JP2007118931A - Shock-absorbing member for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock-absorbing member for an automobile capable of effectively protecting a pedestrian by demonstrating an excellent impact energy absorbing function when legs or the like of the pedestrian are collided, and a low impact load is partially input. <P>SOLUTION: The shock-absorbing member consists of two first and second plate-like ribs 1, 2 consisting of a long cylindrical resin formed body and arranged parallel to each other extending in the direction orthogonal to the impact load input direction, and a cylindrical member 3 consisting of a pair of first load transmission units 31, 32 for performing the tensile deformation of the first plate-like rib 1 when the impact load is input, a pair of second load transmission units 33, 34 for performing the tensile deformation of the second plate-like rib 2 when the impact load is input, an impact load input unit 35, and first and second plate-like connection units 36-38. The tensile yield load is reduced by reducing the wall thickness of the second plate-like rib 2 arranged on the rear side in the impact load input direction more than that of the first plate-like rib 1 arranged on the front side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automobile impact absorbing member that is suitably employed in an automobile bumper and protects a person by absorbing an impact at the time of a collision.

  2. Description of the Related Art Conventionally, in automobiles, various shock absorbing members have been employed in the body frame in order to absorb the impact at the time of collision and protect the human body and the vehicle body. For example, bumpers for absorbing impact energy at the time of a car collision are attached to the front and rear portions of the body frame. Such bumpers are generally made of an iron crash box attached to the body frame by screwing or the like, an iron bumper beam attached to the outside of the crash box, and a resin bumper attached to the outside of the bumper beam. It consists of Fascia.

  In the case of a light collision that occurs during low-speed traveling or the like, this bumper absorbs impact energy by a soft bumper fascia made of a soft resin that softly collides with a collision partner and elastically deforms. Thereby, the damage to the collision partner side can be reduced, and especially a person such as a pedestrian can be protected. However, in order to reduce the damage to the collision partner side, a sufficient amount of elastic deformation of the bumper fascia is required, and accordingly, a large deformation space of the bumper fascia is required.

  Further, during a heavy collision caused by collision between the vehicle bodies or between the vehicle body and a structure during high-speed traveling or the like, the iron bumper beam or the crash box is plastically deformed and crushed to absorb a large impact energy. Thereby, the damage given to a vehicle body, a passenger | crew, etc. can be reduced. Since these bumper beams and crash boxes are generally made of metal such as iron or aluminum, they have a hollow structure with a hollow portion inside to avoid an increase in weight. Yes. In order to improve the strength of the bumper beam, a reinforcing plate is added (see Patent Document 1), the thickness of the metal plate forming the bumper beam is increased, or foamed urethane foam or the like is formed in the hollow portion of the bumper beam. A technique such as filling an elastic body (see Patent Document 2) is employed.

  By the way, in recent years, pedestrian safety at the time of a collision with a pedestrian has been required at a higher level, and in particular, a higher impact energy is required even for a bumper that is likely to collide with a pedestrian. It is required to have an absorption function.

  Therefore, in order to cope with this requirement, there has been proposed an energy absorbing member for protecting a person that can cause a deformation in a cross-sectional direction necessary for energy absorption with a low collision load corresponding to the person collision (Patent Document). 3). This energy absorbing member is composed of a front flange and a rear flange provided substantially parallel to the longitudinal direction of the vehicle body, and left and right webs provided between these flanges, and each web is directed outward. It is made of an aluminum alloy hollow shape that is curved. However, since this energy absorbing member is made of an aluminum alloy hollow shape, it tends to cause an increase in weight as compared with a resin material, which is disadvantageous in terms of fuel consumption.

  Conventionally, a molded body formed of a resin material in a predetermined shape is known as an impact absorbing member that absorbs impact energy when a relatively low impact load is input. Can be classified.

  One is a foamed elastic body such as foamed urethane or foamed PP (polypropylene). For example, the foamed elastic body is filled and arranged in a hollow portion formed in a bumper (see FIG. 49 of Patent Document 1). However, this foamed elastic body shows a relatively flat characteristic curve in the diagram showing the relationship between the load and the amount of displacement at the time of impact load input, and the energy absorption efficiency is relatively good, but the crushing residue is large, and the space This is problematic in that it is inefficient.

  The other is a rib structure formed of PP, PE (polyethylene), ABS resin, or the like. In this rib structure, a rib arranged so as to extend in an impact input direction absorbs impact energy by buckling deformation at the time of impact input. However, this rib structure has a problem in that the initial impact load tends to be large, and the impact on the collision partner tends to be large. Moreover, since this rib structure is produced by injection molding, the long structure tends to increase the manufacturing cost.

  Based on the above viewpoint, the inventors of the present application have developed a shock absorbing member for automobiles that exhibits a good shock energy absorbing function when a low impact load is inputted and can advantageously protect human bodies. A plate-shaped rib made of resin disposed so as to extend in a direction orthogonal to the input direction of the impact load, one end of each of the plate-shaped ribs being connected to both ends of the plate-shaped rib, and the plate-shaped rib from each one of the ends And a pair of plate-like holding portions that are arranged so as to approach each other as they move away from each other in a direction perpendicular to the plate, and tensilely deform the plate-like ribs when an impact load is input. Proposed (Japanese Patent Application No. 2004-359863). This shock absorbing member for automobiles can effectively protect pedestrians by being used by being attached to bumpers or the like equipped in front and rear parts of the automobile.

