JP2008030535A - Bumper beam of car body, and shock absorbing member for car body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy absorbing member for preventing a human injury having a function for surely protecting a person, such as a pedestrian, even when its outer shape has a comparatively large area and a narrow width. <P>SOLUTION: A bumper beam 10 has a shock absorbing member 1 made of metal on its front wall 11. In the shock absorbing member 1, a collision wall portion 2 and mounting wall portions 3, 4 are integratedly formed by a thin metal sheet. The collision wall portion 2 elongates over the whole region of the front surface wall 11 of the bumper beam and in the upward and downward directions of a car body, and has a curved shape projecting forward as a whole. The mounting wall portions 3, 4 have a shape elongating from the respective end portions 2a, 2b of the collision wall portion along the front surface wall 11 of the bumper beam so as to come into contact with the front surface wall 11. The shock absorbing member 1 is supported by the front surface wall 11 of the bumper beam by joining the mounting wall portions with the front surface wall 11 of the bumper beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is excellent in load energy absorption performance at the time of a vehicle body collision, particularly at the time of a collision with a pedestrian, alleviating the impact given to the human body, and having excellent characteristics for reducing damage to the pedestrian, and a vehicle body bumper beam and an impact buffer for the vehicle body This relates to the member.

  In order to ensure the safety of occupants and protect the impacted object, the body of an automobile or the like is equipped with a bumper system that reduces the impact load and absorbs the impact energy by itself deforming in the impact direction when the vehicle collides. .

  A typical bumper system is a steel or aluminum alloy bumper beam attached to the front surface of the bumper stay, a foamed resin cushioning material provided on the front surface, and further provided on the front surface, integrated with the vehicle outer surface. It is a bumper system composed of a bumper cover, which often becomes.

  In recent years, in order to reduce the weight of the vehicle body, an extruded hollow member made of aluminum alloy or the like has begun to be used for these bumper beams instead of steel. The bumper beam made of aluminum alloy is made of a hollow material having a mouth shape, a date shape, an eye shape or a substantially rectangular cross-sectional shape extending in the width direction and having an appropriate bend according to the outer shape of the vehicle body. The steel bumper beam is substantially the same except that the hollow material is often an open section member.

  These body bumper systems have a bumper beam supported by the body and a cushioning material made of foam material placed on the front surface. At the same time, the function of reducing impact load and absorbing impact energy is required.

  In addition to collisions with “high-rigidity objects” such as vehicles and other objects (guardrails, telephone poles, etc.) that have been demanded in the past as these impact energy absorption functions, At the same time, new characteristics for protecting pedestrians have been demanded.

  For example, the damage to the pedestrian when the vehicle collides with the pedestrian is typical in the head, waist, and leg. In the European Vehicle Commission (EEVC WG17), etc., the head, waist, and leg respectively A pedestrian protection property evaluation test method is proposed. According to this evaluation test, the leg test method that is a part related to the bumper system is such that a leg impactor simulating a pedestrian's leg collides with a bumper beam at a speed of 40 km / h. The output (acceleration, shear deformation amount, bending angle) of various sensors provided in the impactor is required to be a certain value or less. In particular, the acceleration value is required to be 150 G or less.

  However, the bumper system disclosed so far was devised on the premise of collision with “high-rigidity objects” such as vehicles and other objects (guardrails, telephone poles, etc.). Most are designed on the premise of collision with a rigid and high-strength material. For this reason, in these bumper systems, at the time of a collision with the pedestrian's leg model, the acceleration in particular exceeds the regulation value among the evaluation values (acceleration, shear deformation amount, bending angle).

  In contrast, a bumper system designed with reduced strength and rigidity to support pedestrian protection, on the contrary, reduces impact load and absorbs impact energy when colliding with high-rigidity and high-strength objects. Function will be reduced. For this reason, the bumper system is required to have both contradictory functions.

  On the other hand, various ideas such as providing an impact absorbing device and an air bag on the front surface of the bumper beam (bumper reinforcing material) have been proposed, but have not yet been put to practical use. For this reason, it is usually (actually) supported by providing a relatively thick absorber (cushion material, energy absorbing member) such as urethane foam or polystyrene on the front side of the bumper beam and on the back side of the bumper cover. I have done it. However, there is a limit to the thickness of the absorber to be provided due to the vehicle body design, and there is a limit to the pedestrian protection performance (impact energy absorption function).

  On the other hand, conventionally, a bumper beam has been proposed in which, in addition to the absorber, an impact buffering member against a vehicle body collision is provided on the front surface. In such a bumper beam, the impact buffer member is deformed in the cross-sectional thickness direction (transverse cross-sectional direction) at the time of a vehicle body collision to buffer the impact of the vehicle body collision. According to this, the function of bumper beam (bumper reinforcement) can protect pedestrians without reducing the impact load reduction and impact energy absorption function when colliding with the original highly rigid and high strength impact object. Newly added bumper reinforcement can be provided.

  For example, in Patent Literature 1, the bumper beam is positioned away from the outer end surface of the bumper beam by a required amount, and extends from a contact wall portion that receives an impact from the object at the time of collision and a mounting wall portion that contacts the bumper beam. There has been proposed a shock absorbing member of a hollow structure having a support wall portion that supports a contact wall portion from the back side. The support wall has a curved support wall extending along the mounting wall in a region having a required width continuous to the mounting wall, and the object is placed on the contact wall. When an impact is applied through the bending support wall, the bending support wall is bent while being deformed in the bending direction.

