JP3992408B2 - Energy absorbing member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an energy absorbing member, for example, an energy absorbing member that is used as a bumper reinforcing material for automobiles and has excellent energy absorbing performance during low-speed collision.
[0002]
[Prior art]
In recent years, it has been reduced in weight for outer panels and structural materials or parts of transportation equipment such as automobiles, ships, and trains, or for structural materials or parts of household electrical appliances, and for building structural members such as roofing materials. From the viewpoint, use of an aluminum (Al) alloy is expected.
[0003]
One of the uses of aluminum alloys is energy absorbing members such as automobile bumper reinforcement (reinforcement) materials. Some energy absorbing members are molded as hollow sections having a rectangular cross section. There are various types of energy absorbing members, but energy absorbing members used as bumper reinforcements, etc., receive impact energy from the shape of the material when energy is applied from the outside due to automobile collisions, etc. Absorbs by plastic deformation. This makes it possible to prevent other members from being damaged as much as possible.
[0004]
An example of the usage state of such an energy absorbing member is shown in FIGS. These drawings are one of the performance evaluation test methods for bumpers for automobiles, and are schematic diagrams showing the test methods whose details are defined in Part 581 standard of NHTSA in the United States. In the test methods shown in FIGS. 6 and 7, the damage of the automobile is evaluated by colliding a bumper 62 having a predetermined shape and weight with a bumper 62 existing at the front end of the automobile 61 at a constant speed. . Normally, the bumper 62 is covered with a bumper cover, and the bumper reinforcement and the cushioning material are often not visible from the outside. However, when the bumper cover is removed, the bumper reinforcement as an energy absorbing member is housed inside. Often has become. When the striker 63 collides with the bumper 62 in this state, the bumper reinforcing member has one location in the longitudinal center (see FIG. 2A) or two locations corresponding to the width of the striker 63 (FIG. 2 ( In b)), plastic bending deformation occurs. By bending deformation of these parts, it is possible to absorb energy at the time of collision and reduce damage to other parts of the vehicle body.
[0005]
[Problems to be solved by the invention]
The energy absorbing member as described above is required to increase the bending rigidity of the shape member and the energy absorption amount at the time of bending while keeping the weight small. Attempts to increase these characteristics by devising the cross-sectional shape are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 8-80789 and 9-109805. Attempts have also been made to change the material of the energy absorbing member to one having higher strength and stickiness.
[0006]
However, in recent years, automobiles have been required to further reduce the weight of the vehicle body from the viewpoint of reducing fuel consumption in order to prevent global warming. Increase is demanded, and the current energy absorbing member does not sufficiently satisfy these requirements.
[0007]
Accordingly, an object of the present invention is to further review the cross-sectional shape of the hollow shape member and provide an energy absorbing member that is lighter and has increased bending rigidity and energy absorption due to bending deformation.
[0008]
[Means for Solving the Problems]
To achieve the above object, the energy absorbing member according to claim 1 includes two upper walls, and two bottom wall portions facing respectively said two upper walls, the two upper walls and two It has two hollow structures composed of three side walls provided between the bottom walls, and is provided from the outside in the direction from the upper wall to the bottom wall provided to the upper wall. In an energy absorbing member that absorbs energy by a load by deformation of a hollow portion, the bottom wall portion and the side wall portion are orthogonal to each other, and each of the upper wall portions swells to the outside of the hollow with the same curvature in any portion. It is an extruded shape made of an aluminum alloy that is curved in the shape of the hollow structure and has no ribs formed inside the hollow structure.
[0009]
According to the first aspect, since the upper wall portion has a curved portion so as to swell outward in the hollow, the bending rigidity of the upper wall portion is improved without increasing the plate thickness, and the upper wall portion is Even when a large load is applied, the upper wall portion serving as a collision surface is unlikely to buckle inside the hollow, and the amount of energy absorption in the energy absorbing member increases. Therefore, the energy absorbing member of claim 1 has a large amount of energy absorption even if it is lightweight. In other words, since the upper wall portion has a curved portion so as to swell outward in the hollow, if the energy absorption amount is the same, there is an advantage that the deformation amount of the energy absorbing member can be suppressed small.