By the way, when the above-mentioned automobile impact absorbing member is used in an automobile bumper, it is usually formed in a long cylindrical shape from a resin, and is attached in a state in which the impact absorbing member extends in a lateral direction with respect to the automobile bumper. . When a car equipped with a shock absorbing member attached in this way collides lightly with a pedestrian during low-speed running, the pedestrian's legs often collide with the mounting position of the shock absorbing member, There are also various patterns of collision with the impact absorbing member. Therefore, when a pedestrian's leg collides, a relatively low impact load is input to a part of the impact absorbing member in the lateral direction, and the impact is not necessarily input to the entire impact absorbing member. do not do. In addition, when the inventors of the present application have tested a shock absorbing member for protecting a pedestrian's leg, when the shock absorbing member is deformed due to a collision, the load tends to be excessively increased from the middle to the second half. It turned out to be.
JP-A-6-171441 JP 2001-132787 A JP 2004-90910 A

  The present invention has been made in view of the above circumstances, and when a pedestrian's legs collide and a low impact load is partially input, it exhibits a good impact energy absorption function and protects the pedestrian. An object of the present invention is to provide an automobile impact absorbing member that can be more effectively achieved.

The impact-absorbing member for automobiles of the present invention that solves the above problems is
It consists of a molded body formed in a predetermined shape with a resin material,
A plurality of plate-like ribs arranged parallel to each other at a distance so as to extend in a direction orthogonal to the impact load input direction;
A plurality of the plate-shaped ribs arranged on the front side in the direction of the shock load input and receiving an impact load input, and one ends of the plate-shaped ribs connected to both ends of the plate-shaped ribs. The other ends are inclined so as to approach each other as they move away from the plate ribs in a direction perpendicular to the plate ribs. A cylindrical member having a load transmitting portion that transmits as a load in the tensile direction of
At least one of the plurality of plate-like ribs is different in at least one of its own tensile yield load and the transmission efficiency of the load in the tensile direction by the load transmission unit, so that when the impact load is input, The load-tensile direction displacement characteristics are different from those of the other plate-like ribs.

  In this specification, the tensile yield load is the maximum load when the tensile displacement of the tensile test piece starts to increase without increasing the load when the tensile test is performed using the tensile test piece shown in FIG. I mean. That is, in the model diagram of FIG. 13 showing the relationship between the load and displacement during the tensile test, the peak value of the initial rise of the load is the tensile yield load. Further, as shown in the model diagram of FIG. 14, the transmission efficiency of the load in the tensile direction by the load transmission unit is determined by the load transmission units 31 to 34 when the impact load F is input to the impact load input unit 35. Means the efficiency of transmission as a tensile load T to the plate-like ribs 1 and 2. The transmission efficiency of the load in the tensile direction varies depending on the inclination angles α and β of the load transmission units 31 to 34 with respect to the input direction of the impact load F.

  The automobile impact-absorbing member of the present invention is usually formed in a long shape with a resin, and the lateral side so that the impact load input portion is located on the front side (outside of the automobile) in the impact load input direction with respect to the bumper of the automobile. Used in a state extending in the direction. The shock absorbing member is attached in a state where the plurality of plate-like ribs extend in a direction orthogonal to the shock load input direction and are parallel to each other at a distance. In this case, at least one of the plurality of plate-like ribs is configured such that the load-tensile direction displacement characteristics when an impact load is input are different from those of the other plate-like ribs.

  For example, when a relatively low impact load is input to a part of the impact load input portion on the front side in the impact load input direction due to a collision of a pedestrian's leg with the impact absorption member attached in this state, the impact absorption member Starts compressive deformation partially from a part of the impact load input section. In this case, the contact surface of the pedestrian's leg with the impact load input portion is small in the initial stage, but the contact area increases with time. Thereby, at the initial stage of deformation, the connecting end portions of the pair of load transmitting portions connected to both ends of the first plate-like rib arranged on the foremost side in the impact load input direction are displaced so as to move away from each other. Accordingly, the first plate-like rib is pulled and deformed by pulling so that both ends are separated.

  Thereafter, as the compressive deformation of the shock absorbing member proceeds to the rear side in the impact load input direction, the second and third plate-like ribs arranged in order from the front side in the impact load input direction are sequentially changed to the plate-like ribs. As with the first plate-shaped rib, the pair of load transmitting portions connected to both ends are pulled away from each other and pulled and deformed, and the impact energy is effectively reduced by the tensile deformation of each plate-shaped rib. Absorbed.

  Thus, since the impact energy is absorbed by utilizing the good elongation characteristics and tensile characteristics of the resin plate-shaped ribs, the initial impact load does not increase suddenly, and the plate-shaped ribs are not deformed in tension. Since the process is continuously performed, the drop after the initial impact load rises is extremely small, so that the impact energy is efficiently absorbed. Moreover, since each load transmission part and each plate-shaped rib do not deform | transform so that it may fold in an impact load input direction, since the crushing residue becomes small, it becomes possible to ensure a larger amount of impact energy absorption. Thereby, the damage given to the leg part of the pedestrian who collides is reduced significantly, and a pedestrian is protected reliably.

  In particular, the impact absorbing member of the present invention is configured such that at least one of the plurality of plate-like ribs is configured such that the load-tensile displacement characteristics at the time of input of an impact load are different from those of other plate-like ribs. In the plate-like rib, it is possible to set so that the mode of tensile deformation at the time of impact load input is different. Therefore, the deformation mode of the shock absorbing member in the shock energy absorbing process can be changed as appropriate according to the purpose, and the degree of tuning freedom is expanded.

