Aluminum cast side member

Abstract

According to the present invention, a first fixing part and a second fixing part to which a suspension member is fixed are provided on one side and the other side in the extension direction of an aluminum cast side member, respectively. A plurality of ribs are radially arranged from the first fixing part and the second fixing part, and a first radial rib structure and a second radial rib structure are respectively formed. A truss rib structure is formed between the first radial rib structure and the second radial rib structure. The truss rib structure is formed by a first rib extending in the extension direction and a plurality of second ribs obliquely intersecting the first rib.

Description

Aluminum cast side member

[0001] The present invention relates to an aluminum cast side member.

[0002] Patent Document 1 discloses an aluminum cast side member composed of a first member with a U-shaped cross section and a second member that closes the upper part of the first member. A plurality of ribs are provided inside the first member at regular intervals in the extending direction thereof, and the inside of the first member is partitioned into a plurality of sections in the extending direction by the plurality of ribs.

[0003] Japanese Patent Laid-Open No. 2004-182189

[0004] Incidentally, a suspension member is attached to the side member. When a side member is formed by aluminum casting, it is necessary to properly attach the suspension member.

[0005] An object of the present invention is to provide an aluminum cast side member to which a suspension member can be suitably attached.

[0006] On one side and the other side in the extending direction of the aluminum cast side member according to an aspect of the present invention, there are respectively provided a first fixing portion and a second fixing portion to which the suspension member is fixed. A plurality of ribs are radially arranged from the first fixing portion and the second fixing portion, and a first radial rib structure and a second radial rib structure are formed respectively. A truss rib structure is formed extending between the first radial rib structure and the second radial rib structure. The truss rib structure is formed by a first rib extending in the extending direction and a plurality of second ribs obliquely intersecting the first rib.

[0007] The suspension member can be suitably attached to the side member according to the above aspect.

[0008] Figure 1 is a perspective view showing the structure of a vehicle equipped with a side member according to an embodiment. Figure 2 is a perspective view showing the rear of the vehicle. Figure 3 is a plan view of the rear. Figure 4 is a perspective view of the left side member according to an embodiment. Figure 5A is a plan view of the left side member. Figure 5B is a left side view of the left side member. Figure 5C is a bottom view of the left side member. Figure 6 is a cross-sectional view of the right side member along the line VI-VI in Figure 3. Figure 7A is a partial plan view of the right side member. Figure 7B is a partial plan view of the right side member.

[0009] The aluminum cast side member 1 according to the embodiment will be described below with reference to the drawings. In the following description, up, down, left, right, front, and rear are relative to the vehicle. In each figure, FR and RR indicate the front and rear in the vehicle's longitudinal direction, respectively, LH and RH indicate the left and right in the vehicle's width direction, respectively, and UP and DN indicate the top and bottom in the vehicle's vertical direction, respectively. Furthermore, components having the same function as those already described are denoted by the same reference numerals and their description is omitted. In the following description, the left side and right side in the vehicle's width direction, and the front, front, rear, and rear sides in the vehicle's longitudinal direction will be simply referred to as left side, right side, front, front, rear, and rear, respectively.

[0010] Figures 4 to 5C show the left side member 1L, and Figures 6 to 7B show the right side member 1R. The left side member 1L and the right side member 1R are symmetrical with respect to the vehicle's center plane, and are simply referred to as side member 1 without distinction.

[0011] As shown in Figures 1 to 3, the pair of side members 1 in this embodiment are rear side members provided at the rear of the vehicle. The side members 1 extend in the longitudinal direction of the vehicle, and hereafter this longitudinal direction will also be referred to as the extending direction. One end of the side member 1 in the extending direction, more specifically the front end on the passenger compartment side, is joined to a structural frame member 2 that surrounds the floor of the passenger compartment. Therefore, this one end of the side member 1 will also be referred to as the joining end 1J (see Figure 4). The structural frame member 2 comprises a pair of side sills 2S, a dash lower cross member 2F connecting the front ends of the side sills 2S, and a seat cross member 2R connecting the rear ends of the side sills 2S. The dash lower cross member 2F is located below the dash panel, and the seat cross member 2R is located below the rear seat.

