Strength member for vehicles

Abstract

According to one embodiment, a strength member for vehicles has a closed cross section and includes a first member 13 having a grooved shape in a cross section intersecting the longitudinal direction, and a second member 14. The first member 13 and the second member 14 respectively have bottom surface portions 13b, 14b, wall portions 13c, 13d, 14c, 14d rising from both side edges of the bottom surface portions 13b, 14b, and opening portions 13a, 14a, wherein the closed cross section is formed by combining the first member 13 and the second member 14 such that the opening portions 13a, 14a face each other. The strength member for vehicles includes: a first overlapping portion 15 in which the inner surface of one wall portion 13c of the first member 13 and the outer surface of one wall portion 14c of the second member 14 overlap in contact with each other; a second overlapping portion 16 in which the outer surface of the other wall portion 13d of the first member 13 and the inner surface of the other wall portion 14d of the second member 14 overlap in contact with each other; and at least one joint portion 17, 18 in which the wall portions are joined in each of the first and second overlapping portions.

Description

Strengthening members for vehicles

[0001] The technology disclosed in this application relates to a strength member for a vehicle.

[0002] Conventionally, vehicle bodies are provided with structures for receiving collision loads during a vehicle collision. For example, bumper structures provided at the front or rear of a vehicle are provided with bumper reinforcements that act as core materials to absorb collision energy. The strength of bumper reinforcements is improved by forming them into closed cross sections. Such closed cross sections can be formed, for example, by combining two members.

[0003] For example, Japanese Patent Application Laid-Open No. 2008-037220 discloses an example of a bumper reinforcement in which a steel sheet material is fixed by spot welding to the end portion of a steel base member having a hat-shaped cross section. In other words, this bumper reinforcement has a closed cross section formed by two members.

[0004] Japanese Patent Application Laid-Open Publication No. 2021-154377 discloses a bumper reinforcement having a closed cross section formed by joining two members with rivets. In this bumper reinforcement, rivets are applied to a flange portion formed at the end of a member having a hat-shaped cross section.

[0005] In bumper reinforcements described in the two publications above, spot welding or riveting outside a closed cross section requires, for example, flanges at the ends of two components to sandwich the joining position with electrodes on both sides. While this approach offers advantages such as easy gap management when assembling two components, it also tends to limit the size of the closed cross section in order to fit within a design space determined by the relationship between the bumper reinforcement and surrounding components. As a result, there is room for improvement in the strength and collision energy absorption of vehicle strength members. Therefore, it is desirable to provide a vehicle strength member having a structure that provides high collision energy absorption efficiency and high component assembly efficiency.

[0006] One aspect of the present technology is a vehicle strength member having a closed cross section, the strength member comprising a first member and a second member, each of which has a groove-shaped cross section intersecting the longitudinal direction, wherein the first member and the second member each have a bottom surface portion having the groove shape, wall portions standing from both side edges of the bottom surface portion, and an opening on the opposite side of the bottom surface portion, and the closed cross section is formed by combining the respective openings so that they face each other, and the strength member has a first overlapping portion in which an inner surface of one of the wall portions of the first member and an outer surface of one of the wall portions of the second member are overlapping in abutting contact, a second overlapping portion in which an outer surface of the other of the wall portions of the first member and an inner surface of the other of the wall portions of the second member are overlapping in abutting contact, and at least one joining portion that joins the abutting wall portions at each of the first and second overlapping portions.

[0007] In some embodiments, the first member is positioned on the side where a load is input during a collision, and the vertical distance from the joint to the plane formed by the bottom surface of the first member is shorter than the vertical distance from the joint to the plane formed by the bottom surface of the second member.

[0008] In some embodiments, the at least one joint between the first and second overlapping portions is a weld formed by laser welding.

[0009] In some embodiments, the bottom surface of at least one of the first member and the second member has a recessed bead formed in the longitudinal direction.