In addition, since it has two upper wall portions that are curved so as to bulge to the outside of the hollow space, it absorbs energy especially when it has a cross-sectional shape in which the width of the bottom wall portion is relatively large compared to the height. The amount is large.
Furthermore, since the energy absorbing member is an extruded shape made of an aluminum alloy, the weight of the member can be reduced, and the member can be manufactured relatively easily.
[0010]
In addition, the energy absorption member of Claim 1 may have arbitrary cross-sectional shapes, and is not restricted to what has a substantially rectangular cross-sectional shape. Further, the upper wall portion and the bottom wall portion do not necessarily have to face each other in parallel. Moreover, the upper wall part, the bottom wall part, and the side wall part do not necessarily need to be configured by one surface, and may be configured by a plurality of surfaces (including both a flat surface and a curved surface) .
[0011]
The energy absorbing member according to claim 2 is provided such that the upper wall portion extends outward beyond a connection portion between the upper wall portion and the side wall portions at both ends of the three side wall portions. It is characterized by being.
[0012]
According to claim 2, since the upper wall portion extends outward beyond the connection portion between the upper wall portion and the side wall portions at both ends of the three side wall portions, the upper wall portion is the side wall portion at the end point thereof. The bending rigidity of the upper wall portion is improved compared to the case where the upper wall portion is connected to the upper wall portion, and the upper wall portion is less likely to buckle at the time of collision, increasing the amount of energy absorption.
[0013]
[0014]
[0015]
The material used in the present invention, the A aluminum alloy, depending on the required characteristics, AA and 1000 system according to the JIS standard, 3000 series, 5000 series, aluminum alloy such as 6000 series or 7000 series is appropriately selected Used. In particular, the present invention, 7000-series aluminum alloy sheet according to JIS standards to no AA is for weight reduction (hereinafter, simply referred to as "7000-series Al alloy plate") is preferably. Further, by using these high strength materials, there is an effect that a bumper or the like can be made thinner.
[0016]
A 7003 aluminum alloy as an example of a 7000 series aluminum alloy is an Al-Zn-Mg-Cu series alloy, and is basically 5.0 to 6.5 wt% Zn and 0.5 to 1.0 Mg. Wt%, Fe 0.35 wt%, Mn 0.3 wt%, Si 0.3 wt%, Cu 0.2 wt%, Cr 0.2 wt%, Ti 0.2 wt% In addition, the remainder contains Al and inevitable impurities. However, even if each component does not necessarily conform to the standard, a change in the component composition is allowed as appropriate. That is, it is permitted to appropriately include other elements according to changes in the component ranges of the above elements and more specific uses and required characteristics.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view of an energy absorbing member used as a bumper reinforcing material for an automobile according to a reference example of the present invention. The energy absorbing member 1 of this reference example is an extruded profile made of a 7000 series Al alloy and has a substantially rectangular hollow structure surrounded by four parts. That is, the energy absorbing member 1 includes an upper wall portion 11 that is curved so as to swell slightly outward (that is, upward), a bottom wall portion 12 that is formed as a flat plate facing the upper wall portion 11, an upper wall portion 11 and A pair of webs (side wall portions) 13 and 14 that are provided between the bottom wall portion 12 and connect these two portions are provided.
[0019]
The upper wall part 11 is composed of three parts: a left end part 11a, a central part 11b, and a right end part 11c. A web 13 is connected to a boundary portion between the left end portion 11a and the central portion 11b, and a web 14 is connected to a boundary portion between the central portion 11b and the right end portion 11c. That is, the left end portion 11a of the upper wall portion 11 extends to the left outer side beyond the connection portion between the upper wall portion 11 and the web 13, and the right end portion 11c of the upper wall portion 11 is extended to the upper wall portion 11 and the web. 14 extends beyond the connection with 14.
[0020]
While the upper wall portion 11 is curved so as to swell outward in the hollow, the bottom wall portion 12 and the webs 13 and 14 are formed as flat plates that are not curved. Moreover, the connection corner | angular part of the bottom wall part 12 and the webs 13 and 14 is made into the comparatively big curvature radius. The webs 13 and 14 are connected to the upper wall portion 11 at an angle of about 110 °, and are connected to the bottom wall portion 12 at an angle of about 90 °.
