Structural member

Abstract

A structural member (100, 100A-100D) comprises attachment portions (11, 12, 13), an arm member (20), and a reinforcing member (30, 30A-30D). The arm member (20) includes first to third vertical walls (221, 222, 223) and a top plate (21). The reinforcing member (30, 30A-30D) includes a reinforcing member body (31) and a flange (32). The reinforcing member body (31) is joined to the third vertical wall (223). A hole edge portion (311) of the reinforcing member body (31) extends along at least a portion of the peripheral edge of a through-hole (211) of the top plate (21) in a plan view of the structural member (100, 100A-100D). The flange (32) is joined to the top plate (21) at least in a position on the attachment portion (11) side on a wheel side and a position on the attachment portion (13) side on a vehicle body side, with respect to the hole edge portion (311).

Description

Structural member

[0001] The present disclosure relates to a structural member for a vehicle.

[0002] A plurality of structural members are used in vehicles such as automobiles. External forces act on each structural member during vehicle travel or in the event of a collision.

[0003] Patent Document 1 discloses a lower arm as an example of a structural member for a vehicle. In Patent Document 1, the lower arm includes an arm member and a reinforcing member. The reinforcing member includes a reinforcing member main body and a flange. The reinforcing member main body faces the top plate of the arm member. The flange protrudes from the reinforcing member main body toward the top plate of the arm member, and is arranged with a gap from the top plate. In Patent Document 1, the reinforcing member main body branches into a first branch portion and a second branch portion, and the flange is arranged along the branch portion of the reinforcing member main body. Patent Document 1 states that, as a result, when an external force is input to a structural member that is, for example, a lower arm, the shear force acting on the arm member and the reinforcing member main body is easily dispersed to the flange, so that out-of-plane deformation of the arm member and the reinforcing member is less likely to occur.

[0004] Patent Document 2 also discloses a lower arm as an example of a structural member for a vehicle. In Patent Document 2, the lower arm includes an arm member and a reinforcing member. The reinforcing member includes a bottom wall portion facing the top wall portion of the arm member, and a flange portion. The reinforcing member is provided over a wide range of the arm member. In the lower arm of Patent Document 2, the flange portion of the reinforcing member is arranged at a position close to the load input point. For example, the length from the mounting portion of the vehicle body-side component to the flange portion is 83% or more of the length from the mounting portion of the vehicle body-side component to the mounting portion of the wheel-side component that is the load input point. Patent Document 2 states that this makes it possible to effectively suppress torsional deformation of the lower arm and improve the mass efficiency of deformation strength.

[0005] JP 2024-126603 A Japanese Patent No. 6717445

[0006] Structural members may have through-holes to avoid interference from tools during assembly to the vehicle. The area near these through-holes is prone to structural weakness and is susceptible to deformation when external forces are applied during vehicle operation or collisions. If a structural member is easily deformed, its strength (yield strength) against external forces may decrease.

[0007] The object of this disclosure is to provide a structural member for a vehicle that can improve strength against external forces.

[0008] The structural member for a vehicle according to this disclosure comprises a first mounting portion for attaching the wheels of the vehicle, a second mounting portion and a third mounting portion for attaching the body of the vehicle, an arm member, and a reinforcing member. The arm member includes a first vertical wall, a second vertical wall, a third vertical wall, and a top plate. The first vertical wall extends from the first mounting portion side to the second mounting portion side. The second vertical wall extends from the second mounting portion side to the third mounting portion side. The third vertical wall extends from the first mounting portion side to the third mounting portion side. The top plate is continuous with each of the first, second, and third vertical walls. A first through hole is formed in the top plate. The reinforcing member includes a reinforcing member body and a flange. The reinforcing member body faces the top plate with a gap between them. The reinforcing member body is joined to the third vertical wall. The flange is continuous with the reinforcing member body on the opposite side of the third vertical wall and protrudes toward the top plate. The reinforcing member body has a first hole edge. The first hole edge extends along at least a portion of the periphery of the first through hole in a plan view of the structural member. The flange is joined to the top plate at least at a position on the first mounting portion side with respect to the first hole edge, and at a position on the third mounting portion side with respect to the first hole edge.

[0009] The structural member for vehicles according to this disclosure can improve strength against external forces.

[0010] Figure 1 is a schematic perspective view showing a structural member according to the first embodiment. Figure 2 is another schematic perspective view showing a structural member according to the first embodiment. Figure 3 is a plan view of the structural member shown in Figures 1 and 2. Figure 4 is an enlarged perspective view showing a part of the structural member shown in Figures 1 and 2. Figure 5A is a cross-sectional view taken along line V-V in Figure 3. Figure 5B is a cross-sectional view taken along line V-V in Figure 3. Figure 6A is a schematic diagram showing the configuration of a press forming apparatus for manufacturing a structural member according to the first embodiment. Figure 6B is a schematic diagram showing the configuration of a press forming apparatus for manufacturing a structural member according to the first embodiment. Figure 7A is a schematic diagram for explaining the operation of the press forming apparatus shown in Figures 6A and 6B. Figure 7B is a schematic diagram for explaining the operation of the press forming apparatus shown in Figures 6A and 6B. Figure 8A is a graph showing the relationship between the height and radius of curvature of a curved section obtained from press forming analysis. Figure 8B is a graph showing the relationship between the height and radius of curvature of a curved section obtained from press forming analysis. Figure 9 is a plan view of a structural member according to the second embodiment. Figure 10 is a cross-sectional view taken along line X-X in Figure 9. Figure 11 is a plan view of a structural member according to the third embodiment. Figure 12 is a cross-sectional view taken along line XII-XII in Figure 11. Figure 13 is a cross-sectional view of a structural member according to the fourth embodiment. Figure 14 is a plan view of a structural member according to the fifth embodiment. Figure 15 is a plan view of a structural member according to a modified example of the above embodiment. Figure 16 is a graph showing the receding force load for comparative examples and each embodiment.

[0011] The structural member for a vehicle according to this embodiment includes a first mounting portion for attaching the vehicle's wheels, a second mounting portion and a third mounting portion for attaching the vehicle's body, respectively, an arm member, and a reinforcing member. The arm member includes a first vertical wall, a second vertical wall, a third vertical wall, and a top plate. The first vertical wall extends from the first mounting portion side to the second mounting portion side. The second vertical wall extends from the second mounting portion side to the third mounting portion side. The third vertical wall extends from the first mounting portion side to the third mounting portion side. The top plate is continuous with each of the first, second, and third vertical walls. A first through hole is formed in the top plate. The reinforcing member includes a reinforcing member body and a flange. The reinforcing member body faces the top plate with a gap between them. The reinforcing member body is joined to the third vertical wall. The flange is continuous with the reinforcing member body on the opposite side of the third vertical wall and protrudes toward the top plate. The reinforcing member body has a first hole edge. The first hole edge extends along at least a portion of the periphery of the first through hole in a plan view of the structural member. The flange is joined to the top plate at least at a position on the first mounting portion side with respect to the first hole edge, and at a position on the third mounting portion side with respect to the first hole edge (first configuration).

[0012] In the structural member relating to the first configuration, a first through-hole is formed in the top plate of the arm member. Therefore, the portion of the arm member near the first through-hole may be a structurally weak point. However, in the structural member relating to the first configuration, the portion of the arm member near the first through-hole is reinforced with a reinforcing member. More specifically, the reinforcing member body is joined to the third vertical wall of the arm member that extends from the first mounting portion on the wheel side to the third mounting portion on the vehicle body side. The reinforcing member body is provided with a first hole edge portion that runs along the first through-hole of the arm member. The flange of the reinforcing member is joined to the top plate of the arm member on both sides of the first hole edge portion. The flange of the reinforcing member is joined to the top plate at least at a position on the first mounting portion side relative to the first hole edge portion, and at a position on the third mounting portion side relative to the first hole edge portion. As a result, for example, when a longitudinal load of the vehicle is applied to the first mounting portion, out-of-plane deformation of the top plate near the first through-hole is suppressed, and torsional deformation of the structural member becomes less likely to occur. Therefore, structural members are less likely to buckle, and their strength against external forces tends to be higher.

