JP2011255748A - Shock absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively absorb collision energy at the time of collision of vehicles while effectively suppressing plastic deformation during transportation or the like in a shock absorbing member comprised of an aluminum alloy cast material.SOLUTION: The shock absorbing member is composed of the aluminum alloy cast material. The shock absorbing member is arranged between a pair of left and right side frames 1 extending in the front and rear directions of the vehicle and a bumper reinforcement 2 extending in a vehicle width direction, and has mounting flanges 19 coupled with the side frames 1 and a tip wall 21 coupled with the bumper reinforcement 2. A hollow part 26 comprised of vertically opposite upper and lower walls and a pair of left and right side walls 24, 25 is arranged between the tip wall 21 and the mounting flanges 19, and a plurality of recesses 28 are arranged at the back surface of the mounting flanges 19.

Description

  The present invention relates to an impact absorbing member disposed between a pair of left and right side frames extending in the front-rear direction of a vehicle and a bumper rain extending in the vehicle width direction.

  Conventionally, in order to improve the fuel efficiency of automobiles and to reduce the environmental load accompanying this, the thickness of the steel plate constituting the vehicle body is reduced, or instead of the steel plate material, an aluminum plate material or extruded material It has been attempted to reduce the weight of the vehicle body, for example, by using a cable. However, when forming a vehicle structure consisting of the above-mentioned shock absorbing member using thin steel plate or aluminum plate material, a complicated process such as press forming multiple parts and then welding them is necessary. It becomes. In particular, when an aluminum plate material is used, there is a problem that the cost required for each process is increased.

  Therefore, it is conceivable to form the vehicle structure with an aluminum alloy casting material. In this case, as a material characteristic of the vehicle structure, for example, in order to prevent it from being easily broken even under a large load, for example, A total elongation characteristic (EL) of 15% or more is required. As a vehicle structure made of such an aluminum alloy casting, as shown in Patent Document 1 below, a structure is provided with a hollow portion in which the wall thickness is changed continuously or partially along the axial direction. By doing so, it is known that an excellent shock absorbing capability can be obtained by plastic deformation in the axial direction in a constant deformation mode at the time of a vehicle collision.

JP 2002-39245 A

  In the shock absorbing member disclosed in Patent Document 1, the hollow portion is plastically deformed into a bellows shape when the vehicle collides, thereby effectively absorbing the shock energy and transmitting the large shock energy to the vehicle interior or the like. There is an advantage that can be suppressed. However, the impact absorbing member disposed between the pair of left and right side frames extending in the front-rear direction of the vehicle and the bumper reinforcement extending in the vehicle width direction has a load other than the front-rear load input at the time of the vehicle collision. Since various loads are applied, it is also required to have strength that can withstand these loads. For example, when a car produced in an automobile factory is loaded on a car carrier or transported to a dealer in Japan or abroad by a loaded car, a tow hook is attached to the bumper reinforcement, and this is attached with a rope. It is being fixed to the floor of the hull.

  An aluminum alloy disposed between the side frame and the bumper reinforcement is applied to the towing hook because a large load corresponding to the weight of the vehicle body is input when a large swaying occurs in a car carrier or the like. The impact-absorbing member made of a casting is subjected to significant plastic deformation under the influence of the load. When such plastic deformation occurs in the impact absorbing member, there is a possibility that the function of absorbing impact energy at the time of a vehicle collision may not be sufficiently exhibited. In this regard, in the impact absorbing member according to Patent Document 1, Nothing was considered.

  The present invention has been made in view of the above-described problems, and in an impact absorbing member made of an aluminum alloy casting material, the impact energy is effectively suppressed in a vehicle collision while effectively suppressing plastic deformation during transportation. The purpose is to be able to absorb.

  The invention according to claim 1 is an impact absorbing member made of an aluminum alloy casting material, wherein the impact absorbing member includes a pair of left and right side frames extending in the front-rear direction of the vehicle, and a bumper reinforcement extending in the vehicle width direction. And a mounting flange connected to the side frame and a tip wall connected to the bumper reinforcement. Between the tip wall and the mounting flange, A hollow portion composed of an upper wall and a lower wall facing each other and a pair of left and right side walls is disposed, and a plurality of recesses are provided on the back surface of the mounting flange.

