JP2014189054A - Vehicle impact absorption member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle impact absorption member that has increased section modulus and plastic section modulus without sacrificing weight saving, and to provide a design method thereof.SOLUTION: Of flanges 2 and 3, and webs 4 and 5 that constitute a rectangular hollow section of a specific size, a thickness of a lower half side 2a of the front flange 2 and an upper half side 3b of the rear flange 3 is caused to be partially larger than the thickness of an upper half side 2b of the front flange 2 and a lower half side 3a of the rear flange 3 by a specific amount. Section modulus and plastic section modulus are increased without sacrificing weight saving even when an aluminum alloy vehicle impact absorption member is rotated around the axis in the vehicle width direction and is tilted by an impact of a collision.

Description

  The present invention relates to an aluminum alloy vehicle impact absorbing member.

  Vehicle impact absorbing members such as bumper reinforcement (hereinafter also referred to as bumper R / F) and under-run protectors of vehicles such as automobiles and trucks absorb the collision energy in the collision of the mounted vehicle. Thus, in order to protect the occupant, the vehicle body or the devices (radiator, alternator, etc.) placed on the rear surface, they are provided at the front end and the rear end of the vehicle, respectively.

  These vehicle impact absorbing members are made of aluminum alloys such as extruded profiles that are lightweight and have high impact energy absorption performance, instead of press-molding steel plates. These aluminum alloy vehicle impact absorbing members have a rectangular cross section, a mouth section, a middle section, an eye section, a pad section, etc., provided with a medium rib for reinforcement. .

  In the following, the bumper R / F made of extruded aluminum alloy having a rectangular cross section will be described as an example. Here, of the bumper R / F, the two flat plate-like walls standing in parallel with an interval in the front-rear direction of the vehicle are called flanges. Further, two flat walls that extend in parallel in the vehicle front-rear direction and are spaced apart from each other in the vertical direction of the vehicle to connect the flanges together are called webs.

  Conventionally, the bumper R / F has a light weight and a small cross-sectional area as light as possible with respect to a bending moment around the vehicle vertical axis and a crushing load in the vehicle front-rear direction caused by the collision of another vehicle. Cross sections have been designed to have the required strength.

  Therefore, in the bumper R / F, the secondary section of the bumper R / F with respect to the bending moment around the vertical axis of the vehicle, such as securing the width of the cross section in the vehicle front-rear direction and increasing the thickness of the flange or the plate thickness. The design has been made so that the moment, section modulus and plastic section modulus can be efficiently secured. For example, a method of welding a reinforcing member limited to a portion where high bending strength is required has been devised (Patent Document 1).

  For the crushing load in the longitudinal direction of the vehicle, it has been carried out to optimize the number and arrangement of webs, the plate thickness or the wall thickness. For example, a method of inserting a member that reinforces the web is also proposed (Patent Document 2), limiting to a portion that requires high crushing strength. In order to improve the crushing strength and bending strength at the same time, a method has been proposed in which the four corners at the intersection of the web and the flange are thick in the rectangular cross section of the bumper R / F (Patent Document 3). Furthermore, as a cross-sectional shape that can achieve both improved bending strength and lighter weight for the bumper R / F, the thickness of the compression flange side from the bending neutral axis of the web is thicker than the thickness of the tension flange side. There has also been proposed a method of forming a taper so as to become thicker toward the flange side (Patent Document 4).

JP 2004-20306 A JP 2006-1446 A JP-A-11-170935 JP 11-59296 A

  In the collision between vehicles, in the collision between the front and rear surfaces of the vehicles or between the front and rear surfaces, the bumper R / Fs colliding with each other due to the situation of the collision or the vehicle types of the vehicles colliding with each other, Of course, there may be a case where the position of the position is shifted and this shift becomes large.

  In order to explain this phenomenon, FIGS. 15 and 16 schematically show the situation when the bumper R / F 40 on the vehicle side provided on the front side (front) of the vehicle collides with the bumper R / F 41 on the other vehicle side. Shown in FIG. 15 shows a case where the bumper R / F 40 having a rectangular hollow cross section on the front side of the vehicle has a lower vehicle height (position) than the bumper R / F 41 having the same rectangular hollow cross section on the other vehicle side. . In this case, an input load (collision load) that is offset in the vehicle height direction is transmitted to the vehicle-side bumper R / F 40, and therefore, a clockwise rotation with the vehicle width direction as the vertical direction in FIG. A “torsional moment” indicated by an arrow occurs. As a result, the vehicle-side bumper R / F 40 rotates around the vehicle width direction as indicated by a clockwise arrow, and the upper side of the bumper R / F 40 is deformed while being tilted (tilted) toward the vehicle rear side.

  FIG. 16 shows that the collision surface of the bumper R / F on the front side of the vehicle (front side flange, hereinafter referred to as the front flange) is, for example, below the axis in the vertical direction of the vehicle due to vehicle layout and design restrictions. The case of a cross-sectional shape that is partially inclined and narrowed is shown. In this case, even if the bumper R / F41 on the other vehicle side and the mounted vehicle height (position) are the same, the collision load of the bumper R / F41 on the other vehicle is evenly applied to the collision surface of the own bumper R / F40. Not transmitted Therefore, as in FIG. 15, a “torsional moment” indicated by a clockwise arrow with the vehicle width direction as the vertical direction in the figure as an axis is generated. As a result, the vehicle-side bumper R / F 40 rotates around the vehicle width direction as indicated by the clockwise arrow, and the upper side of the bumper R / F 40 is deformed while falling toward the vehicle rear side.

  Such a rotational deformation can also occur in a collision test for evaluating the collision safety of a vehicle. That is, in such a collision test, the shape of the barrier that collides with the vehicle, the collision position, the collision speed, and the like are determined in advance according to laws and regulations. However, when these barriers and the bumper R / F as a test body are displaced in the vertical direction of the vehicle, or when the collision surface (front side flange) of the bumper R / F has an inclination as shown in FIG. For some reason, the bumper R / F often rotates around the vehicle width axis as indicated by a clockwise arrow, and the upper side of the bumper R / F is deformed while falling to the rear side of the vehicle.

  As described above, when the vehicle impact absorbing member provided on the front side of the vehicle rotates around the vehicle width direction axis due to the impact of the vehicle collision, as shown in FIG. In addition, the bending neutral axis C0 of the vehicle impact absorbing member having a rectangular hollow cross-sectional shape is inclined toward either the rear side in front of the vehicle or the front side. As shown in FIGS. 15 and 16, in the case of a collision in which the bumper R / F is located below the barrier, as shown in the upper right side of FIG. F40 rotates around the vehicle width direction axis as indicated by the clockwise arrow. For this reason, the vehicle impact absorbing member is inclined toward the vehicle rear side, and the bending neutral axis is often inclined toward the vehicle front side like C1. On the other hand, as shown in the lower right side of FIG. 17, in the case of a collision in which the bumper R / F is positioned above the barrier, the bumper R / F 40 having a rectangular hollow cross section on the vehicle side is It rotates as shown by the counterclockwise arrow about the axis in the width direction. For this reason, the vehicle impact absorbing member is inclined toward the vehicle front side, and the bending neutral axis is often inclined toward the vehicle rear side like C2.

  Therefore, in order for the vehicle impact absorbing member having a rectangular hollow cross-section to exhibit its energy absorbing function, the bending neutral axis is moved forward of the vehicle by rotation of the vehicle impact absorbing member around the vehicle width direction due to a collision load. Even in an inclined state in which the vehicle impact absorbing member is deformed while being inclined toward the rear side of the vehicle, it is necessary to increase the section modulus and the plastic section coefficient with respect to the bending of the vehicle impact absorbing member about the vehicle vertical axis. is there. However, in the past, particularly for vehicle impact absorbing members such as the bumper R / F, there has been so far no design of a cross-section considering the rotation around the axis in the vehicle width direction.

  In the rectangular cross section of the bumper R / F, as in Patent Document 3, if the four corners that are the intersections of the web and the flange are thick, the vehicle impact absorbing member in the vehicle up-down direction shaft in the inclined state. As a result, it is possible to increase the section modulus and the plastic section modulus for the surrounding bending. However, if the thickness is increased in order to sufficiently exhibit this effect, the weight increases and the weight reduction is sacrificed, and the advantage itself of using the aluminum alloy vehicle impact absorbing member instead of steel is impaired. .