[0013] In the structural member relating to the first configuration, when the circumference of the first through hole is L1 and the length of the edge of the first hole is L2, L1 and L2 may satisfy L2 / L1 > 0.5 (second configuration).

[0014] The reinforcing member can form a closed cross-section together with the top plate and third vertical wall of the arm member. By forming a closed cross-section with the arm member and the reinforcing member, the rigidity against torsional deformation in the structural member can be increased. In the second configuration, the length L2 of the first hole edge of the reinforcing member body is more than 0.5 times the circumference L1 of the first through hole in the top plate of the arm member. In this case, a relatively wide area of ​​the top plate around the first through hole can be included within the closed cross-section. As a result, torsional deformation of the structural member becomes less likely to occur.

[0015] In the structural member relating to the first or second configuration, a first peripheral wall portion may be formed on the top plate. The first peripheral wall portion protrudes from the periphery of the first through hole toward the main body of the reinforcing member (third configuration).

[0016] In the structural member relating to the third configuration, the first hole edge may be joined to the first peripheral wall (fourth configuration).

[0017] In the fourth configuration, the first hole edge of the reinforcing member body is joined to the arm member. More specifically, the first hole edge of the reinforcing member body is joined to the first peripheral wall portion that protrudes from the periphery of the first through hole in the top plate of the arm portion. This further improves the strength of the structural member against longitudinal loads of the vehicle.

[0018] In a structural member relating to any of the first to fourth configurations, the first mounting portion may include a first bolt hole. The first bolt hole is formed in the top plate. The reinforcing member body may extend along the third vertical wall to the first mounting portion. In this case, the reinforcing member body may include a second bolt hole. The second bolt hole is formed in the reinforcing member body corresponding to the first bolt hole (fifth configuration).

[0019] In the fifth configuration, a second bolt hole is formed in the reinforcing member body corresponding to a first bolt hole provided in the top plate of the arm member. In this case, the joint component located at the first mounting portion, the arm member, and the reinforcing member can be fastened together with a common bolt. This makes it possible to improve the rigidity of the structural member, particularly at the first mounting portion.

[0020] In a structural member relating to any of the first to fourth configurations, the first mounting portion may include a second through-hole and a second peripheral wall portion. The second through-hole is formed in the top plate. The second peripheral wall portion protrudes from the periphery of the second through-hole. The reinforcing member body may extend along the third vertical wall to the first mounting portion. In this case, the reinforcing member body may include a second hole edge portion and a protruding portion. The second hole edge portion extends along at least a portion of the periphery of the second through-hole in a plan view of the structural member. The protruding portion protrudes from the second hole edge portion toward the top plate and faces the second peripheral wall portion (sixth configuration).

[0021] In the sixth configuration, the second hole edge is provided on the reinforcing member body along the second through hole provided in the top plate of the arm member. The reinforcing member body is also provided with a projection that protrudes from the second hole edge. The projection faces the second peripheral wall provided on the top plate of the arm member. In this case, the joint component placed at the first mounting portion can be supported by the second through hole and the second peripheral wall of the arm member, as well as the second hole edge and projection of the reinforcing member. This makes it possible to improve the rigidity of the structural member, especially at the first mounting portion.

[0022] In a structural member relating to any of the first to sixth configurations, the second vertical wall may include a curved portion. The curved portion is adjacent to, for example, the second mounting portion. The curved portion curves concavely inward from the structural member in a plan view of the structural member. When the height of the second vertical wall in the curved portion is H [mm], the radius of curvature of the curved portion in a plan view of the structural member is R [mm], and the Vickers hardness of the second vertical wall is Hv [HV], the structural member may satisfy any of the following conditions (1) to (6) (seventh configuration): (1) 184 ≤ Hv < 243 and H ≥ 0.690R + 12.8. (2) 243 ≤ Hv < 305 and H ≥ 0.611R + 9.6. (3) The end of the second vertical wall opposite the top plate is a free end, and 305 ≤ Hv < 367 and H ≥ 0.425R + 8.5. (4) A flange portion is provided continuously at the end of the second vertical wall opposite to the top plate, satisfying 305 ≤ Hv < 367 and H ≥ 0.244R + 19.4. (5) The end of the second vertical wall opposite to the top plate is a free end, satisfying 367 ≤ Hv and H ≥ 0.205R + 12.5. (6) A flange portion is provided continuously at the end of the second vertical wall opposite to the top plate, satisfying 367 ≤ Hv and H ≥ 0.125R + 17.5.

[0023] In the structural member relating to the seventh configuration, a curved portion is provided in the second vertical wall adjacent to the second mounting portion on the vehicle body side, which curves inward in a concave shape when viewed from above. The second vertical wall has a relatively large height H in the curved portion. More specifically, the height H of the second vertical wall in the curved portion is set to satisfy any of the above conditions (1) to (6), together with the radius of curvature R of the curved portion in a plan view of the structural member and the Vickers hardness Hv of the second vertical wall. As a result, the rigidity of the curved portion is improved, and when an external force is applied to the structural member, out-of-plane deformation of the structural member is more easily suppressed in and near the curved portion. Therefore, the strength of the structural member against external forces is more easily improved.

[0024] Embodiments of this disclosure will be described below with reference to the drawings. In these drawings, the same or equivalent components are denoted by the same reference numerals, and the same description will not be repeated.

[0025] <First Embodiment> [Structural Member Configuration] Figures 1 and 2 are schematic perspective views showing the structural member 100 according to this embodiment. The structural member 100 is used in vehicles such as automobiles. The structural member 100 is, for example, a chassis component of an automobile. Chassis components include suspension arms such as lower arms and upper arms. In this embodiment, an example in which the structural member 100 is a front lower arm will be described.

[0026] Referring to Figures 1 and 2, the structural member 100 comprises mounting parts 11, 12, and 13, an arm member 20, and a reinforcing member 30.

[0027] The mounting portion 11 is provided on the structural member 100 for attaching the vehicle's wheels. When the structural member 100 is assembled into the vehicle, the mounting portion 11 is positioned outward in the vehicle width direction (left-right direction) relative to the mounting portions 12 and 13. The mounting portion 11 is provided with, for example, a ball joint. The structural member 100 is attached to the wheels via, for example, the ball joint and steering knuckle.

[0028] The mounting portion 12 is provided on the structural member 100 for attaching the vehicle body. The mounting portion 12 is positioned inward in the vehicle width direction relative to the mounting portion 11 when the structural member 100 is assembled into the vehicle. The mounting portion 12 is provided with, for example, a cylindrical collar 121. The structural member 100 is attached to the vehicle body via, for example, a bush and a suspension member that are press-fitted into the collar 121.

[0029] The mounting portion 13 is provided on the structural member 100 for attaching the vehicle body. When the structural member 100 is assembled into the vehicle, the mounting portion 13 is positioned inward in the vehicle width direction relative to the mounting portion 11. When the structural member 100 is assembled into the vehicle, the mounting portion 13 is positioned behind the mounting portion 12. For example, a bushing is provided on the mounting portion 13. The structural member 100 is attached to the vehicle body, for example, via the bushing and suspension member.

[0030] The arm member 20 has an overall curved shape when viewed in plan of the structural member 100. A plan view of the structural member 100 refers to viewing the structural member 100 along the direction corresponding to the vertical direction of the vehicle into which the structural member 100 is incorporated. Hereinafter, with respect to the structural member 100, the direction corresponding to the vertical direction of the vehicle will simply be referred to as the vertical direction.

[0031] The arm member 20 is typically made of a metal plate. The arm member 20 may also be made of a steel plate. The arm member 20 may have a plate thickness of, for example, 0.4 mm or more. The plate thickness of the arm member 20 may be 1.0 mm or more. The plate thickness of the arm member 20 may be 6.0 mm or less, or 4.0 mm or less. The arm member 20 includes a top plate 21 and vertical walls 221, 222, and 223.