  According to a second aspect of the present invention, in the impact absorbing member according to the first aspect, the base end portion of the side wall is provided with a thick portion having a plate thickness larger than that of the front end portion. Is.

  According to a third aspect of the present invention, in the impact absorbing member according to the second aspect, the thick-walled portion includes a bulging portion that extends in a vertical direction in a side view and bulges in a lateral direction in a plan view. It is.

  According to a fourth aspect of the present invention, in the impact absorbing member according to any one of the first to third aspects, the upper wall and the lower wall are provided with ribs extending from the mounting flange toward the tip end side, respectively. It is provided.

  The invention according to claim 5 is the impact absorbing member according to claim 4, wherein the rib is formed in a tapered shape in a side view.

  In the invention according to claim 1, the side frame is coupled to an impact absorbing member disposed between a pair of left and right side frames extending in the front-rear direction of the vehicle and a bumper reinforcement extending in the vehicle width direction. A mounting flange and a tip wall connected to the bumper reinforcement are provided. Between the tip wall and the mounting flange, an upper wall and a lower wall facing each other vertically and a pair of left and right side walls are provided. Since the hollow portion is provided and a plurality of concave portions are provided on the back surface of the mounting flange, the side of the shock absorbing member can be increased by setting the plate thickness large without increasing the weight of the mounting flange. The mounting strength to the frame is sufficiently secured, and the mounting state can be stably maintained. Accordingly, the plastic deformation during transportation of the impact absorbing member formed of the aluminum alloy casting material can be effectively suppressed, and thereby, the impact absorbing member can be fully exerted in the event of a vehicle collision to reduce the collision energy. There is an advantage that it can be absorbed effectively.

  In the invention according to claim 2, the base end portion of the shock absorbing member is reinforced by providing a thick portion having a plate thickness larger than that of the tip end portion of the base end side portion of the side wall. As a result, it is possible to effectively exhibit the function of the impact absorbing member in the event of a vehicle collision while effectively suppressing the plastic deformation during transportation of the impact absorbing member made of an aluminum alloy casting material. There is an advantage that it can be absorbed.

  In the invention according to claim 3, since the thick portion is configured by a bulging portion that extends in the vertical direction in a side view and bulges in a lateral direction in a plan view, the weight of the shock absorbing member is increased so much. In addition, there is an advantage that it is possible to effectively suppress the occurrence of large plastic deformation at the base end portion of the shock absorbing member where the maximum moment load occurs, that is, at the flange, during transportation of the automobile.

  In the invention according to claim 4, since the ribs extending from the mounting flange toward the tip side are provided on the upper wall and the lower wall of the shock absorbing member, plastic deformation of the shock absorbing member made of an aluminum alloy casting material occurs. There is an advantage that the connecting portion between the hollow portion and the mounting flange, which is an easy portion, can be effectively reinforced, and the plastic deformation of the shock absorbing member during transportation or the like can be more effectively suppressed.

  In the invention which concerns on Claim 5, since the said rib was formed in the tapered shape by side view, it can be said that the connection part of the said hollow-shaped part and a mounting flange can be effectively reinforced with a simple and lightweight structure. There are advantages.

  Furthermore, in the inventions according to the first to fifth aspects, the impact absorbing member can be easily formed by a casting method, which is advantageous in terms of manufacturing cost.

It is side surface sectional drawing which shows the rear part vehicle body structure provided with the impact-absorbing member which concerns on this invention. It is a top view which shows the rear part vehicle body structure of the said vehicle. It is the III-III sectional view taken on the line of FIG. It is a perspective view which shows the specific structure of the said impact-absorbing member. It is an end view which shows the specific structure of the said impact-absorbing member. It is the VI-VI sectional view taken on the line of FIG. It is plane sectional drawing which shows the manufacturing process of an impact-absorbing member. It is a perspective view which shows the comparative example of the impact-absorbing member which concerns on this invention. 1 is a perspective view showing a first embodiment of an impact absorbing member according to the present invention. It is a perspective view which shows 2nd Example of the impact-absorbing member which concerns on this invention. It is a graph which shows the correspondence of the deformation amount of an impact-absorbing member, and a load. It is a table | surface which shows the maximum displacement amount and plastic deformation amount of an impact-absorbing member.