  The present invention has been made in view of such a problem, and the bending neutral shaft is inclined toward the vehicle front side due to the rotation of the vehicle impact absorbing member around the vehicle width direction due to the collision load, Even in an inclined state in which the side is deformed while falling to the rear side of the vehicle, a vehicle impact absorbing member with an increased section modulus and plastic section modulus for bending around an axis in the vertical direction of the vehicle can be obtained without sacrificing weight reduction. Is to provide.

  In order to achieve the above-mentioned object, the gist of the vehicle impact absorbing member of the present invention is that two flat flanges (2, 3) erected at intervals in the front-rear direction of the vehicle, and the front and rear flanges (2 3) A rectangular hollow section is formed by two flat upper and lower webs (4, 5) that are connected to each other in the vertical direction of the vehicle and extending in the longitudinal direction of the vehicle. The length H in the vehicle vertical direction of the flanges (2, 3) is in the range of 100 to 200 mm, and the length W in the vehicle longitudinal direction of the upper and lower webs (4, 5) is in the range of 50 to 100 mm. In the alloy shock absorbing member, the lower half side of the front flange located on the front side of the vehicle when the rectangular hollow cross section is divided into four equal parts by dividing the rectangular hollow cross section into the front and rear direction and the height direction of the vehicle ( 2a) and the front half of the lower web (5a) Of the total area (S1) and the total area (S4) of the upper half side (3b) of the rear flange located on the rear side of the vehicle and the rear half side (4b) of the upper web (S1 +) S4), or the total area (S2) of the upper half side (2b) of the front flange and the front half side (4a) of the upper web, the lower half side (3a) of the rear flange and the rear half side of the lower web ( 5b) and the total area (S3) and the sum of the areas (S2 + S3), the sum of either area is larger than the sum of the other areas in the range of 1.5 to 3.5 times The thickness of the lower half side (2a) of the front flange and the upper half side (3b) of the rear flange, or the upper half side (2b) of the front flange and the lower half side (3a) of the rear flange One of the wall thicknesses is partially thicker than the wall thickness of the other upper and lower half side of each flange.

  According to the present invention, the design philosophy takes into account that the vehicle impact absorbing member rotates around the vehicle width direction axis by the load (impact) of the vehicle collision. In other words, the design is made assuming that the bending neutral shaft is inclined toward the front side or the rear side of the vehicle due to the rotation of the vehicle impact absorbing member around the vehicle width direction due to the collision load. In other words, while the upper side of the vehicle impact absorbing member falls to the rear side of the vehicle (the lower side falls to the front side of the vehicle), or the upper side of the vehicle impact absorbing member falls to the front side of the vehicle (the lower side is the rear side of the vehicle). It is designed assuming an inclined state that deforms. As a result, even when the vehicle impact absorbing member rotates about an axis in the vehicle width direction, it is designed to increase the section modulus and the plastic section modulus with respect to the bending of the vehicle impact absorbing member about the vehicle vertical axis. To do.

  For this purpose, in the present invention, a virtual bending neutral axis is selected in a state where the bending neutral axis is inclined toward the vehicle front side, and the meat of the flange portion farthest from the virtual bending neutral axis is selected. The design philosophy is such that the thickness is partially greater than the thickness of other flange portions within a specific range.

  On the other hand, the thickness of the other flange portions is reduced in a specific range, and the increase rate of the cross-sectional area when the thickness is increased is the same as the vehicle impact absorbing member of the original thickness where all the flanges have a uniform thickness. As compared with the above, it is suppressed to 5% or less. In this way, at least in part, an increase in weight due to a simple thickening is suppressed as much as possible, and the advantage of reducing the weight by using an aluminum alloy vehicle impact absorbing member instead of steel is maintained.

  As a result, the present invention does not sacrifice weight, and the above-described vehicle up-and-down movement is possible even in each inclined state where the upper side is tilted toward the rear of the vehicle or the upper side is tilted toward the front of the vehicle. It is possible to provide a vehicle impact absorbing member having an increased section modulus and plastic section modulus with respect to bending around a direction axis.

It is sectional drawing which shows the one aspect | mode of this invention vehicle impact-absorbing member. It is a schematic diagram which shows the design method (design principle) of FIG. It is sectional drawing which shows the other aspect of this invention vehicle impact-absorbing member. It is a schematic diagram which shows the design method (design principle) of FIG. It is sectional drawing which shows the other aspect of this invention vehicle impact-absorbing member. It is sectional drawing which shows the other aspect of this invention vehicle impact-absorbing member. It is sectional drawing which shows the aspect of the vehicle impact-absorbing member of a comparative example or a prior art example. It is a schematic diagram which shows the design method (design principle) of FIG. It is sectional drawing which shows the analysis conditions of this invention Example. It is explanatory drawing which shows the cross-sectional area and displacement of the vehicle impact-absorbing member of FIG. It is a schematic diagram which shows the test conditions of FIG. It is explanatory drawing which shows the test result of an Example. It is explanatory drawing which shows the test result of an Example. It is explanatory drawing which shows the test result of an Example. It is a schematic diagram which shows the collision form of the conventional vehicle impact-absorbing member. It is a schematic diagram which shows the other collision form of the conventional vehicle impact-absorbing member. It is a schematic diagram which shows the rotation state of the vehicle impact absorption member of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

Basic structure of vehicle impact absorbing member:
1 to 6 and 9 show embodiments of the vehicle impact absorbing member of the present invention. 7 and 8 show an embodiment of a vehicle impact absorbing member of a comparative example.

  These drawings show a mode in which the vehicle impact absorbing member is attached and used as a bumper R / F on the front (front) side of the vehicle. Further, an arrow F in the figure indicates a load direction of a collision from the front (front) side of the vehicle on the left side of the figure. Accordingly, the right side of the figure shows the vehicle front (front) side and the left side shows the vehicle rear (rear) side in common. However, the present invention may also be used on the rear (rear) side of the vehicle. In this case, the front and rear flanges 2 and 3 are read as the front and rear sides toward the rear of the vehicle.

  First, although described using the example of FIG. 1, the vehicle impact absorbing member 1 made of an aluminum alloy of the present invention is intended for a vehicle impact absorbing member such as a bumper R / F such as an automobile or a truck or an underlamp protector. It has a rectangular hollow cross-section structure (rectangular cross-section hollow structure). FIGS. 1 to 5 show a vehicle impact absorbing member made of an aluminum alloy extruded shape. When this extruded shape is used, the rectangular hollow cross-sectional shape of the vehicle impact absorbing member is not only a mouth-shaped cross section but also a reinforcing shape. A daily cross section, eye cross section, paddy cross section, or the like provided with a middle rib can be freely selected or applied.

  In FIG. 1, this rectangular hollow cross-sectional structure includes a front flange 2 on the front side (front side) of the vehicle, which is two flat walls standing in the front-rear direction of the vehicle, and a rear side (rear side) of the vehicle. And a rear flange 3 on the side. The flanges 2 and 3 are two flat walls extending in the longitudinal direction of the vehicle and spaced apart from each other in the vertical direction of the vehicle. The ends of the vehicle in the vertical direction are connected to (connected to) the lower web 5.

  These walls constitute a rectangular hollow cross-sectional structure having a vertical bending neutral axis C0 extending in the vertical direction of the vehicle at the center. And in the center part of a cross section, it has the daily cross-sectional shape which provided the middle rib 6 for reinforcement horizontally between the flanges 2 and 3. FIG.

  Here, the lengths of the flanges 2 and 3 are each in the range of 100 to 200 mm, and the lengths of the webs 4 and 5 are in the range of 50 to 100 mm. The vehicle impact absorbing member is designed and used within this range. For this reason, it is meaningless even if it is less than these dimensions or exceeds these dimensions, and it is unclear whether the present invention is effective in a range that deviates from these dimensions.

  The lengths of the flanges 2 and 3 and the lengths of the webs 4 and 5 do not necessarily have to be the same, depending on the design of the vehicle (vehicle body) and the installation space (space) of the vehicle impact absorbing member. You can change it. Similarly, the rectangular hollow cross-sectional structure does not have to be a perfect rectangle (rectangle, rectangle), and the flanges 2, 3 and the webs 4, 5 are not flat, straight, or parallel to each other. May be provided. Furthermore, the outer and inner sides of the corners (corner portions) 7, 8, 9, and 10 that are the intersections of the walls may be in the shape of an arc (curve) provided with R, even if they are not perpendicular intersections as illustrated. .