[0032] The top plate 21 is provided on the arm member 20 so as to intersect in the vertical direction when the structural member 100 is incorporated into the vehicle. In this embodiment, the wheel-side mounting portion 11 is provided on the structural member 100 integrally with the arm member 20. Specifically, the mounting portion 11 includes a recess 111 provided on the end face of the top plate 21 of the arm member 20 and at least one bolt hole 112 formed in the top plate 21. The bolt hole 112 is located near the recess 111 and penetrates the top plate 21 in the thickness direction. The mounting portion 11 may include a plurality of bolt holes 112. For example, a ball joint as a coupling component is placed in the recess 111 and fastened to the structural member 100 using the bolt hole 112 and a bolt.

[0033] In this embodiment, the mounting portion 13 on the vehicle body side is also provided on the structural member 100 integrally with the arm member 20. Specifically, the mounting portion 13 includes a through hole 131. The through hole 131 penetrates the top plate 21 of the arm member 20 in the thickness direction. For example, a bush is press-fitted into the through hole 131.

[0034] The top plate 21 has through holes 211 and peripheral wall portions 212. The through holes 211 are located near the mounting portion 12 and penetrate the top plate 21 in the thickness direction. The through holes 211 are provided in the top plate 21 to avoid interference between the tools used when assembling the structural member 100 to the vehicle and the arm member 20. The through holes 211 are so-called tool holes. The through holes 211 may have a substantially circular shape.

[0035] The peripheral wall portion 212 may be cylindrical. The peripheral wall portion 212 may be substantially cylindrical. The peripheral wall portion 212 rises from the periphery of the through hole 211 in the direction of the thickness of the top plate 21. The through hole 211 and the peripheral wall portion 212 are formed by burring the top plate 21.

[0036] The top plate 21 is continuous with each of the vertical walls 221, 222, and 223. The vertical walls 221, 222, and 223 are connected by the top plate 21. In the curved arm member 20 in plan view, the vertical walls 221 and 222 are positioned on the outside of the curve relative to the vertical wall 223.

[0037] Vertical wall 221 extends from the mounting portion 11 side to the mounting portion 12 side. Vertical wall 222 extends from the mounting portion 12 side to the mounting portion 13 side. Vertical wall 223 extends from the mounting portion 11 side to the mounting portion 13 side. In this embodiment, the vertical wall 223 on the inner side of the curve faces the vertical walls 221 and 222 on the outer side of the curve.

[0038] The reinforcing member 30 is attached to the arm member 20. The reinforcing member 30 is typically made of a metal plate. The reinforcing member 30 may also be made of a steel plate. The thickness of the reinforcing member 30 may be the same as or different from the thickness of the arm member 20. The tensile strength of the reinforcing member 30 may be the same as or different from the tensile strength of the arm member 20.

[0039] The reinforcing member 30 is positioned at a distance from the mounting portions 12 and 13 on the vehicle body side. In this embodiment, the reinforcing member 30 is also positioned at a distance from the mounting portion 11 on the wheel side. The reinforcing member 30 includes a reinforcing member body 31 and a flange 32.

[0040] The reinforcing member body 31 is provided on the reinforcing member 30 so as to intersect in the vertical direction when the structural member 100 is incorporated into the vehicle. The reinforcing member body 31 faces the top plate 21 of the arm member 20 with a gap between them. The reinforcing member body 31 is joined to the vertical wall 223. The flange 32 is continuous with respect to the reinforcing member body 31 on the opposite side of the vertical wall 223. The flange 32 protrudes from the reinforcing member body 31 toward the top plate 21. The flange 32 is joined to the top plate 21.

[0041] The structure of the structural member 100 will be described in more detail below with reference to Figures 3, 4, 5A, and 5B. Figure 3 is a plan view of the structural member 100. Figure 3 shows the structural member 100 as viewed from the reinforcing member 30 side along the vertical direction. Figure 4 is an enlarged perspective view of a part of the structural member 100. Figures 5A and 5B are cross-sectional views taken along line V-V in Figure 3.

[0042] Referring to Figure 3, the vertical wall 223 of the arm member 20 has a concave shape on the inside of the structural member 100 in a plan view of the structural member 100. The vertical wall 223 may extend from the mounting portion 11 side to the mounting portion 13 side, curving concavely toward the mounting portion 12 side in a plan view of the structural member 100. The through hole 211 for tools is formed, for example, in the center of the top plate 21 in the direction in which the vertical wall 223 extends. The through hole 211 may be located near the mounting portion 12.

[0043] The main body 31 of the reinforcing member 30 has a hole edge portion 311. The hole edge portion 311 extends along at least a portion of the periphery of the through hole 211 of the arm member 20 in a plan view of the structural member 100. For example, if the through hole 211 of the arm member 20 is substantially circular, the hole edge portion 311 can be substantially arc-shaped or circular in a plan view of the structural member 100. In the example of Figure 3, the hole edge portion 311 is substantially arc-shaped in a plan view of the structural member 100. That is, the hole edge portion 311 is provided on the reinforcing member main body 31 such that it follows only a portion of the periphery of the through hole 211 in a plan view of the structural member 100.

[0044] When the circumferential length of the through hole 211 in the top plate 21 of the arm member 20 is defined as L1, and the length of the hole edge portion 311 of the reinforcement member main body 31 is defined as L2, L1 and L2 may satisfy L2 / L1 > 0.5. When the peripheral wall portion 212 is provided on the peripheral edge of the through hole 211 in the arm member 20 as in the present embodiment, the circumferential length of the inner peripheral surface of the peripheral wall portion 212 can be treated as the circumferential length L1 of the through hole 211. In the present embodiment, since the hole edge portion 311 of the reinforcement member main body 31 extends only along a part of the peripheral edge of the through hole 211 of the arm member 20 in a plan view of the structural member 100, the length L2 of the hole edge portion 311 is less than the circumferential length L1 of the through hole 211 (L2 / L1 < 1.0).

[0045] The flange 32 is continuous with the reinforcement member main body 31 in the vicinity of the hole edge portion 311. In FIG. 4, of the structural member 100, the flange 32 of the reinforcement member 30 and the vicinity thereof are shown in an enlarged manner.

[0046] With reference to FIG. 4, the flange 32 is joined to the top plate 21 at least at a position on the side of the mounting portion 11 (FIG. 3) relative to the hole edge portion 311 and at a position on the side of the mounting portion 13 (FIG. 3) relative to the hole edge portion 311. In the present embodiment, the flange 32 includes a first portion 321 and a second portion 322.

[0047] In the present embodiment, the first portion 321 and the second portion 322 of the flange 32 are continuously provided at a portion adjacent to the hole edge portion 311 in the reinforcement member main body 31. The first portion 321 is continuous with the reinforcement member main body 31 on the side of the mounting portion 11 (FIG. 3) relative to the hole edge portion 311. The first portion 321 protrudes from the reinforcement member main body 31 toward the top plate 21 side of the arm member 20, and is joined to the top plate 21. The first portion 321 is joined to the top plate 21 by, for example, welding. In the example of FIG. 4, the first portion 321 is joined to the top plate 21 in a state where its end face is abutted against the top plate 21. However, the first portion 321 may be joined to the top plate 21 in a state where its end portion is bent.

[0048] In the present embodiment, the second portion 322 is provided on the reinforcing member main body 31 in a state separated from the first portion 321. The second portion 322 is continuous with the reinforcing member main body 31 on the side opposite to the first portion 321 with respect to the hole edge portion 311. In other words, the second portion 322 is continuous with the reinforcing member main body 31 on the side of the mounting portion 13 (FIG. 3) with respect to the hole edge portion 311. The second portion 322 protrudes from the reinforcing member main body 31 toward the top plate 21 side of the arm member 20, and is joined to the top plate 21. The second portion 322 is joined to the top plate 21 by, for example, welding. In the example of FIG. 4, the second portion 322 is joined to the top plate 21 in a state where its end face is abutted against the top plate 21. However, the second portion 322 may be joined to the top plate 21 in a state where its end portion is bent.

[0049] Returning to FIG. 3, the reinforcing member 30 is adjacent to the vertical wall 223 of the arm member 20, and is arranged spaced apart from the vertical walls 221 and 222. The reinforcing member 30 is not joined to the vertical walls 221 and 222.