  For example, when the impact absorbing member of the present invention collides with a pedestrian's leg part, the contact area of the leg part increases as the compressive deformation of the impact absorbing member proceeds, and the part actually compressed increases. Therefore, if a plate-shaped rib configured to reduce the tensile yield load is arranged on the rear side in the impact load input direction that handles the load in the later stage of deformation of the shock absorbing member, the load increases. Can be moderately suppressed. That is, the actual load is expressed by (load per unit area) x (compressed area), so the load per unit area of the plate-like ribs arranged on the rear side in the impact load input direction is reduced. Will be. For this reason, in the latter half region of the diagram representing the relationship between the load and the amount of displacement when the impact load is input, the load characteristics are more flat than ideal. Therefore, when a low impact load is partially input due to a collision with a pedestrian's leg, etc., the impact load increase in the later stage of deformation is moderately suppressed and a good impact energy absorption function is exhibited. Protection can be made more effective.

  In the present invention, at least one of the plurality of plate-like ribs arranged in parallel with each other so as to extend in a direction orthogonal to the impact load input direction is the tensile yield load of its own and the tensile direction load by the load transmitting portion. Since at least one of the transmission efficiency is different, the load-tensile direction displacement characteristics when an impact load is input are different from those of other plate-like ribs. Different tensile yield loads of the plate-like ribs can be achieved by changing the thickness of the plate-like ribs or changing the forming material of the plate-like ribs. In addition, the transmission efficiency of the load in the tensile direction by the load transmission unit can be changed by changing the inclination angle of the load transmission unit with respect to the input direction of the impact load. In this case, the change in the inclination angle of the load transmitting portion can be achieved by changing the length dimension of the plate-like rib in the width direction (tensile deformation direction). The plate-like ribs configured to have different load-tensile direction displacement characteristics when an impact load is input may be one or more of the plurality of plate-like ribs.

  In the present invention, it is preferable that the plate-like rib disposed on the rear side in the impact load input direction is configured such that the tensile yield load is smaller than that disposed on the front side. In order to make the tensile yield load smaller, the thickness of the plate-like rib arranged on the rear side is made thinner than that of the plate-like rib on the front side, or by adopting, for example, two-color molding. This can be achieved by integrally forming the plate-like ribs arranged on the side with a resin material having a smaller tensile yield stress than the plate-like ribs on the front side.

  The plate-like rib in the present invention is preferably formed of a resin material having a tensile elongation at break of 100% or more and a tensile yield stress of 15 Mpa or more. In this way, it is possible to ensure good characteristics against tensile deformation of the plate-like ribs that are tensilely deformed by the load transmitting portion when an impact load is input, and therefore it is possible to ensure good impact energy absorption performance. In addition, in this specification, the tensile breaking elongation and the tensile yield stress mean the tensile breaking elongation and the tensile yield stress defined by JIS-K7162, respectively.

  In the present invention, the cylindrical member configured to have an impact load input portion and a plurality of pairs of load transmission portions is not limited to a circular shape or an oval cross-sectional shape, for example, a polygonal shape such as an octagon or a plurality of A combination of polygons can be employed. In this case, the plurality of plate-like ribs are arranged inside the cylindrical member in a state where both ends in the width direction are connected to the respective one ends of the load transmitting portions that make a pair. This cylindrical member can be configured to have a plate-like connecting portion that connects the ends of the load transmitting portions adjacent in the circumferential direction.

  It is preferable that the thickness of the plate-like connecting portion is larger than the thickness of the plate-like ribs in order to more reliably fix the position of the other end of the load transmitting portion that forms a pair when an impact load is input. . Moreover, the cylindrical member comprised in this way utilizes the plate-shaped connection part arrange | positioned at the backmost side as an attachment fixing | fixed part. In this case, a slit extending in the axial direction is formed between the other ends of the pair of load transmitting portions arranged at the rearmost side so as to exclude the plate-like connecting portion, and the loads positioned on both sides of the slit. You may make it provide an attachment fixing | fixed part in a transmission part, respectively.

  In this invention, the impact load input part provided in a cylindrical member is arrange | positioned in the front side of the impact load input direction of several plate-shaped rib. The impact load input portion preferably has a larger width in the circumferential direction than the plate-like connecting portion arranged on the most rear side. In this way, the rigidity of the plate-like connecting part can be adjusted in accordance with the method of changing the magnitude of the tensile yield load of each plate-like rib and the way of changing the rigidity of the load transmitting parts that make a pair. Since they can be made different, each plate-like rib can be more smoothly and reliably subjected to tensile deformation.

  It is preferable that the thickness of the load transmitting portion is greater than the thickness of the plate-like rib. In this way, sufficient rigidity of the load transmitting portion is ensured, so that the plate-like rib can be surely pulled and deformed. Moreover, sufficient rigidity of the load transmitting portion can be ensured by making the thickness of the central portion of the load transmitting portion thicker than both end portions. This load transmitting portion is preferably formed of a resin material having a flexural modulus of 1 Gpa or more. In this way, the plate-like rib can be more reliably pulled and deformed when an impact load is input. In addition, in this specification, a bending elastic modulus means the bending elastic modulus defined by JIS-K7171.

