Suspension member, suspension member assembly, and vehicle rear structure

Abstract

The rigidity of the suspension member is improved through casting. [Solution] A suspension member 30 is integrally molded by casting and attached to the rear of a vehicle body 200, and includes left and right side beams 31L, 31R, a first cross member 32 connecting the vehicle width direction between the vehicle body mounting portions 36L, 36R of the left and right side beams 31L, 31R, and a second cross member 33 connecting the vehicle width direction between the left and right side beams 31L, 31R on the vehicle front side of the first cross member 32, wherein the first cross member 32 is configured in a groove shape with the rear of the vehicle open, and the second cross member 33 is configured in a groove shape with the underside of the vehicle open.

Description

Technical Field

[0001] The present disclosure relates to a suspension member of a vehicle, a structure of a suspension member assembly, and a structure of a rear part of a vehicle including the suspension member.

Background Art

[0002] Patent Document 1 discloses a hollow suspension member formed in a rectangular frame shape by casting using a core. When the suspension member is formed hollow, the rigidity of a portion where a large load is input from a suspension arm or the like connected to a wheel carrier may be insufficient. Therefore, in the suspension member described in Patent Document 1, a reinforcing member is provided inside.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a rectangular frame-shaped suspension member, a deformation mode in which the entire suspension member is bent may be caused by a load from a coil spring or the like. Therefore, it is necessary to increase the bending rigidity not only of the load input portion but also of the entire suspension member.

[0005] However, in a suspension member having a hollow structure as described in Patent Document 1, it is difficult to increase the overall bending rigidity even if a reinforcing member is provided inside, and there is room for improvement in this regard.

[0006] Therefore, an object of the present disclosure is to improve the rigidity of a suspension member integrally formed by casting.

Means for Solving the Problems

[0007] The suspension member of this disclosure is integrally molded by casting and attached to the rear of a vehicle body, and includes left and right side beams arranged on both sides of the vehicle and extending in the longitudinal direction of the vehicle, a first cross member connecting the vehicle width direction between the vehicle body mounting portions of the left and right side beams, and a second cross member connecting the vehicle width direction between the left and right side beams on the vehicle front side of the first cross member, wherein the first cross member is configured in a groove shape with the rear of the vehicle open, or in a V-shape including a horizontal plate extending to the rear of the vehicle and a vertical plate extending to the underside of the vehicle, and the second cross member is configured in a groove shape with the underside of the vehicle open.

[0008] The second cross member has a groove-shaped design with an open underside, resulting in increased lateral bending rigidity in the vehicle's longitudinal direction. This increases the overall rigidity of the suspension members and suppresses deformation modes that cause the entire suspension member to flex.

[0009] In the suspension member of this disclosure, the left and right side beams include an upper portion and a lower portion, and the lower portion may be curved downwards convexly such that there is a space between it and the upper portion.

[0010] This increases the overall vertical height of the side beam, resulting in greater longitudinal bending rigidity of the side beam and thus increasing the overall rigidity of the suspension member.

[0011] In the suspension member of this disclosure, the upper portion may be configured in a groove-shaped form with an open outer side in the vehicle width direction.

[0012] This allows for increased vertical bending rigidity in the upper portion.

[0013] In the suspension member of this disclosure, the lower portion may be configured in a groove-shaped form with an open underside to the vehicle.

[0014] This allows for increased lateral bending rigidity in the vehicle width direction of the lower portion.

[0015] In the suspension member of this disclosure, the second cross member may have a lower arm mounting portion to which a suspension lower arm is attached.

[0016] This allows the load from the coil spring, which is input via the suspension lower arm, to be received by the second cross member. The second cross member has a groove-shaped design with an open underside to the vehicle, resulting in increased lateral bending rigidity in the vehicle's longitudinal direction. This suppresses deformation modes that cause the entire suspension member to flex.

[0017] The suspension member assembly of this disclosure may include the suspension member described above and an assembly member connecting the first cross member and the second cross member.

[0018] The connecting member allows the first cross member and the second cross member to be integrated, thereby improving the rigidity of the suspension member assembly.

[0019] In the suspension member assembly of this disclosure, the assembly member may connect the front and vehicle-width ends of the first cross member and the rear and vehicle-width ends of the second cross member.

[0020] In this way, the torsional rigidity of the suspension member assembly can be increased because the ends of the first and second cross members are connected by the assembly members.