[0050] In the arm member 20, the vertical wall 222 can include a curved portion 222c. The curved portion 222c is a portion of the vertical wall 222 that curves concavely toward the inner side of the structural member 100 in a plan view of the structural member 100. The curved portion 222c is adjacent to the mounting portion 12. The curved portion 222c is arranged, for example, next to a collar 121 provided on the mounting portion 12.

[0051] The curved portion 222c has a radius of curvature R. The radius of curvature R is the radius of curvature of the curved portion 222c in a plan view of the structural member 100. The radius of curvature R is, for example, 20 mm or more and 60 mm or less.

[0052] The radius of curvature R of the curved portion 222c can be measured, for example, as follows. That is, in a plan view of the structural member 100, evaluation points are arranged at intervals of, for example, 5.0 mm on the end of the vertical wall 222 on the top plate 21 side, and the radius of curvature of an arc passing through three consecutive evaluation points can be taken as the radius of curvature of the vertical wall 222 at the positions of these evaluation points. For example, a range in which evaluation points having a radius of curvature of 20 mm or more and 60 mm or less in the vertical wall 222 are continuous is the curved portion 222c. The average value of the radii of curvature of the evaluation points located within the curved portion 222c can be taken as the radius of curvature R.

[0053] Figures 5A and 5B schematically show the cross-section of the structural member 100 at the position of the curved portion 222c. The cross-section of the structural member 100 is the cross-section of the structural member 100 when cut by a plane along the vertical direction. Figures 5A and 5B show the cross-section of the structural member 100 passing through the curved portion 222c of the vertical wall 222, the center of the through hole 211 of the top plate 21, and the vertical wall 223. However, Figure 5B shows an example of a different cross-section of the structural member 100 from that in Figure 5A.

[0054] Referring to Figures 5A and 5B, in the arm member 20, the top plate 21 is continuous with the vertical walls 222 and 223, respectively. In a cross-sectional view of the structural member 100, the top plate 21 may have straight sections 213 and 214 adjacent to the vertical walls 222 and 223, respectively. In this embodiment, a recess 215 is provided between the straight sections 213 and 214 in the top plate 21. In the example in Figures 5A and 5B, the through hole 211 for tools and the peripheral wall section 212 are formed on the bottom surface of the recess 215. However, the top plate 21 does not necessarily have to have a recess 215. The top plate 21 may be entirely straight in a cross-sectional view of the structural member 100.

[0055] The vertical wall 222 includes a vertical wall body 222a and a ridge portion 222b. The ridge portion 222b is provided continuously with the top plate 21. The vertical wall body 222a is connected to the top plate 21 via the ridge portion 222b. That is, the ridge portion 222b is the corner portion between the top plate 21 and the vertical wall body 222a. The ridge portion 222b may have a curved shape that protrudes outward from the structural member 100 in a cross-sectional view of the structural member 100. In the examples of Figures 5A and 5B, the ridge portion 222b is provided continuously with the straight portion 213 of the top plate 21.

[0056] The vertical wall body 222a extends substantially vertically in a cross-sectional view of the structural member 100. The vertical wall body 222a may be substantially straight in a cross-sectional view of the structural member 100. The vertical wall body 222a may be parallel or non-parallel to the vertical direction in a cross-sectional view of the structural member 100. In the example in Figure 5A, the end of the vertical wall body 222a opposite to the top plate 21 is a free end. On the other hand, in the example in Figure 5B, a flange portion 222d is continuously provided at the end of the vertical wall body 222a opposite to the top plate 21. As shown in Figure 5B, the flange portion 222d protrudes from the vertical wall body 222a to the outside of the structural member 100 in a cross-sectional view of the structural member 100. The flange portion 222d may be provided only on the curved portion 222c of the vertical wall 222, or it may be provided to extend beyond the curved portion 222c toward the mounting portion 13 (Figure 3).

[0057] The vertical wall 222 has a height H in the curved portion 222c. The height H is, for example, 20 mm or more. The height H may be 25 mm or more. The height H may be 50 mm or less, or 45 mm or less.

[0058] As shown in the example in Figure 5A, when the end of the vertical wall 222 opposite to the top plate 21 is a free end, the height H is the vertical distance from the end of the vertical wall 222 on the top plate 21 side to the free end of the vertical wall 222 in the curved section 222c. On the other hand, as shown in the example in Figure 5B, when a flange section 222d is continuously provided at the end of the vertical wall 222 opposite to the top plate 21, the height H is the vertical distance from the end of the vertical wall 222 on the top plate 21 side to the surface of the flange section 222d opposite to the top plate 21 in the curved section 222c. The end of the vertical wall 222 on the top plate 21 side is the end of the vertical wall 222 on the top plate 21 side on the outer surface of the structural member 100, and is the boundary between the curved ridge section 222b and the straight section 213 of the top plate 21 in a cross-sectional view. The end of the vertical wall 222 on the top plate 21 side may also be the R-end on the top plate 21 side of the outer surface of the ridge section 222b. The radius of curvature R of the curved portion 222c described above (Figure 3) can be measured along the end of the vertical wall 222 on the top plate 21 side.

[0059] The structural member 100 may be configured to satisfy any of the following conditions (1) to (6) with respect to the height H [mm] of the vertical wall 222 in the curved portion 222c, the radius of curvature R [mm] of the curved portion 222c (Figure 3), and the Vickers hardness Hv [HV]. (1) 184 ≤ Hv < 243 and H ≥ 0.690R + 12.8. (2) 243 ≤ Hv < 305 and H ≥ 0.611R + 9.6. (3) The end of the vertical wall 222 opposite to the top plate 21 is a free end (Figure 5A), and 305 ≤ Hv < 367 and H ≥ 0.425R + 8.5. (4) A flange portion 222d is provided continuously at the end of the vertical wall 222 opposite to the top plate 21 (Figure 5B), and 305 ≤ Hv < 367 and H ≥ 0.244R + 19.4. (5) The end of the vertical wall 222 opposite to the top plate 21 is a free end, satisfying 367 ≤ Hv and H ≥ 0.205R + 12.5. (6) A flange portion 222d is provided continuously to the end of the vertical wall 222 opposite to the top plate 21, satisfying 367 ≤ Hv and H ≥ 0.125R + 17.5.

[0060] The Vickers hardness Hv of the vertical wall 222 can be measured as follows: A test specimen having a cross-section along the thickness direction of the vertical wall 222 is cut from the curved portion 222c, and a Vickers hardness test is performed using this specimen in accordance with JIS Z 2244-1:2024. In the Vickers hardness test, the Vickers hardness is measured with a test force of 1 kgw (9.8 N) at a position 1 / 4 of the thickness from the surface of the vertical wall 222 (test specimen). The obtained Vickers hardness is the Vickers hardness Hv of the vertical wall 222.

[0061] Continuing with reference to Figures 5A and 5B, in a cross-sectional view of the structural member 100, the vertical wall 223 is positioned on the opposite side of the vertical wall 222 from the top plate 21. The vertical wall 223 includes a vertical wall body 223a and a ridge portion 223b. The ridge portion 223b is provided continuously with the top plate 21. The vertical wall body 223a is connected to the top plate 21 via the ridge portion 223b. That is, the ridge portion 223b is the corner portion between the top plate 21 and the vertical wall body 223a. The ridge portion 223b may have a curved shape that protrudes outward from the structural member 100 in a cross-sectional view of the structural member 100. In the example in Figures 5A and 5B, the ridge portion 223b is provided continuously with the straight portion 214 of the top plate 21.

[0062] The vertical wall body 223a extends substantially vertically in a cross-sectional view of the structural member 100. The vertical wall body 223a may be substantially linear in a cross-sectional view of the structural member 100. The vertical wall body 223a may be parallel or non-parallel to the vertical direction in a cross-sectional view of the structural member 100. In this embodiment, the end of the vertical wall body 223a opposite to the top plate 21 is a free end. However, a flange portion (not shown) may be continuously provided at the end of the vertical wall body 223a opposite to the top plate 21.

