JP2011051364A - Bumper structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bumper structure ensuring an amount of absorption of an expected peak load and collision energy absorption while bumper stays are made by drawn molding. <P>SOLUTION: The bumper structure B is provided with: a pair of right and left bumper stays 1, 1 which are drawn products; and a bumper reinforcement 2 supported by the bumper stays 1, 1. The bumper stay 1 has: a bottom section fixed to a vehicle body; a flat plate-like upper wall section 12 which protrudes from the bottom section toward the bumper reinforcement member 2; a lower wall section 13; and a pair of right and left sidewall sections 14, 15. The upper wall section 12 and lower wall section 13 are parallel and face each other. An opening of the bumper stay 1 is fixed with the bumper reinforcement member 2, and a peripheral edge of the opening of the bumper stay 1 is secured to the bumper reinforcement member 2 by means of welding, etc. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a bumper structure.

  A bumper reinforcement composed of a bumper reinforcement having a curved portion in the center and a bumper stay that supports the bumper reinforcement. After the curved portion of the bumper reinforcement is straightened, the bumper reinforcement moves in the front-rear direction. There is known a bumper structure in which crushing proceeds (see Patent Document 1). According to this bumper structure, the amount of collision energy absorbed can be increased while keeping the peak of the crush load low, thus reducing damage to the vehicle body while preventing malfunction of safety devices such as air bags during light collisions. It becomes possible to do.

  A bumper structure using a bumper stay made of a drawn product is known (see, for example, Patent Documents 2 to 4). The bumper structures disclosed in Patent Documents 2 to 4 are techniques that focus on crushing the bumper stay in the front-rear direction.

  In this specification, the process in which the curved or bent part of the bumper reinforcement extends linearly is referred to as the “elongation process”, and the process in which the bumper reinforcement is crushed in the front-rear direction is referred to as the “cross-section crushing process”. A process in which the stay is crushed in the front-rear direction is referred to as a “stay crushing process”.

International Publication No. 2007/110938 Pamphlet Japanese Patent No. 3327030 JP 2003-312400 A JP 2006-347527 A

  If the thickness of the bumper stay is reduced in order to reduce the weight of the bumper structure, the deformation resistance of the bumper stay is reduced. Therefore, the stay crushing process may proceed at a stretch during the expansion process or the cross-section crushing process. If the stay crushing process progresses at a stretch during the expansion process or the cross-section crushing process, the collision load (crushing load) transmitted to the vehicle body increases at a stretch and the collision load decreases greatly thereafter. While the load is increased, the amount of collision energy absorbed may be decreased.

  From such a viewpoint, it is an object of the present invention to provide a bumper structure capable of ensuring the intended peak load and the amount of collision energy absorbed while the bumper stay is a drawn product.

  A bumper structure according to the present invention that solves such a problem is a bumper structure including a pair of left and right bumper stays made of a drawn product and bumper reinforcement supported by both the bumper stays. Has a bottom portion fixed to the vehicle body, and a flat plate-like upper wall portion, a lower wall portion, and a pair of left and right side wall portions projecting from the bottom portion toward the bumper reinforcement, and the upper wall portion and the lower wall portion Wall portions are opposed in parallel, an opening portion of the bumper stay is closed by the bumper reinforcement, and an opening peripheral edge portion of the bumper stay is fixed to the bumper reinforcement. .

  According to the present invention, since the bumper stay is formed of a draw-molded product, the bottom portion, the upper wall portion, the lower wall portion, and the side wall portion can be formed at the same time. Therefore, the cost of the bumper stay can be reduced. become. In addition, when the bumper stay is made of a draw-molded product, the bumper stay has a shape with an opening on one side due to the properties of the draw molding. In the present invention, the bumper stay opening is closed by bumper reinforcement, and the bumper stay is Since the periphery of the opening is fixed to the bumper reinforcement, the inside of the bumper stay becomes a closed space, and the deformation resistance (crushing strength) of the bumper stay becomes high. That is, according to the present invention, the deformation resistance (crushing strength) of the bumper stay is high even though it is a draw-molded product, so that the deformation of the bumper reinforcement and the like are advanced while maintaining the shape of the bumper stay. Therefore, the desired peak load and the amount of collision energy absorbed can be ensured. The bumper stay opening peripheral portion and the bumper reinforcement can be fixed by means such as welding, adhesion, bolts, rivets, etc., but when fixed by welding, formation of a large flange portion for joining, etc. Is suitable because it becomes unnecessary.