  In Patent Document 2, at least two frame rails attached to the vehicle body, at least two brackets respectively connected to these frame rails, beam portions attached to these brackets, a plate member attached to the beam portions, A vehicle impact reduction bumper device having a frame rail extension connected to the bracket has been proposed.

  In Patent Document 3, the bellows shape is extended so that the bellows shape is parallel to the collision load from the front surface, and the bellows shape is deformed at the time of a pedestrian collision. An energy absorbing member for protecting people has been proposed that lowers the load and secures the amount of energy absorption necessary for protecting pedestrians.

Patent Document 4 includes a front flange and a rear flange provided substantially parallel to the longitudinal direction of the vehicle body, and left and right webs provided substantially parallel to connect the flanges. An energy-absorbing member for protecting people has been proposed, which is made of a hollow aluminum alloy that is curved toward the direction. According to this, each web is deformed at the time of a pedestrian collision, and the whole is deformed flatly just like the open / close state of a pantograph of a train, reducing the maximum load in load displacement and walking. Energy absorption necessary for the protection of the elderly.
Japanese Unexamined Patent Publication No. 2004-114864 (full text) JP 2003-285704 A (full text) Japanese Patent Laid-Open No. 2003-312397 (full text) JP 2004-90910 A (full text)

  However, in Patent Document 1, since the buffer member is a resin hollow member, in order to obtain sufficient pedestrian leg protection performance, the thickness is made considerably thicker than that of a metal buffer material. There is a need to sacrifice weight. In addition, the material and thickness of the resin are also limited in the production, and there is a problem that the recyclability is inferior as compared with a metal cushioning material.

  On the other hand, in order to narrow the distance (gap) between the front side of the body of the bumper beam (bumper reinforcement) and the bumper cover, such as in car body design and small cars, an impact buffer member (for personal protection) The energy absorbing member is required to have a thinner width in the longitudinal direction of the vehicle body. In this regard, in the shock absorbing member as in Patent Document 2, the length of the plate member in the longitudinal direction of the vehicle body is relatively long in order to ensure the amount of energy absorption necessary for protecting the pedestrian (the plate member is the front surface of the bumper beam). It cannot be used depending on the design of the car body (model).

  Moreover, in an actual collision accident, the pedestrian's collision position is different. For this reason, the collision position of a pedestrian may largely shift with respect to the installation position of the energy absorbing member. That is, the collision position of the pedestrian leg is shifted in the vehicle width direction, the collision direction of the pedestrian leg is shifted from the horizontal direction, and the like. Corresponding to these cases, in order to cause the deformation expected of the buffer member (energy absorbing member), an energy absorbing member for protecting human beings having a relatively large area over the front surface of the bumper reinforcing material is necessary. It becomes.

  When the buffer member has a relatively large area as described above, the buffer member configured with a relatively thick wall as in Patent Documents 3 and 4 increases in weight and sacrifices weight reduction. Assuming that the collision direction of the pedestrian leg is deviated from the horizontal direction, in the buffer member using the crushing in the cross-sectional thickness direction of the profile as in Patent Documents 3 and 4, the action line of the compression force It means that it shifts. When the line of action of the compressive force is deviated, the energy absorption characteristics are likely to deteriorate in the buffer member using the crushing in the cross-sectional thickness direction. Therefore, in this type of buffer member, the thickness of the cross-section must be increased in order to maintain this energy absorption characteristic even when the pedestrian collides with the collision position. Also from this point of view, it is difficult to secure the amount of energy absorption necessary for protection of pedestrians with the buffer members as in Patent Documents 3 and 4.

  Therefore, the object of the present invention is to reduce the generated load, acceleration, etc. at the time of collision even when the area is relatively large and the weight is light and the width is reduced (thinned) in the cross-sectional thickness direction. An object of the present invention is to provide a vehicle body bumper beam and a vehicle body shock-absorbing member having excellent protection characteristics for pedestrian legs.

  In order to achieve the above object, the gist of the vehicle body bumper beam of the present invention is a bumper beam in which a metal shock absorbing member against a vehicle body collision is provided on the front wall, and the shock absorbing member has a thickness of 3. A collision wall portion that is integrally formed of a metal material of 0 mm or less and receives an impact at the time of a vehicle body collision and a mounting wall portion to the front wall of the bumper beam, and the collision wall portion is formed on the front surface of the bumper beam front wall. And the whole surface of the front wall extends in the vertical direction of the vehicle body, and has an overall shape that protrudes and curves toward the front of the bumper beam. It has a shape that extends and contacts the bumper beam front wall from each end in the vertical direction of the vehicle body, and by joining this mounting wall to the bumper beam front wall, the shock absorbing member is moved by the bumper beam front wall. In addition to supporting, the bumper beam front wall and the collision wall portion constitute a hollow structure, and at the time of a vehicle body collision, the collision wall portion is deformed in the cross-sectional thickness direction to buffer the impact of the vehicle body collision. A.

  In order to reduce the maximum load in load displacement and ensure deformation in the cross-sectional thickness direction that secures the energy absorption necessary for protection of pedestrians, the impact wall of the impact cushioning member is the starting point of deformation at the time of vehicle collision. It is preferable to have a dent. Similarly, it is preferable that the impact buffer member is formed by molding an aluminum alloy plate.