[0010] In some embodiments, the bottom surface of each of the first and second members includes a recessed bead formed in the longitudinal direction.

[0011] In some embodiments, a concave bead formed on the bottom surface of the first member and a concave bead formed on the bottom surface of the second member abut each other, and the first member and the second member are joined at the abutment point of the concave beads.

[0012] In some embodiments, the vehicle strength member is a bumper reinforcement.

[0013] FIG. 4 is a schematic diagram showing the position of a bumper device relative to a vehicle body. FIG. 5 is a schematic perspective view of a vehicle strength member according to one embodiment. FIG. 6 is a schematic plan view of the vehicle strength member of FIG. 2. FIG. 7 is a cross-sectional view of the vehicle strength member of FIG. 3 taken along line IV-IV. FIG. 8 is a cross-sectional view schematically showing the orientation of the set of the first member and the second member. FIG. 9 is a cross-sectional view schematically showing the process of laser welding the first and second overlapping portions. FIG. 10 is a cross-sectional view of a vehicle strength member according to another embodiment. FIG. 11 is a cross-sectional view of a vehicle strength member according to yet another embodiment. FIG. 12 is a cross-sectional view of a vehicle strength member for comparison in which the two members are arranged differently.

[0014] Various embodiments will be described below with reference to the drawings.

[0015] 1 shows a bumper reinforcement 10 according to one embodiment, which is provided as a core material of a bumper device 2 provided at the front or rear of a body 4 of a vehicle such as an automobile. Note that the front-rear, left-right, and up-down directions in the following description and drawings are based on the direction of travel of the vehicle.

[0016] First, the arrangement of a vehicle bumper device 2 equipped with a bumper reinforcement 10, which is a strength member for a vehicle, will be described. As shown in Figure 1, the bumper device 2 is usually arranged at the front and rear of a vehicle body 4 in the width direction of the vehicle body 4.

[0017] The bumper device 2 includes an elongated bumper reinforcement 10, a bumper covering member 6, and a bumper support structure 8. The bumper reinforcement 10 is designed as a member that provides the strength of the bumper device 2. On the other hand, the bumper covering member 6 is designed as a member that provides the appearance of the vehicle, and is disposed so as to cover the front surface of the bumper reinforcement 10.

[0018] The bumper support structure 8 is disposed between a frame member (not shown) of the vehicle body 4 and the bumper reinforcement 10, at positions on both sides of the bumper reinforcement 10 in the longitudinal direction (vehicle width direction). The bumper support structure 8 transmits the collision load received by the bumper reinforcement 10 to the vehicle body 4, and is supported by the vehicle body 4.

[0019] This embodiment will be described taking as an example the case of a bumper reinforcement 10 disposed in the front of a vehicle body 4. In the bumper device 2, a collision load acting on the center position of the bumper device 2 due to, for example, a head-on collision of an automobile is received by the bumper covering member 6, and this load is supported by the bumper reinforcement 10. The load acting on the bumper reinforcement 10 is then received by the vehicle body 4 via the bumper support structure 8.

[0020] As shown in Figures 2 and 3, the bumper reinforcement 10 has an elongated shape, is disposed in the width direction of the vehicle body 4, and is formed with a curved shape with both longitudinal ends recessed. The bumper reinforcement 10 is composed of an elongated first member 13 and a second member 14. The first member 13 and the second member 14 have a groove-shaped cross section intersecting the longitudinal direction. As shown in Figure 4, the bumper reinforcement 10 has openings 13a, 14a of the first member 13 and the second member 14 arranged opposite each other, forming a substantially rectangular closed cross section in a cross section intersecting the longitudinal direction. In this embodiment, the first member 13 is disposed on the outer side in the fore-and-aft direction of the vehicle body (the side to which a load is input during a collision), and the second member 14 is disposed on the inner side (the opposite side).