  In addition, as a preferable form of the impact absorbing member of the present invention, the plurality of plate-shaped ribs include a first plate-shaped rib disposed on the front side in the impact load input direction, and a rear side of the first plate-shaped rib in the impact load input direction. Each of the cylindrical members is connected to both ends of the impact load input portion and the first plate rib and to both ends of the impact load input portion. A pair of first load transmission parts to which the other ends are connected, a pair of second load transmission parts whose one ends are connected to both ends of the second plate-shaped rib, and the other ends of the pair of second load transmission parts And a pair of second load connecting portions that connect one ends of the pair of first load transmitting portions and a pair of second load transmitting portions. . If it does in this way, it will become space efficient and a compact structure, and the preferable impact-absorbing member which can exhibit a favorable impact-absorbing effect can be produced simply.

  In the present invention, examples of the resin material used for forming the molded body include trade name “UBE nylon 6” (manufactured by Ube Industries, product number “1013IU50”), PC (polycarbonate), PC / PBT (polybutylene terephthalate). ) Alloys, PP (polypropylene), PE (polyethylene), ABS (acrylonitrile / butadiene / styrene) and the like can be suitably employed. Among these resin materials, the above-mentioned “UBE nylon 6” has a flexural modulus of 1 Gpa or more, a tensile elongation at break of 100% or more, and a tensile yield stress of 15 Mpa or more, and therefore can be particularly preferably employed. Moreover, conventionally well-known methods can be employed for the molding treatment, and in particular, extrusion molding or the like that is advantageous for manufacturing a long product can be employed.

  According to the automobile impact absorbing member of the present invention, a good impact energy absorbing function is exhibited when the impact absorbing member is deformed by a collision of a leg part of a pedestrian and the partial input of a low impact load. Protecting pedestrians more effectively. Further, at least one of the plurality of plate-like ribs is different in at least one of its own tensile yield load and the transmission efficiency of the load in the tensile direction by the load transmitting portion, so that the load − when the impact load is input − Since the displacement characteristics in the tensile direction are different from those of other plate-like ribs, it is possible to change the deformation mode of the shock absorbing member in the shock energy absorption process as appropriate according to the purpose, increasing the degree of tuning freedom. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view in the direction perpendicular to the axis of an automobile impact absorbing member according to this embodiment, and FIG. 2 is a perspective view of the automobile impact absorbing member.

  As shown in FIGS. 1 and 2, the impact absorbing member of the present embodiment is formed of a long cylindrical molded body integrally formed of a resin material, and extends in a direction orthogonal to the impact load input direction. Two first and second plate-like ribs 1 and 2 arranged in parallel with each other at a predetermined distance, a pair of first load transmission parts 31 and 32, a pair of second load transmission parts 33 and 34, and an impact It is comprised from the cylindrical member 3 which consists of the load input part 35, the 1st plate-shaped connection part 36, and a pair of 2nd plate-shaped connection parts 37 and 38. As shown in FIG.

  The first plate-like rib 1 is formed in a flat plate shape having a wall thickness t1 of 0.8 mm and a width dimension W1 of 50 mm. The second plate-like rib 2 has a thickness t2 of 0.5 mm and is formed in a flat plate shape having the same width W1 as the first plate-like rib 1. The second plate-like rib 2 is made thinner than the first plate-like rib 1 so that the tensile yield load is reduced. Thus, the load-tensile direction in the impact load input direction. The displacement characteristics are different from those of the first plate-like rib 1. The first plate-like rib 1 and the second plate-like rib 2 are arranged in parallel with a distance corresponding to the width dimension W5 of the second plate-like connecting portions 37, 38.

  The cylindrical member 3 has an impact load input portion 35 disposed on the first plate-like rib 1 side and one end connected to both ends of the first plate-like rib 1 and both ends of the impact load input portion 35. A pair of first load transmission portions 31 and 32 to which the other ends of the second plate-shaped ribs 2 are connected, a pair of second load transmission portions 33 and 34 to which both ends are connected to both ends of the second plate-like rib 2, and a pair of first load transmission portions 33 and 34. 2 The first plate-like connecting part 36 that connects the other ends of the load transmitting parts 33 and 34, the pair of first load transmitting parts 31 and 32, and the one end of the pair of second load transmitting parts 33 and 34 are connected. It consists of a pair of 2nd plate-shaped holding parts 37 and 38, and the cross-sectional shape is formed in the cylinder shape of an octagon.

  As the pair of first load transmitting portions 31 and 32 are moved away from the respective first ends connected to both ends of the first plate-like rib 1 in the direction perpendicular to the first plate-like rib 1, the other ends approach each other. It is arranged so as to be inclined. The pair of second load transmitting portions 33, 34 is connected to the other end of the second plate-like rib 2 from the one end of the second plate-like rib 2 as the other end of the second load transmitting portion 33, 34 moves away from the second plate-like rib 2. It is arranged to be inclined so as to approach. That is, the 1st and 2nd load transmission parts 31-34 are arrange | positioned in the state which inclined and opposed toward the impact load input direction. Then, one end (left side in FIG. 1) of the first plate-like rib 1 and the second plate-like rib 2 is connected by one second plate-like connecting portion 37, and the first plate-like rib 1 and the second plate-like rib. The other ends (right side in FIG. 1) of the two are connected by the other second plate-like connecting portion 38.

  Each of the first and second load transmitting portions 31 to 34 has a flat inner surface and a curved outer surface so that the central portion bulges outward. It is also made thicker. The thickness t3 of the central part of the first load transmission parts 31, 32 is 2.8 mm, the thickness t4 of the central part of the second load transmission parts 33, 34 is 2.0 mm, and the second load transmission The portions 33 and 34 are generally thinner than the first load transmitting portions 31 and 32. The width dimension W2 of the 1st and 2nd load transmission parts 31-34 is 20 mm.