[0021] In the suspension member assembly of this disclosure, the assembly member may be a plate-shaped member, or a plurality of brace members that intersect and connect both ends of the first and second cross members in the vehicle width direction.

[0022] As a result, the torsional rigidity of the suspension member assembly can be easily improved in configuration.

[0023] In the suspension member assembly of the present disclosure, the assembly member may be an in-vehicle component.

[0024] The torsional rigidity of the suspension member assembly can be improved by the in-vehicle component, and the number of components can be reduced.

[0025] In the suspension member assembly of the present disclosure, the in-vehicle component may be a dynamic rear steering.

[0026] The torsional rigidity of the suspension member assembly can be improved by the in-vehicle component, and the number of components can be reduced.

[0027] In the suspension member assembly of the present disclosure, it has an assembly member that connects the first cross member and the second cross member. The second cross member extends from each lower surface of the left and right side beams and has a downwardly convex U-shaped configuration. The assembly member may connect one and the other end portions on the vehicle front side of the first cross member and the other and one end portions on the vehicle rear side of the second cross member.

[0028] As a result, the torsional rigidity of the suspension member assembly can be increased by integrating the first cross member and the second cross member in the vertical direction.

[0029] The vehicle rear structure of the present disclosure is a vehicle rear structure including the suspension member described above, a rear unit including left and right rear side member portions arranged at the vehicle rear and extending in the front-rear direction, and left and right crash boxes attached to the rear ends of the left and right rear side member portions and extending toward the vehicle rear, wherein each vehicle rear end portion of the left and right side beams is located on the vehicle rear side of the vehicle front side end portion of the crash box.

[0030] In the event of a rear-end collision, the rear end of the side beam absorbs the impact force together with the crash box, thereby improving the impact load absorption performance.

[0031] In the vehicle rear structure of this disclosure, stabilizer support portions may be provided on the lower surface of each rear end of the left and right side beams.

[0032] In this way, the stabilizer support and the rear end of the side beam are shared, which reduces the number of parts. [Effects of the Invention]

[0033] This disclosure can improve the rigidity of a suspension member integrally formed by casting. [Brief explanation of the drawing]

[0034] [Figure 1] This is a bottom view of the rear of the vehicle to which the suspension member of the embodiment is attached. [Figure 2] This is a perspective view of the suspension member of the embodiment, seen from the upper rear at an oblique angle. [Figure 3] This is a perspective view of the suspension member of the embodiment, seen from below and diagonally rear. [Figure 4] Figure 2 is a schematic cross-sectional view of the suspension member, specifically section AA shown in Figure 2. [Figure 5] Figure 2 is a schematic cross-sectional view of the suspension member assembly, specifically the BB cross-section shown in Figure 2. [Figure 6] This is a schematic elevation view of the suspension member assembly of the embodiment as seen from the rear of the vehicle. [Figure 7] This is an explanatory diagram showing the bending moment applied to the side beam and second cross member when a load is applied from the coil spring in the longitudinal direction of the vehicle. [Figure 8] This is a diagram illustrating the mold used to form the lower portion of the side beam by casting, and the direction of removal from the mold. [Figure 9]This diagram shows a mold for casting the lower portion of the side beam and an explanatory diagram indicating the direction of removal from the mold. The upper diagram is the CC cross section shown in Figure 8, and the lower diagram is the DD cross section shown in Figure 8. [Figure 10] This is a diagram illustrating the mold for forming the front cross member by casting, and the direction of mold removal. [Figure 11] This is a schematic cross-sectional view of a suspension member assembly of another embodiment. [Modes for carrying out the invention]

[0035] The suspension member 30 of the embodiment will be described below. First, the vehicle 100 to which the suspension member 30 is attached will be described. In each figure, FR, UP, and RH indicate the front, upper, and right sides of the vehicle 100 to which the suspension member 30 is attached, respectively. The opposite directions of FR, UP, and RH indicate the rear, lower, and left sides. Hereafter, when simply using the directions front / back, left / right, and up / down, unless otherwise specified, these refer to the front / back, left / right, and up / down of the vehicle 100. Furthermore, the front / back, left / right, and up / down of the vehicle 100 refer to the front / back, left / right, and up / down of the suspension member 30.

[0036] As shown in Figure 1, the vehicle 100 includes a vehicle body 200 and a suspension member 30 attached to the rear of the vehicle body 200.

