and (c) having a uniform plate thickness of 1.7 times. In the bumper beam having the conventional structure, the outer dimensions of the bumper beam and the plate thickness of the front and rear flanges are the same as those of the bumper beam 1 according to the present embodiment.

In FIG. 4, the weight and load bearing capacity of the bumper beam 1 according to the present embodiment are set to 100%, and the weight and load bearing capacity of three types of conventional bumper beams are shown in relative comparison.
As shown in FIG. 4, the bumper beam 1 according to the present embodiment is 10% or more superior in load resistance compared to a bumper beam having a conventional structure and having the same weight.
In addition, it can be seen that the bumper beam 1 according to the present embodiment can be reduced in weight by about 15% as compared with the bumper beam having the same load resistance as that of the conventional structure.

(Effect of bumper beam 1)
As described above, the bumper beam 1 according to the present embodiment includes the plate-shaped front flange 2, the plate-shaped rear flange 3 that is disposed to face the front flange 2 and is connected to the front end of the side member. , Three plate-like webs 4 to 6 (upper end web 4, lower end web 5, intermediate web 6) for connecting the front flange 2 and the rear flange 3 are provided. The bumper beam 1 is configured such that the longitudinal vertical cross section (the cross section shown in FIG. 3) is a cross section closed by the front flange 2, the rear flange 3, the upper end web 4, and the lower end web 5.
Further, the thickness of the webs 4 to 6 gradually decreases from the connecting portion with the front flange 2 to the intermediate portion between the front flange 2 and the rear flange 3, and the connecting portion with the rear flange 3 from the intermediate portion. Each is formed so as to be constant.
Further, the plate thickness of the front flange 2 is larger than the plate thickness of the webs 4 to 6 at the connection portion with the rear flange 3.

According to this configuration, the buckling load in the vicinity of the front flange 2 of the webs 4 to 6 can be increased. Thereby, when an impact load is applied to the front flange 2, buckling of the webs 4 to 6 in the vicinity of the front flange 2 can be suppressed.

The inventor of the present application has found the following about the deformation state at the time of collision of the bumper beam having the conventional structure. FIG. 5 is a schematic diagram showing a cross-sectional deformation state of a bumper beam 1 ′ having a conventional structure at the time of a collision. FIG. 5A is a longitudinal vertical sectional shape of the bumper beam 1 ′ before the collision, and FIG. The cross-sectional shape of the bumper beam 1 ′ immediately after the occurrence of buckling, (c) shows the cross-sectional shape in which the width in the front-rear direction of the bumper beam 1 ′ is reduced by buckling.
That is, as shown in FIGS. 5A and 5B, in the bumper beam 1 ′ having a conventional structure, when receiving an impact load from the front surface, the front flange 2 ′, the upper end web 4 ′, and the lower end web 5 ′. Are deformed almost simultaneously. At this time, the front flange 2 'is deformed over the entire vertical width. Further, when a moment is generated in the corner 1a ′ of the bumper beam 1 ′ (see FIG. 6), the upper end web 4 ′ and the lower end web 5 ′ are buckled and deformed so as to be bent outward in the vicinity of the front flange 2 ′. . On the other hand, in the intermediate web 6 ′, moments in opposite directions are generated on both the upper and lower sides. Therefore, these moments are offset and bending deformation is unlikely to occur. Thereafter, as shown in FIG. 5C, the section of the bumper beam 1 ′ is crushed by buckling the vicinity of the front flange 2 ′ of the intermediate web 6 ′. That is, the bumper beam 1 ′ starts compressive deformation in the longitudinal direction of the vehicle. As a result, the bending load resistance decreases.

In this respect, in the bumper beam 1 according to the present embodiment, the thickness of the webs 4 to 6 is gradually increased toward the connecting portion of the front flange 2, so that the buckling of the webs 4 to 6 in the vicinity of the front flange 2 is performed. Can be suppressed. Furthermore, since the thickness of the entire webs 4 to 6 is not uniformly increased, an increase in the weight of the bumper beam 1 can be suppressed.