  Further, the impact load input part 35 for connecting the other ends of the first load transmitting parts 31 and 32 and the first plate-like connecting part 36 for connecting the other ends of the second load transmitting parts 33 and 34 are provided on the inner surface and the outer surface. Is flat, and the wall thickness t7 is constant at 2 mm. The wall thickness t5 of the impact load input portion 35 is 2 mm, and the wall thickness t6 of the first plate-like connecting portion 36 is 2.5 mm. The width dimension W3 of the impact load input portion 35 is 25 mm, the width dimension W4 of the first plate-like connecting portion 36 is 15 mm, and the impact load input portion 35 is wider than the first plate-like connecting portion 36. The dimensions have been increased.

  The pair of second plate-like connecting portions 37 and 38 are curved surfaces so that the inner surface and the outer surface bulge outward, and the wall thickness t7 is substantially constant, and the width dimension W5 thereof is 20 mm. It is said that. Therefore, the thickness of the cylindrical member 3 which consists of the 1st and 2nd load transmission parts 31-34, the impact load input part 35, and the 1st and 2nd plate-shaped connection parts 36-38 is the 1st and 2nd board. The ribs 1 and 2 are thicker than the wall thickness.

  The impact absorbing member of the present embodiment is formed into a predetermined curved shape after cutting an extrusion molding material integrally formed with a trade name “UBE nylon 6” (product number “1013IU50” manufactured by Ube Industries, Ltd.) into a predetermined dimension. It is made by processing. Thereby, the first and second load transmitting portions 31 to 34 of the cylindrical member 3 have a flexural modulus of 1 Gpa or more, and the first and second plate-like ribs 1 and 2 have a tensile breaking elongation of 100% or more. The tensile yield stress is 15 Mpa or more. In this embodiment, the second plate-like rib 2 has a smaller thickness than the first plate-like rib 1 so that the tensile yield load is reduced as described above. It is.

  As shown in FIGS. 3 and 4, for example, the shock absorbing member for an automobile of the present embodiment configured as described above extends in the lateral direction with respect to the bumper mounted on the front and rear parts of the automobile. Installed and used as pedestrian protection. This shock absorbing member is fixedly attached to the front surface of the iron bumper beam 6 (rear surface in the case of the rear portion of the vehicle body frame) attached to the front portion of the vehicle body frame (not shown) via a pair of crash boxes 5 and 5. The outer surface of the second plate-like connecting part 36 which is a part is attached by being fixed with an adhesive, and is disposed between the bumper beam 6 and the bumper fascia 7 attached to the outside thereof. In this case, in the impact absorbing member, the impact load input portion 35 is located on the front side in the impact load input direction (bumper fascia 7 side), and the first and second plate-like ribs 1 and 2 are in the impact load input direction (mainly illustrated in FIG. 4 is attached so as to extend in a direction (vertical direction) substantially orthogonal to the arrow x direction in FIG.

  When a vehicle having a shock absorbing member attached thereto collides with a pedestrian's leg during low-speed traveling or the like and a relatively low impact load is input to the bumper fascia 7, the displacement due to the elastic deformation of the bumper fascia 7 The impact load is input to a part of the impact load input portion 35 of the impact absorbing member in the lateral direction, and the impact absorbing member is partially pressed from the front side of the impact load input direction by the portion of the impact load input portion 35 being pressed by the bumper fascia 7. The compression deformation starts. In this case, the contact surface to the impact load input unit 35 is small at the initial point, but the contact area increases with the passage of time. Thereby, in the initial stage of deformation, the first load transmitting portions 31 and 32 are disposed in a state of being opposed to each other while being inclined toward the impact load input direction. The first plate-like rib 1 disposed on the foremost side in the impact load input direction is displaced so that the connecting end portions of the pair of first load transmitting portions 31 and 32 connected to both ends thereof are separated from each other. It is pulled and deformed by pulling its both ends away.

  After that, as the compressive deformation of the shock absorbing member proceeds, the second plate-like rib 2 disposed on the rear side in the shock load input direction of the first plate-like rib 1 has a pair of second loads connected to both ends thereof. Since the transmission parts 33 and 34 are arranged in a state of being inclined and opposed toward the impact load input direction, by displacing the connecting end parts of the second load transmission parts 33 and 34 away from each other, The both ends of the first and second plate-like ribs 1 and 2 are pulled and deformed by being pulled away, and the impact energy is effectively absorbed by the tensile deformation of the first and second plate-like ribs 1 and 2.

  Thus, since the impact energy is absorbed using the good elongation characteristics and tensile characteristics of the first and second plate-like ribs 1 and 2 made of resin, the initial impact load does not increase rapidly, Moreover, since the tensile deformation of the first and second plate-like ribs 1 and 2 is continuously performed, the initial impact load is hardly reduced, so that the impact energy is absorbed very efficiently. Further, in the structure of the shock absorbing member of the present embodiment, the first and second load transmitting portions 31 to 34 and the plate-like ribs 1 and 2 are not crushed because they are not deformed so as to be folded in the direction of impact load input. Therefore, a large impact energy absorption amount can be secured even in a limited installation space. Therefore, the damage to the leg of the collision partner pedestrian is greatly reduced, and the pedestrian is reliably protected.