Guideline for thickening flange parts by equalizing rectangular hollow cross section:
In order to clearly define a partial thick wall portion in the aluminum alloy shock absorbing member 1 in FIG. It is assumed that each is divided into four equal parts by dividing each into the same direction. More specifically, the rectangular hollow cross section is divided equally into the maximum length (width) in the vehicle front-rear direction (left-right direction in the figure) and the maximum length in the height direction (up-down direction in the figure) ( Divide into 4 equal parts (divide into 4 parts).

  Thereby, the front (front side) flange 2 with respect to the collision load direction of F is divided into two equal parts, the lower half side 2a and the upper half side 2b. Similarly, the rear (rear) flange 3 with respect to the collision load direction of F is equally divided into an upper half side 3b and a lower half side 3a. Further, the lower (lower) web 5 is divided into two equal parts, a front half side 5a and a rear half side 5b. Further, the upper (upper) web 4 is divided into two equal parts, a front half side 4a and a rear half side 4b.

  Incidentally, in FIG. 1, a dotted line (horizontal line) obtained by equally dividing the rectangular hollow section in the height direction runs along the central portion of the reinforcing middle rib 6, which happens to be a rectangular hollow section. It is because it is in the central part of. On the other hand, when the middle rib 6 is not in the central portion of the rectangular hollow cross section, the dotted line divided in this way is shifted up and down from the middle portion of the middle rib 6 as a matter of course.

  In FIG. 1, the total area of the lower half side 2a of the front flange 2 and the front half side 5a of the lower web 5 out of the area of the rectangular hollow section divided into four equal parts is S1. The total area of the upper half side 3b of the rear flange 3 and the rear half side 4b of the upper web 4 is defined as S4. The total area of the upper half side 2b of the front flange 2 and the front half side 4a of the upper web 4 is S2. The total area of the lower half side 3a of the rear flange 3 and the rear half side 5b of the lower web 5 is defined as S3. This also applies to FIGS. However, these areas do not include the area of the reinforcing intermediate ribs, and all the above-mentioned areas are calculated by treating them as a mouth-shaped cross section having no intermediate ribs. This is the same for one horizontal rib 6 in the cross section of the mold shown in FIGS. 1, 3 and 6, two medium ribs at the top and bottom of the cross section of the eye-shaped cross section, and two medium ribs in the vertical and horizontal form of the cross section.

  Based on this premise, in the present invention, among these four equally divided rectangular hollow cross-sectional areas, the lower half side (2a) of the front flange located on the front side of the vehicle and the front half side (5a) of the lower web Of the total area (S1) and the total area (S4) of the upper half side (3b) of the rear flange located on the rear side of the vehicle and the rear half side (4b) of the upper web (S1 + S4) ) Or the total area (S2) of the upper half side (2b) of the front flange and the front half side (4a) of the upper web, the lower half side (3a) of the rear flange and the rear half side (5b of the lower web) ) And the total area (S3) and the sum of the areas (S2 + S3), either the sum of the areas (S1 + S4) or (S2 + S3) is greater than the sum of the other areas. Increase in the range of 5 times to 3.5 times.

  For this purpose, the thickness of the lower half side (2a) of the front flange and the upper half side (3b) of the rear flange, or the upper half side (2b) of the front flange and the lower half side (3a) of the rear flange Is made partially thicker than the thickness of the other upper and lower half side of each flange.

  In FIG. 1, due to the impact of the vehicle collision from the right side (in FIG. 1) of the vehicle impact absorbing member 1, the vehicle impact absorbing member 1 is shown in FIG. It is preliminarily assumed to rotate as indicated by a clockwise arrow around the vehicle width direction axis. This assumes the case where the bumper R / F is located below the barrier as shown in FIGS. 15 and 16, and the vehicle impact absorbing member 1 is inclined toward the rear side of the vehicle and is being bent. The design is based on the assumption that the vertical axis is inclined toward the front side of the vehicle like C1.

For this reason, the sum of the total area S1 and the total area S4 is made larger in a range of 1.5 to 3.5 times than the sum of the total area S2 and the total area S3. That is, the total area (S1) of the lower half 2a of the front flange 2 and the front half 5a of the lower web 5 with respect to the collision load direction, and the rear half of the upper half 3b and the upper web 4 of the rear flange 3 with respect to the collision load direction. The sum of the total area (S4) with the dividing side 4b is the total area (S2) of the upper half side 2b of the front flange 2 and the front half side 4a of the upper web 4 and the lower half side of the rear flange 3 The total area (S3) of 3a and the rear half side 5b of the lower web 5 is made larger in a range of 1.5 times to 3.5 times.
Then, the thickness of the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 is set to be larger than that of the front flange 2 so that this area relationship is obtained. The thickness of the half side 2b and the lower half side 3a of the rear flange 3 is partially increased within the range described later.

  In FIG. 1, the sum of the total area S1 and the total area S4 is made 1.5 times or more larger than the sum of the total area S2 and the total area S3, so that the vehicle impact absorbing member at the time of collision is obtained. Even if 1 is rotated and the original bending neutral axis C0 is inclined, the thickness of the flange that is farthest from the inclined bending neutral axis C1, that is, the lower half side 2a of the front flange 2 and the rear flange 3 The thickness of the upper half side 3b is partially increased. For this reason, an inclined state in which the bending neutral shaft inclines toward the vehicle front side due to the rotation of the vehicle impact absorbing member around the vehicle width direction due to the collision load, and the upper side of the vehicle impact absorbing member is deformed while falling toward the vehicle rear side. Also, the collision energy absorption performance can be improved. In other words, the impact energy absorption performance is improved by increasing the section modulus and plastic section modulus of the vehicle impact absorbing member around the vehicle vertical axis and by deforming the cross section and bending the longitudinal direction (vehicle width direction). Can be increased.

  In this respect, the sum of the total area (S1) and the total area (S4) among the areas of the rectangular hollow cross section divided into four equal parts is the area of the total area (S2) and the total area (S3). If it is less than 1.5 times the sum, partial thickening of the front flange 2 and the rear flange 3 is insufficient, and this effect cannot be obtained. On the other hand, the sum of the total area (S1) and the total area (S4) is the sum of the areas of the total area (S2) and the total area (S3) among the areas of the rectangular hollow cross section divided into four equal parts. If it exceeds 3.5 times, the partial thickness increase of the front flange 2 and the rear flange 3 is too large. For this reason, the rate of increase in the cross-sectional area when the thickness is increased in front cannot be suppressed to 5% or less as compared with the original vehicle impact absorbing member having a uniform flange thickness. The weight savings are sacrificed.

  On the other hand, in the case of a collision in which the bumper R / F is located above the barrier as in the lower right side of FIG. 17, the vehicle impact absorbing member 1 is caused by the impact of the vehicle collision from the right side of the figure. It is necessary to design in advance based on the assumption that the motor rotates as shown by the counterclockwise arrow around the vehicle width direction axis. Therefore, contrary to FIGS. 1 and 3, the sum of the total area S2 and the total area S3 is 1.5 to 3.5 times the sum of the total area S1 and the total area S4. Try to make it larger within the range. The thicknesses of the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3 are set to be opposite to those shown in FIGS. The thickness of the lower half side 2a and the thickness of the upper half side 3b of the rear flange 3 are partially increased.

Bending neutral axis considerations:
In order to combine the improvement of the collision energy absorption performance and the weight reduction, the flange is preferably designed to be thick in consideration of the bending neutral axis of the vehicle impact absorbing member. In other words, in order to make the sum of the total area S1 and the total area S4 larger in a range of 1.5 times to 3.5 times than the sum of the total area S2 and the total area S3, the vehicle impact absorbing member The flange is designed to be partially thickened in consideration of the bending neutral axis.

  In the design method of the portion where the flange is thickened in consideration of the bending neutral axis of the vehicle impact absorbing member, the virtual bending neutral axis inclined from the vertical direction is used as a reference. At this time, when the vehicle impact absorbing member rotates around the vehicle width direction axis due to the impact of the vehicle collision, the original bending neutral axis C0 of the vehicle impact absorbing member 1 having a rectangular hollow cross section perpendicular to the vehicle vertical direction is provided. Selects whether the vehicle is inclined toward the vehicle front side or the vehicle rear side.