[0063] The main body 31 of the reinforcing member 30 is joined to the vertical wall 223. The reinforcing member main body 31 is joined to the vertical wall 223, for example, by welding. The reinforcing member main body 31 may have a substantially straight shape in a cross-sectional view of the structural member 100. The reinforcing member main body 31 extends from the vertical wall 223 toward the vertical wall 222 in a cross-sectional view of the structural member 100. However, the reinforcing member main body 31 does not reach the vertical wall 222.

[0064] In this embodiment, the reinforcing member body 31 is joined to the inner surface of the vertical wall 223. That is, the reinforcing member body 31 is joined to the vertical wall 223 on the side of the top plate 21, rather than the free end or flange portion of the vertical wall 223. In the example shown in Figures 5A and 5B, the end face of the reinforcing member body 31 is joined to the inner surface of the vertical wall body 223a with abutting against it. However, the reinforcing member body 31 may also be joined to the inner surface of the vertical wall body 223a with its end bent upward or downward.

[0065] In the top plate 21 of the arm member 20, the peripheral wall portion 212 protrudes from the periphery of the through hole 211. In the examples shown in Figures 5A and 5B, the end face of the peripheral wall portion 212 is positioned inside the structural member 100 in the vertical direction relative to the reinforcing member body 31. The reinforcing member body 31 is not joined to the peripheral wall portion 212. However, the end face of the peripheral wall portion 212 may be positioned outside the structural member 100 in the vertical direction relative to the reinforcing member body 31. That is, the hole edge portion 311 of the reinforcing member body 31 may face the outer circumferential surface of the peripheral wall portion 212.

[0066] [Method for Manufacturing Structural Members] Structural members 100 can be manufactured by press forming of metal sheets. Of the structural members 100, the curved portion 222c of the vertical wall 222 has a small radius of curvature R in plan view and is a relatively difficult part to form. In this embodiment, an example of a method for forming this curved portion 222c will be described.

[0067] A press forming apparatus 40, as shown in Figures 6A and 6B, can be used to form the curved portion 222c of the vertical wall 222. By press forming the blank 50 using the press forming apparatus 40, the curved portion 222c of the vertical wall 222 (Figures 3 and 5A or 5B) can be formed. Referring to Figure 6A, the press forming apparatus 40 comprises a punch 41, a die 42, a blank holder 43, and at least one shim-shaped spacing holder 44.

[0068] The punch 41 and blank holder 43 are configured to be movable relative to the die 42 in the pressing direction P. The shim-shaped spacing holder 44 is positioned between the die 42 and the blank holder 43 to maintain a predetermined distance between the die 42 and the blank holder 43. The shim-shaped spacing holder 44 may also be positioned on the blank holder 43.

[0069] Figure 6B schematically shows the relationship between the punch 41, die 42, blank holder 43, and shim-shaped spacing holder 44 when viewed from the press direction P. Referring to Figure 6B, when viewed from the press direction P, the edge 411 of the punch 41 on the die 42 side (punch edge) extends along the edge 421 of the die 42 on the punch 41 side (die edge). When viewed from the press direction P, the punch edge 411 may be substantially parallel to the die edge 421 over its entire length.

[0070] The die edge 421 includes a curved portion 421a. The curved portion 421a curves convexly toward the punch 41 when viewed from the pressing direction P. The curved portion 421a is the part for forming the curved portion 222c (Figure 3, and Figure 5A or Figure 5B) of the vertical wall 222 of the structural member 100.

[0071] The blank holder 43 is provided so as to correspond to a portion of the die edge 421. More specifically, when viewed from the pressing direction P, the blank holder 43 is positioned to correspond to the curved portion 421a of the die edge 421.

[0072] When viewed from the pressing direction P, the distance C between the punch 41 side edge (holder edge) 431 of the blank holder 43 and the die edge 421 changes along the die edge 422. The distance C between the holder edge 431 and the die edge 421 is smallest at the curved portion 421a. The distance C is the distance between the holder edge 431 and the die edge 421 on the perpendicular line to the extending direction of the die edge 421 when viewed from the pressing direction P. The minimum value of the distance C is, for example, smaller than the clearance between the punch edge 411 and the die edge 421 when viewed from the pressing direction P. The minimum value of the distance C may be 0 mm. In this case, when viewed from the pressing direction P, the holder edge 431 and the die edge 421 overlap at the point where they are closest to each other. When the minimum value of the distance C is greater than 0 mm, when viewed from the pressing direction P, the entire holder edge 431 is positioned on the opposite side of the punch 41 from the die edge 421. In this embodiment, the distance C between the holder edge 431 and the die edge 421 is minimized at the top of the curved portion 421a.

[0073] When viewed from the pressing direction P, the wire length of the part of the holder edge 431 with the smallest gap C between it and the die edge 421 may be, for example, 0.5 times or more and 2.5 times or less the wire length of the curved portion 421a of the die edge 421. The wire length of the curved portion 421a may be the product of the clamping angle θ (rad) and the radius of curvature of the curved portion 421a. The clamping angle θ is the angle formed by the tangents at both ends of the curved portion 421a when viewed from the pressing direction P. The clamping angle θ may be 1 / 3π (rad) or more and 2 / 3π (rad) or less.

[0074] Figures 7A and 7B are schematic diagrams illustrating the operation of the press forming apparatus 40. Figures 7A and 7B show a cross-section of the press forming apparatus 40 along the pressing direction P at the position of the curved portion 421a of the die edge 421. Referring to Figure 7A, when forming the curved portion 222c (Figures 3 and 5A or 5B) of the vertical wall 222 of the structural member 100, first, the blank 50 is placed between the punch 41 and the blank holder 43 and the die 42. Then, the blank 50 is sandwiched and pressed between the die 42 and the blank holder 43. The portion of the blank 50 located on the punch 41 may be pressed down by a pad (not shown).

[0075] Referring to Figure 7B, with the blank 50 sandwiched between the die 42 and the blank holder 43, the die 42 and the punch 41 are brought relatively closer in the pressing direction P. This causes the blank 50 to be pushed towards the die 42 by the punch 41. If the flange portion 222d is not provided on the curved portion 222c of the vertical wall 222 (Figure 5A), as shown in Figure 7B, the pushing (forming) by the punch 41 is completed after the blank 50 has been completely pulled out from between the die 42 and the blank holder 43. If the flange portion 222d is provided on the curved portion 222c of the vertical wall 222 (Figure 5B), the pushing (forming) by the punch 41 is completed with a part of the blank 50 remaining between the die 42 and the blank holder 43. This makes it possible to form the curved portion 222c of the vertical wall 222 of the structural member 100 (Figures 1 and 2).

[0076] When the blank 50 is pulled out from between the die 42 and the blank holder 43, the distance between the die 42 and the blank holder 43 is adjusted to the thickness s of the shim-shaped spacing retainer 44. The shim-shaped spacing retainer 44 is provided in the area of ​​the die 42 or the blank holder 43 other than the area where the blank 50 is clamped. When the thickness of the blank 50 is t, the thickness s of the shim-shaped spacing retainer 44 is set to satisfy 0.1t ≤ s < 1.0t. The thickness s may also satisfy 0.1t ≤ s ≤ 0.75t.

[0077] By using such a punch 41, die 42, blank holder 43, and shim-shaped spacing holder 44, a curved portion 222c having a height H that satisfies any of the above conditions (1) to (6) can be formed.

[0078] Specifically, when the blank 50 is pressed towards the die 42 by the punch 41 to perform forming, the blank 50 is pulled toward the die edge 421 (Figure 6B). The portion of the blank 50 that is pulled toward the curved portion 421a (Figure 6B) of the die edge 421 is stretched in the direction of the extension of the curved portion 421a as it is pulled toward the curved portion 421a, and its thickness decreases. However, in the press forming apparatus 40 described above, the distance C between the holder edge 431 and the die edge 421 is minimized at the curved portion 421a when viewed from the pressing direction P. Therefore, compressive stress can be applied in the thickness direction by the die 42 and the blank holder 43 up to the vicinity of the curved portion 421a to the portion of the blank 50 that is pulled toward the curved portion 421a and experiences a decrease in thickness. This makes it possible to suppress the occurrence of cracks in the blank 50.