  In particular, in the case of this shock absorbing member, as the compression deformation progresses, the contact area of the pedestrian's leg increases and the load increases because the portion that is actually compressed increases. Since the second plate-like rib 2 configured to reduce the tensile yield load is disposed on the rear side in the impact load input direction that handles the load in the later stage of deformation, an increase in the load is moderately suppressed. That is, since the actual load is expressed by (load per unit area) × (area to be compressed), in the shock absorbing member of the present embodiment, the first load disposed on the rear side in the shock load input direction. The load per unit area of the two plate-like ribs 2 is reduced. Therefore, as will be apparent from the test results described later, a flat characteristic curve that is closer to the ideal is obtained in the latter half of the diagram (see FIG. 10) that represents the relationship between the load and the amount of displacement when an impact load is input. . Therefore, the impact absorbing member of the present embodiment exhibits a good impact energy absorbing function when a low impact load is input, and can more effectively protect the pedestrian's legs.

  As described above, the impact absorbing member of the present embodiment is formed of a molded body integrally formed of a resin material, and is arranged in parallel with each other so as to extend in a direction orthogonal to the impact load input direction. One end is connected to both ends of the first and second plate-like ribs 1 and 2 and the first and second plate-like ribs 1 and 2 to pull the first and second plate-like ribs 1 and 2 when an impact load is input. Since it is composed of the cylindrical member 3 having the first and second load transmitting portions 31 to 34 to be deformed, it can exhibit a good impact energy absorbing function when a low impact load is applied, A pedestrian can be protected reliably and advantageously.

  In particular, in the impact absorbing member of this embodiment, the two first and second plate-like ribs 1 and 2 arranged in parallel with each other are the second plate-like ribs arranged on the rear side in the direction of impact load input. 2 is configured such that the tensile yield load is reduced by making the wall thickness thinner than that of the first plate-like rib 1 disposed on the front side. Since the rise can be moderately suppressed, the pedestrian's legs can be protected more effectively. Moreover, since the impact-absorbing member of this embodiment can be integrally produced by extrusion molding advantageous for manufacturing a long product, an increase in manufacturing cost can be avoided.

  In the above-described embodiment, the second plate-like rib 2 is made thinner than the first plate-like rib 1 so that the tensile yield load is reduced. For example, the second plate-shaped rib 2 is formed by adopting a material having a smaller tensile elongation at break or tensile yield stress than the first material. It may be made smaller than 1. Moreover, it replaces with making the tensile yield load of the 1st plate-like rib 1 and the 2nd plate-like rib 2 different, and the tension direction by the load transmission parts 31-34 of the 1st plate-like rib 1 and the 2nd plate-like rib 2 By changing the load transmission efficiency, the load-tensile displacement characteristics of the first plate-like rib 1 and the second plate-like rib 2 at the time of impact load input may be made different.

  Further, the impact absorbing member of the above embodiment is configured to be attached and fixed by fixing the outer surface of the first plate-like connecting portion 36 of the cylindrical member 3 to the bumper beam 6 with an adhesive. As shown in FIG. 5, a slit extending in the axial direction is formed in a portion between the second load transmitting portions 33 and 34 forming a pair of the cylindrical member 3 so as to exclude the first plate-like connecting portion 36, and the pair is formed. You may make it provide the attachment fixing | fixed part 33b and 34b in each edge part along the slit of the 2nd load transmission parts 33 and 34 to make.

  Moreover, although the impact-absorbing member of the said embodiment has two 1st and 2nd plate-shaped ribs 1 and 2 from which thickness differs, for example, as shown in FIG.6 and FIG.7, thickness differs. It can be configured to have three first to third plate-like ribs 11, 12, and 13, and in this case as well, what is arranged on the rear side in the impact load input direction is arranged on the front side By being configured so that the tensile yield load becomes smaller, the same operation and effect as the impact absorbing member of the above embodiment can be obtained.

  The shock absorbing member shown in FIG. 6 has three first to third plate-like ribs 11 arranged in parallel to each other at a predetermined distance so as to extend in a direction orthogonal to the shock load input direction (arrow a direction). -13, a pair of first load transmission units 131 and 131, a pair of second load transmission units 132 and 132, a pair of third load transmission units 133 and 133, a pair of fourth load transmission units 137 and 138, and an impact load It is comprised from the cylindrical member 30 formed in the polygonal cylinder shape which consists of the input part 135 and the 1st plate-shaped connection part 136. As shown in FIG. In this case, the first plate-like rib 11 configured so that the tensile yield load is maximized due to the thickest wall thickness is arranged on the foremost side in the impact load input direction. The third plate-like rib 13 is arranged on the most rear side so that the tensile yield load is minimized by making the wall thickness the smallest. In addition, the first load transmitting portions 131 and 131 arranged on the foremost side in the impact load input direction are configured to have the highest rigidity due to the largest thickness, and are the most in the impact load input direction. The third load transmitting portions 133 and 133 arranged on the rear side are configured to have the lowest rigidity because the thickness is the thinnest.

  Further, the impact absorbing member shown in FIG. 7 is connected to one third plate-like rib 13 and both ends of the third plate-like rib 13 with respect to the impact absorbing member shown in FIG. 1 of the above embodiment. One end of each of the third plate-shaped ribs 13 is connected to both ends of the pair of third load transmitting portions 133 and 133 and the third plate-shaped ribs 13 arranged on the one surface side of the third plate-shaped rib 13. This is a structure in which a cylindrical member 103 having a pair of fourth load transmission portions 134 and 134 disposed on the surface side is assembled. In this case, the third plate-like rib 13 is arranged on the front side of the first plate-like rib 1 in the impact load input direction (arrow b direction), and is thicker than the first plate-like rib 1. Therefore, the tensile yield load is maximized. The third load transmission units 133 and 133 and the fourth load transmission units 134 and 134 have the same thickness and width dimension. The third plate connecting portion 139 that connects the other ends of the pair of third load transmitting portions 133 and 133 has the same thickness and width as the impact load input portion 35, and this shock absorbing member In this case, the third plate-like connecting portion 139 serves as the impact load input portion instead of the impact load input portion 35 because it is disposed at the most front side in the impact load input direction.