  FIG. 2 shows a design method based on a virtual bending neutral axis inclined from the vertical direction. The vehicle impact absorbing member 1 on the right side of FIG. 2 is moved around the axis in the vehicle width direction by the impact of the vehicle collision from the right side of FIG. 2 as in FIG. 1, as in the case of the upper right side of FIG. It is assumed (designed) to rotate as indicated by the clockwise arrow. In the case of FIG. 2, in the original attached state, the bending neutral axis C0 that is in the center of the rectangular hollow cross-sectional shape and is perpendicular to the vehicle vertical direction is virtually the same as the vehicle impact absorbing member 1 on the right side of FIG. It is assumed that the vehicle is inclined toward the vehicle front side as the bending neutral axis C1. That is, in a tilted state where the upper side of the vehicle impact absorbing member rotates due to a collision load around the axis in the vehicle width direction and the upper side of the vehicle collapses toward the rear side of the vehicle, the neutral neutral axis is inclined toward the front side of the vehicle. I assume that. The thickening of FIG. 1 is based on this design concept.

  Conversely, when the vehicle impact absorbing member 1 rotates counterclockwise around an axis in the vehicle width direction, the bending neutral axis is inclined toward the vehicle rear side as indicated by C2 in FIG. In this case, as described above, contrary to FIGS. 1 and 3, the sum of the total area S2 and the total area S3 is 1.5 times larger than the sum of the total area S1 and the total area S4. To do. In order to obtain this area ratio (area relationship), the thickness of the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3 is set to the lower half side of the front flange 2 in reverse to FIG. 2a and the thickness of the upper half side 3b of the rear flange 3 are partially thickened.

  The direction in which the virtual bending neutral axis C1 tilts and the tilt angle are determined (designed) based on the balance between the cross-sectional shape, mounting position, mounting conditions, and collision conditions of the vehicle impact absorbing member. That is, it is predicted whether the vehicle impact absorbing member 1 is in the upper or lower collision form on the right side of FIG. 17 or which virtual bending neutral axis is inclined with respect to the impact of the collision received from the front. To decide. In other words, the vehicle impact absorbing member 1 is designed to be either the upper or lower collision form on the right side of FIG. 17, and the mounting position and the attachment method are designed to be so.

  Here, as the inclination angle of the virtual bending neutral axis C1, the virtual bending neutral axis C1 having one specific angle is selected from the angles where the inclination angle from the vertical bending neutral axis C0 is 45 degrees or less. The flanges 2 and 3 that are farthest from the virtual bending neutral axis C1 with respect to the selected one virtual bending neutral axis C1 and the portions of the regions of the webs 4 and 5 that accompany this flange 2 and 3 Increase the wall thickness. If the inclination angle of the virtual bending neutral axis C1 is 90 degrees or less, the flanges 2 and 3 that are farthest from the virtual bending neutral axis C1 and the web 4 can be selected any number of inclination angles. 5 parts are the same. Therefore, the inclination angle of the virtual bending neutral axis C1 may be appropriately selected as an inclination angle of 90 degrees or less. However, when the vehicle impact absorbing member rotates too much and tilts too much, the collision mode itself is unlikely to occur. If this happens, the way the impact energy is transmitted to the cross section of the vehicle impact absorbing member becomes distorted, and the original impact energy is lost. Since the absorption performance cannot be exhibited, problems such as mounting that cause such rotation are greater. Therefore, since it is not necessary to consider the inclination angle exceeding 45 degrees, in the present invention, the inclination angle (inclination) of the virtual bending neutral axis C1 from the perpendicular bending neutral axis C0 is defined as an angle of 45 degrees or less.

  By partially thickening the flanges 2 and 3 farthest away from the virtual bending neutral axis C1 and the portions of the webs 4 and 5 that intersect with the flanges 2 and 3, the vehicle of the vehicle impact absorbing member 1 due to a collision load is obtained. The section modulus and the plastic section modulus for bending the vehicle impact absorbing member 1 about the axis in the vertical direction of the vehicle, even in an inclined state in which the upper side of the vehicle is deformed while being tilted to the rear side of the vehicle due to the rotation about the axis in the width direction Can be increased. The section modulus and the plastic section modulus are the areas of the flanges 2 and 3 away from the bending neutral axis and the portions (regions) of the webs 4 and 5 that intersect with the flanges 2 and 3 away from the bending neutral axis. Increasing (designing larger) can increase the efficiency efficiently.

  Of course, since the vehicle collision modes and collision conditions vary widely, the vehicle does not always have the predicted collision mode and does not always follow the predicted virtual bending neutral axis. However, the present invention provides a vehicle impact absorbing member 1 having a rectangular hollow cross-sectional shape around the axis in the vertical direction of the vehicle at the conventional level, even if the collision mode is opposite to the prediction or the inclination direction of the virtual bending neutral axis. Since the section modulus and the plastic section modulus for bending are maintained and the energy absorption performance is also maintained, there is no problem.

Thickening part:
In the vehicle impact absorbing member 1 on the left side of FIG. 2 in a state where it is attached to the vehicle, a distance from the bending neutral axis C0 to the bending neutral axis C0 perpendicular to the vehicle vertical direction at the center of the rectangular hollow cross-sectional shape. The portions of the flanges 2 and 3 and the webs 4 and 5 that are farthest from each other are two regions on the left and right sides surrounded by dotted lines A and B and C and D. That is, the expansion is a region including the entire height portion of the flanges 2 and 3 in the vehicle vertical direction and the corner portions 7, 8, 9 and 10.

  On the other hand, like the vehicle impact absorbing member 1 on the right side of FIG. 2, the vehicle is rotated as shown by the clockwise arrow around the vehicle width axis due to the impact of the vehicle collision from the right side of the diagram. In the vehicle impact absorbing member 1, the bending neutral axis at the center of the rotated vehicle impact absorbing member 1 is the virtual bending neutral axis C1. Then, the portions of the flanges 2 and 3 and the webs 4 and 5 that are farthest from the virtual bending neutral axis C1 are changed into two left and right regions surrounded by dotted lines A and D. That is, the spread is only a region including a portion near the corners of the flanges 2 and 3 and the webs 4 and 5 with the corners 7 and 10 serving as diagonal lines as the center.

  In FIG. 1, the left and right two regions surrounded by the dotted lines A and D that are the farthest from the virtual bending neutral axis C1 are the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3. It corresponds to a part of the portions 4b and 5a of the webs 4 and 5 that intersect with this.

  In the present invention, the right and left of the lower region 12 of the flange 2 surrounded by the dotted line D and the upper region 11 of the flange 2 surrounded by the dotted line A, which are regions farthest from the virtual bending neutral axis C1. The two areas are partially thickened. Specifically, the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 corresponding to the two left and right regions surrounded by the dotted lines A and D in FIG. A part of 4 and 5 part 4b, 5a is thickened. On the contrary, when the vehicle impact absorbing member 1 rotates counterclockwise around an axis in the vehicle width direction, it is a region before such a distance from the virtual bending neutral axis is surrounded by a dotted line C. The two left and right regions of the upper region of the flange 2 and the lower region of the rear flange 3 surrounded by the dotted line B are partially thickened. Specifically, the thickness of the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3 in FIG. It becomes thicker partially than the thickness.

  Accordingly, the thicknesses of the portions 4b and 5a of the webs 4 and 5 that intersect (connect) to the thickened flanges 2a and 3b at the respective corners (corner corners) are also partially It is preferable to make it thick. This is to avoid a sudden change in thickness at the connecting portion, and to avoid difficulty in making and a decrease in strength due to this sudden change in thickness. The thickness of the flanges 2a and 3b is increased. Depending on the wall thickness, it is preferable that the thickness is partially increased only by a length (region) in an appropriate range.