  Further, according to the present invention, since the upper wall portion and the lower wall portion have a flat plate shape (planar shape), occurrence of buckling at the initial stage of the collision can be suppressed. In addition, if the upper wall portion and the lower wall portion of the bumper stay face each other in parallel, forming wrinkles are less likely to occur during drawing, and moreover, the buckling load is larger than when the bumper stays are not faced in parallel. Therefore, it is possible to reduce the thickness while securing the desired crushing load.

  In addition, you may perform a bead process along the front-back direction with respect to the upper wall part and lower wall part of a bumper stay. If it does in this way, it will become possible to improve buckling strength further.

  Corners having an arcuate cross section may be formed at a boundary portion between the upper wall portion and each side wall portion and at a boundary portion between the lower wall portion and each side wall portion. In this way, the deformation resistance of the bumper stay is increased, so that it is possible to reduce the thickness (weight).

  In the present invention, it is preferable to set rigidity of the bumper reinforcement and the bumper stay so that the bumper stay is crushed after the bumper stay is reduced to the bumper reinforcement. In this way, the peak of the collision load (crush load) transmitted to the vehicle body during the cross-section crushing process (the process of crushing the bumper reinforcement in the front-rear direction by the bumper stay being reduced in the bumper reinforcement) and the stay crushing process ( The peak of the collision load transmitted to the vehicle body during the crushing process of the bumper stay itself appears with a time difference, so that the collision load transmitted to the vehicle body is prevented from increasing at a stretch and after the collision load increases It becomes possible to prevent the collision load from being greatly reduced, and as a result, the load value of the collision load can be maintained.

  When the bumper reinforcement is bent or curved between the two bumper stays, the bumper stay becomes the bumper reinforcement after the bent or curved portion of the bumper reinforcement is straightened. It is preferable to set the rigidity of the bumper reinforcement and the bumper stay so as to decrease. In this way, the peak of the collision load that is transmitted to the vehicle body in the extension process (the process in which the bent or curved part of the bumper reinforcement is linearly extended), the cross-section crushing process, and the stay crushing process appears sequentially with a time difference. Therefore, the collision load transmitted to the vehicle body is prevented from increasing at a stretch, and the collision load is prevented from greatly decreasing after the collision load is increased. Can be maintained.

  It is preferable that the bumper stay has a shape in which a width dimension gradually increases from the vehicle body toward the bumper reinforcement. In this way, the distance between the fulcrum points of the bumper reinforcement becomes narrower, so that it becomes possible to reduce the thickness of the bumper reinforcement while maintaining the deformation resistance of the bumper reinforcement between the bumper stays, and therefore the expansion. It is possible to reduce the weight of the bumper reinforcement without reducing the amount of collision energy absorbed in the process.

  The bumper stay is preferably made of a 5000 series aluminum alloy. A 5000 series aluminum alloy (for example, JIS A 5052 alloy, etc.) has good drawability, so that it is possible to increase the productivity of the bumper stay.

  According to the present invention, it is possible to ensure the desired peak load and the amount of collision energy absorbed while the bumper stay is a drawn product.

It is a perspective view which shows the bumper structure which concerns on embodiment of this invention. It is an expansion perspective view which shows the bumper structure which concerns on embodiment of this invention. (A) is an enlarged plan view showing a bumper structure according to an embodiment of the present invention, (b) is a sectional view taken along line XX of (a), and (c) is a sectional view taken along line YY of (a). . It is a top view which shows the manufacturing method of a bumper stay. (A) is a plan view showing a bumper structure before a collision load is applied, (b) is a plan view showing an extension process, (c) is a plan view showing a cross-section crushing process, and (d) is a stay crushing process. It is a top view. It is a top view which shows the modification of the bumper structure which concerns on embodiment of this invention.