〔test〕
In order to confirm the excellent effects of the impact absorbing member for automobiles of the present invention, the impact absorbing member shown in FIG. 1 of the above embodiment is prepared as an example, and the impact absorbing member shown in FIG. 8 is prepared as a comparative example. Then, a test for examining the impact energy absorption performance was conducted. The comparative example is formed in an octagonal cylindrical shape with the same resin material as the example, and is arranged in parallel to each other so as to extend in a direction orthogonal to the impact load input direction as shown in FIG. The first plate-like rib 1a and the second plate-like rib 2a, the pair of first load transmission portions 31a and 32a, the pair of second load transmission portions 33a and 34a, the impact load input portion 35a, and the first and second And a cylindrical member 3a composed of plate-like connecting portions 36a to 38a.

  This comparative example is significantly different from the example in that the thickness t11 of the first plate-like rib 1a and the thickness t12 of the second plate-like rib 2a are the same at 0.9 mm. The width dimension W11 of the first and second plate-like ribs 1a and 2a is 50 mm. Moreover, the thickness t13 of the center part of the 1st load transmission parts 31a and 32a and the thickness t14 of the center part of the 2nd load transmission parts 33 and 34 are made the same at 3.3 mm, and the 1st and 2nd The width dimension W12 of the load transmitting portions 31a to 34a is 25 mm. The impact load input part 35a and the first plate-like connecting part 36a have a flat outer surface and a curved surface so that the inner surface swells inward, and the wall thicknesses t15 and t16 at the center are 3 mm. Have been the same. The second plate-shaped connecting portions 37a and 38a have inner and outer surfaces that are flat, a thickness t17 that is constant at 2 mm, and a width dimension W15 of 18 mm.

  In this test, as shown in FIG. 9, the outer surface of the first plate-like connecting portion 36 (36a) of each test piece is fixed to the upper surface of the metal plate 71, and the diameter is 70 mm from above the test piece. A cylindrical striker 73 having a length of 200 mm is made to collide with the test piece so as to intersect at right angles, and an impact load is applied at a speed of 3 m / s. The load value (kN) applied by the load and the test piece at that time 11 is examined, and the result is shown in FIG. In FIG. 11, the energy absorption amount of each test piece corresponds to the area of the region surrounded by the characteristic curve and the horizontal axis indicating the deformation rate, and the larger the area, the larger the energy absorption amount. Be evaluated. Further, in FIGS. 10A to 10F, the state in which the impact absorbing member according to the embodiment is deformed by the impact load input is shown step by step from (a) to (f) in order.

  As is clear from FIG. 11, in the case of the comparative example, at the initial stage of the load application, after suddenly rising until the load value becomes 2 kN, the state becomes level until the displacement amount is about 13 mm, and then the displacement After the load value rises gently until the amount reaches about 25 mm, the load value rises slightly abruptly until the displacement amount reaches about 40 mm. That is, in the case of the comparative example, since the load value increases in the latter half when the displacement amount is 25 mm or more, the damage given to the leg of the pedestrian increases.

  On the other hand, in the case of the embodiment, as is apparent from FIG. 11, in the initial stage of the load application, after suddenly rising until the load value becomes close to 3 kN, the state is level until the displacement amount is about 25 mm. After that, the load value has risen drastically after the load value has been leveled in a state of maintaining about 2.7 kN until the displacement amount is about 40 mm. In other words, in the case of the example, the initial rising slope of the load value is slightly gentler than that of the comparative example, but the load value rises greatly to around 3 kN, and then the load value is increased until the displacement amount is about 40 mm. The value is kept flat and high without much fluctuation, and the load characteristics are more ideal.

  In particular, it can be seen that the increase in the load value is greatly suppressed as compared with the comparative example in the range of the displacement amount of 25 to 40 mm in the later stage of deformation of the shock absorbing member. The major reason for this difference is that in the comparative example, the first plate-like rib 1a and the second plate-like rib 2a have the same thickness, whereas in the example, they are arranged on the rear side in the direction of impact load input. This is because the second plate-like rib 2 is configured to have a smaller tensile yield load by being thinner than the first plate-like rib 1 disposed on the front side. is there. In the case of the example as well, a large impact energy absorption amount substantially equal to that of the comparative example is obtained as a whole.

  When the impact absorbing member of the embodiment is partially compressed and deformed by impact load input, as shown in FIGS. 10A to 10F, the impact load input portion 35 side (striker) of the cylindrical member 3 is used. 73 side), and the compressive deformation of the shock absorbing member proceeds to the rear side in the impact load input direction and from the first plate-like rib 1 arranged on the front side in the impact load input direction to the rear side. The second plate-like ribs 2 arranged are sequentially pulled and deformed. Since the first and second plate-like ribs 1 and 2 are continuously subjected to the tensile deformation, the impact energy is efficiently absorbed, so that a large impact energy absorption amount can be obtained.