[0021] As shown in Figure 4, the first member 13 has a groove-shaped bottom surface 13b, wall portions 13c and 13d standing up from both side edges of the bottom surface 13b, and an opening 13a on the opposite side of the bottom surface 13b. In this embodiment, the bottom surface 13b is located on the side where a load is input during a collision (the front side of the vehicle body), and the two wall portions 13c and 13d are located above and below. Here, the "bottom surface" refers to the portion of the first member 13 and the second member 14 whose cross section is groove-shaped, and includes cases where the bottom surface 13b faces any of the front-rear, left-right, and up-down directions depending on the position where the vehicle strength member is installed.

[0022] 2 and 4, the bottom surface portion 13b is provided with a plurality of recessed beads 13e. The recessed beads 13e are recessed from the outside toward the inside of the bottom surface portion 13b in the vehicle front-rear direction, and are formed along the longitudinal direction, for example, in the center of the first member 13 (bumper reinforcement 10) in the vehicle width direction.

[0023] 4, the second member 14 has a groove-shaped bottom surface 14b, wall portions 14c and 14d standing upright from both side edges of the bottom surface 14b, and an opening 14a on the opposite side of the bottom surface 14b. In this embodiment, the bottom surface 14b is located on the side opposite to the side to which a load is input during a collision, and the two wall portions 14c and 14d are located one above the other.

[0024] The dimensions of the upper and lower wall portions 13c, 13d, 14c, and 14d of the first member 13 and the second member 14 in the fore-and-aft direction of the vehicle body are set appropriately to correspond to the arrangement of the joints 17 and 18 in the first overlapping portion 15 and the second overlapping portion 16 described below.

[0025] The bumper reinforcement 10 is arranged so that the upper and lower wall portions 13c, 13d of the first member 13 overlap the upper and lower wall portions 14c, 14d of the second member 14, respectively. In this embodiment, the overlapping portion of the upper wall portions 13c, 14c is referred to as a first overlapping portion 15, and the overlapping portion of the lower wall portions 13d, 14d is referred to as a second overlapping portion 16. In the first overlapping portion 15, the inner surface of the upper wall portion 13c of the first member 13 and the outer surface of the upper wall portion 14c of the second member 14 overlap in abutting contact. That is, the upper wall portion 13c of the first member 13 is located on the outside of the closed cross section, and the upper wall portion 14c of the second member 14 is located on the inside. Meanwhile, in the second overlapping portion 16, the outer surface of the lower wall portion 13d of the first member 13 and the inner surface of the lower wall portion 14d of the second member 14 overlap in abutting contact. That is, the lower wall portion 13d of the first member 13 is located on the inside of the closed cross section, and the lower wall portion 14d of the second member 14 is located on the outside.

[0026] The bumper reinforcement 10 has multiple joints 17, 18 in each of the first and second overlapping portions 15, 16. Specifically, as shown in FIGS. 2 and 4 , the abutting upper wall portions 13c, 14c are joined at multiple locations along the longitudinal direction of the first overlapping portion 15, and the abutting lower wall portions 13d, 14d are joined at multiple locations along the longitudinal direction of the second overlapping portion 16. The joints 17, 18 can be spot welds formed by, for example, laser screw welding (LSW). Note that although the positions of the joints 17, 18 are indicated by x marks in the figures, any number of joints 17, 18 can be disposed at any location on the first overlapping portions 15, 16, and the x marks do not specify the number or positions of the joints 17, 18. The joints 17, 18 may also be formed by other methods, such as laser welding or arc welding.

[0027] 4, the joints 17, 18 are each disposed so as to be closer to the side to which a load is input during a collision in a cross-sectional view intersecting the longitudinal direction of the bumper reinforcement 10. In other words, the positions of the joints 17, 18 are set so that the vertical distance L1 from the joints 17, 18 to the plane formed by the bottom surface portion 13b of the first member 13 (the portion without the recessed bead 13e) is shorter than the vertical distance L2 from the joints 17, 18 to the plane formed by the bottom surface portion 14b of the second member 14. Note that the vertical distance L1 from the joints 17, 18 to the bottom surface portion 13b is the vertical distance from the joints 17, 18 to the outermost surface of the bottom surface portion 13b.