[0079] In addition, in molding using the press molding apparatus 40, when the blank 50 is pulled towards the die edge 421, the distance between the die 42 and the blank holder 43 is controlled to the thickness s of the shim-shaped spacing holding portion 44 that satisfies 0.1t ≤ s < 1.0t. This reduces the compressive stress and compressive strain acting on the blank 50 when the edge of the blank 50 is pulled out from between the die 42 and the blank holder 43. Therefore, the reduction in plate thickness caused by compressive stress can be mitigated.

[0080] As a result, the curved portion 222c, which has a relatively small radius of curvature R and a relatively large height H, is more easily formed without cracking.

[0081] Figures 8A and 8B are graphs showing the relationship between the height H and radius of curvature R of the curved portion 222c obtained from press forming analysis using commercially available analysis software (LS-DYNA, manufactured by Ansys). Figure 8A shows the analysis results for each Vickers hardness Hv when the curved portion 222c is formed without leaving the flange portion 222d, and Figure 8B shows the analysis results for each Vickers hardness Hv when the curved portion 222c is formed with the flange portion 222d remaining. Figures 8A and 8B show the height H and radius of curvature R at which forming became impossible when attempting to form the curved portion 222c using a normal press forming apparatus that does not have a shim-shaped spacing holding portion 44, and where the gap C between the holder edge 431 and the die edge 421 is not minimized at the curved portion 421a of the die edge 421. In this analysis, molding was deemed impossible when the damage value I, expressed by the following formula, at the free end of the vertical wall 222 or the tip of the flange portion 222d was equal to or greater than the reference value. The reference value for damage value I was determined by confirming the moldability of each material through a stretch flange molding test conducted separately, specifically a test in which a saddle-shaped molded product simulating the stretch flange shape was obtained by press molding, and the damage value I at which molding became impossible in this stretch flange molding test was taken as the reference value.

[0082]

[0083] Referring to Figure 8A, when the curved portion 222c is formed by normal press forming without leaving the flange portion 222d, the height H that could not be formed is expressed as a linear equation of the radius of curvature R for each Vickers hardness Hv as follows: • When Hv = 184: H = 0.690R + 12.8 • When Hv = 243: H = 0.611R + 9.6 • When Hv = 305: H = 0.425R + 8.5 • When Hv = 367: H = 0.205R + 12.5

[0084] Referring to Figure 8B, when the curved portion 222c is formed by normal press forming while leaving the flange portion 222d intact, the height H that could not be formed can be expressed as a linear equation of the radius of curvature R for each Vickers hardness Hv as follows: • When Hv = 305: H = 0.244R + 19.4 • When Hv = 367: H = 0.125R + 17.5

[0085] In contrast, when the curved portion 222c is formed by press forming in this embodiment using the punch 41, die 42, blank holder 43, and shim-shaped spacing holding portion 44, it has been confirmed that it is possible to form even a height H that could not be formed by normal press forming. In other words, when the curved portion 222c is formed by press forming as described in this embodiment, the height H of the curved portion 222c can be set to a height that satisfies any of the above conditions (1) to (6).

[0086] [Effect] In the structural member 100 according to this embodiment, a through hole 211 for tools is formed in the top plate 21 of the arm member 20. In this case, the portion of the arm member 20 near the through hole 211 may be a structurally weak point. However, in the structural member 100 according to this embodiment, the portion of the arm member 20 near the through hole 211 is reinforced by a reinforcing member 30. More specifically, the main body 31 of the reinforcing member 30 is joined to a vertical wall 223 that extends from the mounting portion 11 on the vehicle side to the mounting portion 13 on the vehicle body side, and the flange 32 of the reinforcing member 30 is joined to the top plate 21 on the opposite side of the vertical wall 223. The flange 32 is joined to the top plate 21 at least at a position on the mounting portion 11 side relative to the hole edge 311 of the reinforcing member body 31, and at a position on the mounting portion 13 side relative to the hole edge 311. That is, the flange 32 is joined to the top plate 21 on both sides of the hole edge 311 of the reinforcing member body 31 and the through hole 211 of the top plate 21. As a result, when a load (reverse force) is applied to the mounting portion 11 from the front to the rear of the vehicle, for example, out-of-plane deformation of the top plate 21 near the through hole 211 is suppressed, and torsional deformation of the structural member 100 is less likely to occur. Therefore, the structural member 100 is less likely to buckle, and the strength of the structural member 100 against external forces tends to be higher.

[0087] In the structural member 100 according to this embodiment, the reinforcing member 30 is joined to the top plate 21 and vertical wall 223 of the arm member 20, thereby forming a closed cross-section together with the top plate 21 and vertical wall 223. This closed cross-section increases the rigidity of the structural member 100 against torsional deformation. In particular, in this embodiment, the length L2 of the hole edge 311 of the reinforcing member body 31 is greater than 0.5 times the circumference L1 of the through hole 211 in the top plate 21 of the arm member 20. In this case, a relatively wide area of ​​the top plate 21 around the through hole 211 can be included within the closed cross-section. Therefore, torsional deformation of the structural member 100 is easily suppressed.

[0088] In the structural member 100 according to this embodiment, a curved portion 222c is provided in the vertical wall 222 of the arm member 20 near the mounting portion 12. The vertical wall 222 can have a relatively large height H, at least in the curved portion 222c. Specifically, the curved portion 222c can have a height H that satisfies any of the above conditions (1) to (6), along with the radius of curvature R and Vickers hardness Hv. This improves the rigidity of the curved portion 222c, and when an external force is applied to the structural member 100, out-of-plane deformation of the structural member 100 is easily suppressed in and near the curved portion 222c. In particular, when a receding force is applied to the mounting portion 11 on the wheel side, the structural member 100 becomes less susceptible to out-of-plane deformation. Therefore, the strength (yield strength) of the structural member 100 is easily improved.

[0089] <Second Embodiment> Figure 9 is a plan view of the structural member 100A according to this embodiment. Figure 9 shows the structural member 100A viewed from the side of the reinforcing member 30A along the vertical direction. The structural member 100A according to this embodiment has basically the same configuration as the structural member 100 according to the first embodiment. However, the structural member 100A differs from the structural member 100 according to the first embodiment mainly in the area where the reinforcing member 30A is provided.

[0090] Referring to Figure 9, the reinforcing member 30A is positioned at a distance from the mounting portions 12 and 13 on the vehicle body side, similar to the first embodiment. On the other hand, the reinforcing member 30A is provided on the structural member 100A such that a part of it is included in the mounting portion 11 on the wheel side. In the reinforcing member 30A, the reinforcing member body 31 extends along the vertical wall 223 of the arm member 20 to the mounting portion 11. In a plan view of the structural member 100A, the reinforcing member body 31 overlaps with the top plate 21 of the arm member 20 on the vertical wall 223 side, from near the through hole 211 for tools to the position of the mounting portion 11.

[0091] In this case, the reinforcing member body 31 may have at least one bolt hole 312. The reinforcing member body 31 may have a plurality of bolt holes 312. Each of the bolt holes 312 is formed in the reinforcing member body 31 corresponding to one of the bolt holes 112 in the top plate 21 of the arm member 20.

[0092] The reinforcing member body 31 has at least one bolt hole 312 at the mounting portion 11, which allows the joint component, such as a ball joint, the arm member 20, and the reinforcing member 30A to be fastened together with a common bolt. This makes it easier to improve the rigidity of the structural member 100A, especially at the mounting portion 11.

[0093] Figure 10 is a cross-sectional view taken along the line X-X in Figure 9. Figure 10 shows a cross-section of the structural member 100A between the through-hole 211 for the tool and the mounting portion 11 on the wheel side.