[0012] The joint ends 1J of a pair of side members 1 are connected by a sheet cross member 2R. On the other hand, the other ends of the pair of side members 1 in the extending direction, more specifically the rear ends on the vehicle body end side, are connected by a cross member 3. Crash boxes 4 are attached to each rear end of the side member 1. A bumper reinforcement member (not shown) is attached to connect the rear ends of the pair of crash boxes 4. The side members 1 in this embodiment are made of cast aluminum, and many ribs are formed on each part to ensure their strength and rigidity.

[0013] As will be described later, the side member 1 of this embodiment also includes a cover 1C that closes the open portion above it, and a wheelhouse panel 1W joined to the outer surface of the side member 1. The cover 1C of this embodiment is a press-formed steel panel. The wheelhouse panel 1W of this embodiment is a hybrid of a press-formed steel panel and an aluminum casting.

[0014] The parts of the side member 1 will be described with reference to the left side member 1L shown in Figures 4 to 5C. On one side of the side member 1 in the direction of extension, which in this embodiment is the vehicle interior side and the front side, there is a first fixing part 11 to which the suspension member 5 (see Figure 5B) is fixed. The first fixing part 11 is a bolt hole for fixing the suspension member 5. For example, a long nut may be cast into the first fixing part 11. The suspension member 5 is a structural frame member, and its four corners are fastened to a pair of side members 1 by bolts. On the other side of the side member 1 in the direction of extension, which in this embodiment is the vehicle body end side and the rear side, there is a second fixing part 12 to which the suspension member 5 (see Figure 5B) is fixed. The second fixing part 12 is also a bolt hole for fixing the suspension member 5, and a long nut may be cast into it.

[0015] Multiple ribs 11R are formed radially from the first fixing part 11, constructing a first radial rib structure 11S. The first radial rib structure 11S has a structure in which radial ribs 11R are arranged inside a box-shaped interior, with the first fixing part 11 located at the radial center. Multiple ribs 12R are also formed radially from the second fixing part 12, constructing a second radial rib structure 12S. The second radial rib structure 12S also has a structure in which radial ribs 12R are arranged inside a box-shaped interior, with the second fixing part 12 located at the radial center.

[0016] The suspension member 5 is fixed to the vehicle body from below, that is, to a pair of side members 1. At that time, the bolts to the first fixing part 11 and the second fixing part 12 are also fastened vertically from below upward. For this reason, the bolt holes of the first fixing part 11 and the second fixing part 12 extend vertically, and the ribs 11R and 12R arranged radially in the first radial rib structure 11S and the second radial rib structure 12S are formed as vertical ribs. A vertical rib is a rib that extends vertically, and its normal extends horizontally. As described above, the second radial rib structure 12S is formed in a box shape and has a pair of first side walls 12W1 and second side walls 12W2 oriented in the vehicle width direction, a third side wall 12W3 oriented toward the first radial rib structure 11S, that is, toward the joint end 1J, and a bottom wall 12WB. As mentioned above, the first radial rib structure 11S is also formed in a box shape and has a pair of side walls facing the vehicle width direction, a side wall facing the second radial rib structure 12S, and a bottom wall.

[0017] A truss rib structure 1T is formed between the first radial rib structure 11S and the second radial rib structure 12S. The truss rib structure 1T comprises a first rib 1TR1 extending in the aforementioned extending direction from the first radial rib structure 11S to the second radial rib structure 12S, and a plurality of second ribs 1TR2 that intersect the first rib 1TR1 diagonally and are rigidly connected to the first rib 1TR1. The truss rib structure 1T also comprises an inner wall 1TWI (see Figures 4 and 5C) facing inward in the vehicle width direction, an outer wall 1TWO facing outward in the vehicle width direction, and a bottom wall 1TWB facing downward. That is, a truss structure is formed by the first rib 1TR1 and the second rib 1TR2 inside the trough-shaped portion formed by the inner wall 1TWI, the outer wall 1TWO, and the bottom wall 1TWB.