  Similarly, it is preferable that the bumper beam has a flange further extending in the vertical direction of the vehicle body from the front wall of the bumper beam, and the mounting wall portion of the shock absorbing member is joined to the flange. Similarly, the bumper beam is preferably made of a hollow extruded shape made of aluminum alloy.

  In order to achieve the above object, the gist of the shock absorber for a vehicle body of the present invention is an impact buffer member for a vehicle body collision provided on a front wall of a vehicle body bumper beam, and a collision wall portion and a bumper that receive an impact at the time of vehicle body collision. An attachment wall portion to the beam front wall is integrally formed of an aluminum alloy material having a plate thickness of 3.0 mm or less, and the collision wall portion extends in the vertical direction of the vehicle body over the entire area of the bumper beam front wall. The mounting wall portion extends along the bumper beam front wall from each end of the collision wall portion in the vertical direction of the vehicle body. It has a shape that touches.

  This impact buffer member reduces the maximum load in load displacement and ensures deformation in the cross-sectional thickness direction that secures energy absorption necessary for protection of pedestrians. It is preferable to have a dent serving as a starting point.

  The vehicle body bumper beam of the present invention is characterized by the structure and shape of an impact buffering member against vehicle body collision provided on the front surface of the bumper beam. That is, in the vehicle body bumper beam of the present invention, first, the collision wall portion of the shock absorbing member extends in the vehicle body vertical direction on the front surface of the bumper beam front wall and over the entire area of the front wall. , Having an overall shape that protrudes and curves toward the front of the bumper beam.

  As described above, in the vehicle body bumper beam of the present invention, the area of the collision wall portion of the shock absorbing member is enlarged so as to extend over the front surface of the bumper beam (so that the entire surface of the bumper beam front wall can be covered). For this reason, an energy absorption function can be exhibited irrespective of a pedestrian's collision position. Further, the hollow structure itself formed by the bumper beam front wall and the collision wall portion can be enlarged, and the impact absorption and buffering function at the time of a vehicle collision can be increased due to deformation in the cross-sectional thickness direction of the hollow structure (collision wall portion).

  The vehicle body bumper beam according to the present invention has a shape in which the mounting wall portion of the shock absorbing member extends from each end portion of the collision wall portion in the vertical direction of the vehicle body and extends in contact with the front wall of the bumper beam. ing. Therefore, the attachment wall portion of the shock absorbing member can be supported by the bumper beam front wall by joining the attachment wall portion to the bumper beam front wall. Such support and joining are continuously performed over the longitudinal direction (vehicle body width direction) of the bumper beam and the shock absorbing member.

  For this reason, it is possible to control the force for supporting and joining the mounting wall portion of the shock absorbing member over the longitudinal direction of the bumper beam and the shock absorbing member. For example, the force for supporting and joining the mounting wall portion of the shock absorbing member is set to a relatively strong joint strength, and when a collision load is applied, the joint portion is prevented from being broken and necessary for protecting a pedestrian. It is possible to ensure the deformation in the cross-sectional thickness direction of the hollow structure that secures the energy absorption amount. On the other hand, by using this as a relatively weak bonding strength, the reaction force and acceleration generated in the event of a collision can be suppressed low.

  Therefore, the vehicle body bumper beam of the present invention can reduce the generated load and acceleration at the time of collision even when the shock absorbing member is relatively large and narrow (thinned), and is necessary for protecting pedestrians. Characteristics can be secured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows one embodiment of the vehicle body bumper beam of the present invention provided on the front side or rear side of the vehicle body, and a perspective view showing an embodiment in which the metal shock absorbing member of the present invention is attached to the front surface (front wall) of the vehicle body bumper beam. FIG. FIG. 2 is a perspective view showing another aspect of only the shock absorbing member to be attached.

  1 and 2, the metal shock absorbing member 1 of the present invention has, as a basic structure, a collision wall portion 2 that receives an impact at the time of a vehicle body collision, a mounting wall portion 3 (upper side in the figure) to the front wall of the bumper beam, 4 (the lower side of the figure).

  The bumper beam 10 in FIGS. 1 and 2 has two flanges 15 (upper side in the figure) and 16 (lower side in the figure) extending from the front wall 11 of the bumper beam in the vertical direction of the vehicle body. On the surface side (front side: right side in the figure) of the flanges 15 and 16, the mounting wall portions 3 (upper side in the figure) and 4 (lower side in the figure) of the shock absorbing member 1 are joined.

  In FIGS. 1 and 2, the arrow F indicates the load direction at the time of vehicle collision. In FIGS. 1 and 2, the load direction at the time of vehicle collision is from right to left in the drawing, and the right side of the drawing is the bumper beam or the vehicle body. Indicates the front or rear side. Also, a vehicle body panel (bumper cover, hood, trunk, etc.) is shown on the right side of the shock absorbing member 1 by a one-dot chain line 22.

  Although not shown in FIGS. 1 and 2, an absorber made of foamed urethane, foamed polystyrene, or the like may be disposed between the shock-absorbing member 1 and the vehicle body indicated by a one-dot chain line as usual. Further, a steel or aluminum alloy stay, a steel vehicle body side member, and the like that support the bumper beam 10 are sequentially arranged on the rear side of the vehicle body of the bumper beam 10 (left side in the drawing). In the present invention, the thickness of the absorber can be made thinner or smaller than in the prior art, and it is possible to use no absorber.