[0021]
When the energy absorbing member 1 configured as described above is used as a bumper reinforcing material for an automobile, for example, as shown in FIGS. 2A and 2B, the bottom wall of the energy absorbing member 1 formed as a long member. Two support members 21 and 22 are attached in the vicinity of the end of the portion 12, and a cushioning material 24 made of a foam material and a cover material 25 are attached to the upper wall portion 11 side. In such a state, the pendulum-type striker 23 and the energy absorbing member 1 described with reference to FIGS. 6 and 7 collide with each other via the cushioning material 24 and the cover material 25, and the energy absorbing member 1 is mainly bent. When a moment load is applied, a compressive force mainly acts on the upper wall portion 11 in the direction perpendicular to the paper surface, and a tensile stress acts on the lower wall portion 12 in the same manner. Then, the energy absorbing member 1 bends and deforms at one central portion in the longitudinal direction as shown in FIG. 2 (a), or corresponds to the widthwise end of the striker 23 as shown in FIG. 2 (b). Bend and deform at the two locations.
[0022]
At this time, in the energy absorbing member 1 of the present reference example , the upper wall portion 11 is curved so as to swell outward in the hollow, so that the bending rigidity of the upper wall portion 11 is an ordinary energy absorbing member having a rectangular cross section. Therefore, the upper wall portion 11 is less likely to buckle at the time of a collision, so that the amount of energy absorbed by the energy absorbing member 1 is larger than that of a normal plate-shaped upper wall portion.
[0023]
Further, the energy absorbing member 1 of the present reference example has an upper wall portion 11 having a left end portion 11a and a right end portion 11c that extend outward beyond the connection portions with the webs 13 and 14, so Compared with the case where 11 is connected to the webs 13 and 14 at the end points, the bending rigidity of the upper wall portion 11 is large. For this reason, the upper wall portion 11 is unlikely to buckle at the time of a collision, and the energy absorption amount by the energy absorbing member 1 also increases from this point.
[0024]
Next, a description will be given implementation of the present invention. Figure 3 is a cross-sectional view of an energy absorbing member used as a bumper reinforcement of the vehicle according to the embodiment of the present implementation. The energy absorbing member 3 of the present embodiment is a extruded profile made of 7000 series Al alloy, the upper wall region 31, a bottom wall region 32 formed as a flat plate facing the upper wall region 31, top wall A pair of webs (side wall portions) 33 and 34 provided between the region 31 and the bottom wall region 32 and connecting these two regions , and ribs (side wall portions) connecting the upper wall region 31 and the bottom wall region 32 in the middle 35 ) .
[0025]
The upper wall region 31 includes four portions, that is, a left end portion 31a, a left center upper wall portion 31b, a right center upper wall portion 31c, and a right end portion 31d. The left end portion 31a and the left center upper wall portion 31b, and the right center upper wall portion 31c and the right end portion 31d are substantially equal in size and are curved so as to swell independently to the outside of the hollow, The upper wall region 31 as a whole has a shape in which two portions curved so as to swell outward in the hollow are connected to each other, so that the connected portion protrudes into the hollow. A web 33 is connected to the boundary between the left end 31a and the left center upper wall 31b, and a rib 35 is connected to the boundary between the left center upper wall 31b and the right center upper wall 31c. A web 34 is connected to a boundary portion between the right center upper wall portion 31c and the right end portion 31d. That is, the left end portion 31a of the upper wall region 31 is then extended in the left outwardly beyond the connection point of the upper wall region 31 and the web 33, the right end portion 11d of the upper wall region 31 has an upper wall area 31 and the web 34 extends beyond the connection with 34.
[0026]
The bottom wall region 32 is composed of a flat left-side bottom wall portion 32a and a right-side bottom wall portion 32b. A rib 35 is connected to a boundary portion between the left bottom wall portion 32a and the right bottom wall portion 32b.
[0027]
While the upper wall region 31 is curved so as to swell outward in the hollow, the bottom wall region 32, the rib 35, and the webs 33, 34 are formed as flat plates that are not curved. Further, the connecting corner between the bottom wall region 32 and the webs 33 and 34 has a relatively large radius of curvature. The webs 33 and 34 are connected to the upper wall region 31 at an angle of about 110 °, and are connected to the bottom wall region 32 at an angle of about 90 °. The rib 35 is connected to the left center upper wall portion 31b and the right center upper wall portion 31c of the upper wall region 31 at an angle of about 110 °, and is connected to the bottom wall region 32 at an angle of about 90 °. ing.