[0018] In this embodiment, a truss structure is formed by the first rib 1TR1 and the second rib 1TR2 in a plan view. That is, the first rib 1TR1 and the second rib 1TR2 are vertical ribs. Multiple second ribs 1TR2 intersect on the first rib 1TR1 and also intersect on the inner wall 1TWO. However, at least some of the multiple second ribs 1TR2, and in this embodiment most of the multiple second ribs 1TR2, are arranged so as not to intersect on the outer wall 1TWO. As shown in Figure 7A (right side member 1R) described later, the second ribs 1TR2 intersect on the outer wall 1TWO only at section X in Figure 7A.

[0019] The aforementioned joint end 1J of the side member 1 is formed as an inclined flange in a side view. The joint end 1J is joined to the structural frame member 2 by bolts, and the front end of the wheelhouse panel 1W described above is also joined to its upper part. An extension 1E extends from the outer edge of the joint end 1J toward the structural frame member 2. The extension 1E is also joined to the structural frame member 2 by bolts, and the front end of the wheelhouse panel 1W described above is also joined to its upper part.

[0020] A grid rib structure 1G is provided between the first radial rib structure 11S and the joint end 1J, that is, one end of the side member 1. As shown in Figure 4, the grid rib structure 1G comprises a plurality of first grid ribs 1GR1 extending in the aforementioned extending direction and a second grid rib 1GR2 perpendicular to the first grid ribs 1GR1. The first grid ribs 1GR1 and the second grid ribs 1GR2 are formed as vertical ribs.

[0021] As shown in Figure 5A, the section in which the first radial rib structure 11S is formed along the extending direction of the side member 1 will be called the first section S1, and the section in which the second radial rib structure 12S is formed will be called the second section S2. The section between the first radial rib structure 11S and the second radial rib structure 12S will be called the central section SM. The truss rib structure 1T described above is formed in the central section SM. Furthermore, the section between the first radial rib structure 11S and the joint end 1J will be called the joint section SJ. The lattice rib structure 1G described above is formed in the joint section SJ.

[0022] A flange 1F extending horizontally inward is formed on the inner edge of the side member 1. The flange 1F is formed along the direction of extension along the entire length of the side member 1, and its front end is integrally joined to the flange-shaped joint end 1J. In the truss rib structure 1T of the central section SM, the flange 1F extends horizontally inward from the upper edge of its inner wall 1TWI. In the second radial rib structure 12S of the second section S2, the flange 1F extends horizontally inward from the upper edge of its second side wall 12W2. In the first radial rib structure 11S of the first section S1 and the lattice rib structure 1G of the joint section SJ, the flange 1F also extends horizontally inward from the upper edge of the inner wall.

[0023] The side member 1 having the structure described above has an opening formed at the top. The cover 1C described above is attached to the side member 1 so as to close this opening. The cover 1C is equipped with a horizontal flange 1CFH extending inward from its inner edge, and the horizontal flange 1CFH is joined to the flange 1F of the side member 1. The joining method is not limited, but can be done with structural adhesive, welding, or a flow drilling screw (FDS) described later. The cover 1C is also equipped with a vertical flange 1CFV extending upward from its outer edge, and the vertical flange 1CFV is joined to the wheelhouse panel 1W. The joining method is also not limited, and can be done with structural adhesive, welding, or a flow drilling screw (FDS) described later.

[0024] As shown in Figure 6, in the central section SM, the outer wall 1TWO of the side member 1 and the wheelhouse panel 1W are joined together. In this embodiment, the outer wall 1TWO and the wheelhouse panel 1W are joined by FDS 6. The FDS 6 are provided at approximately constant intervals along the outer wall 1TWO.

[0025] As shown in Figure 3, the wheelhouse panel 1W in this embodiment is a hybrid of a press-formed steel panel and an aluminum casting. The central part 1WC of the wheelhouse panel 1W is an aluminum casting, to which the upper end of the suspension damper is attached. For this reason, the central part 1WC is made of aluminum casting to ensure strength and rigidity. The front part 1WF and rear part 1WR of the wheelhouse panel 1W are press-formed steel panels and are joined to the front and rear edges of the central part 1WC, respectively. The method of joining is not limited. Figure 6 shows a cross-section of the central part 1WC, but in the front part 1WF and rear part 1WR as well, the outer wall 1TWO and the wheelhouse panel 1W are joined by an FDS 6.