[0094] In this embodiment, when the reinforcing member body 31 extends along the vertical wall 223 of the arm member 20 to the mounting portion 11 (Figure 9), the flange 32 of the reinforcing member 30 can also extend along the reinforcing member body 31 on the opposite side of the vertical wall 223 to the vicinity of the mounting portion 11. When the flange 32 is divided into a first portion 321 on the mounting portion 11 side and a second portion 322 on the mounting portion 13 side, with the hole edge 311 of the reinforcing member body 31 in between (Figure 9), the first portion 321 of the flange 32 may be in contact with the top plate 21 from a position adjacent to the hole edge 311 to a position near the mounting portion 11.

[0095] <Third Embodiment> Figure 11 is a plan view of the structural member 100B according to this embodiment. Figure 11 shows the structural member 100B viewed from the reinforcing member 30B side along the vertical direction. The structural member 100B according to this embodiment has basically the same configuration as the structural member 100A according to the second embodiment. However, the structural member 100B differs from the structural member 100A according to the second embodiment mainly in the configuration of the mounting portion 11.

[0096] In the structural member 100B according to this embodiment, as in other embodiments, the wheel-side mounting portion 11 is provided integrally with the arm member 20 on the structural member 100. However, in this embodiment, the mounting portion 11 includes a through hole 113 and a peripheral wall portion 114 instead of a recess 111 and a bolt hole 112.

[0097] The through-hole 113 is provided in the top plate 21 of the arm member 20. The through-hole 113 penetrates the top plate 21 in the thickness direction. The through-hole 113 may have a substantially circular shape.

[0098] The peripheral wall portion 114 may have a cylindrical shape. The peripheral wall portion 114 may also have a substantially cylindrical shape. The peripheral wall portion 114 protrudes from the periphery of the through hole 113 toward the reinforcing member 30B. The through hole 113 and the peripheral wall portion 114 are formed by burring the top plate 21. A bushing, which serves as a joint component, is press-fitted into the through hole 113 and the peripheral wall portion 114.

[0099] The reinforcing member 30B is positioned at a distance from the mounting portions 12 and 13 on the vehicle body side, as in other embodiments. On the other hand, the reinforcing member 30B is provided on the structural member 100B such that a portion of it is included in the mounting portion 11 on the wheel side. In the reinforcing member 30B, the reinforcing member body 31 extends along the vertical wall 223 of the arm member 20 to the mounting portion 11. In a plan view of the structural member 100B, the reinforcing member body 31 overlaps with the top plate 21 of the arm member 20 on the vertical wall 223 side, from near the through hole 211 for tools to the position of the mounting portion 11.

[0100] The reinforcing member body 31 may include a hole edge portion 313 and a projection portion 314. The hole edge portion 313 extends along at least a portion of the periphery of the through hole 113 of the mounting portion 11 in a plan view of the structural member 100. For example, if the through hole 113 is substantially circular, in the example of Figure 11, the hole edge portion 313 has a substantially arc shape in a plan view of the structural member 100. That is, the hole edge portion 313 is provided on the reinforcing member body 31 such that it follows only a portion of the periphery of the through hole 113 in a plan view of the structural member 100. Preferably, the length of the hole edge portion 313 is at least half the circumference of the through hole 113. The hole edge portion 313 may also follow the entire circumference of the through hole 113 in a plan view of the structural member 100. In this case, the hole edge portion 313 may have a substantially circular shape in a plan view of the structural member 100.

[0101] The protrusion 314 is provided continuously with the hole edge 313. The protrusion 314 extends from the hole edge 313 toward the top plate 21. The protrusion 314 may also be provided along the entire length of the hole edge 313.

[0102] Figure 12 is a cross-sectional view taken along line XII-XII in Figure 11. As shown in Figure 12, the protruding portion 314 of the reinforcing member body 31 faces the peripheral wall portion 114 of the arm member 20. More specifically, in the axial direction of the peripheral wall portion 114, the end face of the protruding portion 314 faces the end face of the peripheral wall portion 114 with a gap between them.

[0103] At the mounting portion 11, the reinforcing member 30B has a hole edge portion 313 and a peripheral wall portion 114, allowing the bush, which is press-fitted into the through hole 113 and peripheral wall portion 114 of the arm member 20, to be supported by the reinforcing member 30B. This makes it easier to improve the rigidity of the structural member 100B, especially at the mounting portion 11.

[0104] <Fourth Embodiment> Figure 13 is a cross-sectional view of the structural member 100C according to this embodiment. Figure 13 schematically shows a cross-section of the structural member 100C at the location of the through hole 211 for a tool, passing through the first portion 321 and the second portion 322 of the flange 32 of the reinforcing member 30C. The structural member 100C according to this embodiment has basically the same configuration as the structural member 100B according to the second embodiment. However, the structural member 100C differs from the structural member 100B according to the second embodiment mainly in the configuration of the reinforcing member 30C.

[0105] Referring to Figure 13, in the arm member 20 of this embodiment, a portion of the peripheral wall portion 212 provided around the periphery of the through hole 211 for the tool protrudes from the reinforcing member body 31 to the outside of the structural member 100C. The hole edge portion 311 of the reinforcing member body 31 is joined to the peripheral wall portion 212. The hole edge portion 311 is joined to the peripheral wall portion 212, for example, by welding. The entire hole edge portion 311 may be joined to the peripheral wall portion 212, or only a portion of it may be joined to the peripheral wall portion 212.

[0106] In the example shown in Figure 13, the hole edge 311 is joined to the peripheral wall 212 in a state where it abuts against the outer surface of the peripheral wall 212. However, the manner in which the hole edge 311 and the peripheral wall 212 are joined is not limited to the example shown in Figure 13.

[0107] In the structural member 100C according to this embodiment, the hole edge portion 311 of the reinforcing member body 31 is joined to the arm member 20. More specifically, the hole edge portion 311 of the reinforcing member body 31 is joined to the peripheral wall portion 212 that protrudes from the periphery of the through hole 211 in the top plate 21 of the arm member 20. In this case, a closed cross section is formed by the top plate 21 of the arm member 20, the peripheral wall portion 212, and the reinforcing member 30C. As a result, when a receding force is applied to the structural member 100C, the structural member 100C becomes less prone to twisting. Therefore, the strength of the structural member 100C against receding force is more easily improved.

[0108] The configuration of structural member 100C according to this embodiment can also be applied to structural members 100 and 100B according to the first and third embodiments. That is, in structural members 100 and 100B, the hole edge portion 311 of the reinforcing member body 31 may be joined to the peripheral wall portion 212 of the arm member 20.

[0109] <Fifth Embodiment> Figure 14 is a plan view of the structural member 100D according to this embodiment. Figure 14 shows the structural member 100D viewed from the reinforcing member 30D side along the vertical direction. The structural member 100D according to this embodiment has basically the same configuration as the structural member 100A according to the second embodiment. However, the structural member 100D differs from the structural member 100A according to the second embodiment mainly in the shape of the hole edge portion 311 of the reinforcing member body 31.

[0110] In the structural member 100A according to the second embodiment, the hole edge portion 311 of the reinforcing member body 31 follows only a part of the periphery of the through hole 211 in a plan view of the structural member 100A. On the other hand, in the structural member 100D according to this embodiment, the hole edge portion 311 is provided on the reinforcing member body 31 so as to follow the entire periphery of the through hole 211 in a plan view of the structural member 100D. The hole edge portion 311 can, for example, have a substantially circular shape in a plan view of the structural member 100D.

[0111] In this case, the flange 32 may be in continuous contact with the top plate 21 from the mounting portion 11 side to the mounting portion 13 side relative to the through hole 211. More specifically, the first portion 321 on the mounting portion 11 side of the flange 32 may be continuous with the second portion 322 on the mounting portion 13 side. The first portion 321 of the flange 32 may be continuous with the second portion 322 on the opposite side of the vertical wall 223 relative to the reinforcing member body 31 and may extend to a position near the mounting portion 11.

[0112] In this embodiment, in a plan view of the structural member 100D, the hole edge 311 of the reinforcing member body 31 follows the entire circumference of the periphery of the through hole 211 of the arm member 20. In this case, the periphery L1 of the through hole 211 and the length L2 of the hole edge 311 can satisfy L2 / L1 = 1.0. However, the length L2 of the hole edge 311 may be slightly longer or slightly shorter than the periphery L1 of the through hole 211. Even with the configuration of the structural member 100D according to this embodiment, the strength of the structural member 100D against receding forces can be increased.