  As shown in FIG. 1, a bumper structure B according to an embodiment of the present invention includes a pair of left and right bumper stays 1 and 1 fixed to a side member (vehicle body) S, and a bumper supported by both bumper stays 1 and 1. Reinforcement 2.

  In the present embodiment, the case where the bumper structure B constitutes a front bumper is illustrated, and “front and rear”, “right and left”, and “up and down” are based on the state of being attached to the vehicle body. Further, “vehicle width direction” is synonymous with “left-right direction”.

  The bumper stay 1 has a shape (a diverging shape) in which the width dimension gradually increases from the side member S toward the bumper reinforcement 2. The bumper stay 1 is made of a drawn product. The bumper stay 1 of the present embodiment has a bottomed box shape in which an opening is formed on the bumper reinforcement 2 side. The opening part of the bumper stay 1 is closed by the bumper reinforcement 2, and the opening peripheral edge parts 1a to 1d of the bumper stay 1 are fixed to the bumper reinforcement 2 by welding (see FIG. 2).

  As shown in FIG. 2, the bumper stay 1 includes a bottom portion 11, an upper wall portion 12, a lower wall portion 13 (see FIG. 1), and a pair of left and right side wall portions 14 and 15. In the following description, when the side wall portions 14 and 15 are distinguished from each other, the side wall 14 on the outer side in the vehicle width direction (near the end in the longitudinal direction of the bumper reinforcement 2) is referred to as an “outer wall portion 14”. The side wall 15 on the inner side in the width direction (near the center in the longitudinal direction of the bumper reinforcement 2) may be referred to as an “inner wall 15”.

  The bottom part 11 is a flat part fixed to the front end surface of the side member S (see FIG. 1). The bottom 11 is a punch bottom at the time of drawing and has a rectangular shape (see FIG. 2). Bolt insertion holes are formed at appropriate positions on the bottom 11. A bolt for fastening the bottom 11 to the front end surface of the side member S is inserted into the bolt insertion hole. In addition, the front wall and the rear wall of the bumper reinforcement 2 are formed with through holes (see FIG. 1). When the bumper reinforcement 2 is fixed to the bumper structure B side member S, the bottom 11 Insert the bolt into the bolt insertion hole.

  The upper wall portion 12 is a flat plate-like portion projecting from the upper edge portion of the bottom portion 11 toward the bumper reinforcement 2. As shown to (a) of FIG. 3, the upper wall part 12 is exhibiting the divergent shape where a width dimension increases gradually as it goes to the bumper reinforcement 2 from the bottom part 11. As shown in FIG. As shown in FIG. 3B, the upper wall portion 12 of this embodiment projects horizontally from the bottom portion 11 and is substantially flush with the upper surface of the bumper reinforcement 2. The front edge (opening peripheral edge portion 1 a) of the upper wall portion 12 is formed in a shape that matches the shape of the bumper reinforcement 2 and is welded in a line contact with the bumper reinforcement 2. In addition, the front edge (opening peripheral part 1a) of the upper wall part 12 is exhibiting the small flange shape bent toward the upper side of the upper wall part 12. FIG. A portion having a small flange shape is formed at the time of drawing. When the peripheral edge of the opening is adjusted by trimming or the like after drawing, a structure that does not form a portion having a small flange shape can be used.