Thus, the buckling of the webs 4 to 6 is prevented, so that the compressive deformation of the bumper beam 1 is suppressed, whereby the bending strength of the bumper beam 1 at the time of collision can be maintained. As a result, the bending deformation of the bumper beam 1 at the time of the collision is suppressed, and the impact load can be more reliably transmitted to the side member 10.

Furthermore, as shown in FIG. 5, it is known that the entire front flange 2 is deformed to bend in the initial stage after the collision. Therefore, like the bumper beam 1 of the present embodiment, the plate thickness tf of the front flange 2 is configured to be larger than the plate thickness tb of the webs 4 to 6 at the connection portion with the rear flange 3, The bending of the front flange 2 is suppressed, and the deformation of the bumper beam 1 can be suppressed more effectively (without excessively increasing the weight).

In the bumper beam 1 according to the present embodiment, the portion of the webs 4 to 6 where the plate thickness gradually decreases (hereinafter referred to as the plate thickness changing portion) is the vehicle longitudinal direction (from the front flange 2 to the rear flange 3). The length in the direction of heading) is 40% of the total length of the webs 4 to 6 in the same direction.

Here, when the lengths Lv1, Lv2, and Lv3 of the plate thickness changing portions in the upper end web 4, the lower end web 5, and the intermediate web 6 are smaller than 30% of the interval Lw between the front flange 2 and the rear flange 3, respectively. Immediately after the collision, the connecting portion between the front flange 2 and the webs 4 to 6 may rotate. As a result, there is a possibility that buckling may occur in a portion where the thickness of the webs 4 to 6 is constant (hereinafter referred to as a uniform thickness portion).
For example, as shown in FIG. 6, when an impact load is applied to the front flange 2, a counterclockwise moment is generated at the corner 1 a at the upper end of the bumper beam 1. At this time, if the length Lv1 of the thickness change portion in the upper end web 4 is smaller than 30% of the interval Lw, only the thick portion remains at a right angle while maintaining the right angle as shown in FIG. It becomes easy to rotate and may cause buckling deformation in a narrow range of the upper end web 4 (the deformation state is indicated by a two-dot chain line in FIG. 6A). On the other hand, as shown in FIG. 6B, according to the present embodiment, the length Lv1 of the thickness change portion in the upper end web 4 is 30% or more of the interval Lw. Since the entire upper end web 4 is deformed (the deformed state is indicated by a two-dot chain line in FIG. 6B), the load required for the deformation becomes large. That is, the load bearing capacity of the bumper beam 1 is increased.

On the other hand, if the lengths Lv1, Lv2, and Lv3 of the plate thickness changing portion are larger than 50% of the interval Lw, the same weight as that of the webs 4 to 6 with the same thickness is obtained, and the weight is reduced. This reduces the effect of increasing the load bearing capacity. That is, even if the thickness of the web is increased in a range larger than 50% of the distance Lw, the increase in the load bearing capacity is reduced, but the weight of the web is increased. Therefore, it is desirable that the lengths Lv1, Lv2, and Lv3 of the thickness change portions in 4 to 6 of the upper end web 4, the lower end web 5, and the intermediate web 6 are 50% or less of the interval Lw.

In this respect, according to the configuration of the bumper beam 1 according to the present embodiment, the lengths Lv1, Lv2, and Lv3 are 40% of the interval Lw, so that buckling occurs in the uniform thickness portion of the webs 4 to 6. And the load bearing capacity can be significantly increased without excessively increasing the weight.

Further, in the bumper beam 1 according to the present embodiment, the plate thicknesses ta1, ta2, and ta3 of the connection portions of the upper end web 4, the lower end web 5, and the intermediate web 6 and the front flange 2 are the rear webs 4 to 6, respectively. It is 190% of the plate thickness tb1, tb2, tb3 of the connecting portion with the side flange 3.