[0026] As a result, as shown in Figure 6, a closed section is formed in the central section SM by the wheelhouse panel 1W, cover 1C, inner wall 1TWI, and bottom wall 1TWB. In this embodiment, the wheelhouse panel 1W and the outer wall 1TWO are superimposed and joined to each other by the FDS 6, so the outer wall 1TWO of the side member 1 also contributes to the formation of a closed section.

[0027] As shown in Figures 5A to 5C, the side member 1 is provided with reinforcing ribs to improve the strength and rigidity of each part. For example, as shown in Figure 5C, triangular ribs 1RR are provided as reinforcing ribs on the outer surfaces of the first side wall 12W1, the second side wall 12W2, and the third side wall 12W3 of the second radial rib structure 12S. The triangular rib 1RR provided on the first side wall 12W1 is formed in the inner corner between the flange 1FO, which extends horizontally outward from the upper edge of the second radial rib structure 12S, and the first side wall 12W1. The triangular rib 1RR provided on the second side wall 12W2 is formed in the inner corner between the flange 1F and the second side wall 12W2. The triangular rib 1RR provided on the third side wall 12W3 is formed in the inner corner between the bottom wall 1TWB and the third side wall 12W3.

[0028] The triangular ribs 1RR, which serve as reinforcing ribs, are also provided between the first section S1 and the joining section SJ, that is, between the first radial rib structure 11S and the lattice rib structure 1G. Furthermore, the triangular ribs 1RR, which serve as reinforcing ribs, are also provided between the joining section SJ and the flange-shaped joining end 1J, that is, between the lattice rib structure 1G and the joining end 1J.

[0029] As shown in Figure 5B, the height of the side member 1 in the joint section SJ from the first radial rib structure 11S to the joint end 1J, i.e., the total height of the lattice rib structure 1G, is defined as HG. The height of the first radial rib structure 11S is defined as H1, and the height of the second radial rib structure 12S is defined as H2. In this embodiment, the height HG is higher than the height H1 and higher than the height H2.

[0030] (1) The aluminum cast side member 1 according to the embodiment includes a first fixing portion 11 provided on one side in the extending direction to which the suspension member 5 is fixed, and a first radial rib structure 11S formed of a plurality of ribs 11R arranged radially from the first fixing portion 11. The side member 1 also includes a second fixing portion 12 provided on the other side in the extending direction to which the suspension member 5 is fixed, and a second radial rib structure 12S formed of a plurality of ribs 12R arranged radially from the second fixing portion 12. The side member 1 also includes a truss rib structure 1T formed between the first radial rib structure 11S and the second radial rib structure 12S. The truss rib structure 1T includes a first rib 1TR1 extending in the extending direction and a plurality of second ribs 1TR2 that intersect the first rib 1TR1 at an angle.

[0031] With the above configuration, the suspension member 5 is fixed to the first radial rib structure 11S and the second radial rib structure 12S, which have radial ribs 11R and 12R. As a result, the mounting rigidity of the suspension member 5 is improved, and the suspension performance attached to the suspension member 5 is improved. Furthermore, the strength and rigidity of the side member 1 in the central section SM between them, as well as the first radial rib structure 11S and the second radial rib structure 12S, are also improved by the truss rib structure 1T. As a result, the strength and rigidity of the vehicle body are also improved, and the suspension performance is improved. The truss rib structure 1T can improve the torsional rigidity of the central section SM while suppressing the weight increase of the side member 1. The fact that the side member 1 is an aluminum casting also contributes to suppressing the weight increase. In addition, the side member 1, which has a structure with many ribs 11R, 12R, 1TR1, 1TR2, can be efficiently manufactured by aluminum casting.