[0028]
Even when the energy absorbing member 3 configured as described above is used as a bumper reinforcing material for an automobile, the two support members 21 are provided in the vicinity of the end of the bottom wall region 32 as described with reference to FIGS. 22 are attached, and a cushioning material 24 and a cover material 25 made of foam are attached to the upper wall region 31 side. In such a state, the pendulum-type striker 23 and the energy absorbing member 3 described with reference to FIGS. 6 and 7 collide with each other via the cushioning material 24 and the cover material 25, and the energy absorbing member 3 is mainly bent. When a moment load is applied, the energy absorbing member 3 bends and deforms as shown in FIG. 2 (a) or 2 (b).
[0029]
At this time, in the energy absorbing member 3 according to the present embodiment, the upper wall region 31 has two portions that are curved so as to swell outward in the hollow, so that the bending rigidity of the upper wall region 31 is normal. Therefore, the upper wall region 31 is less likely to buckle at the time of collision, so that the amount of energy absorbed by the energy absorbing member 3 is larger than that of a normal plate-shaped upper wall portion. Become. In particular, the energy absorbing member 3 according to the present embodiment is divided into two parts that are curved so that the upper wall region 31 swells to the outside of the hollow, so that the width l of the bottom wall region 32 (see FIG. 3). In the case where the cross-sectional shape is relatively large compared to the height, there is an advantage that the energy absorption amount is larger than that of the energy absorbing member 1 of the reference example .
[0030]
Furthermore, the energy absorbing member 3 according to the present embodiment has the upper wall region 31 having a left end portion 31a and a right end portion 31d that extend outward beyond the connection portions with the webs 33 and 34. The bending rigidity of the upper wall region 31 is larger than when the region 31 is connected to the webs 33 and 34 at the end points. Therefore, the upper wall region 31 is unlikely to buckle at the time of collision, and the amount of energy absorbed by the energy absorbing member 3 also increases from this point.
[0031]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various design changes are possible. For example, in the above-described embodiment, the energy absorbing member having a substantially rectangular cross section has been described. However, the present invention is not limited to this, and for example, the cross section may be a substantially pentagonal shape.
[0032]
【Example】
Next, reference examples of the present invention will be described.
[0033]
2 (a) and (b) for an energy absorbing member (upper wall width 70 mm, bottom wall width 50 mm, web length 40 mm, plate thickness 1.5 mm) having the same cross-sectional shape as shown in FIG. A collision test using a pendulum-type impactor as shown in FIG. 3 was conducted to examine the load-displacement characteristics ( Reference Example). In addition, with respect to the energy absorbing member (the cross-sectional shape of which is shown in FIG. 4) which is the same as that of the reference example except that the upper wall portion is not curved, a collision test using a pendulum striker is similarly performed. The load-displacement characteristics were examined (comparative example).
[0034]
The test conditions at this time are as follows. In this test, the energy absorbing member is supported in front of a cart (not shown), and is installed so that the upper wall side faces the striker. The striker is suspended so as to be swingable about a fulcrum. The striker is adjusted so that the tip of the protruding portion collides with the upper end of the upper wall portion of the energy absorbing member. The inclination angle of the striker during the collision test was adjusted so that the collision speed between the energy absorbing member and the striker was 4.0 km / h. Under such conditions, the temporal relationship between the amount of dent displacement (buckling) and the load in the vicinity of the center of the bottom wall portion of the energy absorbing member from when the load due to collision occurs until it disappears was examined. The result is shown in FIG.