  The range in which the thickness is increased (in the cross section, the range of the length of the wall to be increased) is the two left and right regions surrounded by dotted lines A and D, which are the farthest from the virtual bending neutral axis C1, or The lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 corresponding to these and the regions 4b and 5a of the webs 4 and 5 intersecting therewith are appropriately selected. In other words, in relation to each thickness (thickening thickness) and range (wall length in cross section) of other thinned portions of the flange (in some cases, the web), even in the inclined state, The section modulus and the plastic section modulus with respect to the bending of the vehicle impact absorbing member about the axis in the vehicle vertical direction can be increased and appropriately determined so that the energy absorbing function can be exhibited.

Thickness of thickened part:
In order to exhibit such characteristics, the thickness of the upper or lower half of each flange on the side to be thickened is set to a range of 3.5 to 12 mm, while the other thickness of each flange to be thinned is set. The thickness of the upper and lower half sides is in the range of 1 to 4 mm. That is, the thickness of the part farthest from the virtual bending neutral axis is increased along with the range of the part to be thickened.

1 and 2, assuming that the vehicle impact absorbing member 1 rotates clockwise around an axis in the vehicle width direction, the thickest wall is defined as the part farthest from the virtual bending neutral axis C1. The thickness of the regions A and D to be changed is determined in order to increase the thickness.
Conversely, when the vehicle impact absorbing member 1 rotates counterclockwise around an axis in the vehicle width direction, as shown in the lower right side of FIG. 17, the part farthest from the virtual bending neutral axis C2 As described above, the thickness of the regions B and C to be thickened is determined in order to increase the thickness.
In the following, embodiments such as thickening and thinning in the case of FIGS. 1 and 2 will be described in detail. However, as in the case of the lower right side of FIG. When designing on the assumption that it rotates counterclockwise around an axis in the vehicle width direction, the thickened portions are the areas of the upper flange 2b of the front flange 2 and the rear flange 3 which are the regions B and C described above. The lower half side 3a, the part 5b of the lower web 5, the part 4a of the upper web 4 and the like are designed. Further, the thinned portion is replaced with the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 and the portions 4b and 5a of the webs 4 and 5 that intersect with the lower half side 2a of the front flange 2 and the like. Design.

In the case of FIGS. 1 and 2, the regions included in A and D include the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3, and portions 4b and 5a of the webs 4 and 5 that intersect with the lower half side 2a. Is partially thicker than the thickness of the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3, and the thickness ranges from 3.5 to 12 mm. It is preferable to do. This also applies to the present invention examples such as FIGS.
Incidentally, in FIG. 1, the lower half side 2a of the front flange 2 and a part of the portion 5a of the lower web 5 intersecting with the lower flange side 2a of the area D surrounded by the dotted line, and the upper half of the rear flange 3 of the area A surrounded by the dotted line The side 3b and a part of the portion 4b of the upper web 4 intersecting with the side 3b are thickened in a tapered shape so as to be point-symmetric with respect to the center of the rectangular hollow cross section.

  More specifically, the thickness (plate thickness) of the partial thick portion 12 surrounded by the dotted line D in the lower portion 2a of the flange 2 is t2, and the partial thickness surrounded by the dotted line A in the upper portion 3b of the flange 3 The thickness (plate thickness) of the thick part 11 is set to t3. On the other hand, the thickness (plate thickness) of the partial thin portion surrounded by the dotted line C in the upper portion 2b of the flange 2 is t1, and the thickness (plate thickness) of the partial thin portion surrounded by the dotted line B of the flange 3 lower portion 3a. ) Is t4. Furthermore, the thickness (plate thickness) of the upper web 4 is t5, and the thickness (plate thickness) of the lower web 5 is t6.

  In FIGS. 1 and 2, the thickened portion in the region of the thickened portions A and D, which is the farthest from the virtual bending neutral axis C <b> 1 (C <b> 2), is the lower half side of the front flange 2. These are t2 of the thickened portion 12 in 2a and t3 of the thickened portion 11 in the upper half side 3b of the rear flange 3. When the part farthest from the virtual bending neutral axis C1 (C2) extends to the parts of the webs 4 and 5 in the vicinity of the corners 7 and 10 that intersect the corners 7 and 10, these corners 7 The thicknesses t5 and t6 of the rear half 4b of the upper web 4 near 10 and the front half 5a of the lower web 5 are also partially increased.

  Then, the thickness (plate thickness) t2, t3, and in some cases t5, t6 of these thickening portions are selected from the range of 3.5 to 12 mm, and the other (thinning) flanges and webs Each part is thicker than the thickness of each part. In this thickening method, the thickness of the other flange (thinning) flange and web, and the plate thickness step may be provided to increase the thickness uniformly in the extending direction of the flange or web wall, as shown in FIG. In addition, the thickness may be increased or decreased sequentially or stepwise (stepwise) in an inclined manner (tapered).

  Here, if the thickness of the portion to be thickened, such as t2, t3, is less than 3.5 mm, the thickening is insufficient, and the section modulus with respect to the bending of the vehicle impact absorbing member about the vehicle vertical axis in the inclined state In addition, the plastic section modulus cannot be increased, and the energy absorption function cannot be enhanced.

  On the other hand, even if the thickness of the part to be thickened such as t2, t3 exceeds 12 mm, the energy absorption function is not improved, and there is a limit to the thinning of other parts to be described later. The increase in cross-sectional area and weight due to thickening cannot be compensated. For this reason, the increase rate of the cross-sectional area cannot be suppressed to 5% or less as compared with the original vehicle impact absorbing member having a uniform flange thickness.

  By the way, there is an example in which the thickness of the flanges 2 and 3 is in the range of 3.5 to 12 mm and is partially thicker than the thicknesses of the other flanges and webs. . However, these do not reduce the thickness of other parts, which will be described later, and the increase rate of the cross-sectional area cannot be suppressed to 5% or less compared to the original vehicle impact absorbing member having a uniform flange thickness. . In addition, the wall thickness of the flanges 2 and 3 is usually selected from the range of 2 to 12 mm as usual (except for the case where the wall thickness is partially increased for the above-described reinforcement). The thickness of each wall is uniform in the longitudinal direction.

Thinning part thickness:
On the other hand, it is preferable that the thicknesses of the flanges 2 and 3 and the webs 4 and 5 other than the thickening are made thinner in the range of 1 to 4 mm. In FIG. 1, the thickness of the upper half side 2 b of the front flange 2 and the lower half side 3 a of the rear flange 3 is set to be larger than the thickness of the lower half side 2 a of the front flange 2 and the upper half side 3 b of the rear flange 3. It is preferable to make each partially thin in the range of 1 to 4 mm. This also applies to the present invention examples such as FIGS.

  Specifically, in FIGS. 1 and 2, the thinning is performed as a part other than the thickening part including a C region surrounded by a dotted line above the flange 2 (on the front flange 2. The thickness (plate thickness) t1 of the region from the half side 2b) to the thickened region D (the lower half side 2a of the front flange 2). Then, the region A (the upper half side of the rear flange 3) is increased from the region including the B region surrounded by the dotted line below the flange 3 (the lower half side 3a of the rear flange 3 and the rear half side 5b of the lower web 5). It is the thickness (plate thickness) t4 of the region up to 3b). Further, in the region (wall length or wall width) up to the corner portion 9 other than the region thickened in the vicinity of the corner portion 7, the rear half side 4b and the front half side 4a of the upper web 4 are arranged. Thickness (plate thickness) t5, the rear half side 5b and the front half of the lower web 5 in the region (wall length or wall width) up to the corner portion 8 other than the region where the thickness is increased in the vicinity of the corner portion 10 This is the thickness (plate thickness) t6 of the minute side 5a.

  Thus, in addition to the thinned portion of the flange described above, the portions of the webs 4 and 5 that intersect the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3 at the respective corner portions (corner corner portions). It is preferable to reduce the thickness of each of 4a and 5b. This is, of course, to suppress an increase in weight due to the partial thickening of the flange described above, and also to avoid difficulty in making and a decrease in strength due to a sudden change in the thickness at the connecting portion. Therefore, it is preferable that the thickness of the upper half side 2b of the thinned front flange 2 and the thickness of the lower half side 3a of the rear flange 3 be partially thinned by an appropriate range of length (region). .

  1 and 2, conversely, when the vehicle impact absorbing member 1 rotates counterclockwise around an axis in the vehicle width direction, the left and right regions surrounded by the dotted lines A and D in FIG. Correspondingly, the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 and the portions 4b and 5a of the webs 4 and 5 intersecting with this are similarly thinned.