[0037] As shown in Figure 1, the vehicle body 200 includes a rear unit 10, a center unit 17, and a front unit (not shown). The rear unit 10 constitutes the rear of the vehicle body 200. The center unit 17 constitutes the central part of the vehicle body 200. The front unit (not shown) constitutes the front of the vehicle body 200. The rear unit 10, the center unit 17, and the front unit are all die-cast products manufactured by integral casting. The front drive unit of the vehicle 100 is mounted on the front unit.

[0038] The rear unit 10 includes left and right rear side member sections 11L and 11R, left and right rear wheelhouse sections 12L and 12R, and a rear floor section 13.

[0039] The left and right rear side member sections 11L and 11R are skeletal parts located on the left and right sides of the rear unit 10 and extending in the longitudinal direction of the vehicle. The rear side member sections 11L and 11R may, for example, be configured in a groove-shaped form with the outer side in the vehicle width direction open, and may have a structure in which multiple reinforcing ribs are arranged. Coil spring seats 15L and 15R that hold the upper ends of the coil springs 22L and 22R are arranged on the left and right rear side member sections 11L and 11R. The left and right crash boxes 14L and 14R are attached to the rear ends of the left and right rear side member sections 11L and 11R. The rear bumper reinforcement 16 is attached to the rear ends of the left and right crash boxes 14L and 14R. The rear bumper reinforcement 16 is a skeletal member that connects the rear ends of the left and right crash boxes 14L and 14R in the vehicle width direction.

[0040] The left and right rear wheel well sections 12L and 12R are semicircular, arc-shaped plate-like portions that connect to the outer edges of the left and right rear side member sections 11L and 11R in the vehicle width direction. The left and right rear wheel well sections 12L and 12R house the rear wheels inside.

[0041] The rear floor section 13 is a plate-shaped member that connects the left and right rear side member sections 11L and 11R.

[0042] The center unit 17 is connected to the front of the rear unit 10 by bolts or welding. A cabin (not shown) is mounted above the center unit 17. A battery pack 18 is mounted on the center unit 17. As shown in Figure 1, the center of the battery pack 18 in the vehicle width direction protrudes rearward toward the suspension member 30. This protruding portion may house auxiliary components of the battery pack 18, such as a junction box and an ECU.

[0043] The suspension member 30 is integrally formed by casting and mounted under the rear unit 10 of the vehicle body 200. The suspension member 30 is a rectangular frame-shaped member that includes left and right side beams 31L and 31R, a rear first cross member 32, a second cross member 33, and a front cross member 34.

[0044] The left and right side beams 31L and 31R are positioned on both the left and right sides of the vehicle 100 and extend in the longitudinal direction of the vehicle. At the front ends of the left and right side beams 31L and 31R, there are left and right front body mounting parts 35L and 35R which are attached to the underside of the left and right rear side member parts 11L and 11R by mounting members. At the rear ends of the left and right side beams 31L and 31R, there are rear body mounting parts 36L and 36R which are attached to the underside of the rear unit 10 by mounting members. The left and right rear ends 37L and 37R of the left and right side beams 31L and 31R extend towards the rear of the vehicle from the rear body mounting parts 36L and 36R. The left and right rear ends 37L and 37R are located further rearward than the front ends of the left and right crash boxes 14L and 14R. On the underside of the left and right rear ends 37L and 37R of the vehicle, there are left and right stabilizer support parts 38L and 38R that support the stabilizer 26.

[0045] The front cross member 34 is the part that connects the left and right front body mounting parts 35L and 35R in the vehicle width direction. The rear first cross member 32 is the part that connects the left and right rear body mounting parts 36L and 36R in the vehicle width direction. The second cross member 33 is located in front of the first cross member 32 and is the part that connects the left and right side beams 31L and 31R in the vehicle width direction. As will be explained later, the second cross member 33 extends from the lower surface of the left and right side beams 31L and 31R and is a U-shaped part that protrudes downwards. The left and right ends of the second cross member 33 are provided with left and right lower arm mounting parts 39L and 39R to which the suspension lower arms 21L and 21R are attached.