  The lower wall portion 13 is a flat plate-like portion protruding from the lower edge portion of the bottom portion 11 toward the bumper reinforcement 2. The lower wall portion 13 has a divergent shape in which the width dimension gradually increases from the bottom portion 11 toward the bumper reinforcement 2. The upper wall portion 12 of the present embodiment projects horizontally from the bottom portion 11 and is substantially flush with the lower surface of the bumper reinforcement 2. That is, the lower wall portion 13 has the same planar shape as the upper wall portion 12 and faces the upper wall portion 12 in parallel. The front edge (opening peripheral edge portion 1 b) of the lower wall portion 13 is formed in a shape that matches the shape of the bumper reinforcement 2 and is welded in a line contact with the bumper reinforcement 2. In addition, the front edge (opening peripheral part 1b) of the lower wall part 13 is exhibiting the small flange shape bent toward the lower side of the lower wall part 13. FIG. A portion having a small flange shape is formed at the time of drawing. When the peripheral edge of the opening is adjusted by trimming or the like after drawing, a structure that does not form a portion having a small flange shape can be used.

  As shown in FIG. 3A, the outer side wall portion 14 is a curved plate-like portion that protrudes toward the bumper reinforcement 2 from the outer edge of the bottom portion 11 in the vehicle width direction, and is entirely viewed in plan view. It has an arc shape. The outer wall portion 14 is curved so as to protrude toward the inner space of the bumper stay 1. As shown in (c) of FIG. 3, the outer wall portion 14 connects the side edges of the upper wall portion 12 and the lower wall portion 13 on the outer side in the vehicle width direction. As shown in FIG. 2, the front edge (opening peripheral edge portion 1 c) of the outer wall portion 14 is welded in a state of line contact with the bumper reinforcement 2. In addition, the front edge (opening peripheral part 1c) of the outer side wall part 14 is exhibiting the small flange shape bent toward the vehicle width direction outer side. A portion having a small flange shape is formed at the time of drawing. When the peripheral edge of the opening is adjusted by trimming or the like after drawing, a structure that does not form a portion having a small flange shape can be used.

  The inner wall portion 15 is a curved plate-like portion projecting from the inner edge in the vehicle width direction of the bottom portion 11 toward the bumper reinforcement 2, and as shown in FIG. It has an arc shape. The inner wall portion 15 is curved so as to protrude toward the inner space of the bumper stay 1. As shown in FIG. 3C, the inner wall portion 15 connects the side edges of the upper wall portion 12 and the lower wall portion 13 on the inner side in the vehicle width direction. As shown in FIG. 2, the front edge (opening peripheral edge portion 1 d) of the inner wall portion 15 is welded in a state of line contact with the bumper reinforcement 2. In addition, the front edge (opening peripheral part 1d) of the inner side wall part 15 is exhibiting the small flange shape bent toward the vehicle width direction inner side. A portion having a small flange shape is formed at the time of drawing. When the peripheral edge of the opening is adjusted by trimming or the like after drawing, a structure that does not form a portion having a small flange shape can be used.

  The outer side wall part 14 and the inner side wall part 15 are opposed to each other with an interval in the vehicle width direction (left-right direction). As shown in FIG. 3A, the crossing angle (inner angle) α between the outer wall part 14 and the bottom part 11 and the crossing angle (inner angle) β between the inner wall part 15 and the bottom part 11 are both obtuse angles. The separation distance between the two is gradually increased from the bottom 11 toward the bumper reinforcement 2. That is, the outer side wall part 14 and the inner side wall part 15 are opposed to each other in a letter C shape so that the interval increases from the bottom part 11 toward the bumper reinforcement 2.

As shown in FIG. 3 (c), the boundary portion 1e between the upper wall portion 12 and the outer wall portion 14 and the boundary portion 1f between the upper wall portion 12 and the inner wall portion 15 have corner portions having an arcuate cross section. Is formed. Similarly, corner portions having an arcuate cross section are formed at the boundary portion 1g between the lower wall portion 13 and the outer wall portion 14 and at the boundary portion 1h between the lower wall portion 13 and the inner wall portion 15. The radius R inside the corner is preferably set so as to satisfy the following formula 1.
2 <R / t <12 (1)
t: Wall thickness of each of the wall portions 12 to 15 When the value of R / t is set to 2 or less, the rigidity (buckling strength) of the bumper stay 1 is increased, while the drawability is deteriorated. When the value of 12 is 12 or more, the drawability is improved while the rigidity of the bumper stay 1 is reduced.