[0028] <Method of Manufacturing Bumper Reinforcement> Next, a manufacturing process for the bumper reinforcement 10 described above will be described. The first member 13 and the second member 14 constituting the bumper reinforcement 10 are formed in a forming process by press-forming a metal member such as a steel plate. As shown in FIGS. 3 and 4 , the first member 13 is elongated and has a groove-shaped cross section intersecting the longitudinal direction, a bottom surface 13b, wall portions 13c and 13d rising from both side edges of the bottom surface 13b, and an opening 13a on the opposite side of the bottom surface 13b. A plurality of recessed beads 13e are formed on the bottom surface 13b. The second member 14 is elongated and has a groove-shaped cross section intersecting the longitudinal direction, a bottom surface 14b, wall portions 14c and 14d rising from both side edges of the bottom surface 14b, and an opening 14a on the opposite side of the bottom surface 14b.

[0029] As shown in Fig. 5, the first member 13 and the second member 14 press-formed in the molding process are combined in the assembling process so that the openings 13a, 14a of the first member 13 and the second member 14 face each other. For example, the first member 13 is combined from an upward diagonal direction with the second member 14, which has been aligned using a jig or the like. This results in a substantially rectangular closed cross section in a cross section intersecting the longitudinal direction of the bumper reinforcement 10. In the first overlapping portion 15, the upper wall portion 13c of the first member 13 is located on the outside of the closed cross section, and the upper wall portion 14c of the second member 14 is located on the inside. Meanwhile, in the second overlapping portion 16, the lower wall portion 13d of the first member 13 is located on the inside of the closed cross section, and the lower wall portion 14d of the second member 14 is located on the outside.

[0030] 9 , for example, when two vehicle strength members 31 and 32 are arranged such that one member 31 has both wall portions 32c and 32d of the other member 32 positioned inside the other member 31, the dimension between the upper wall portion 31c and the lower wall portion 31d of the one member 31 is larger than the dimension between the upper wall portion 32c and the lower wall portion 32d of the other member 32 in a cross-sectional view intersecting the longitudinal direction, and the two members 31 and 32 have different dimensions. When these members 31 and 32 are joined by laser welding or the like, the dimensional accuracy of the members is further limited. Specifically, if the gap between the two members 31 and 32 is large, good welding quality may not be achieved at the joining position. If the gap is too narrow, the walls of the two members 31 and 32 may interfere with each other when they are joined.

[0031] 4 and 5, the bumper reinforcement 10 according to this embodiment is configured by combining two members 13, 14 so that the wall portions 13c, 13d of the first member 13 and the wall portions 14c, 14d of the second member 14 are positioned alternately. This allows the dimension between the upper wall portion 13c and the lower wall portion 13d of the first member 13 to be the same as the dimension between the upper wall portion 14c and the lower wall portion 14d of the second member 14 in a cross-sectional view intersecting the longitudinal direction of the bumper reinforcement 10, and also allows the first member 13 to be set obliquely relative to the second member 14. This relaxes restrictions on the dimensional accuracy and assembly accuracy of the members, making it easier to control accuracy.

[0032] As shown in FIG. 6 , the first member 13 and the second member 14 are spot-welded and integrated at any desired locations at the first and second overlapping portions 15 and 16 during the joining process. For example, laser screw welding is used for spot welding. Laser screw welding is a type of welding that uses laser irradiation to heat the members, and heating is performed from only one side. Furthermore, compared to spot welding, laser screw welding can join the members in a shorter heating time and also allows for a shorter welding pitch. In other words, by using LSW welding, more spot welds can be arranged and the joints 17 and 18 can be joined without gaps, thereby improving the rigidity of the bumper reinforcement 10. Furthermore, faster welding is possible, improving production efficiency.