[0046] A rear-wheel drive unit 19 is mounted between the front cross member 34 and the second cross member 33 of the suspension member 30. A dynamic rear steering system 25 is mounted between the second cross member 33 and the first cross member 32. The dynamic rear steering system 25 is a device that steers the rear wheels, and for example, at low and medium speeds, it steers the rear wheels in the opposite direction to the front wheels, and at high speeds, it steers the rear wheels in the same direction as the front wheels.

[0047] Here, the suspension member 30 and the dynamic rear steering 25 constitute the suspension member assembly 70. Furthermore, the suspension member 30, the rear unit 10 including the left and right rear side member sections 11L and 11R, and the left and right crash boxes 14L and 14R constitute the vehicle rear structure 80.

[0048] Multiple arms of the left and right suspension devices 20L and 20R, which suspend the left and right rear wheels, are connected to the suspension member 30. The suspension devices 20L and 20R consist of multiple arms that connect the left and right rear wheel knuckles to the suspension member 30, coil springs 22L and 22R, and left and right shock absorbers (not shown). Of these, the vehicle body ends of the left and right suspension lower arms 21L and 21R are connected to the left and right lower arm mounting portions 39L and 39R of the second cross member 33. The left and right coil springs 22L and 22R are attached to the upper parts of the left and right suspension lower arms 21L and 21R. The upper ends of the left and right coil springs 22L and 22R are held by the coil spring seats 15L and 15R of the left and right rear side member portions 11L and 11R. The arms other than the left and right suspension lower arms 21L and 21R are not shown or described.

[0049] Next, we will describe the details of the structure of the suspension member 30 with reference to Figures 2 to 5.

[0050] As explained earlier with reference to Figure 1, the suspension member 30 is a rectangular frame-shaped member that includes the left and right side beams 31L and 31R, the rear first cross member 32, the second cross member 33, and the front cross member 34.

[0051] As shown in Figures 2 and 3, the left side beam 31L includes an upper portion 41L and a lower portion 51L. The lower portion 51L is curved downwards, creating a space 50L between it and the upper portion 41L.

[0052] The upper section 41L includes the front section 42L, the central section 43L, the rear section 44L, and the rear end section 37L of the vehicle. The front section 42L is the part that extends diagonally upward and rearward from the left front body mounting section 35L. The central section 43L connects to the rear end of the front section 42L and is the part that curves upward in a convex shape and extends horizontally toward the rear of the vehicle. The rear section 44L connects to the rear end of the central section 43L and extends horizontally toward the rear of the vehicle to the rear body mounting section 36L. The left rear end section 37L is the part that extends horizontally toward the rear of the vehicle from the left rear body mounting section 36L, as described above.

[0053] As shown in Figure 4, the central section 43L is composed of a web 43A, an upper flange 43B, and a lower flange 43C, and has a groove-shaped form with the outer side in the vehicle width direction (to the left of the vehicle) open. Similarly, the front section 42L and the rear section 44L also have a groove-shaped form with the outer side in the vehicle width direction (to the left of the vehicle) open. In addition, the front section 42L and the rear section 44L are provided with plate-shaped rib plates 47 that extend in the vehicle width direction (to the left of the vehicle).

[0054] The front section 42L and the upper part of the central section 43L are provided with arm connection sections 45L and 46L to which the arm of the left suspension device 20L is connected. In addition, the rear of the central section 43L is provided with a mount attachment section 58L to which the mount of the drive device 19 is attached.

[0055] The lower left portion 51L includes a front end 52L, a rear end 54L, and a curved portion 53L. The front end 52L is the portion that connects to the lower side of the front portion 42L of the upper portion 41L. The rear end 54L is the portion that connects to the lower side of the rear portion 44L of the upper portion 41L. The curved portion 53L is the portion that curves downwards convexly between the front end 52L and the rear end 54L. A cylindrical space 50L is open between the upper surface of the curved portion 53L and the lower surface of the central portion 43L of the upper portion 41L. As shown in Figure 4, the space 50L is the space through which the drive shaft 19A passes in the vehicle width direction.

[0056] As shown in Figures 3 and 4, the curved portion 53L of the lower part 51L is composed of a web 53A, an inner flange 53B, and an outer flange 53C, and has a groove-shaped form that is open on the underside of the vehicle. Similarly, the front end portion 52L and the rear end portion 54L also have a groove-shaped form that is open on the underside of the vehicle. The front end portion 52L, the curved portion 53L, and the rear end portion 54L are provided with a plurality of plate-shaped rib plates 55 that extend in the vertical direction of the vehicle.