(Collision wall)
1 and 2, the collision wall portion 2 of the metal shock-absorbing member 1 is in the vehicle body vertical direction (in the drawing) in front of the front wall 11 of the bumper beam 10 and over the entire area of the front wall 11. It has an overall shape that extends in the vertical direction and protrudes and curves toward the front of the bumper beam 10. The collision wall portion 2 forms a hollow structure with the bumper beam front wall 11, and when the vehicle collides with a pedestrian, the entire shape is deformed in the cross-sectional thickness direction to absorb and buffer the impact of the collision. Part.

  Thus, the collision wall portion 2 extends over the entire area of the front wall 11 of the front wall 11 of the bumper beam 10 in the vertical direction of the vehicle body (the entire surface of the bumper beam front wall 11 in the vertical direction of the vehicle body). Enlarge to be able to cover. For this reason, the energy absorbing function can be exhibited regardless of the deviation of the collision position of the pedestrian against the bumper beam 10 from the horizontal direction (shift in the vertical direction of the vehicle body). Moreover, the hollow structure itself comprised by the bumper beam front wall 11 and the collision wall part 2 can be enlarged. For this reason, it is possible to increase the shock absorption and shock absorbing function at the time of a vehicle body collision due to the deformation of the hollow structure (collision wall portion 2) in the cross-sectional thickness direction.

  However, in the present invention, although the collision wall portion 2 extends over the entire region of the front wall 11 of the front wall 11 of the bumper beam 10 in the vertical direction, the longitudinal direction (vehicle width direction) is the longitudinal direction of the front wall 11. There is no need to extend over the entire region (entire region) in the direction (vehicle width direction). The examples of the metal shock absorbing member 1 of the present invention shown in FIGS. 1 and 2 have a basic structure in which a single shock absorbing member 1 is disposed in the entire longitudinal direction (vehicle body width direction) of the front wall 11 of the bumper beam 10. It extends over the whole area. On the other hand, the shock absorbing member 1 and the collision wall portion 2 are partially or divided only in a necessary portion in the longitudinal direction (vehicle body width direction) of the front wall 11 of the bumper beam 10 or only in a necessary length. A plurality of them may be provided. Further, the collision wall portion 2 may be partially cut out only in an unnecessary portion (unnecessary portion) on the front surface in the longitudinal direction (vehicle body width direction) of the front wall 11 of the bumper beam 10.

  When the impact buffer member 1 and the collision wall portion 2 are provided in a partially or divided manner, the bumper beam 10 is supported from the rear surface by a stay or the like. It is necessary to protect the pedestrian legs at both ends of the bumper beam 10 that is provided, and the shock absorbing members 1 are provided indispensably. On the other hand, the central portion of the bumper beam 10 in the longitudinal direction (vehicle body width direction) may be provided with only the absorber without providing the shock absorbing member 1 partially. As described above, when the shock absorbing member 1 and the collision wall portion 2 are provided partially or divided, only the necessary portion on the front surface in the longitudinal direction of the front wall 11 of the bumper beam 10 or only the necessary length is provided. The impact buffer member can be reduced in weight.

(Thin plate integrated)
The collision wall portion 2 and the mounting wall portions 3 and 4 are integrally formed from a metal material having a thickness of 3.0 mm or less. The metal material is a metal thin plate such as a steel plate having a thickness of 3.0 mm or less, preferably an aluminum alloy material having a thickness of 3.0 mm or less, more preferably an aluminum alloy thin plate having a thickness of 3.0 mm or less. Illustrated. Preferably, the impact buffer member is formed integrally with the impact wall portion 2 and the mounting wall portions 3 and 4 by press molding of these thin plates. The thickness of at least the collision wall 2 in the impact buffering member (the energy absorbing member for protecting pedestrians) is 3.0 mm or less, more preferably 2.0 mm or less. If the thickness or thickness is not small (thickness is not thin), the deformation in the cross-sectional thickness direction that secures the amount of energy absorption necessary to protect the pedestrian is unlikely triggered by the collision load load at the time of pedestrian collision. Therefore, the function as an impact buffer member cannot be exhibited. In addition, when the thickness exceeds 3.0 mm, the weight increases and the weight can be reduced even if an aluminum alloy thin plate is used when used for a large (wide) area over the entire front surface of the bumper beam. It becomes difficult. In addition, as an aluminum alloy material constituting the shock absorbing member, in addition to a thin plate such as a rolled plate, an aluminum alloy having a plate thickness (wall thickness) of 3.0 mm or less can be extruded. 3 and 4 may be integrally formed as an aluminum alloy extruded hollow shape.

  In addition, when the collision wall portion 2 and the attachment wall portions 3 and 4 are not integrated, but divided into structures, there are necessarily divided portions or joint portions. For this reason, it becomes easy to fracture | rupture from these division | segmentation parts thru | or a junction part, and also the deformation | transformation of the cross-sectional thickness direction which ensures the energy absorption amount required for a pedestrian's protection becomes difficult to occur, and the function as an impact buffer member cannot be exhibited. Moreover, the process and cost of manufacturing the shock absorbing member will increase.