[0032] Furthermore, in the event of a collision with the vehicle's end (rear collision), the first rib 1TR1 of the truss rib structure 1T extends in the direction of extension, and the first rib 1TR1 generates a reaction force, which can deform the crash box 4, bumper reinforcement member, and bumper stay during the collision, effectively absorbing the collision energy. In this embodiment, the ribs 11R, 12R, 1TR1, and 1TR2 forming the first radial rib structure 11S, the second radial rib structure 12S, and the truss rib structure 1T are vertical ribs, and the truss structure of the truss rib structure 1T is also formed in plan view. This arrangement allows for effective resistance to lateral forces, i.e., horizontal forces, input from the suspension.

[0033] The truss structure of the truss rib structure 1T may be formed in a plan view or in a side view. When the truss structure of the truss rib structure 1T is formed in a side view, the first rib 1TR1 and the second rib 1TR2 are horizontal ribs. However, since the side member 1 is formed by aluminum casting, it is preferable from a manufacturing standpoint that all of its ribs are formed in the same direction, that is, as vertical ribs similar to the radial ribs 11R and 12R. A horizontal rib is a rib that extends horizontally, and its normal vector extends vertically.

[0034] (2) In the embodiment, a grid rib structure 1G is provided between the first radial rib structure 11S and the one end (joint end 1J in the above embodiment). The grid rib structure 1G comprises a plurality of first grid ribs 1GR1 extending in the extending direction. The plurality of first grid ribs 1GR1 can effectively receive the collision load described above. Furthermore, the grid rib structure 1G forms a grid structure rather than a truss structure like the truss rib structure 1T. If the joint section SJ in which the grid rib structure 1G is formed is a truss structure, the length of the diagonal ribs intersecting the first grid rib 1GR1 will increase, and the weight will increase. By forming the grid rib structure 1G, the tilting of the first grid rib 1GR1 can be suppressed by the grid structure, and the collision load can be reliably received by the first grid rib 1GR1.

[0035] (3) Furthermore, in this embodiment, the side member is joined to the structural frame member 2 of the vehicle body at the joint end 1J, which is one end. As shown in Figure 5B, the height HG of the side member 1 in the joint section SJ from the first radial rib structure 11S to the joint end 1J is higher than the height H1 of the first radial rib structure 11S and the height H2 of the second radial rib structure 12S. The side member 1 is cantilevered to the structural frame member 2. The support rigidity of the suspension member 5 at the second fixing part 12, which is far from the joint end 1J, is lower than the support rigidity at the first fixing part 11, which is close to the joint end 1J. However, by ensuring a large height HG of the side member in the joint section SJ, the joint rigidity of the side member 1 to the structural frame member 2 at the joint end 1J can be improved. This improves the overall rigidity of the side member 1 and also improves the support rigidity at the second fixing part 12.

[0036] (4) In this embodiment, the outer walls (first side wall 12W1, second side wall 12W2, third side wall 12W3) that are joined to the structural frame member 2 at the joint end 1J and constitute the second radial rib structure 12S have reinforcing ribs 1RR that extend outward from the outer walls. As described above, the support rigidity of the suspension member 5 at the second fixed part 12, which is far from the joint end 1J, is weakened. Therefore, the rigidity of the second radial rib structure 12S itself is further improved by surrounding the second radial rib structure 12S with at least three side walls 12W1 to 12W3. Furthermore, the rigidity of the second radial rib structure 12S is further improved by providing reinforcing ribs 1RR on the outer surfaces of these side walls 12W1 to 12W3. As a result, the support rigidity at the second fixed part 12 can be further improved. By providing such reinforcing ribs 1RR, the side member 1 can effectively resist the lateral force, i.e., horizontal force, input from the suspension member 5, and the suspension performance is improved. Furthermore, in the above embodiment, all ribs, including the reinforcing rib 1RR, are formed as vertical ribs, which is preferable from a manufacturing standpoint.