  1 and 2 show a rear body structure of a vehicle including an impact absorbing member according to an embodiment of the present invention. The vehicle connects a vehicle body side member composed of a pair of left and right rear side frames 1 extending in the longitudinal direction of the vehicle body on the left and right sides of the rear vehicle body, and the rear end portions of the rear side frames 1 on the rear side of the rear side frame 1. Thus, a bumper reinforcement 2 extending in the vehicle width direction is provided, and a pair of left and right impact absorbing members 3 are disposed between the rear side frame 1 and the bumper reinforcement 2.

  The rear side frame 1 is formed of a member having a rectangular cross section made of a ferrous material such as a steel plate material having a pair of upper and lower horizontal walls 4 and 5 and a pair of left and right side walls 6 and 7, or a hat-shaped member. The rear end flange 8 is fixed to the rear end portion by means such as spot welding. The shock absorbing member 3 is detachably attached to the rear end flange 8 of the rear side frame 1 by bolting.

  The bumper reinforcement 2 is made of a metal material such as a steel plate having a front wall portion 10 and a rear wall portion 11 opposed to each other in the front-rear direction, and an upper wall portion 12 and a bottom wall portion 13 opposed to each other in the vertical direction. It consists of a square pipe-shaped member or a cross-sectional hat-shaped member. A pair of left and right hook mounting members 17 formed of a cylindrical body in which a screw hole into which a base end portion of the pulling hook 16 is screwed are welded to the upper wall portion 12 of the bumper reinforcement 2. It is fixed by. The shock absorbing member 3 is fixed to the front wall portion 10 of the bumper reinforcement 2 by means such as bolting.

  The impact absorbing member 3 is made of an aluminum alloy casting material, and as shown in FIGS. 3 to 5, the mounting flange 19 connected to the rear end flange 8 of the rear side frame 1 via a connecting bolt 18, and the bumper. The tip wall 21 is connected to the reinforcement 2 via a connecting bolt 20. Between the front end wall 21 of the shock absorbing member 3 and the mounting flange 19, a hollow portion 26 having an upper wall 22 and a lower wall 23 facing each other in the vertical direction and a pair of left and right side walls 24, 25 is arranged. It is installed. Then, when a rear-end collision such as a collision of another vehicle with the rear portion of the vehicle occurs, the hollow portion 26 of the shock absorbing member 3 is configured to absorb impact energy by plastic deformation or the like. ing.

  The mounting flange 19 is made of a plate-like body having a plate thickness Ft of about 7 mm to 15 mm extending so as to surround the outer periphery of the hollow portion 26, and insertion portions 27 for the connection bolts 18 are provided at the four corners. ing. A plurality of recesses 28 are formed on the back surface of the mounting flange 19, that is, on the joint surface to the rear end flange 8 of the rear side frame 1. In this embodiment, a pair of recesses 28 and 28 are formed between the insertion portions 27 and 27 provided at the four corners of the mounting flange 19, respectively, and the depth of the recess 28 depends on the plate thickness Ft of the mounting flange 19. Is set to about 1/2 to 3/4. Thereby, between the insertion parts 27 and 27 which the mounting flange 19 opposes, the peripheral part and the center part are formed thick, and other parts (installation part of the said recessed part 28) are formed thinly. Has been.

  Further, a thick portion 29 having a plate thickness larger than that of the distal end portion is provided at the proximal end portions of the side walls 24 and 25. In the present embodiment, a thick portion 29 is formed at the base end side portion of the side walls 24 and 25, which is a bulging portion that bulges laterally in a plan view and extends in a vertical direction in a side view. The protruding amount T to the side of the thick portion 29 is set to be approximately the same as the plate thickness t (for example, 3 mm) of the side walls 24 and 25. Further, the front-rear width W of the thick portion 29 is set to about 1/3 to 1/5 of the front-rear length L of the side walls 24, 25.

  The upper wall 22 and the lower wall 23 of the shock absorbing member 3 are provided with a plurality of ribs 30 extending from the end face of the mounting flange 19 toward the distal end side. In the present embodiment, three ribs 30 project from the upper surface of the upper wall 22 and the lower surface of the lower wall 23, respectively. The rib 30 has a front-rear dimension of about 20 mm, a vertical dimension of about 10 mm, and a plate thickness of about 3 mm, and is formed in a tapered triangular shape in side view.