[0035]
In FIG. 5, a thick line indicates a reference example, and a thin line indicates a comparative example. In the load-displacement characteristics of FIG. 5, when the results of the reference example and the comparative example are compared, the energy absorbing member of the reference example has a maximum load of about 1050 kgf, whereas the energy absorbing member of the comparative example has a maximum load. Is about 950 kgf. On the other hand, the energy absorbing member of the reference example has a maximum displacement of about 32 mm, whereas the energy absorbing member of the comparative example has a maximum displacement of about 35 mm. That is, when the same amount of energy is absorbed, the energy absorbing member of the reference example has a smaller maximum displacement than the comparative example because the maximum load is larger. Accordingly, the energy absorbing member of the reference example has a permanent deformation amount (deformation amount after returning to the load 0 after the collision) of about 8 mm, which is smaller than that of the comparative example of about 12 mm. . It has been confirmed by the present inventor that the temporal relationship between the amount of displacement of the dent and the load in the vicinity of the center of the upper wall of the energy absorbing member also shows the same tendency as in FIG.
[0036]
Therefore, under the condition that the amount of energy absorption is the same, the amount of permanent deformation (or maximum displacement) in the reference example is smaller than that of the comparative example, in other words, the amount of permanent deformation (or maximum displacement) is the same. Then, the energy absorption amount of the reference example is larger than that of the comparative example. Therefore, it can be seen that the amount of energy absorbed by the energy absorbing member can be increased without increasing the plate thickness or the amount of deformation of the energy absorbing member can be suppressed by curving the upper wall portion so as to swell outward in the hollow. .
[0037]
【The invention's effect】
As described above, according to the first aspect, since the upper wall portion has a curved portion so as to swell outward in the hollow, the bending rigidity of the upper wall portion is improved without increasing the plate thickness. Even when a large load is applied to the upper wall portion, the upper wall portion serving as a collision surface is difficult to buckle inside the hollow, and the amount of energy absorption in the energy absorbing member increases. Therefore, the energy absorbing member of claim 1 has a large amount of energy absorption even if it is lightweight. Further, according to the first aspect, since the upper wall portion is curved so as to swell outward in the hollow, when the energy absorption amount is the same, the deformation amount of the energy absorption member can be suppressed to a small value.
In addition, since it has two upper wall portions that are curved so as to bulge to the outside of the hollow space, it absorbs energy especially when it has a cross-sectional shape in which the width of the bottom wall portion is relatively large compared to the height. The amount is large.
Furthermore, since the energy absorbing member is an extruded shape made of an aluminum alloy, the weight of the member can be reduced, and the member can be manufactured relatively easily.
[0038]
According to claim 2, since the upper wall portion extends outward beyond the connection portion between the upper wall portion and the side wall portions at both ends of the three side wall portions, the upper wall portion is the side wall portion at the end point thereof. The bending rigidity of the upper wall portion is improved as compared with the case where the upper wall portion is connected to the upper wall portion, and the upper wall portion is less likely to buckle at the time of collision, and the amount of energy absorption is increased.
[0039]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an energy absorbing member used as a bumper reinforcing material for an automobile according to a reference example of the present invention.
FIG. 2 is a schematic diagram showing a case where the energy absorbing member shown in FIG. 1 is used as a bumper reinforcing material for an automobile.
3 is a cross-sectional view of the energy absorbing member according to the implementation of the embodiment of the present invention.
FIG. 4 is a cross-sectional view of an energy absorbing member of a comparative example of the present invention.
FIG. 5 is a graph showing load-displacement characteristics in energy absorbing members of reference examples and comparative examples of the present invention.
FIG. 6 is a schematic side view showing a state of a collision test.
FIG. 7 is a schematic plan view showing a state of a collision test.
[Explanation of symbols]
1, energy absorbing member 11 upper wall portion 12 bottom wall portion 13, 14 web

Claims (2)

2 consisting of the two upper wall portion, and two bottom wall portions facing respectively said two upper walls, and three side wall portions provided between said two upper walls and two bottom wall In the energy absorbing member that has two hollow structures and absorbs energy due to external load in a direction from the upper wall portion to the bottom wall portion given to the upper wall portion by deformation of the hollow portion,
The bottom wall portion and the side wall portion are orthogonal to each other, and each of the upper wall portions is curved so as to swell outwardly with the same curvature in any portion, and ribs are formed inside the hollow structure. An energy absorbing member, which is an extruded shape made of an aluminum alloy, which is not formed. The said upper wall part is extended and provided outside the connection part with the said side wall part in both ends among the said upper wall part and three said side wall parts, It is provided. Energy absorbing member.

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