(Deformation part)
Here, as shown in FIG. 2, in order to facilitate the deformation in the cross-sectional thickness direction triggered by the collision load load at the time of the pedestrian collision, the collision wall 2 is formed at the center in the vertical direction. It is preferable to have the deformed portion 5 which is a dent (concave portion) serving as a starting point of deformation. The dent deforming portion 5 extends over the vehicle body width direction (longitudinal direction) of the collision wall portion 2 in order to exert the effect of facilitating deformation in the cross-sectional thickness direction regardless of the pedestrian collision position. To be provided. For this reason, the shock absorbing member 1 provided with the deformed portion 5 in FIG. 2 has a so-called double-mountain cross-sectional hollow shape by the recess 5 as compared with the dome-type shock absorbing member not provided with the deformed portion in FIG. is doing. In addition, the meaning of the dent means that it is retracted or recessed with respect to the load direction F.

  As will be explained in the examples described later, the double mountain type shock absorbing member of FIG. 2 provided with the deformable portion 5 that easily causes the deformation in the cross-sectional thickness direction (transverse cross-sectional deformation) does not include the deformable portion 5. If the other conditions are the same as those of the dome-type impact buffer member, the maximum acceleration (maximum load) is small and the energy absorption amount is relatively large. In order to exhibit the effect of facilitating deformation in the cross-sectional thickness direction, the deformed portion 5 does not necessarily have to be the dent, and can be a notched portion or a thinner portion than other portions. . However, a dent is preferable because it is easy to integrally form the shock-absorbing member when it is press-molded from the base plate and the effect of promoting deformation is easily exhibited.

(Mounting wall)
In FIGS. 1 and 2, the mounting wall portions 3 and 4 of the shock absorbing member 1 are connected to flanges 15 (see FIG. 1) from the respective end portions 2 a and 2 b of the collision wall portion 2 in the vertical direction of the vehicle body. ) And 16 (lower side of the figure), and extends in the vertical direction of the vehicle body, and has a shape that contacts the front side of each flange (the front side of the front wall 11: the right side of the figure). As described above, at the flanges 15 (upper side) and 16 (lower side), the mounting wall portions 3 (upper side in the figure) and 4 (lower side in the figure) are respectively connected to the front side (front side) of the bumper beam front wall 11. It is joined with. As shown in FIGS. 1 and 2, such joining is continuous over the longitudinal direction (vehicle body width direction) of the bumper beam 10 (front wall 11) and the shock absorbing member 1 (mounting wall portions 3 and 4). Has been done.

  For this reason, it is possible to control the force which supports the attachment wall part of an impact buffer member over the longitudinal direction of a bumper beam and an impact buffer member. That is, the bonding strength (support strength) of the shock absorbing member between the mounting wall of the shock absorbing member and the front wall of the bumper beam can be freely set partially or entirely over the longitudinal direction of the bumper beam and the shock absorbing member. Can be changed. For example, if this is a strong joint strength, the support surface of the shock absorbing member becomes a wide area of the front wall of the bumper beam, and when the collision load is applied, the joint is local, for example. However, it is difficult for the joint to break. For this reason, the deformation | transformation of the cross-sectional thickness direction of a hollow structure which ensures the amount of energy absorption required for a pedestrian protection is securable. On the other hand, when this is set to a relatively weak bonding strength, reaction force and acceleration generated at the time of a collision can be suppressed low.

  In Patent Document 2, the mounting wall portion of the shock absorbing member is joined to the upper and lower wall surfaces of the bumper beam. However, in this way, when the mounting wall portion of the shock absorbing member is joined to the upper and lower wall surfaces of the bumper beam, when the bumper beam has a closed cross section, it can be coupled only from one side from the mounting wall portion of the shock absorbing member. . In this one-side coupling method, there is no choice but to weld or make a pilot hole and couple with a blind rivet or the like. At this time, if welding is used, if the bumper beam is made of an aluminum alloy, the strength is partially reduced due to the thermal effect during welding. Further, in the blind rivet, an extra work for making a pilot hole is required, and the bonding strength is weakened. For this reason, the force which supports the attachment wall part of an impact buffer member becomes weak, and when a collision load is applied, the local joint part of both tends to break. Therefore, it is difficult to ensure the deformation in the cross-sectional thickness direction that secures the energy absorption necessary for protecting the pedestrian. In Patent Document 2, a hollow structure is formed by the point that the collision wall portion and the mounting wall portion are integrally formed of a thin metal plate, or the bumper beam front surface and the collision wall portion. It is the same as the present invention in that the impact of the vehicle body collision is buffered by being deformed in the direction. Nevertheless, the reason why it is difficult to ensure the deformation in the cross-sectional thickness direction that ensures the protection characteristics of the pedestrian is due to the way the mounting wall portion of the shock absorbing member is attached to the bumper beam.

  The attachment wall portions 3 and 4 of the shock absorbing member 1 may be joined to the bumper beam front wall 11 or the flanges 15 and 16 which are parts thereof by mechanical joining 21 such as rivets and bolts. Instead of this, it may be welded in combination with this. This joining position is arbitrary as long as the joining strength can be ensured, and it extends over the longitudinal direction (vehicle body width direction) of the bumper beam 10 (front wall 11) and the shock absorbing member 1 (mounting wall portions 3 and 4). Are provided at appropriate intervals. Note that the bonding strength (support strength) of the shock absorbing member 1 can be changed by changing the bonding position or the bonding interval. For example, at a site where a strong bonding strength is required, the bonding strength (bonding force) can be increased by selecting a bonding method having a high bonding force or by reducing the bonding pitch. Further, when it is desired to suppress the reaction force and acceleration generated at the time of collision low, the bonding strength (bonding force) can be reduced by selecting a bonding method with a low bonding force or increasing the bonding pitch.