  As shown in FIG. 6, a bobbin-like member 31 made of an iron-based material having an insertion hole for the connecting bolt 18 is disposed in the insertion portion 27 provided in the mounting flange 19 of the shock absorbing member 3. . The bobbin-shaped member 31 has a cylindrical main body portion 32 and donut plate-like flange portions 33 and 34 provided at both front and rear ends thereof. Then, in the state where the end surface of the bobbin-shaped member 31, specifically, the outer wall surface of the flange portions 33 and 34 protrudes outward by about 1 to 3 mm from the end surface of the mounting flange 19, the mounting flange 19. The cylindrical main body portion 32 of the bobbin-shaped member 31 is cast inside.

  Further, as shown in FIGS. 3 and 4, a connecting portion in which an insertion hole for a connecting bolt 20 that connects the tip wall 21 and the bumper reinforcement 2 is formed in the tip wall 21 of the shock absorbing member 3. 35 are provided at the four corners, and a connecting portion 36 having a predetermined width extending in the vertical direction is provided so as to be connected to the front end portion of the upper wall 22 and the front end portion of the lower wall 23. It is also possible to adopt a structure in which a bobbin-like member is cast in the connecting portion 35 of the tip wall 21 and the connecting bolt 20 is screwed into a screw hole formed in the bobbin-like member. .

  In order to manufacture a vehicle structure comprising the shock absorbing member 3 and to connect the shock absorbing member 3 to a vehicle body side member comprising the rear side frame 1, a vehicle body is first constructed as shown in FIG. By closing a casting mold 44 having a fixed mold 42 in which a support pin 41 of the member 31 is protruded and a movable mold 43 installed so as to be able to contact with and separate from the fixed mold 42, the mold is closed. With the end surface of the bobbin-shaped member 31 projecting outward from the flange forming space 45, a shock absorbing member forming cavity having the flange forming space 45 is formed.

  After forming a cavity for forming an impact absorbing member between the fixed mold 42 and the movable mold 43 in the mold closing process, a die casting method in which a molten aluminum alloy is injected into the cavity at a high pressure in the casting process. The impact absorbing member 3 is cast. In place of the die casting method, the impact absorbing member 3 can be cast by a gravity casting method in which a molten aluminum alloy is poured into the cavity of the casting mold 44 by its own weight. From the viewpoint of forming the impact absorbing member 3 appropriately and ensuring its strength sufficiently, it is desirable to use the die casting method.

  After the shock absorbing member 3 manufactured in the casting process is taken out from the casting mold 44 and deburred, etc., the mounting flange 19 of the shock absorbing member 3 is connected to the rear end of the rear side frame 1 in the connecting process. They are fixed to the flange 8 by connecting bolts 18 to connect them. Next, the vehicle body structure having the shock absorbing member 3 and the rear side frame 1 is conveyed to an electrodeposition coating process, and is applied with electrodeposition coating in which a voltage is applied while being immersed in the electrodeposition coating liquid, and is shown in FIG. As described above, the electrodeposition coating liquid is allowed to enter between the end surface of the mounting flange 19 and the wall surface of the vehicle body side member facing the mounting flange 19, that is, the rear surface of the rear end flange 8, and the electrodeposition coating 46 is formed on each surface. To do.

  That is, the mounting flange 19 of the shock absorbing member 3 is cast with the end surface of the bobbin-shaped member 31 protruding outward from the end surface of the mounting flange 19. Even when the rear side frame 1 is firmly connected to the rear end flange 8 of the rear side frame 1, the bobbin-shaped member 31 is disposed between the end surface of the mounting flange 19 and the rear surface of the rear end flange 8 opposed thereto. A gap corresponding to the protrusion amount is formed. Therefore, the electrodeposition coating liquid can surely enter the gap formed between the mounting flange 19 of the shock absorbing member 3 and the rear end flange 8 of the rear side frame 1 in the electrodeposition coating process. Thus, the electrodeposition coating 46 can be easily and properly formed on the end surface of the mounting flange 19 and the rear surface of the rear end flange 8 facing the mounting flange 19, respectively, and the gap can be reliably sealed. It is also possible to prevent electrolytic corrosion due to the end surface coming into contact with the rear end flange 8 of the rear side frame 1 through moisture.