  Here, if the thicknesses t1, t4, t5, and t6 of the flange and web portions to be thinned are less than 1 mm, the strength and rigidity of these portions are reduced, and are easily broken when subjected to the impact. The energy absorbing function as a vehicle impact absorbing member cannot be exhibited regardless of whether the vehicle is inclined. In addition, when the thickness exceeds 4 mm, it becomes impossible to compensate for the increase in the cross-sectional area and weight due to the thickened portion, and the flange has a uniform thickness compared to the original vehicle impact absorbing member. Thus, the increase rate of the cross-sectional area cannot be suppressed to 5% or less.

  As for the thickness (plate thickness) t1 and t4 of these thinned portions, the thinning method is similar to the above thickening in that the thickness of the flange and the web portion (thickening) and the thickness difference between the thicknesses are reduced. It may be provided to make it evenly thin in the extending direction of the flange or web wall. As shown in FIG. 1, the thickness is increased or decreased sequentially or stepwise (stepwise) in an inclined manner (tapered shape). You may let them.

  “The original vehicle impact absorbing member having a uniform flange thickness” as a reference for the rate of increase in cross-sectional area is the average value of the maximum thickness portion and the minimum thickness portion of the present invention, regardless of the thickness of the flange. And a rectangular hollow cross-sectional structure of the same size (shape).

Other examples of vehicle impact absorbing members:
Figures 3 and 4:
3 and 4 are modified examples of the cross-section of the daily shape of FIG. 1, and have the same cross section as FIG. That is, the front side flange 2 that is the collision surface of the vehicle impact absorbing member 1 is inclined with respect to an axis in the vertical direction of the vehicle, for example, as the lower side 12 goes downward due to vehicle layout or design restrictions. The cross-sectional shape is gradually narrowed (the web 5 is the narrowest). FIG. 3 also shows a vehicle impact absorbing member made of the same aluminum alloy extruded shape as in FIG.

  Also in this case, even if the vehicle impact absorbing member on the other vehicle side and the attached vehicle height (position) are the same, the collision load of the other vehicle impact absorbing member is not uniformly transmitted to the collision surface of the vehicle impact absorbing member 1. . Therefore, as in FIG. 15, a “torsional moment” indicated by a clockwise arrow with the vehicle width direction as the vertical direction in the figure as an axis is generated. As a result, the vehicle impact absorbing member 1 is also deformed while rotating around an axis in the vehicle width direction as indicated by the clockwise arrow.

  3 and 4, the thickened portion that is most distant from the virtual bending neutral axis C <b> 1 that is assumed to be inclined toward the front side of the vehicle is the central portion of the front flange 2 in the region E surrounded by the dotted line. T2 of 14, and t3 of the upper portion 13 of the rear flange 3 of the region A surrounded by the dotted line. That is, t2 of the center portion 14 of the front flange 2 in the region E surrounded by the dotted line at the center portion between the lower half side 2a and the upper half side 2b of the front flange 2 and the dotted line of the upper half side 3b of the rear flange 3 The rear flange 3 upper part 13 of the surrounding area A is thickened.

  Among these, t3 of the upper part 13 of the rear flange 3, which is a thickened portion, is the same as the thickened portion 7 in FIG. On the other hand, t2 of the center part 14 of the front flange 2 is different from the lower part 12 of the front flange 2 to be thickened in FIG. This is because the cross-sectional shape of FIGS. 3 and 4 is different from the cross-sectional shape of FIGS. This is because the part farthest away from the neutral axis C1 (the part to be thickened) is different. On the other hand, in the rear flange 3 in which the cross-sectional shape of FIGS. 3 and 4 is the same as the cross-sectional shape of FIGS. 1 and 2, the distance from the virtual bending neutral axis C1 of the rear flange 3 is inevitably farthest ( The thickening part) is the same.

  That is, in FIG. 3, the two left and right regions of the upper portion 13 of the rear flange 3 of the region A surrounded by the dotted line and the center portion 14 of the front flange 2 of the region E surrounded by the dotted line are thickened in a tapered shape. Then, the thickness (plate thickness) t2, t3, and in some cases t5, t6 of these thickening portions are selected from the range of 3.5 to 12 mm, and the other flanges (thinning) and web Each part is thicker than the thickness of each part.

  On the other hand, the thinning in FIGS. 3 and 4 is from the region C surrounded by the dotted line at the top of the front flange 2 to the region E surrounded by the thickening dotted line as other portions other than the thickening. The lower half side of the front flange 2 from the region D surrounded by the dotted line below the front flange 2 to the region E to be thickened 2a region thickness (plate thickness) t1. The thickness (plate) of the upper half side 3b of the rear flange 3 in the region from the lower half side 3a region of the rear flange 3 including the B region surrounded by the dotted line below the rear flange 3 to the region A to be thickened. Thickness) t4. Furthermore, the thickness (plate thickness) of the upper web 4 (4a, 4b) in the region (wall length or wall width) up to the corner portion 9 other than the region thickened in the vicinity of the corner portion 7. t5 is also the thickness (plate thickness) t6 of the web 5 (5a, 5b) under the region (wall length or wall width) from the corner portion 10 to the corner portion 8.

Example of FIG.
5A, 5B, and 5C are examples of a mouth-shaped cross section in which the rectangular hollow cross-sectional structure of the vehicle impact absorbing member 1 has no reinforcing middle rib 6 in common. FIG. 5 also shows a vehicle impact absorbing member made of the same aluminum alloy extruded shape as FIG.

  In FIG. 5 as well, the virtual bending neutral axis C1 is assumed to be inclined toward the front side of the vehicle, as in FIGS. And the thickness of the area | region of the site | parts A and D on a diagonal line is thickened in the said specific range as a site | part with the longest distance from this virtual bending neutral axis C1.

  5 (a) and 5 (b) show the thicknesses (plate thicknesses) of the flanges 16 and 18 below the flange 2 to be thickened surrounded by the dotted line D and the flanges 15 and 17 surrounded by the dotted line A, respectively. Within the specific range, FIG. 5 (a) is stepped, and FIG. 5 (b) is tapered so as to be point-symmetric with each other. Then, the portions of the webs 4 and 5 in the vicinity of the corner portions 7 and 10 where the portion farthest from the virtual bending neutral axis C1 intersects the corner portions 7 and 10 are also increased in the specific range. That is, the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 corresponding to the two left and right regions surrounded by the dotted lines A and D, and the portions 4b and 5a of the webs 4 and 5 that intersect with the lower half side 2a. Thicken part of the wall.

  Further, as other parts, the thickness (plate thickness) of the part including the C region surrounded by the dotted line above the flange 2, the part including the B region surrounded by the dotted line below the flange 3, the upper web 4 and the lower web 5 etc. Is thinned in a region up to the region where the thickness is increased. That is, the upper half side 2b of the front flange 2 and the lower half side 3a of the rear flange 3 corresponding to the two left and right regions surrounded by the dotted lines C and B, and the portions 4a and 5b of the webs 4 and 5 that intersect with the upper half side 2b. Reduce the thickness.

  FIG. 5 (c) has the same cross-sectional shape as FIG. 3, and the thickened part that is the most distant from the virtual bending neutral axis C1 that is assumed to be inclined toward the front side of the vehicle is shown in FIG. The center part 20 of the flange 2 in the area E surrounded by the dotted line and the flange 3 upper part 19 in the area A surrounded by the dotted line. That is, the center part 14 (t2) of the front flange 2 in the region E surrounded by the dotted line at the center part between the lower half side 2a and the upper half side 2b of the front flange 2 and the dotted line on the upper half side 3b of the rear flange 3 The rear flange 3 upper part 13 (t3) of the area A surrounded by is thickened.

  5 (c) is the same as that shown in FIGS. 3 and 4 except that the thickness is increased from the region C surrounded by the dotted line above the flange 2. The thickness (plate thickness) of the region from the region E surrounded by the dotted line to the region E and the region D surrounded by the dotted line below the flange 2 to the region E to be thickened. And it is the thickness (plate | board thickness) of the area | region from the site | part containing B area | region enclosed with the dotted line of the flange 2 lower part to the area | region A to be thickened. Further, the thickness (plate thickness) of the web 4 on the upper side of the region up to the corner portion 9 other than the region thickened in the vicinity of the corner portion 7, also from the corner portion 10 to the corner portion 8. This is the thickness (plate thickness) of the web 5 on the lower side of the region.