Here, when the plate thickness of the connection portion between the webs 4 to 6 and the front flange 2 is smaller than 120% of the plate thickness of the connection portion between the webs 4 to 6 and the rear flange 3, the front side of the webs 4 to 6 The effect of preventing buckling in the vicinity of the flange 2 is reduced, but if it exceeds 200%, the effect of reducing the weight cannot be obtained significantly.
In this regard, according to the configuration of the bumper beam 1 according to the present embodiment, the plate thicknesses ta1, ta2, and ta3 of the connecting portions between the webs 4 to 6 and the front flange 2 are respectively the web 4 to 6 and the rear flange 3. Since it is 190% of the plate thickness tb1, tb2, tb3 of the connecting portion, it is possible to prevent buckling from occurring in the vicinity of the front flange 2 of the webs 4-6. In addition, according to the configuration of the bumper beam 1 according to the embodiment, it is possible to significantly increase the load bearing capacity without excessively increasing the weight.

Further, in the bumper beam 1 according to the present embodiment, the plate thicknesses ta1 and ta2 of the connecting portions of the upper end web 4, the lower end web 5 and the front flange 2 are equal. Moreover, plate | board thickness tb1, tb2 of the connection part of the upper end web 4, the lower end web 5, and a rear side flange is equal. Further, the lengths Lv1 and Lv2 of the thickness change portions in the upper end web 4 and the lower end web 5 are equal. That is, ta1 = ta2, tb1 = tb2, and Lv1 = Lv2.

According to this configuration, when an impact load is applied to the front flange 2, the buckling of the upper end web 4 and the lower end web 5 in the vicinity of the front flange 2 can be delayed, and the load bearing force of the bumper beam 1 can be further increased. it can.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

(Modification)
The number of webs provided between the front flange 2 and the rear flange 3 is not limited to the case of three sheets at the upper end, the lower end, and the center thereof. It suffices that at least two or more are provided so that the longitudinal cross section of the bumper beam is a closed cross section.

In the bumper beam 1 of the present embodiment, the thickness of the connecting portion between the webs 4 to 6 and the front flange 2, the thickness of the connecting portion with the rear flange 3, and the length of the thickness changing portion are as follows. Although it was the same also about all of 6, it is not restricted to this case, Each may differ for every web.

This application is based on a Japanese patent application filed on March 30, 2009 (Japanese Patent Application No. 2009-080829), the contents of which are incorporated herein by reference.

The present invention can be used as a bumper beam attached to a vehicle in order to protect an occupant from an impact.

1 Bumper Beam 2 Front Flange 3 Rear Flange 4 Upper Web 5 Lower Web 6 Intermediate Web 10 Side Member

Claims

A plate-like front flange, a plate-like rear flange disposed opposite to the front flange and connected to the front end of the side member, and a plurality of plate-like members connecting the front flange and the rear flange A vehicle bumper beam configured to have a longitudinal vertical section closed by the front flange, the rear flange, and a plurality of the webs,
The thickness of the web gradually decreases from the connection portion between the web and the front flange to the intermediate portion between the front flange and the rear flange, and from the intermediate portion to the connection portion with the rear flange. Constant,
A vehicular bumper beam in which a plate thickness of the front flange is larger than a plate thickness of the web at a connection portion between the web and the rear flange.
The length in the direction from the front flange to the rear flange of the portion where the thickness of the web gradually decreases is 30 to 50% of the total length of the web in the same direction. Bumper beam for vehicles.
The thickness of the web at the connecting portion between the web and the front flange is 120 to 200% of the thickness of the web at the connecting portion between the web and the rear flange. The bumper beam for vehicles described in 1.
An upper end web connecting the upper end of the front flange and the upper end of the rear flange, a lower end web connecting the lower end of the front flange and the lower end of the rear flange, and the vertical direction of the front flange An intermediate web connecting the intermediate part and the intermediate part in the vertical direction of the rear flange,
The plate thickness of the upper end web and the lower end web gradually decreases from the connection portion with the front flange to the intermediate portion between the front flange and the rear flange, and the connection from the intermediate portion to the rear flange. Is constant up to
The plate thickness of the upper end web and the plate thickness of the lower end web at the connection portion with the front flange are equal, and the plate thickness of the upper end web and the plate thickness of the lower end web at the connection portion with the rear flange are equal. 2. The vehicle bumper beam according to claim 1, wherein lengths of portions of the upper end web and the lower end web that gradually decrease in thickness are equal in a direction from the front flange toward the rear flange.