[0033] <Advantageous Effects> Next, advantageous effects of the above-described embodiment will be described.

[0034] According to this embodiment, the bumper reinforcement 10 (vehicle strength member) has a closed cross section formed by the first member 13 and the second member 14, each of which has a groove-shaped cross section intersecting the longitudinal direction. As a result, a closed cross section is formed with no flange portion on the outside in a longitudinal cross section view of the bumper reinforcement 10. In other words, the bumper reinforcement 10 is formed with a closed cross section that makes full use of the design space S. Therefore, the strength of the bumper reinforcement 10 is improved, and the energy absorption efficiency is also improved.

[0035] In the bumper reinforcement 10 according to this embodiment, the wall portions 13c, 13d of the first member 13 and the wall portions 14c, 14d of the second member 14 are arranged so that they alternately overlap in the vertical direction. This prevents interference between the first member 13 and the second member 14 when they are combined, making it easier to control dimensional accuracy and assembly accuracy. In other words, even when LSW welding or other laser welding, which allows access from one side at the joining position, is selected, it is easy to align the two members 13, 14. This improves the assembly efficiency of the members.

[0036] In this embodiment, in a cross-sectional view intersecting the longitudinal direction of the bumper reinforcement 10, the first member 13 is disposed on the side to which a load is input during a collision of the vehicle body 4 (for example, outside the center in the vehicle front-rear direction), and the joint positions are set so that the vertical distance L1 from the joints 17, 18 to the plane formed by the bottom surface portion 13b of the first member 13 (the portion without the recessed bead 13e) is shorter than the vertical distance L2 from the joints 17, 18 to the plane formed by the bottom surface portion 14b of the second member 14. In other words, the joints 17, 18 in the first and second overlapping portions 15, 16 are disposed in positions closer to the side to which a load is input during a collision. The joints 17, 18 are formed by joining the wall portions 13c, 13d, 14c, and 14d in a state where they overlap in the thickness direction, and therefore are regions with higher strength. By arranging the high-strength portion on the side where the load is input during a collision rather than the center of the bumper reinforcement 10 in the longitudinal direction of the vehicle body, rigidity against deformation and compression is improved. In other words, the collision load of the bumper reinforcement 10 increases, and energy absorption efficiency is improved.

[0037] In this embodiment, joints 17, 18 are spot-welded using laser screw welding at the first and second overlapping portions 15, 16, respectively. LSW welding can join overlapping members by irradiating a laser from only one side, so it can be applied to a bumper reinforcement 10 that does not have a flange portion on the outside of the closed cross section formed by the first member 13 and the second member 14. In other words, it is suitable for configuring a closed cross section that makes full use of the design space S of the bumper reinforcement 10.

[0038] The first member 13 of the bumper reinforcement 10 according to this embodiment is provided with a recessed bead 13e formed in the longitudinal direction. By providing the recessed bead 13e on the first member 13 disposed on the side to which a load is input during a collision, the rigidity and strength against deformation, compression, etc. are improved. In other words, the rigidity and strength of the bumper reinforcement 10 are improved.

[0039] <Concave Bead on Bottom Surface of Second Member> As shown in Figure 7, in another embodiment, a concave bead 24e can be provided on the bottom surface 24b of the second member 24. The bumper reinforcement 20 has a first member 23 and a second member 24 that are elongated and have a groove-shaped cross section intersecting the longitudinal direction. The openings 23a, 24a of the first member 23 and the second member 24 are arranged facing each other, thereby forming a closed cross section.

[0040] The first member 23 has a bottom surface 23b, upper and lower wall portions 23c and 23d, and an opening 23a. The bottom surface 23b is provided with a plurality of recessed beads 23e. The recessed beads 23e are formed, for example, along the longitudinal direction in the center of the first member 23 in the vehicle width direction. The second member 24 has a bottom surface 24b, upper and lower wall portions 24c and 24d, and an opening 24a. The bottom surface 24b is provided with the recessed beads 24e. The recessed beads 24e are formed, for example, along the longitudinal direction in the center of the second member 24 in the vehicle width direction, and the center of the bottom surface 24b in the vertical direction is recessed toward the opening 24a. At the location where the recessed beads 24e are formed, the closed cross section of the bumper reinforcement 20 has a B-shape.