(Shape in the longitudinal direction of the entire shock absorbing member)
In FIGS. 1 and 2, the bumper beam 10 is not linear due to the design of the vehicle body, but has both ends retreated and curved in the longitudinal direction of the vehicle body, and the entire shape is curved in the vehicle body width direction over the longitudinal direction. is doing. For this reason, the shock absorbing member 1 also has a shape in which both end portions are retracted and curved in the longitudinal direction of the vehicle body in accordance with the curved shape of the bumper beam 10 and the entire body is curved in the vehicle body width direction over the longitudinal direction. is doing. As described above, the shape of the entire shock absorbing member 1 in the longitudinal direction is adapted to the shape of the entire bumper beam 10 in the longitudinal direction, such as linear if the shape of the bumper beam in the vehicle body width direction is linear. Shall.

(Other aspects of shock absorbing member)
3A and 3B show other aspects of the shock absorbing member 1 in cross section. 3A, the basic configuration is the same as that of the shock absorbing member 1 shown in FIGS. 3 (a) is different from FIGS. 1 and 2 in that only the mounting wall portion 3 (upper side in the drawing) of the shock absorbing member 1 is on the back side (rear side) of the flange 15 (upper side in the drawing) of the front wall 11 of the bumper beam. Side: A point having a shape that is in contact with and joined to the left surface in the drawing.

  As shown in FIG. 3A, either or both of the mounting walls of the shock absorbing member 1 are not the front side of the bumper beam front wall 11 (flanges 15 and 16), and the bumper beam front wall 11 ( You may contact | abut and join to the back surface side of the flanges 15 and 16). By making the contact or joining of either or both of the mounting wall portions of the shock absorbing member 1 on the back surface side of the bumper beam front wall 11 (flange), the deformation stroke after the collision is lengthened by devising the joining method. It becomes possible. That is, with a predetermined collision load, it is possible to remove the joint (joint part) such as welding, rivet, or bolt, to maintain the deformation, and to lengthen the deformation stroke after the collision. In other words, it is possible to change the energy absorption characteristics and increase the degree of design freedom.

  On the other hand, in FIG. 3B, the positions of the end portions 2a and 2b in the vertical direction of the vehicle body of the collision wall 2 are further set in the vertical direction of the vehicle body than the upper and lower ends of the flanges 15 and 16 of the bumper beam 10, respectively. Each is stretched by the length of s. That is, in FIG. 3B, the length or area of the collision wall portion 2 in the vertical direction of the vehicle body is made larger than the collision wall portion 2 of the shock absorbing member 1 of FIGS. The collision wall portion 2 of the shock absorbing member 1 in FIGS. 1 and 2 is substantially the same as the area of the front wall 11 of the bumper beam 10. On the other hand, in FIG. 3B, the area of the collision wall portion 2 is larger than the area of the front wall 11 of the bumper beam 10, and the energy absorbing function is exhibited regardless of the collision position of the pedestrian. The effect that can be demonstrated more. Moreover, the hollow structure itself composed of the bumper beam front wall 11 and the collision wall portion 2 can be made larger, and the shock absorption function and the shock absorbing function at the time of the vehicle body collision due to the deformation in the cross-sectional thickness direction of the hollow structure (collision wall portion 2). Can be bigger.

(Material of shock absorbing member)
The material of the shock absorbing member having a plate thickness of 3.0 mm or less may be a normal steel plate or a high-tensile steel plate, but it is lightweight and has a large energy absorption effect even when used over a large area over the entire front surface of the bumper beam. Aluminum alloys are preferred. The type of this aluminum alloy is usually 3000 series, which is widely used for this kind of structural member application as a thin plate or extruded shape, as referred to in AA to JIS standards, 5000 series, 6000 having excellent moldability and relatively high yield strength. A general-purpose (standard) aluminum alloy (such as one that has been tempered or heat-treated to meet the required performance such as O, T4, T5, T6, and T7) is preferably and selectively used.

(Bumper beam)
The bumper beam 10 shown in FIGS. 1 to 3 connects the front wall 11 and the rear wall 12, and has a mouth-shaped cross-section hollow portion composed of an upper web 13 and a lower web 14 that are arranged substantially in parallel with each other. Have Moreover, it has two flanges 15 (upper side) and 16 (lower side) respectively extending from the bumper beam front wall 11 in the vertical direction of the vehicle body. Although the flanges 15 (upper side) and 16 (lower side) are optional, the front wall is not provided with this flange in that the mounting wall portions 3 (upper side) and 4 (lower side) of the shock absorbing member 1 are joined. 11 and the attachment wall portions 3 and 4 are more easily joined and more efficient than joining them.

(Other aspects of bumper beam)
4 (a), 4 (b), and 4 (c) show other aspects of the bumper beam (bumper reinforcing material) 10 in cross section. These show the aspect which reinforced the bumper beam 10 of FIGS. 1-3.