  In addition, since a plurality of recesses 28 are provided on the back surface of the mounting flange 19, the plate thickness Ft can be increased without increasing the weight of the mounting flange 19 so much. Therefore, even if the plate thickness Ft of the mounting flange 19 is set to a relatively large value, for example, about 10 mm, the depth of the concave portion 28 is set to, for example, 1/2 or more of the plate thickness Ft of the mounting flange 19. In addition, it is possible to sufficiently secure the mounting strength of the shock absorbing member 3 to the rear side frame 1 while suppressing the weight of the shock absorbing member 3 from increasing, and to stabilize the mounting state of the shock absorbing member 3. Can be maintained.

  In the impact absorbing member 3 made of an aluminum alloy casting material disposed between the pair of left and right rear side frames 1 extending in the front-rear direction of the vehicle and the bumper reinforcement 2 extending in the vehicle width direction as described above, the rear side A mounting flange 19 connected to the rear end flange 8 of the frame 1 and a tip wall 21 connected to the bumper reinforcement 2 are provided, and between the tip wall 21 and the mounting flange 19, vertically. An aluminum alloy casting has a structure in which a hollow portion 26 including an upper wall 22 and a lower wall 23 facing each other and a pair of left and right side walls 24 and 25 is provided and a plurality of recesses 28 are provided on the back surface of the flange. It is possible to effectively suppress plastic deformation during transportation of the shock absorbing member 3 made of a material, and to thereby prevent a vehicle collision. Has the advantage of effectively absorb the impact energy sufficiently to exhibit the function of the impact absorbing member 3 in.

  That is, by providing a plurality of recesses 28 on the rear surface of the mounting flange 19 and increasing its thickness Ft without increasing the weight of the mounting flange 19 so much, the shock absorbing member 3 can be mounted on the rear side frame 1. A sufficient mounting strength can be secured. For this reason, even when the impact absorbing member 3 is made of an aluminum alloy casting material for the purpose of reducing the weight of the vehicle body and providing sufficient ductility, the mounting state can be stably maintained. Therefore, the automobile having the shock absorbing member 3 is loaded on an automobile carrier or the like, and the automobile is transported in a state where the rope connected to the tow hook 16 attached to the bumper reinforcement 2 is fixed to the floor of the hull. In this case, it is possible to effectively prevent a large plastic deformation from occurring in the installation portion of the mounting flange 19, which is a portion where the maximum moment load acts on the shock absorbing member 3.

  Even when a high load corresponding to the weight of the vehicle is input from the tow hook 16 and the bumper reinforcement 2 to the shock absorbing member 3 according to the shaking of the hull or the like during transportation of the automobile as described above, It is possible to effectively prevent a large plastic deformation from occurring in the shock absorbing member 3 made of an aluminum alloy casting disposed between the rear side frame 1 and the bumper reinforcement 2. For this reason, the occurrence of a situation where the shock absorbing function of the shock absorbing member 3 is not sufficiently exhibited is effectively suppressed, and when the rear collision occurs such that another vehicle collides with the rear portion of the own vehicle, By plastically deforming the hollow portion 26 of the shock absorbing member 3 into a bellows shape, it is possible to effectively absorb the impact energy acting on the rear portion of the vehicle body and reliably suppress the influence of the impact on the vehicle interior. There is.

  As a casting material for the impact absorbing member 3, Mn: 1.4 to 1.6, Fe: 0.4 to 0.7, Mg: 0.2 to 0.5, Ti: 0.00. Al-1.5Mn containing ~ 0.2, Si: <0.10, Zn: <0.10, Cu: <0.05, N: <0.05 (wt%), the balance being Al -0.7 Fe die-cast material, 180MPa tensile strength (TS), 90MPa proof stress (YS), and 25% total elongation characteristics (EL) are used. As shown in FIG. 9, the shock absorbing member 3 ′ according to the comparative example in which the plate thickness Ft of the mounting flange 19 is set to 5 mm, and the plate thickness Ft of the mounting flange 19 to 10 mm as shown in FIG. The impact absorbing member 3a according to the first embodiment of the present invention, which is different from the comparative example described above, was cast only in that it was set and the recesses 28... Having a depth of 7.5 mm were formed on the back surface. And the simulation test which measures the deformation amount by applying a predetermined load to these was performed.