  From the above, as in the embodiment, the second plate-like rib 2 arranged on the rear side in the impact load input direction has a smaller tensile yield load than the first plate-like rib 1 arranged on the front side. Since it is possible to moderately suppress an increase in impact load in the later stage of deformation of the shock absorbing member, it is possible to protect the pedestrian's leg more effectively, and the pedestrian's leg It was found that an optimal shock absorbing member for protection can be obtained.

1 is a cross-sectional view in a direction perpendicular to an axis of an automobile impact absorbing member according to an embodiment of the present invention. 1 is a perspective view of an automobile impact absorbing member according to an embodiment of the present invention. It is a top view which shows the state which attached the shock absorption member for motor vehicles based on embodiment of this invention to the bumper. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is sectional drawing of the axis orthogonal direction of the impact-absorbing member for motor vehicles which concerns on other embodiment of this invention. It is sectional drawing of the axis orthogonal direction of the impact-absorbing member for motor vehicles which concerns on other embodiment of this invention. It is sectional drawing of the axis-perpendicular direction of the impact-absorbing member for motor vehicles which concerns on other embodiment of this invention. It is explanatory drawing which shows the shape and dimension of the comparative example used by the test. (A) (b) It is explanatory drawing which shows a test method. (A)-(f) It is explanatory drawing which shows a mode that the impact-absorbing member which concerns on an Example deform | transforms by impact load input in a test. It is a graph which shows the load-displacement curve of the Example in a test, and a comparative example. It is explanatory drawing which shows the shape and dimension of a tensile test piece used for a tensile test. It is a model diagram which shows the relationship between the load and displacement at the time of a tension test. It is a model figure for demonstrating the transmission efficiency of the tensile direction load in the impact-absorbing member for motor vehicles of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 11 ... 1st plate-like rib 2, 2a, 12 ... 2nd plate-like rib 13 ... 3rd plate-like rib 3, 3a, 30, 103 ... Cylindrical member 31, 32, 31a, 32a, 131 ... 1st load transmission part 31b, 32b ... Attachment fixing part 33, 34, 33a, 34a, 132 ... 2nd load transmission part 133 ... 3rd load transmission part 134, 137, 138 ... 4th load transmission part 35, 35a, 135 ... Impact load input part 36, 36a, 136 ... 1st plate-like connection part 37, 37a, 38, 38a ... 2nd plate-like connection part 139 ... 3rd plate-like connection part (impact load input part)
71 ... Metal plate 73 ... Strike

Claims (10)

It consists of a molded body formed in a predetermined shape with a resin material,
A plurality of plate-like ribs arranged parallel to each other at a distance so as to extend in a direction orthogonal to the impact load input direction;
A plurality of the plate-shaped ribs arranged on the front side in the direction of the shock load input and receiving an impact load input, and one ends of the plate-shaped ribs connected to both ends of the plate-shaped ribs. The other ends are inclined so as to approach each other as they move away from the plate ribs in a direction perpendicular to the plate ribs. A cylindrical member having a load transmitting portion that transmits as a load in the tensile direction of
At least one of the plurality of plate-like ribs is different in at least one of its own tensile yield load and the transmission efficiency of the load in the tensile direction by the load transmission unit, so that when the impact load is input, A shock-absorbing member for automobiles, characterized in that load-tensile direction displacement characteristics are different from those of the other plate-like ribs.   The automobile impact absorbing member according to claim 1, wherein the plurality of plate-like ribs have different tensile yield loads of their own due to differences in at least one of a member size and a forming material.   3. The automobile impact absorbing member according to claim 1, wherein the plurality of plate-like ribs are configured such that a tensile yield load is smaller in a rear side than in a front side in the impact load input direction.   The plate-like rib arranged on the rear side in the impact load input direction is made thinner than the plate-like rib arranged on the front side, so that the tensile yield load is reduced. The automobile impact absorbing member according to any one of the above.   The shock absorbing member for automobile according to any one of claims 1 to 4, wherein a thickness of the load transmitting portion is thicker than a thickness of the plate-like rib.   The shock absorbing member for an automobile according to any one of claims 1 to 5, wherein the thickness of the load transmitting portion is thicker at the center than at both ends.   The said cylindrical member is an impact-absorbing member for motor vehicles in any one of Claims 1-6 which have a plate-shaped connection part which connects the edge parts of each said load transmission part adjacent in the circumferential direction.   The automobile impact absorbing member according to claim 7, wherein the impact load input portion has a circumferential width larger than that of the plate-like connecting portion arranged on the most rear side in the impact load input direction.   The cylindrical member has a slit extending in the axial direction formed between the other ends of the pair of load transmitting portions arranged on the most rear side in the impact load input direction, and on both sides of the slit, respectively. The impact-absorbing member for automobiles according to any one of claims 1 to 7, wherein an attachment fixing portion is provided.   The plurality of plate-shaped ribs are a first plate-shaped rib disposed on the front side in the impact load input direction, and a second plate-shaped disposed on the rear side of the first plate-shaped rib in the impact load input direction. The cylindrical member is configured such that one end is connected to both ends of the impact load input portion and the first plate-shaped rib, and the other end is connected to both ends of the impact load input portion. A pair of first load transmission portions, a pair of second load transmission portions whose one ends are coupled to both ends of the second plate-shaped rib, and the other ends of the pair of second load transmission portions are coupled to each other. Any of Claims 1-8 which consist of a 1st plate-shaped connection part and a pair of 2nd plate-shaped connection part which connects the said one ends of a pair of said 1st load transmission part and a pair of said 2nd load transmission part. A shock absorbing member for automobiles according to any one of the above.

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