[0037] (5) Furthermore, in this embodiment, the side member 1 is further provided with a wheelhouse panel 1W joined to the outer surface in the vehicle width direction and a cover 1C joined to its upper surface. At least one of the wheelhouse panel 1W and the cover 1C is made of iron, and the central section SM of the side member 1 has an inner wall 1TWI facing inward in the vehicle width direction and a bottom wall 1TWB facing downward. In plan view, the truss rib structure 1T is formed as a truss structure by a first rib 1TR1 and a plurality of second ribs 1TR2. As shown in Figure 6, a closed section is formed by the wheelhouse panel 1W, the cover 1C, the inner wall 1TWI and the bottom wall 1TWB. Since the central section SM not only has a truss rib structure 1T but also a closed section, the bending rigidity and torsional rigidity of the side member 1 are further improved. As a result, the suspension performance and collision safety performance are further improved.

[0038] Here, by forming at least one of the cover 1C and the wheelhouse panel 1W from iron (including steel), which has higher strength than aluminum, the amount of energy absorbed by crushing during a collision can be increased. Furthermore, by providing an iron cover 1C or wheelhouse panel 1W, the strength of the side member 1 is increased, which allows the crash box 4, the bumper reinforcement member, and the bumper stays connecting them to be reliably deformed during a collision. By reliably deforming the crash box 4, the bumper reinforcement member, and the bumper stays during a collision, the amount of energy absorbed can be increased.

[0039] (6) In this embodiment, a wheelhouse panel 1W is joined to the outer surface of the side member 1 in the vehicle width direction, and the truss rib structure 1T is formed in a truss structure by a first rib 1TR1 and a plurality of second ribs 1TR2 in a plan view, and the central section SM has an outer wall 1TWO facing outward in the vehicle width direction. At least some of the adjacent second ribs 1TR2 of the plurality of second ribs 1TR2 of the truss rib structure 1T are arranged so as not to intersect on this outer wall 1TWO. Furthermore, the wheelhouse panel 1W and the outer wall 1TWO are superimposed and joined to each other by an FDS 6. The FDS 6 is fastened from the wheelhouse panel 1W side toward the side member 1.

[0040] By arranging at least some adjacent second ribs 1TR2 so that they do not intersect on the outer wall 1TWO, interference between the second ribs 1TR2 and the tips of the FDS6 can be avoided, and the FDS6 can be arranged at a narrower pitch. As a result, the joint strength between the side member 1 and the wheelhouse panel 1W can be improved. This point will be explained with reference to Figures 7A and 7B. Figures 7A and 7B show the right side member 1R shown at the top in Figure 3, and the wheelhouse panel 1W is located above Figures 7A and 7B. As described above, in the above embodiment, the second ribs 1TR2 do not intersect on the outer wall 1TWO except for two X-shaped sections in Figure 7A. Therefore, the FDS6 can be fastened as shown by the multiple arrows (downward-pointing arrows) in Figure 7A, and the pitch can also be narrowed.

[0041] When the second rib 1TR2 intersects on the outer wall 1TWO, the pitch of the FDS6 must be widened. In the above embodiment, the second rib 1TR2 intersects on the opposite inner wall 1TWI, so this is used as an example to explain the case where the second rib 1TR2 intersects on the side wall. The position of the FDS6 when assumed to be fastened to the inner wall 1TWI is shown in Figure 7A by multiple arrows (upward arrows). As can be seen from the figure, since the second rib 1TR2 intersects on the inner wall 1TWI, the pitch of the FDS6 must be widened to avoid interference with the second rib 1TR2, and the fastening strength between the side member 1 and the wheelhouse panel 1W cannot be increased. Here, in the inner wall 1TWI of Figure 7A, one FDS6 is fastened per span to avoid interference with the second rib 1TR2. Figure 7B shows the case where two FDS6 are fastened per span in order to narrow the pitch of the FDS6.

[0042] Figure 7B shows only four fastening positions for the FDS6. The fastening positions for the FDS6 are indicated by upward arrows so that the pitch of the FDS6 is nearly uniform. In this case, as shown by the dotted line in Figure 7B, the second rib 1TR2 will be positioned at an angle so that it is more likely to interfere with the FDS6. Therefore, there is a risk that the desired pitch cannot be achieved, and the degree of freedom in placement will be reduced. As explained using the inner wall 1TWI as an example, by positioning the second rib 1TR2 so that it does not intersect on the outer wall 1TWO, it is possible to narrow the pitch of the FDS6 that fix the wheelhouse panel 1W to the side member 1, which has the advantage of improving the joint strength.