Example of FIG. 6:
6 (a), 6 (b), and 6 (c) are common examples in which the rectangular hollow cross-sectional structure of the vehicle impact absorbing member 1 is a daily cross section having a reinforcing middle rib 6, an aluminum alloy plate. It is an example consisting of. That is, a rolled and tempered aluminum alloy plate is formed into a rectangular hollow cross-sectional structure by forming such as bending, and the ends are welded to form a rectangular hollow cross-sectional structure. A separate flat middle rib 6 is attached in the hollow and joined by welding or the like. Note that FIG. 6 (d) shows a mouth-shaped cross section, which is also formed from an aluminum alloy plate.

  6 also assumes that the virtual bending neutral axis C1 is inclined toward the front side of the vehicle, as in FIGS. Then, as the portion farthest from the virtual bending neutral axis C1, the thickness of the regions A and D on the diagonal line is increased in the specific range, as in FIGS. That is, the lower half side 2a of the front flange 2 and the upper half side 3b of the rear flange 3 corresponding to the two left and right regions surrounded by the dotted lines A and D are thickened.

  In addition, the other parts are thinned. That is, the upper half side 2b of the front flange 2 and the lower half side 3 of the rear flange 3 corresponding to the two left and right regions surrounded by the dotted lines of C and B are thinned. The thickening and thinning regions and thickness are designed in the same manner as in FIGS.

  However, since this FIG. 6 is a molding material of a plate, it cannot be manufactured by selecting and designing the thickness and the cross-sectional shape of the thick part and the thin part freely like the extruded material. For this reason, thickening of the specific range of the thicknesses of the regions A and D is performed by joining (bonding) of another (separately prepared) aluminum alloy plates.

  FIG. 6A shows a rectangular hollow cross-section structure in which one aluminum alloy plate is formed and both end portions are welded together at the corner portion 7 to be integrated. Then, separate flat plates 21 and 22 are bonded to the portions of the flanges 2 and 3 that are thickened surrounded by dotted lines A and D by welding or an adhesive. The thickened areas A and D are thickened so that they are point-symmetric with each other.

  FIG. 6B shows a rectangular hollow cross-sectional structure in which two separately formed aluminum alloys composed of the flange 2 and the web 4 and the flange 3 and the web 5 are integrated with each other by welding at both ends. Is shown. The two end portions are welded to each other at portions corresponding to the thickened flanges 2 and 3 surrounded by dotted lines A and D, and the L-shaped projections (projecting flanges) 23 and 24 are hollow. The projections are projected inward and the projections are bonded together by welding or an adhesive to form a thick portion. The thickened areas A and D are thickened so that they are point-symmetric with each other.

  FIG. 6C shows a rectangular hollow cross-sectional structure in which one aluminum alloy plate is formed and both end portions are welded and integrated at the corner portions 7. However, these aluminum alloy plates are formed (bent) so as to partially overlap each other, thereby forming thickened flanges 2 and 3 surrounded by dotted lines A and D. The middle rib 6 itself is also formed by molding the same aluminum alloy plate.

  FIG. 6 (d) shows a rectangular hollow cross section in which two separately formed aluminum alloy plates composed of the flange 2 and the web 4, and the flange 3 and the web 5 are integrated with each other by welding at both ends. The structure is the same as FIG. 6B. However, one end portion of these aluminum alloy plates is folded and overlapped, and corresponds to the flanges 2 and 3 that are thickened and surrounded by dotted lines A and D. The thickened areas A and D are thickened so that they are point-symmetric with each other.

  In the case of FIG. 6, since a rolled plate that does not have a difference in plate thickness in the plate width direction or the longitudinal direction is used except for a minute rolled crown, the plate thickness must be uniform regardless of the portion of the plate. . That is, the thickness of the aluminum alloy rolled sheet can be varied depending on the part, except for a special rolled sheet. Therefore, in order to reduce the thickness of the portion other than the thickness increase, the thickness of the material aluminum alloy rolled plate must be reduced in advance, and the thickness increase is adjusted by the number of the rolled plates stacked or bonded. I have to.

Comparative example:
7 and 8 show a comparative example. In the aluminum alloy vehicle impact absorbing member 1, a virtual bending neutral axis C1 in which the vertical bending neutral axis C0 is inclined toward the front side of the vehicle, and the rear side of the vehicle. Both of these are selected together instead of any one of the virtual bending neutral axes C2 inclined toward the side. That is, as in the present invention, the flange having the farthest distance from the virtual bending neutral axes C1 and C2 with respect to the two virtual bending neutral axes C1 and C2 instead of one specific virtual bending neutral axis. The thicknesses of portions 2 and 3 and webs 4 and 5 are both increased.

  In this comparative example, the vehicle impact absorbing member 1 is not only rotated by the impact of the vehicle collision as shown by a clockwise arrow around the vehicle width direction axis on the upper right side of FIG. The case of rotating around the axis in the vehicle width direction on the lower right side as indicated by the counterclockwise arrow is also considered. In the present invention, which of the virtual bending neutral axes C1 and C2 is used is the collision form on the right side of FIG. Which of the virtual bending neutral axes to incline is predicted and determined. However, even if the vehicle impact absorbing member 1 is designed to be either the upper or lower collision type on the right side of FIG. 17 and the mounting position and the mounting method are designed to be so, in an actual collision, the prediction is The reverse case is also possible.

  Therefore, in this comparative example, from the virtual bending neutral axis C1 so that the vehicle impact absorbing member 1 may rotate in the case of the upper right side or the lower right side of FIG. Of the flanges 2 and 3 and the webs 4 and 5 which are the farthest away from each other and surrounded by dotted lines A and D, and the flanges 2 and 3 which are farthest from the virtual bending neutral axis C2 The two left and right regions surrounded by the dotted lines B and C of the webs 4 and 5 are both thickened. FIG. 7A shows that the four corners (four corners) are both thickened in the same taper shape as in FIG. 1, and FIG. 7A shows that the four corners (four corners) are both in the case of FIG. Thickened to the same step.

  However, as in this comparative example, the flanges 2 and 3 and the webs 4 and 5 and the parts A and D and B and C that are the farthest from the two virtual bending neutral axes C1 and C2 are all thickened. In such a case, the thickness and the area to be thickened are kept to a minimum, and even if the other part is thinned to the limit of strength, the increase in cross-sectional area and weight due to the thickened part should be compensated. As a result, the rate of increase in cross-sectional area cannot be suppressed to 5% or less as compared with the original vehicle impact absorbing member having a uniform flange thickness. Therefore, no matter how high the impact absorbing effect is in this respect, the advantage of practical use is lost at the expense of weight reduction due to aluminum alloying.

Aluminum alloy used:
The aluminum alloy used as a vehicle impact absorbing member in the present invention is a 5000 series or 6000 specified in AA or JIS standards because of its high strength and workability to a vehicle impact absorbing member such as extrusion, rolling, and bending. An aluminum alloy such as a system is preferable, and tempering conditions such as solution treatment, quenching treatment, and aging treatment are appropriately selected and used.

  Next, examples of the present invention will be described. The effect of the present invention was confirmed by finite element analysis using a center barrier collision test. FIG. 9 shows a sectional shape and numerical conditions of a rectangular hollow sectional structure of a bumper R / F as a vehicle impact absorbing member used for analysis. The analysis results are shown in FIGS.

  In FIG. 9 (a), the length and the cross-sectional structure of the flange and the web are the same as the rectangular hollow cross-sectional structure of the present invention, and the thickness of the flange and the web is uniform regardless of each part. The above-mentioned “virtual rectangular hollow cross-sectional structure” in the present invention, which is 4 mm. That is, the thickness of the flanges 2 and 3 designed without considering the rotation around the axis in the vehicle width direction is as uniform as 4 mm regardless of each part, and the bumper R / F of the present invention shown in FIG. A bumper R / F of a conventional example having the same flange and web length (same size) is shown. The thickness of the regions A and D to be thickened is set to a specific range. In this comparative example, as shown in FIG. 9A, the thicknesses (plate thicknesses) t1 and t4 of the flanges 2 and 3 are both 4 mm and uniform regardless of the part. Further, t5 and t6 of the webs 4 and 5 were 2 mm, which was uniform regardless of the part. Further, the position, length, and thickness of the middle rib 6 are also common at 2 mm.