[0041] The bumper reinforcement 20 has a first overlapping portion 25 and a second overlapping portion 26. The first overlapping portion 25 overlaps the inner surface of the upper wall portion 23c of the first member 23 and the outer surface of the upper wall portion 24c of the second member 24 in abutting contact with each other. The second overlapping portion 26 overlaps the outer surface of the lower wall portion 23d of the first member 23 and the inner surface of the lower wall portion 24d of the second member 24 in abutting contact with each other. The first and second overlapping portions 25, 26 are spot-welded at selected locations to be integrated. Laser screw welding, for example, is used for the spot welding.

[0042] In the bumper reinforcement 20, the concave bead 23e formed on the bottom surface portion 23b (first member 23) that is located in the center in the vertical direction abuts against the concave bead 24e formed on the bottom surface portion 24b (second member 24). The abutment surfaces (abutment portions) of these concave beads 23e, 24e are configured to be wider to facilitate welding and the like. The abutment surfaces of the concave beads 23e, 24e are joined by, for example, LSW welding, to form a joint 29. The abutment surfaces of the concave beads 23e of the first member 23 and the concave bead 24e of the second member 24 may also be joined by other methods such as laser welding or spot welding.

[0043] As shown in FIG. 8 , in yet another embodiment, the bumper reinforcement 20 may be configured such that the recessed bead 24 e formed in the second member 24 is shallow so that it does not come into contact with the recessed bead 23 e of the first member 23 .

[0044] <Advantageous Effects> The bumper reinforcement 20 according to the above embodiment has the following advantageous effects in addition to the advantageous effects of the embodiment shown in FIGS.

[0045] Recessed beads 23e, 24e are formed in the longitudinal direction of the bumper reinforcement 20 on the bottom surfaces 23b, 24b of the first member 23 and the second member 24, respectively. This improves the rigidity and strength of the bumper reinforcement 20. Furthermore, the recessed bead 23e formed on the bottom surface 23b of the first member 23 and the recessed bead 23e formed on the bottom surface 24b of the second member 24 abut against each other, and the first member 23 and the second member 24 are joined at the abutting portions of the recessed beads 23e, 24e, forming a joint 29. This further improves the rigidity and strength of the bumper reinforcement 20.

[0046] Other Embodiments The various features described above can be applied not only to bumper reinforcements but also to other vehicle strength members such as center pillars in other embodiments.

[0047] In various embodiments, the position and shape of the recessed beads 13e, 23e formed on the first members 13, 23 or the recessed bead 24e formed on the second member 24 can be changed as appropriate.

[0048] In another embodiment, the bumper reinforcement 10, 20 (vehicle strength member) may have a configuration in which the overlapping arrangement of the first member 13, 23 and the second member 14, 24 is reversed from that of the above embodiment. For example, the second member 14, 24 may be combined with the first member 13, 23 from diagonally above.

[0049] In another embodiment, the joining method for the first and second overlapping portions 15, 16, 25, 26 may be selected to be arc welding in addition to laser welding.

[0050] <Advantageous Effects of the Embodiment> Finally, the advantageous effects of the above embodiment will be summarized.

[0051] In the above embodiment, two elongated members each having a groove-shaped cross section intersecting the longitudinal direction are combined with their openings facing each other. As a result, a closed cross section without an outer flange is formed in the longitudinal cross section of the vehicle strength member. In other words, a vehicle strength member having a closed cross section that fully utilizes the design space of the member is formed. This improves the strength of the vehicle strength member and improves energy absorption efficiency. Furthermore, the wall portions of the first member and the second member are arranged to overlap alternately. This prevents interference between the first member and the second member when they are combined, making it easier to control dimensional accuracy and assembly accuracy. In other words, even when a joining method such as welding is selected for the joining position from one side, alignment of the two members is easy. This improves the assembly efficiency of the member.