  In FIG. 4A, the deformation strength in the cross-sectional thickness direction of the hollow portion is improved by inserting a single inner rib 17 into the mouth-shaped cross-sectional hollow portion of the bumper beam 10 of FIGS. An aspect is shown. FIG. 4B shows an aspect in which two middle ribs 18 and 19 are inserted into the mouth section hollow portion of the bumper beam 10 of FIGS. FIG. 4C shows a bumper beam 10 shown in FIGS. 1 to 3 having a large corner R at the connecting portion (corner portion) between the upper and lower webs 13 and 14 and the rear wall 12, and without being provided with an intermediate rib. The deformation strength in the cross-sectional thickness direction of the part is improved.

  In these examples, including the bumper beam 10 shown in FIGS. 1 to 3, the material of the bumper beam is an aluminum alloy, and an aluminum alloy hollow extruded shape is used because of the ease of forming a hollow cross-sectional shape extending in the longitudinal direction. The embodiment is intended. The bumper beam 10 may be made of a high-tensile steel plate, but is preferably an aluminum alloy that is lighter and has a large energy absorption effect due to the plate thickness effect even with a thin metal plate. Generally used for this kind of structural member, 3000 series, which is generally used for AA or JIS standards, and 5000 series, 6000 series, 7000 series etc. Extruded shapes (those that have been tempered or heat-treated to meet the required performance of O, T4, T5, T6, T7, etc.) are preferably and selectively used.

  In addition, although the suitable example was shown as mentioned above, the material of the cross section thickness direction (transverse section) on the bumper beam side and the material made of steel, aluminum alloy, etc. are mainly determined from the convenience of the automobile design side. For this reason, the present invention can be applied to various bumper beams such as various cross-sectional thickness direction (transverse cross-sectional) shapes, longitudinal direction shapes, and materials, which are determined on the vehicle design side, regardless of the above preferred examples.

  Using the analysis model of the bumper beam of the present invention shown in FIG. 1 and FIG. 2, the acceleration-displacement relationship by static crush analysis at the time of loading assuming a pedestrian collision using general-purpose finite element analysis software ABAQUS It was determined by analysis. However, no absorber is provided in the analysis model. In the analysis, in accordance with the above-mentioned evaluation test of the European Vehicle Commission (EEVC WG17), when a leg impactor simulating a pedestrian's leg is collided at 40 km / h, the leg impactor receives it. An acceptance standard was that the load (acceleration) was 150 G or less.

  For comparison, the acceleration-displacement relationship of a comparative example (conventional example) in which only an absorber made of foamed urethane or polystyrene is disposed on the front surface of the bumper beam 10 shown in FIG.

  The analysis conditions were the following common conditions for both the above invention examples and comparative examples. That is, as shown in FIG. 1, the load is applied as indicated by an arrow F to the front and center of each bumper beam 10 (of the shock absorbing member 1). The shock absorbing member 1 was a 6000 series aluminum alloy plate T4 tempered material and a press-molded product having a thickness of 1.2 mm. The external dimensions are commonly 1300 mm in length (vehicle body width direction), 120 mm in the maximum height of the collision wall (vehicle body vertical direction), 45 mm in the maximum projecting length of the arc (vehicle body longitudinal direction), Each length (vertical direction of the vehicle body) was 15 mm. When the impact buffer member 1 has the recess 5 over the entire length, the recess 5 has a width (vehicle body vertical direction) of 70 mm and a depth (vehicle body longitudinal direction) of 10 mm.

  The bumper beam 10 was a 7000 series aluminum alloy extruded shape T5 tempered material and had a thickness of 3.0 mm. The external dimensions are commonly 1300 mm in the length (vehicle body width direction), 90 mm in the length of the front wall (vehicle body vertical direction), 15 mm in each length of the flanges 3 and 4 (vehicle body vertical direction), and each web 14, 15. The length (vehicle body longitudinal direction) was 35 mm.

  5 and 6 show changes over time in the deformation state at each stage of deformation. FIG. 5 shows the bumper beam of the present invention shown in FIG. 2, and FIG. 6 shows the bumper beam of the present invention shown in FIG. 1. Reference numeral 10 denotes a bumper beam, 1 denotes an impact buffer member, and 2 denotes a collision wall portion. Also, 22 is a body panel, 30 is a model simulating a pedestrian's leg, and the pedestrian's leg collides at a position shifted by 300 mm in the longitudinal direction (vehicle width direction) from the longitudinal center of the bumper beam 10. Assuming that

  5 and 6, each figure (a) is an initial stage of deformation, each figure (b) is an intermediate stage of deformation, and each figure (c) is an end stage of deformation. As can be seen from FIGS. 5 and 6, even if the collision position of the impact buffer member 1 in the bumper beam of the present invention is shifted in the collision position of the pedestrian's leg, the collision wall part 2 is collapsed or broken through the deformation stage, including the joint. Without deformation, it can be seen that the cross-sectional thickness direction (transverse cross-sectional direction: from right to left in the figure) is crushed and deformed, and is continuously deformed so as to spread in the vehicle body vertical direction (vertical direction in the figure). .

  FIG. 7 shows the acceleration-displacement relationship in the case of FIG. 6 for the bumper beam of the present invention shown in FIGS. 1 and 2 and the comparative example bumper beam in which only the absorber is arranged. In FIG. 7, the dotted line indicates the dome-type shock absorbing member 1 in FIG. 1, the thick solid line indicates the double mountain-type shock absorbing member 1 in FIG. 2, and the thin line indicates a comparative example (conventional example) in which only a conventional absorber is arranged.