[0057] The right side beam 31R is symmetrical to the left side beam 31L and includes an upper portion 41R and a lower portion 51R. The upper portion 41R includes a front portion 42R, a central portion 43R, a rear portion 44R, and a vehicle rear end portion 37R, and is provided with arm connection portions 45R, 46R, and a mount attachment portion 58R. The lower portion 51R includes a front end portion 52R, a rear end portion 54R, and a curved portion 53R.

[0058] As shown in Figures 3 and 5, the front cross member 34 has a T-shaped cross section comprising a flat plate 34A and transverse ribs 34B.

[0059] As shown in Figures 3 and 5, the first cross member 32 is composed of a web 32A, an upper flange 32B, and a lower flange 32C, and has a groove-shaped form with the rear of the vehicle open. The first cross member 32 is also provided with a rib plate 32D extending from the web 32A toward the rear of the vehicle. Furthermore, a mounting seat 32E for the device to which the upper part of the dynamic rear steering 25 is attached is provided on the front surface of the web 32A of the first cross member 32.

[0060] The second cross member 33 extends downward from the lower surfaces of the rear ends 54L and 54R of the left and right lower portions 51L and 51R, and is a skeletal part that connects the left and right side beams 31L and 31R in the vehicle width direction. The second cross member 33 is composed of a left end 33L, a right end 33R, and a horizontal portion 33H. The left end 33L and the right end 33R are portions that extend downward from the lower surfaces of the rear ends 54L and 54R. The horizontal portion 33H is the portion that connects the left end 33L and the right end 33R in the vehicle width direction. The left end 33L, the right end 33R, and the horizontal portion 33H have a downward-convex U-shape.

[0061] The horizontal section 33H is composed of a web 33A, a front flange 33B, and a rear flange 33C, and has a groove-shaped form with the underside of the vehicle open. The horizontal section 33H is also provided with a rib plate 33D extending from the web 33A toward the underside of the vehicle. The left and right ends of the horizontal section 33H are provided with left and right lower arm mounting sections 39L and 39R. The left and right lower arm mounting sections 39L and 39R are through holes that penetrate in the longitudinal direction of the vehicle. Furthermore, the rear surfaces of the left and right ends of the rear flange 33C of the second cross member 33 are provided with mounting seats 33E to which the lower part of the dynamic rear steering 25 is attached.

[0062] As shown in Figures 5 and 6, the dynamic rear steering 25 is an assembly component of the suspension member assembly 70 and is attached to the device mounting seats 32E and 33E, connecting the first cross member 32 and the second cross member 33. As shown in Figures 5 and 6, the dynamic rear steering 25 comprises left and right upper brackets 25A and left and right lower brackets 25B. The left and right upper brackets 25A are bolted to the left and right device mounting seats 32E of the first cross member 32. The left and right lower brackets 25B are bolted to the device mounting seats 33E of the second cross member 33. In this way, the dynamic rear steering 25 connects the vehicle front surface of the first cross member 32 and the vehicle rear surface of the second cross member 33 in the vertical direction. Furthermore, the dynamic rear steering 25 connects the left end of the first cross member 32 to the right end of the horizontal portion 33H of the second cross member 33, and also connects the right end of the first cross member 32 to the left end of the horizontal portion 33H of the second cross member 33. In this way, the dynamic rear steering 25 connects both ends of the first cross member 32 on the vehicle front side and in the vehicle width direction to both ends of the second cross member 33 on the vehicle rear side and in the vehicle width direction.

[0063] Next, referring to Figure 7, we will explain the deformation of each part of the suspension member 30 when loads from the left and right coil springs 22L and 22R are applied to the suspension member 30.

[0064] As shown by arrow 91 in Figure 7, the forward load from the left and right coil springs 22L and 22R is transmitted to the second cross member 33 via the suspension lower arms 21L and 21R and the left and right lower arm mounting parts 39L and 39R. The load is then transmitted from the left end 33L and the right end 33R of the second cross member 33 to the left and right side beams 31L and 31R. Due to this forward load, the portions of the left and right side beams 31L and 31R in front of the second cross member 33 are subjected to bending moments as shown by arrows 92 and 93 in Figure 9. Due to this bending moment, the portions of the left and right side beams 31L and 31R in front of the second cross member 33 are curved inward in the vehicle width direction. Furthermore, when the left and right side beams 31L and 31R are curved, a bending moment is applied to the second cross member 33 as shown by arrow 94 in Figure 9. This bending moment causes the second cross member 33 to curve such that the central portion in the vehicle width direction is convex toward the rear of the vehicle.