[0043] The embodiments described above are merely illustrative examples provided to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the embodiments above, but also includes various modifications, changes, and alternative technologies that can be easily derived therefrom.

[0044] For example, the side member 1 in the above embodiment is a rear side member provided at the rear portion of a vehicle. However, the side member of the present invention is also applicable to a front side member provided at the front portion of a vehicle. Regardless of whether the side member is a rear side member or a front side member, "one side in the extending direction" where the first fixing portion 11 is provided is the vehicle compartment side, and "the other side in the extending direction" where the second fixing portion 12 is provided is the vehicle body end portion side.

[0045] 1 (1L, 1R) Side member 11 First fixing portion 12 Second fixing portion 11R, 12R (radial) rib 11S First radial rib structure 12S Second radial rib structure 12W1 First side wall (outer wall) 12W2 Second side wall (outer wall) 12W3 Third side wall (outer wall) 1T Truss rib structure 1TR1 First rib 1TR2 Second rib 1TWI Inner side wall 1TWO Outer side wall 1TWB Bottom wall 1G Lattice rib structure 1GR1 First lattice rib 1J Joint end 1RR Triangular rib (reinforcing rib) 1C Cover 1W Wheel house panel 2 Structural frame member 5 Suspension member 6 Flow drilling screw (FDS) SM Central section (the portion between the first radial rib structure and the second radial rib structure)

Claims

1. A side member made of cast aluminum, comprising: a first fixing portion provided on one side of the side member in the direction of extension to which a suspension member is fixed; a first radial rib structure formed of a plurality of ribs arranged radially from the first fixing portion; a second fixing portion provided on the other side of the side member in the direction of extension to which the suspension member is fixed; a second radial rib structure formed of a plurality of ribs arranged radially from the second fixing portion; and a truss rib structure formed between the first radial rib structure and the second radial rib structure, wherein the truss rib structure comprises a first rib extending in the direction of extension and a plurality of second ribs diagonally intersecting the first rib.

2. The side member according to claim 1, wherein a grid rib structure is provided between the first radial rib structure and the one end, and the grid rib structure comprises a plurality of first grid ribs extending in the extending direction.

3. The side member according to claim 1 or 2, wherein one end is a joint end that is joined to a structural frame member of the vehicle body, and the height of the side member in the joint section from the first radial rib structure to the joint end is greater than the height of the first radial rib structure and the height of the second radial rib structure.

4. The side member according to any one of claims 1 to 3, wherein the one end is a joint end that is joined to a structural frame member of the vehicle body, and the outer wall constituting the second radial rib structure has reinforcing ribs that extend outward from the outer wall.

5. The side member according to any one of claims 1 to 4, comprising: a wheelhouse panel joined to the outer surface of the side member in the vehicle width direction; and a cover joined to the upper surface of the side member, wherein at least one of the wheelhouse panel and the cover is made of iron; the truss rib structure is formed in a truss structure by the first rib and the plurality of second ribs in a plan view; the portion between the first radial rib structure and the second radial rib structure has an inner wall facing inward in the vehicle width direction and a bottom wall facing downward; and a closed cross section is formed by the wheelhouse panel, the cover, the inner wall and the bottom wall.

6. The side member according to any one of claims 1 to 5, comprising a wheelhouse panel joined to the outer surface of the side member in the vehicle width direction, wherein the truss rib structure is formed in a truss structure by the first rib and the plurality of second ribs in a plan view, the portion between the first radial rib structure and the second radial rib structure has an outer wall facing outward in the vehicle width direction, at least some of the adjacent second ribs of the plurality of second ribs of the truss rib structure are arranged so as not to intersect on the outer wall, and the wheelhouse panel and the outer wall are superimposed and joined to each other by flow drilling screws.

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