  FIG. 9 (b) shows the left and right two regions of the lower portion 12 of the flange 2 in the region D surrounded by the dotted line and the upper portion 11 of the flange 3 in the region A surrounded by the dotted line in FIG. An example of the present invention in which the thickness is increased in a tapered shape so as to be point-symmetric with each other will be described. In the example of the present invention, as shown in FIG. 9B, the thickness (plate thickness) t2 of the thickened flange 2 lower portion 12 and the thickness (plate thickness) t3 of the flange 3 upper portion 11 are set to the thickest webs 4, 5 The thickness distribution is 8 mm at the intersection (corner portion) and 4 mm at the intersection with the thinnest middle rib 6. On the other hand, as the thinned portion, t2 at the upper part of the flange 2 (C region in FIG. 1) and t4 at the lower part of the flange 3 (B region in FIG. 1) were each 2 mm. Further, t5 and t6 of the webs 4 and 5 are thinned to 2 mm except for a portion (thickness = length = 8 mm) which is thickened together with the flange at the corner portion. ) Of the same thickness as the conventional example. 9A and 9B, the height H in the vehicle vertical direction is 120 mm, and the width in the vehicle front-rear direction is the same as 60 mm.

  These bumper R / Fs having the same cross-sectional area were analyzed on the assumption that a center barrier collision test of IIHS (American Road Safety Insurance Association) schematically shown in FIG. 11 was conducted. In this center barrier crash test, the vehicle vertical displacement between the lower barrier end on the right side of FIG. 11 and the upper and lower ends of the left bumper R / F is 60 mm, and the right barrier in FIG. Collide like an arrow at the top. Therefore, as shown in the upper right side of FIG. 2 or FIG. 17, the vehicle rotates as indicated by a clockwise arrow around the vehicle width direction axis. 9 (a) and 9 (b), the bending neutral axis C0 perpendicular to the vehicle vertical direction at the center of the rectangular hollow cross-sectional shape is virtually the same as the vehicle impact absorbing member 1 on the right side of FIG. The bending neutral axis C1 is inclined 10 degrees toward the vehicle front side.

As a result of this analysis, first, FIG. 10 shows the sectional area (mm ² ) and the maximum displacement (/ mm) of the conventional example (cross section A) in FIG. 9A and the invention example (cross section B) in FIG. 9B. ). As shown in FIG. 10, even when the cross-sectional areas are the same, the maximum displacement of the barrier is 4% larger in the conventional example (cross section A), and the bending neutral axis C is inclined in the inventive example (cross section B). It can be seen that the ability to absorb the collision energy in such a state is high.

  This is supported by the relationship between the reaction force and displacement of the barrier in FIG. In FIG. 12, there is no significant difference in the barrier reaction force between the thick line conventional example (cross section A) and the thin line invention example (cross section B) in the first half of the collision. However, from the middle to the second half of the collision, the barrier reaction force of the thin line invention example (cross section B) is about 10% higher than that of the thick line conventional example (cross section A). It can be seen that the maximum barrier displacement can be suppressed by about 6 mm, about 4%.

  FIG. 13 shows the relationship between the rotation angle (tilt angle) of the bumper R / F or the virtual bending neutral axis C1 from the vehicle vertical direction to the vehicle front side and the section coefficient around the vehicle vertical axis. Similarly, FIG. 14 shows the relationship between these rotation angles (tilt angles) and the plastic section modulus around the vertical axis of the vehicle body. 14 and 15, the invention example (cross section B) in which the white square marks are connected with thin lines is consistently independent of the rotation angle as compared to the conventional example (section A) in which the white circle marks are connected with thick lines. It can be seen that the section modulus around the vertical axis and the plastic section modulus around the vertical axis of the vehicle body are high. This is about 3% higher in the section modulus around the vertical axis of the vehicle body in FIG. 13, and about 2% higher in the plastic section modulus around the vertical axis of the vehicle body in FIG. As a result of these, the maximum displacement of the barrier shown in FIG. 11 is 6 mm, about 4%, which can be suppressed as compared with the conventional example (cross section A).

  As described above, the vehicle impact absorbing member according to the present invention is configured such that the neutral axis of the bend is inclined toward the front side of the vehicle due to the rotation of the vehicle impact absorbing member around the vehicle width direction due to the collision load, and the upper side is the vehicle Even in an inclined state in which the vehicle is deformed while tilting backward, the vehicle impact absorbing member can be provided with an increased section modulus and plastic section modulus for bending around an axis in the vertical direction of the vehicle without sacrificing weight reduction. . For this reason, it can be suitably used for a vehicle impact absorbing member such as a bumper reinforcement such as an automobile or a truck or an underrun protector.

1: vehicle impact absorbing member, 2, 3: flange, 4, 5: web, 6: middle rib, 7, 8, 9, 10: corner portion (corner portion), 11-29: thick portion, A, B, C, D: Thickening or thinning region, C0, C1, C2: Bending neutral axis

Claims (5)

  Two flat flanges (2, 3) standing up and down in the longitudinal direction of the vehicle and the front and rear flanges (2, 3) are spaced apart from each other in the vertical direction of the vehicle and Two flat plate-like upper and lower webs (4, 5) extending in the front-rear direction form a rectangular hollow cross section, and the length H in the vehicle vertical direction of the front and rear flanges (2, 3) is 100. In the aluminum alloy shock absorbing member having a range of ˜200 mm and a length W of the upper and lower webs (4, 5) in the vehicle longitudinal direction of 50-100 mm, the rectangular hollow cross section is defined as the vehicle longitudinal direction. Total area of the lower half side (2a) of the front flange located on the front side of the vehicle and the front half side (5a) of the lower web when divided into four equal parts in the height direction ( S1) and the rear franc located behind the vehicle The total area (S1 + S4) of the upper half side (3b) of the die and the rear half side (4b) of the upper web (S4), or the upper half side (2b) of the front flange and the upper web Of the total area (S2) of the front half side (4a) and the total area (S3) of the lower half side (3a) of the rear flange and the rear half side (5b) of the lower web (S2 +) S3) The lower half side (2a) of the front flange and the rear flange so that the sum of the areas of either one is larger than the sum of the other areas in the range of 1.5 to 3.5 times. Either the thickness of the upper half (3b) or the thickness of the upper half (2b) of the front flange and the lower half (3a) of the rear flange A vehicle impact absorbing member characterized in that it is partially thickened rather than thick.   The total area (S1) of the lower half side (2a) of the front flange and the front half side (5a) of the lower web, the upper half side (3b) of the rear flange, and the rear half side (4b) of the upper web The sum (S1 + S4) of the total area (S4) and the total area (S2) of the front flange is the total area (S2) of the upper half side (2b) of the front flange and the front half side (4a) of the upper web, and the rear flange Larger in the range of 1.5 times to 3.5 times the sum (S2 + S3) of the total area (S3) of the lower half side (3a) and the rear half side (5b) of the lower web (S3) The thickness of the lower half side (2a) of the front flange and the upper half side (3b) of the rear flange is determined so that the upper half side (2b) of the front flange and the lower half side (3a) of the rear flange The vehicle impact absorbing member according to claim 1, wherein the vehicle impact absorbing member is partially thicker than the thickness of the vehicle.   While the thickness on the upper or lower half side of each flange on the side to be thickened is in the range of 3.5 to 12 mm, the thickness on the other upper and lower half side of each flange to be thinned is 1 to 4 mm. The vehicle impact absorbing member according to claim 1 or 2.   The vehicle impact absorbing member has a vertical bending neutral axis (C0) at the center of the rectangular hollow cross section, and a virtual bending neutral axis in which the bending neutral axis (C0) is inclined toward the front side of the vehicle. The wall thickness on the upper or lower half side of the front flange 2 and the rear flange 3 that is the farthest from (C1) is larger than the wall thickness on the other upper and lower half side of the front flange 2 and the rear flange 3. The vehicle impact absorbing member according to any one of claims 1 to 3, wherein the vehicle impact absorbing member is partially thickened. The vehicle impact absorbing member according to claim 1, wherein the vehicle impact absorbing member is made of an aluminum alloy extruded profile.