  As can be seen from FIG. 7, in the comparative example (conventional example) in which only the absorber indicated by the thin line is arranged, the maximum acceleration (maximum load) is large, and the load (acceleration) received by the leg impactor exceeds the target limit value of 150G. And damage to the legs of pedestrians is large. It can also be seen that the acceleration is rapidly reduced and the amount of energy absorption is relatively small.

  On the other hand, the bumper beam of the present invention indicated by a dotted line or a thick solid line has a smaller maximum acceleration (maximum load) than the comparative example (conventional example) even if the collision position of the pedestrian's leg is shifted (300 mm), The load (acceleration) received by the leg impactor is 150 G or less, and damage to the leg of the pedestrian is small. It can also be seen that the acceleration is not reduced and the energy absorption is relatively large.

  Further, as can be seen from FIG. 7, the double mountain type shock absorbing member of FIG. 2 shown by a thick solid line provided with the deforming portion 5 is more than the dome type shock absorbing member of FIG. The maximum acceleration (maximum load) is smaller and the energy absorption is relatively large. Therefore, the effect of providing the deformation part 5 is supported.

  According to the present invention, the maximum load in load displacement can be lowered even with a relatively large and thin outer size shape, which is necessary for energy absorption with an appropriate collision load commensurate with a pedestrian collision. Deformation in the cross-sectional direction can occur. As a result, it is possible to provide a bumper beam and an impact buffering member having a function of reliably protecting a human such as a pedestrian. In addition, it is possible to provide a bumper beam to which a pedestrian protection function is newly added without deteriorating the original function of the bumper beam. For this reason, an effective pedestrian protection effect can be given to a bumper beam.

It is a perspective view which shows the one aspect | mode of this invention vehicle body bumper beam. It is a perspective view which shows the other aspect of this invention vehicle body bumper beam. It is a cross-sectional side view which shows the other aspect of this invention vehicle body bumper beam. It is a cross-sectional side view which shows the other aspect of this invention vehicle body bumper beam. It is explanatory drawing which shows each time-dependent change of the deformation | transformation state of this invention vehicle body bumper beam. It is explanatory drawing which shows each time-dependent change of the deformation | transformation state of this invention vehicle body bumper beam. It is explanatory drawing which shows the acceleration-displacement relationship of this invention vehicle body bumper beam.

Explanation of symbols

1: impact buffer member, 2: collision wall portion, 3, 4: mounting wall portion, 5: deformation portion,
10: Bumper beam, 11: Bumper beam front wall,
12: Bumper beam front wall, 13, 14: Bumper beam web,
15, 16: Bumper beam flange, 21: Joining means, 22: Body panel,
30: Pedestrian leg model,

Claims (7)

  A bumper beam having a metal shock absorbing member against a vehicle body collision provided on a front wall, the shock absorbing member having a thickness of 3. A collision wall portion that is integrally formed of a metal material of 0 mm or less and receives an impact at the time of a vehicle body collision and a mounting wall portion to the front wall of the bumper beam, and the collision wall portion is formed on the front surface of the bumper beam front wall. And the whole surface of the front wall extends in the vertical direction of the vehicle body, and has an overall shape that protrudes and curves toward the front of the bumper beam. It has a shape that extends and contacts the bumper beam front wall from each end in the vertical direction of the vehicle body, and by joining this mounting wall to the bumper beam front wall, the shock absorbing member is moved by the bumper beam front wall. In addition to supporting, the bumper beam front wall and the collision wall portion constitute a hollow structure, and at the time of a vehicle body collision, the collision wall portion is deformed in the cross-sectional thickness direction to buffer the impact of the vehicle body collision. Vehicle bumper beam, characterized.   The vehicle body bumper beam according to claim 1, wherein the collision wall portion of the impact buffering member has a recess serving as a starting point of deformation at the time of vehicle body collision.   3. The vehicle body bumper beam according to claim 1, wherein the bumper beam has a flange further extending in a vertical direction of the vehicle body from a front wall of the bumper beam, and the mounting wall portion of the shock absorbing member is joined to the flange.   The vehicle body bumper beam according to any one of claims 1 to 3, wherein the bumper beam is formed of an aluminum alloy hollow extruded shape member.   The vehicle body bumper beam according to any one of claims 1 to 4, wherein the shock absorbing member is formed of an aluminum alloy plate.   An impact buffering member for a vehicle body collision provided on a front wall of a vehicle body bumper beam, wherein a collision wall portion that receives an impact at the time of the vehicle body collision and an attachment wall portion to the front wall of the bumper beam has an aluminum thickness of 3.0 mm or less. The collision wall portion is formed integrally with an alloy material, and extends in the vertical direction of the vehicle body over the entire region of the front wall of the bumper beam, and has an overall shape that protrudes and curves toward the front of the bumper beam. The mounting wall portion has a shape that extends and abuts along the front wall of the bumper beam from each end portion of the collision wall portion in the vertical direction of the vehicle body.   The vehicle body shock absorbing member according to claim 6, wherein the collision wall portion has a recess serving as a starting point of deformation at the time of a vehicle body collision.

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