[0052] In some embodiments, the first member is disposed on the side where a load is input during a collision, and the joint positions are set so that the vertical distance from the joint to the plane formed by the bottom surface of the first member is shorter than the vertical distance from the joint to the plane formed by the bottom surface of the second member. That is, the joints in each of the first and second overlapping portions are disposed closer to the side where a load is input during a collision. Because the joints that join the wall portions to each other are high-strength portions, by disposing them on the side where a load is input during a collision, rigidity against deformation, compression, etc. is improved. Therefore, the collision load is increased, and energy absorption efficiency is improved.

[0053] In some embodiments, the joint between the first and second overlapping members is a weld formed by laser welding. That is, welding is performed from one side (outside) of the overlapping first and second members, making this suitable for a vehicle strength member that does not have a flange portion that protrudes outward from a wall portion that forms a closed cross section.

[0054] In some embodiments, a recessed bead is formed in the bottom surface of at least one of the first member and the second member in the longitudinal direction of the vehicle strength member, thereby improving the rigidity and strength of the vehicle strength member.

[0055] In some embodiments, a recessed bead is formed on the bottom surface of each of the first and second members in the longitudinal direction of the vehicle strength member, thereby improving the rigidity and strength of the vehicle strength member.

[0056] In some embodiments, a recessed bead formed on the bottom surface of the first member and a recessed bead formed on the bottom surface of the second member abut against each other, and the first member and the second member are joined at the abutting portion of the recessed bead, thereby further improving the rigidity and strength of the vehicle strength member.

[0057] In some embodiments, the vehicle strength member is a bumper reinforcement. Therefore, it is possible to provide a bumper reinforcement that has higher rigidity and strength and can efficiently absorb energy.

[0058] <Other Embodiments> Although specific embodiments have been described above, the present technology is not limited to those embodiments, and those skilled in the art can make various substitutions, modifications, and improvements.

Claims

1. A vehicle strength member having a closed cross section, comprising a first member and a second member, each of which has a groove-shaped cross section intersecting the longitudinal direction, wherein the first member and the second member each have a bottom surface, walls rising from both side edges of the bottom surface, and an opening on the opposite side of the bottom surface, and the closed cross section is formed by combining the respective openings so that they face each other, and the vehicle strength member has: a first overlapping portion where the inner surface of one of the wall portions of the first member and the outer surface of one of the wall portions of the second member are overlapping in abutting contact; a second overlapping portion where the outer surface of the other of the wall portion of the first member and the inner surface of the other of the wall portion of the second member are overlapping in abutting contact; and at least one joining portion joining the abutting wall portions at each of the first and second overlapping portions.

2. A strength member for a vehicle as described in claim 1, wherein the first member is disposed on the side to which a load is input during a collision, and the vertical distance from the joint to the plane formed by the bottom surface of the first member is shorter than the vertical distance from the joint to the plane formed by the bottom surface of the second member.

3. A strength member for a vehicle according to claim 1 or 2, wherein the at least one joint in the first and second overlapping portions is a welded portion formed by laser welding.

4. A strength member for a vehicle according to any one of claims 1 to 3, wherein the bottom surface of at least one of the first member and the second member has a recessed bead formed in the longitudinal direction.

5. A strength member for a vehicle according to claim 4, wherein the bottom surface of each of the first member and the second member has a recessed bead formed in the longitudinal direction.

6. A strength member for a vehicle as described in claim 5, wherein the concave bead formed on the bottom surface of the first member and the concave bead formed on the bottom surface of the second member abut against each other, and the first member and the second member are joined at the abutting portion of the concave beads.

7. A strength member for a vehicle according to any one of claims 1 to 6, wherein the strength member for a vehicle is a bumper reinforcement.

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