  Specifically, the upper surface of the bumper reinforcement 2 in the state where the shock absorbing members 3 ′ and 3 a according to the comparative example and the first embodiment are disposed between the rear side frame 1 and the bumper reinforcement 2. The pulling hooks 16 attached to the left and right are pulled obliquely outward and rearward at an inclination angle α of about 20 ° in plan view (see FIG. 2), and are pulled obliquely outward and downward at an inclination angle β of about 45 ° in side view. A tensile load was applied (see FIG. 1). Then, as shown in FIG. 11, the tensile load is gradually increased to 7.65 kN to measure the maximum displacement amount of the impact absorbing members 3 ′ and 3a, and after the tensile load is removed, the impact absorbing member 3 is removed. When the amount of plastic deformation generated in 'and 3a was measured, data as shown in FIG. 12 was obtained.

  From the above data, in the shock absorbing member 3 ′ according to the comparative example, a plastic deformation amount of 8.4 mm was generated. In contrast, in the impact absorbing member 3a according to the first example of the present invention, it was confirmed that the amount of plastic deformation can be suppressed to 3.6 mm, which is half or less. Accordingly, for example, the plate thickness Ft of the mounting flange 19 is set to 10 mm so that it is at least twice the thickness of the hollow portion 26 (for example, 3 mm), and a plurality of recesses 28 are provided on the back surface. Thus, without significantly increasing the weight of the shock absorbing member 3a, the shock absorbing member 3a made of an aluminum alloy casting material is effectively suppressed from plastic deformation during transportation or the like, and the shock absorbing member is absorbed during a vehicle collision. It can be seen that the collision energy can be effectively absorbed by fully exerting the function of the member 3a.

  Further, as shown in FIG. 10, a thick portion 29 having a front-rear width W of about 20 mm and a protruding amount T of about 3 mm is provided on the base end side portion of the side walls 24, 25 constituting the hollow portion 26. Except for the above, the impact absorbing member 3b according to the second embodiment of the present invention, which is configured in the same manner as the first embodiment, is cast, and the amount of deformation is measured by applying the same load as above. When a simulation test was performed, data as shown in FIG. 12 was obtained. From the data, the impact made of an aluminum alloy casting material is obtained by providing a structure in which a thick portion 29 having a plate thickness larger than that of the distal end portion is provided in the proximal end portion of the side walls 24 and 25. It was confirmed that the impact energy can be effectively absorbed by sufficiently exerting the function of the shock absorbing member 3 at the time of a vehicle collision while suppressing the plastic deformation during the transportation of the absorbing member 3b more effectively.

  In particular, as shown in the second embodiment, the thick wall portion 29, which extends in the vertical direction in a side view and bulges out in a side view in a plan view, is a proximal end portion of the side walls 24, 25. When the structure is provided, the base portion of the shock absorbing member 3 where the maximum moment load is generated when the vehicle is transported without increasing the weight of the shock absorbing member 3b, that is, the mounting flange. It is possible to effectively suppress the occurrence of large plastic deformation in 19. For this reason, the impact absorbing member 3b is formed of an aluminum alloy casting material to effectively reduce the weight and suppress the deformation at the time of transportation and the like even though the structure can be easily manufactured. There is an advantage that the effect that the function can be sufficiently maintained can be remarkably obtained.

  Further, as shown in FIG. 4, the upper wall 22 and the lower wall 23 constituting the hollow portion 26 of the shock absorbing member 3 have a front and rear dimension of about 20 mm, a vertical dimension of about 10 mm, and a thickness of about 3 mm. Except that three ribs 30 formed in a tapered triangular shape are installed so as to extend from the end face of the mounting flange 19 toward the tip end side. When the impact absorbing member 3 according to the third embodiment of the present invention configured as described above is cast and a deformation test is performed by applying the same load as described above to measure the deformation, data as shown in FIG. was gotten.

  From the above data, by providing ribs 30 extending from the mounting flange 19 toward the tip side on the upper wall 22 and the lower wall 23 of the shock absorbing member 3, plastic deformation of the shock absorbing member 3 made of an aluminum alloy casting material is provided. It is possible to effectively reinforce the connecting portion between the hollow portion 26 and the mounting flange 19, which is a region where the shock absorbing member 3 is likely to occur, and further effectively suppress the plastic deformation of the shock absorbing member 3 during transportation. It has been confirmed that the function of the shock absorbing member 3 can be sufficiently exerted in the event of a vehicle collision. In particular, as shown in the third embodiment of the present invention, when the rib 30 is formed in a tapered shape in a side view, the hollow portion 26 and the mounting flange 19 can be formed with a simple and lightweight structure. By effectively reinforcing the connecting portion, there is an advantage that the deformation can be sufficiently suppressed.