  In addition, the corner | angular part of cross-section circular arc shape is also formed in the boundary part (part shape | molded by a punch shoulder part) of each wall parts 12-15 and the bottom part 11. FIG.

  When adjusting the rigidity (easiness of crushing) of the bumper stay 1, the wall thicknesses of the wall portions 12 to 15, the sizes of the inner angles α and β, the radii of the boundary portions 1 e to 1 h, and the like may be increased or decreased. For example, if the wall thickness of each of the walls 12-15 is increased or the inner angles α, β are decreased, the buckling load of each of the walls 12-15 increases, so that the bumper stay 1 is not easily crushed, and each wall 12 When the thickness of ˜15 is reduced or the inner angles α, β are increased, the buckling load of each of the walls 12-15 is reduced, so that the bumper stay 1 is easily crushed.

  The bumper stay 1 is formed by subjecting a base plate made of a 5000 series aluminum alloy (for example, made of JIS A 5052 alloy) to deep drawing or drilling. When deep drawing is performed, although not shown in the drawing, the periphery of the processing target portion of the base plate may be held between the die and the presser foot, and the punch may be pushed into the processing target portion in such a state. When the punch is pushed into the portion to be processed, the drawing process proceeds while the portion around the portion to be processed is drawn between the die and the punch holder. Then, an excess part is cut out so that the small flange part of opening peripheral part 1a-1d may remain about the part left between die | dye and a heel presser. Moreover, as shown in FIG. 4, when the shape of the opening end surface of the box-shaped body 1 ′ obtained by deep drawing is not compatible with the shape of the bumper reinforcement 2 (see FIG. 3A). The trimming process may be performed on the box-shaped body 1 ′. When the bumper reinforcement 2 is curved, the shape of the opening end surface of the bumper stay 1 needs to be adapted to the curved surface of the bumper reinforcement 2, but the die used for deep drawing and the pressing surface of the heel presser By forming a curved surface corresponding to the curved surface of the bumper reinforcement 2, the shape of the opening end face of the box-shaped body can be adapted to the bumper reinforcement 2, and in this way Trimming processing is unnecessary.

  In addition, although illustration is abbreviate | omitted, you may perform a bead process along the front-back direction with respect to the upper wall part 12 and the lower wall part 13 of the bumper stay 1. FIG. In this way, the buckling strength can be improved.

  As shown in FIG. 2, the bumper stay 1 is fixed to the bumper reinforcement 2 by welding over the entire periphery of the opening peripheral edge portions 1 a to 1 d (front edges of the wall portions 12 to 15). In addition, in this embodiment, since the small flange part was formed in opening peripheral part 1a-1d, if it puts, it will become easy to perform a welding operation.

  The bumper reinforcement 2 is constructed on the bumper stays 1 and 1 as shown in FIG. The bumper reinforcement 2 shown in the figure has a circular arc shape as a whole (including not only a case where the bumper reinforcement 2 is formed as a single arc but also a case where the bumper reinforcement 2 is formed in a substantially arc shape constituted by a plurality of arcs and straight lines). It is curved and both end portions are inclined toward the vehicle body side (rear). Incidentally, such bumper reinforcement 2 can be obtained by bending a hollow extruded shape member made of an aluminum alloy (for example, 7000 series aluminum alloy).

  As shown in FIG. 3B, the bumper reinforcement 2 includes a rectangular tube-shaped main body portion 21 serving as an outer shell thereof, and an inner wall 22 disposed inside the main body portion 21. The middle wall 22 is arranged for the purpose of improving the cross-sectional rigidity of the bumper reinforcement 2, and in this embodiment, the inner wall 22 is arranged so as to divide the internal space of the main body 21 into two parts.