[0113] The configuration of structural member 100D according to this embodiment can also be applied to structural members 100, 100B, and 100C according to the first, third, and fourth embodiments. That is, in a plan view of structural members 100, 100B, and 100C, the hole edge portion 311 of the reinforcing member body 31 may extend along the entire circumference of the periphery of the through hole 211.

[0114] However, from the viewpoint of efficiently improving strength against receding forces, it is preferable that the hole edge 311 of the reinforcing member body 31 is interrupted on the opposite side of the vertical wall 223. That is, it is preferable that the circumference L1 of the through hole 211 and the length L2 of the hole edge 311 satisfy L2 / L1 < 1.0. This makes it possible to improve the strength of the structural member against receding forces while suppressing an increase in the weight of the structural member.

[0115] While embodiments relating to this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible as long as they do not deviate from its spirit.

[0116] In the structural members 100, 100A to 100D according to the above embodiment, the circumferential length L1 of the through hole 211 of the arm member 20 and the length L2 of the hole edge 311 of the reinforcing member body 31 preferably satisfy L2 / L1 > 0.5. However, as shown in Figure 15, in each embodiment, the circumferential length L1 of the through hole 211 and the length L2 of the hole edge 311 may satisfy L2 / L1 ≤ 0.5.

[0117] In each of the above embodiments, the top plate 21 of the arm member 20 has a through hole 211 and a peripheral wall portion 212. However, the top plate 21 does not necessarily have to have a peripheral wall portion 212.

[0118] The present disclosure will be further described below with reference to examples. However, the present disclosure is not limited to the following examples.

[0119] To confirm the effects of this disclosure, a collision analysis was performed on a structural member having a shape similar to that of the structural member according to the above embodiment, using general-purpose structural analysis software (ABAQUS / STANDARD, manufactured by DASSAULT SYSTEMS). More specifically, a load directed from the front to the rear of the vehicle (reverse force) was input to the mounting part 11, and the reaction force (reverse force load) to this load was investigated. The results of this analysis are shown in Figure 16.

[0120] In Comparative Example 1, the reinforcing member 30 was removed from the structural member 100 according to the first embodiment, and collision analysis was performed. In Examples 1 to 4, the structural member 100A according to the second embodiment was used as the basic configuration, and collision analysis was performed by changing the value of L2 / L1. In Example 1, L2 / L1 = 0.2, and in Example 2, L2 / L1 = 0.5. In Examples 3 and 4, L2 / L1 = 0.9. In Examples 1 to 3, the hole edge 311 of the reinforcing member body 31 was not joined to the peripheral wall portion 212 around the through hole 211 of the arm member 20, whereas in Example 4, the hole edge 311 was joined (welded) to the peripheral wall portion 212. Other conditions were common to the Comparative Example and Examples 1 to 4.

[0121] As shown in Figure 16, in Examples 1 to 4, where the arm member 20 was reinforced with a reinforcing member 30A, the receding force load increased significantly compared to the comparative example without a reinforcing member. In Example 3, where L2 / L1 > 0.5, the receding force load increased significantly more than in Examples 1 and 2, where L2 / L1 ≤ 0.5. In Example 4, where the hole edge 311 was welded to the peripheral wall 212, the receding force load increased compared to Example 3, where L2 / L1 was the same but the hole edge 311 was not welded to the peripheral wall 212.

[0122] This analysis confirmed that reinforcing the arm member with a reinforcing member suppresses torsional deformation of the structural member, increases the reversal force load, and improves the strength of the structural member against external forces in the longitudinal direction of the vehicle. Furthermore, it was confirmed that setting L2 / L1 > 0.5 further increases the reversal force load. In addition, it was confirmed that joining the hole edge of the reinforcing member to the peripheral wall of the arm member also increases the reversal force load.

[0123] 100, 100A, 100B, 100C, 100D: Structural members 11: Mounting part (first mounting part) 112: Bolt hole (first bolt hole) 113: Through hole (second through hole) 114: Peripheral wall part (second peripheral wall part) 12: Mounting part (second mounting part) 13: Mounting part (third mounting part) 20: Arm member 21: Top plate 211: Through hole (first through hole) 212: Peripheral wall part (first peripheral wall part) 221: Vertical wall (first vertical wall) 222: Vertical wall (second vertical wall) 222c: Curved part 222d: Flange part 223: Vertical wall (third vertical wall) 30, 30A, 30B, 30C, 30D: Reinforcement members 31: Reinforcement member body 311: Hole edge part (first hole edge part) 312: Bolt hole (second bolt hole) 313: Hole edge (second hole edge) 314: Projection 32: Flange

Claims

1. A structural member for a vehicle, comprising: a first mounting portion for attaching the wheels of the vehicle; a second mounting portion and a third mounting portion for attaching the body of the vehicle, respectively; an arm member including a first vertical wall extending from the first mounting portion side to the second mounting portion side; a second vertical wall extending from the second mounting portion side to the third mounting portion side; a third vertical wall extending from the first mounting portion side to the third mounting portion side; and a top plate continuous with each of the first, second, and third vertical walls, having a first through hole formed therein; a reinforcing member including a reinforcing member body facing the top plate with a gap between them and joined to the third vertical wall; and a flange continuous with the reinforcing member body on the opposite side of the third vertical wall and projecting toward the top plate, wherein the reinforcing member body has a first hole edge portion extending along at least a portion of the periphery of the first through hole in a plan view of the structural member, The flange is a structural member that is joined to the top plate at least at a position on the first mounting portion side with respect to the first hole edge, and at a position on the third mounting portion side with respect to the first hole edge.

2. A structural member according to claim 1, wherein when the circumference of the first through hole is L1 and the length of the edge of the first hole is L2, L1 and L2 satisfy L2 / L1 > 0.

5.

3. A structural member according to claim 1, wherein the top plate has a first peripheral wall portion formed thereon that protrudes from the periphery of the first through hole toward the main body of the reinforcing member.

4. A structural member according to claim 3, wherein the first hole edge is joined to the first peripheral wall.

5. A structural member according to claim 1, wherein the first mounting portion includes a first bolt hole formed in the top plate, and the reinforcing member body extends along the third vertical wall to the first mounting portion and includes a second bolt hole formed in the reinforcing member body corresponding to the first bolt hole.

6. A structural member according to claim 1, wherein the first mounting portion includes a second through hole formed in the top plate and a second peripheral wall portion protruding from the periphery of the second through hole, and the reinforcing member body includes a second hole edge portion extending along the third vertical wall to the first mounting portion and extending along at least a portion of the periphery of the second through hole in a plan view of the structural member, and a protruding portion protruding from the second hole edge portion toward the top plate and facing the second peripheral wall portion.

7. A structural member according to claim 1, wherein the second vertical wall includes a curved portion adjacent to the second mounting portion and curves concavely inward in a plan view of the structural member, and the height of the second vertical wall in the curved portion is H [mm], the radius of curvature of the curved portion in a plan view of the structural member is R [mm], and the Vickers hardness of the second vertical wall is Hv [HV], satisfying any of the following conditions (1) to (6): (1) 184 ≤ Hv < 243 and H ≥ 0.690R + 12.

8. (2) 243 ≤ Hv < 305 and H ≥ 0.611R + 9.

6. (3) The end of the second vertical wall opposite to the top plate is a free end, and 305 ≤ Hv < 367 and H ≥ 0.425R + 8.

5. (4) A flange portion is provided continuously at the end of the second vertical wall opposite to the top plate, satisfying 305 ≤ Hv < 367 and H ≥ 0.244R + 19.

4. (5) The end of the second vertical wall opposite to the top plate is a free end, satisfying 367 ≤ Hv and H ≥ 0.205R + 12.

5. (6) A flange portion is provided continuously at the end of the second vertical wall opposite to the top plate, satisfying 367 ≤ Hv and H ≥ 0.125R + 17.5.

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