  Further, as shown in the third embodiment, the connection flange 19 of the impact absorbing member 3 made of an aluminum alloy casting material is connected to the vehicle body side member (the rear end flange 8 of the rear side frame 1) made of an iron-based material. A bobbin-shaped member 31 made of an iron-based material having an insertion hole for a member (connection bolt 18) is provided on the mounting flange 19, and the end surface of the bobbin-shaped member 31 is protruded outward from the end surface of the mounting flange 19. In the state where the cylindrical main body 32 of the bobbin-shaped member 31 is cast in the mounting flange 19, as shown in FIG. 6, the rear end flange 8 of the rear side frame 1 made of the iron-based material, Both the members are strengthened by the connecting bolts 18 while preventing direct contact with the mounting flange 19 of the shock absorbing member 3 made of an aluminum alloy casting. It can be sintering. Therefore, it is possible to effectively prevent the occurrence of electrolytic corrosion due to current flowing in the contact portion of the dissimilar metal in contact with the impact absorbing member 3 made of the aluminum alloy casting material and the rear side frame 1 made of the iron-based material. can do.

  Further, in a state where the rear end flange 8 of the rear side frame 1 and the mounting flange 19 of the shock absorbing member 3 are firmly connected by the connecting bolt 18, they are conveyed to the electrodeposition coating process and immersed in the electrodeposition coating liquid. In this state, by applying a voltage and applying electrodeposition, as shown in FIG. 6, the electrodeposition coating liquid is allowed to enter between the end face of the mounting flange 19 and the rear face of the rear end flange 8 opposed thereto, The electrodeposition coating 46 can be easily and properly formed on each surface. Even when rainwater or the like enters between the end face of the mounting flange 19 and the rear face of the rear end flange 8 opposed thereto by forming the electrodeposition coating 46, an aluminum alloy is used with the rainwater or the like as a medium. The advantage that current can be prevented from flowing between the mounting flange 19 of the shock absorbing member 3 made of a casting and the rear end flange 8 of the rear side frame 1 made of an iron-based material, thereby effectively suppressing the occurrence of the electrolytic corrosion. There is.

  In the above embodiment, the vehicle body side member composed of a pair of left and right rear side frames 1 extending in the longitudinal direction of the vehicle body at the left and right sides of the rear vehicle body, and the rear end portions of the rear side frames 1 at the rear side of the rear side frame 1 are used. Although an example in which the present invention is applied to the shock absorbing member 3 disposed between the bumper reinforcement 2 extending in the vehicle width direction so as to connect each other has been described, a front disposed at the front of the vehicle body The present invention can also be applied to an impact absorbing member disposed between a side frame and a front pan reinforcement for the side frame.

DESCRIPTION OF SYMBOLS 1 Rear side frame 2 Bumper reinforcement 3 Shock absorption member 21 Tip wall 22 Upper wall 23 Lower wall 24, 25 Side wall 26 Hollow part 28 Recessed part 29 Thick part 30 Rib

Claims (5)

  An impact absorbing member made of a cast aluminum alloy material, wherein the impact absorbing member is disposed between a pair of left and right side frames extending in the front-rear direction of the vehicle and a bumper reinforcement extending in the vehicle width direction. A mounting flange connected to the side frame, and a tip wall connected to the bumper reinforcement, and an upper wall and a bottom facing each other between the tip wall and the mounting flange. An impact-absorbing member, wherein a hollow portion comprising a wall and a pair of left and right side walls is disposed, and a plurality of recesses are provided on the back surface of the flange.   2. The shock absorbing member according to claim 1, wherein a thick portion having a plate thickness larger than that of the distal end portion is provided at a proximal end portion of the side wall.   The impact-absorbing member according to claim 2, wherein the thick portion includes a bulging portion that extends in a vertical direction in a side view and bulges in a lateral direction in a plan view.   The impact absorbing member according to any one of claims 1 to 3, wherein the upper wall and the lower wall are each provided with a rib extending from the mounting flange toward the tip end side.   The shock absorbing member according to claim 4, wherein the rib is formed in a tapered shape in a side view.

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