  The bumper reinforcement 2 absorbs collision energy during the process of extending the curved portion between the bumper stays 1 and 1 (extension process) (see FIG. 5B) and is adjacent to the bumper stay 1. In the region, the collision energy is absorbed in the process in which buckling or plastic bending deformation occurs in the main body 21 and the inner wall 22 (cross-section crushing process) (see FIG. 5C). In the present embodiment, the bending rigidity of the bumper reinforcement 2 is set so that the cross-sectional crushing process proceeds after the expansion process proceeds.

  Incidentally, it is mainly the bending rigidity of the entire bumper reinforcement 2 that affects the start / end timing of the extension process. The bending stiffness is adjusted by increasing or decreasing the cross-sectional secondary moment. The main factors affecting the magnitude of the moment of inertia of the bumper reinforcement 2 are mainly the thickness of the front and rear walls of the main body 21 and the distance between the front and rear walls of the main body 21. Therefore, by increasing or decreasing these, the start / end timing of the expansion process can be adjusted. On the other hand, it is mainly the thickness of the upper wall, the lower wall, and the middle wall 22 of the main body 21 and the front wall and the rear wall of the main body 21 that affects the timing of starting and ending the cross-section crushing process. Since it is the size of the separation distance, the start / end timing of the cross-section crushing process can be adjusted by increasing / decreasing these.

  Further, in the present embodiment, the rigidity of the bumper stay 1 and the bumper reinforcement 2 (the thickness of each part, cross-sectional dimensions, etc.) so that the stay crushing process proceeds after the expansion process and the cross-section crushing process of the bumper reinforcement 2 have progressed. ) Is set.

  Next, the collision energy absorption process at the time of a frontal collision will be described with reference to FIG. When a collision load in the longitudinal direction of the vehicle body acts on the bumper structure B, as shown in FIG. 5B, first, the curved portion of the bumper reinforcement 2 is linearly extended between the bumper stays 1 and 1, The collision energy is absorbed (elongation process). As the bumper reinforcement 2 is bent and stretched (elongated), the inner wall 15 of the bumper stay 1 is bent and deformed, so that the initial shape of the bumper stay 1 is not firmly maintained. The bumper stay 1 is appropriately deformed so as not to obstruct the bending extension of the bumper reinforcement 2 while stably supporting the bumper reinforcement 2 during the extension process.

  When the collision energy cannot be absorbed only by the extension process, the bumper stay 1 is reduced to the bumper reinforcement 2 as shown in FIG. 5C, so that the collision energy is absorbed (cross-section crushing process). That is, the cross-section crushing process starts to proceed when the extending process reaches the end of the process or when the extending process is completed. If the bumper stay 1 is reduced to the bumper reinforcement 2 after the curved portion of the bumper reinforcement 2 is straightened, the peak of the collision load transmitted to the side member S during the extension process and the cross-section crushing process (bumper reinforcement) The peak of the collision load transmitted to the side member S during the crushing of the ment 2 in the front-rear direction appears with a time difference. In the cross-section crushing process, buckling or plastic bending deformation occurs in the main body 21 and the inner wall 22 (see FIG. 2) of the bumper reinforcement 2 in the region adjacent to the bumper stay 1, and the internal space of the main body 21. Collapses.

  If the collision energy cannot be absorbed even after the cross-sectional crushing process proceeds, the bumper stay 1 itself is crushed in the front-rear direction as shown in FIG. Stay crushing process). That is, when the cross-section crushing process reaches the final stage or the cross-section crushing process ends, the stay crushing process starts to proceed. If the bumper stay 1 is crushed after the bumper stay 1 is reduced to the bumper reinforcement 2, the peak of the collision load transmitted to the side member S during the cross-section crushing process and the collision load transmitted to the side member S during the stay crushing process Appears with a time difference. In the stay crushing process, buckling, plastic bending deformation, and the like occur in the upper wall portion 12, the lower wall portion 13, the outer wall portion 14, and the inner wall portion 15 (see FIG. 3) of the bumper stay 1, and the bumper stay 1 The volume of the interior space is reduced. In the stay crushing process of the present embodiment, first, buckling or plastic bending deformation occurs in the inner wall portion 15 of the bumper stay 1 and its peripheral portion, and then buckling or plastic bending deformation occurs in the outer wall portion 14 or the like. appear.

  Incidentally, since the outer wall 14 and the inner wall 15 of the bumper stay 1 are curved toward the inner space of the bumper stay 1, the initial buckling modes of the outer wall 14 and the inner wall 15 are many. In this case, the buckling mode is set so as to enter the inside of the bumper stay 1. That is, according to the bumper stay 1, variations in the crushing process and the form after the crushing are less likely to occur, so that variations in the amount of collision energy absorbed in the stay crushing process are less likely to occur.

  According to the bumper structure B described above, since the bumper stay 1 is formed of a drawn molded product, the bottom part 11, the upper wall part 12, the lower wall part 13 and the side wall parts 14 and 15 can be molded simultaneously, and the bumper stay 1 can be reduced in production cost.

  If the bumper stay 1 is constituted by a draw-molded product, the bumper stay 1 having a shape with an open surface is formed due to the properties of the draw molding. The opening of the bumper stay 1 is closed by the bumper reinforcement 2, and the bumper stay 1 is opened. Since the peripheral edge portions 1a to 1d are fixed to the bumper reinforcement 2 by welding, the inside of the bumper stay 1 becomes a closed space, and as a result, the deformation resistance (crushing strength) of the bumper stay 1 becomes high. That is, according to the bumper structure B, the deformation resistance (crushing strength) of the bumper stay 1 is high even though it is a drawn product, so that the deformation of the bumper reinforcement 2 and the like are maintained while maintaining the form of the bumper stay 1. Therefore, it is possible to secure the desired peak load and the amount of collision energy absorbed.

  Moreover, according to the bumper stay 1, since the upper wall part 12 and the lower wall part 13 are made into flat form (planar shape), generation | occurrence | production of buckling at the initial stage of a collision can be suppressed. Moreover, since the upper wall portion 12 and the lower wall portion 13 of the bumper stay 1 face each other in parallel (see FIG. 3B), molding wrinkles are less likely to occur during drawing, Since the buckling load is larger than the case where they do not face each other in parallel, it is possible to reduce the thickness while ensuring the desired crushing load.

  3C, boundary portions 1e and 1f between the upper wall portion 12 and the side wall portions 14 and 15, and boundary portions 1g and 1h between the lower wall portion 13 and the side wall portions 14 and 15, respectively. In addition, since the corner portion having the arcuate cross section is formed, the deformation resistance of the bumper stay 1 is increased, and as a result, it is possible to reduce the thickness (weight reduction).

  Further, the bumper stays 1 and 1 are not crushed in the front-rear direction during the process in which the curved portion of the bumper reinforcement 2 is linearly stretched between the bumper stays 1 and 1 (during the expansion process). The distance between the fulcrum points of the reinforcement 2 is reduced not only in appearance but also substantially.

  If the thickness of the front wall and the rear wall of the main body portion 21 of the bumper reinforcement 2 is reduced without taking any measures, the bumper reinforcement 2 can be reduced in weight, while the bumper reinforcement 2 is bent. The rigidity becomes small, the deformation resistance of the bumper reinforcement 2 decreases, and the amount of collision energy absorbed in the extension process decreases. On the other hand, according to the bumper structure B of the present embodiment, since the distance between the fulcrums of the bumper reinforcement 2 is narrowed by the bumper stay 1 having a divergent shape, the front wall and the rear wall of the main body portion 21 of the bumper reinforcement 2 Even if the wall thickness of the bumper reinforcement is reduced, the deformation resistance of the bumper reinforcement 2 is not greatly reduced, so that the amount of collision energy absorbed during the extension process is greatly reduced. There is nothing wrong. That is, according to the bumper structure B, the thickness of the bumper reinforcement 2 is reduced without reducing the deformation resistance of the bumper reinforcement 2 between the bumper stays 1 and 1 (particularly, the thickness of the front wall and the rear wall of the main body 21). ) Can be reduced, and therefore, it is possible to reduce the weight without reducing the amount of collision energy absorbed in the extension process.

  By the way, in the bumper structure B, if the thickness of the bumper reinforcement 2 is equal to the case where the bumper reinforcement 2 is supported by a bumper stay having a constant width dimension, the deformation resistance of the bumper reinforcement 2 between the bumper stays 1 and 1 becomes the width dimension. Is higher than the case where it is supported by a constant bumper stay, so that the amount of collision energy absorbed in the extension process increases.

  Also, according to the bumper structure B, the peak of the collision load transmitted to the side member S sequentially appears with a time difference during each of the extension process, the cross-section crushing process, and the stay crushing process. It is possible to maintain the load value while preventing the load from greatly decreasing.

  Furthermore, according to the bumper structure B, since the bumper stay 1 having a divergent shape is used, it is possible to increase the crushing range of the bumper reinforcement 2 as compared with the case of using a bumper stay having a non-divergent shape. As a result, the amount of collision energy absorbed can be increased.

  In addition, according to the bumper structure B, the bumper stay 1 is made of an aluminum alloy drawn product, and the bumper reinforcement 2 is made of an extruded shape made of aluminum alloy. It becomes possible to reduce the cost, and further, the manufacture becomes easy and the quality is stabilized.

  Note that the configurations of the bumper stay 1 and the bumper reinforcement 2 may be appropriately changed.

  Further, in the above-described embodiment, the bumper reinforcement 2 that is curved in the shape of an arc as a whole is illustrated. However, as shown in FIG. 6, two bent portions 2 a and 2 a are provided between the bumper stays 1 and 1. Even bumper reinforcement 2 can be used. In this case, the bending energy 2a, 2a of the bumper reinforcement 2 is linearly extended, so that the collision energy at the initial stage of the collision is absorbed. Although illustration is omitted, a linear bumper reinforcement and a bumper stay made of a drawn product may be combined.

B Bumper structure 1 Bumper stay 11 Bottom 12 Upper wall 13 Lower wall 14 Outer wall (side wall)
15 Inner wall (side wall)
1a to 1d Opening peripheral edge 1e to 1h Corner 2 Bumper reinforcement

Claims (7)

A pair of left and right bumper stays made of drawn products,
A bumper structure comprising a bumper reinforcement supported by both the bumper stays,
The bumper stay has a bottom portion fixed to a vehicle body, a flat plate-like upper wall portion projecting from the bottom portion toward the bumper reinforcement, a lower wall portion, and a pair of left and right side wall portions,
The upper wall portion and the lower wall portion face each other in parallel,
The opening of the bumper stay is closed by the bumper reinforcement,
A bumper structure characterized in that an opening peripheral edge of the bumper stay is fixed to the bumper reinforcement.   The bumper structure according to claim 1, wherein an opening peripheral edge of the bumper stay is fixed to the bumper reinforcement by welding.   2. A corner portion having a circular arc shape in cross section is formed at a boundary portion between the upper wall portion and each side wall portion and a boundary portion between the lower wall portion and each side wall portion. The bumper structure according to claim 2.   The rigidity of the bumper reinforcement and the bumper stay is set so that the bumper stay is crushed after the bumper stay is reduced to the bumper reinforcement. The bumper structure as described in any one. The bumper reinforcement is bent or curved between the bumper stays,
Rigidity of the bumper reinforcement and the bumper stay is set so that the bumper stay is reduced to the bumper reinforcement after the bent part or the curved part of the bumper reinforcement is linearly extended. The bumper structure according to claim 4.   The bumper structure according to claim 5, wherein the bumper stay has a shape in which a width dimension gradually increases from the vehicle body toward the bumper reinforcement. The bumper structure according to any one of claims 1 to 6, wherein the bumper stay is made of a 5000 series aluminum alloy.

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