[0065] Here, the bending moment applied to the left side beam 31L is the moment M1 around the Z1 axis shown in Figure 4. The curved section 53L has a groove-like shape with an open bottom, and its bending stiffness around the Z1 axis is greater than its bending stiffness around the X1 axis. Here, the Z1 axis is a vertical coordinate axis passing through the center of the cross-section of the curved section 53L, and the X1 axis is a coordinate axis in the vehicle width direction passing through the center of the cross-section of the curved section 53L. Therefore, the moment applied to the left side beams 31L and 31R by the coil spring 22L is absorbed by the bending stiffness of the curved section 53L around the Z1 axis. As a result, the curvature deformation of the left side beam 31L due to the load input from the coil spring 22L is suppressed.

[0066] Furthermore, the bending moment applied to the second cross member 33 is the moment M2 around the Z2 axis shown in Figure 5. Similar to the curved section 53L, the second cross member 33 has a groove-shaped form with an open bottom, and its bending stiffness around the Z2 axis is greater than its bending stiffness around the Y2 axis. Here, the Z2 axis is a vertical coordinate axis passing through the center of the cross-section of the second cross member 33, and the Y2 axis is a longitudinal coordinate axis passing through the center of the cross-section of the second cross member 33. Therefore, the bending moment applied to the second cross member 33 by the coil spring 22L is absorbed by the bending stiffness of the second cross member 33 around the Z2 axis. As a result, the bending deformation of the second cross member 33 due to the load input from the coil spring 22L is suppressed.

[0067] On the other hand, the suspension member 30 receives vertical loads from the left and right suspension devices 20L and 20R. The left and right side beams 31L and 31R are composed of upper portions 41L and 41R, and left and right lower portions 51L and 51R which are positioned with a gap 50L and 50R between them and the upper portions 41L and 41R. As a result, the overall vertical height of the left and right side beams 31L and 31R is increased, improving the longitudinal bending rigidity of the left and right side beams 31L and 31R, and increasing the overall rigidity of the suspension member 30. Also, as shown in Figure 4, the upper portions 41L and 41R have a groove-shaped form with the outer side in the vehicle width direction open. As a result, the bending rigidity of the upper portions 41L and 41R around the X axis is greater than the bending rigidity around the Z axis. Here, the X axis is a coordinate axis in the vehicle width direction passing through the center of the cross-section of the upper portion 41L, and the Z axis is a coordinate axis in the vertical direction passing through the center of the cross-section of the upper portion 41L. The bending moment applied to the side beams 31L and 31R by the vertical loads from the left and right suspension devices 20L and 20R is the moment M3 around the X-axis shown in Figure 4. Therefore, the bending moment applied to the side beams 31L and 31R is absorbed by the bending rigidity of the upper portions 41L and 41R around the X-axis. In this way, the left and right side beams 31L and 31R have high rigidity against longitudinal bending.

[0068] Furthermore, as shown in Figure 5, the first cross member 32 has a groove-shaped form with the rear of the vehicle open. As a result, the bending rigidity of the first cross member 32 around the Y axis is greater than the bending rigidity around the Z3 axis, and the first cross member 32 has high rigidity against longitudinal bending. This allows the first cross member 32 to withstand a moment M4 around the Y axis. Here, the Y axis is a coordinate axis in the longitudinal direction of the vehicle that passes through the center of the cross section of the first cross member 32, and the Z3 axis is a coordinate axis in the vertical direction that passes through the center of the cross section of the upper portion 41L.

[0069] As explained above, the suspension member 30 has a groove-shaped form with an open underside to the vehicle and is equipped with a second cross member 33 that has high lateral bending rigidity in the longitudinal direction of the vehicle. Therefore, the overall rigidity of the suspension member 30 can be increased, and deformation modes that cause the entire suspension member 30 to flex can be suppressed.

[0070] Furthermore, since the suspension member 30 is integrally molded with left and right lower portions 51L and 51R which have high lateral bending rigidity in the vehicle width direction, and a second cross member 33 which has high lateral bending rigidity in the vehicle longitudinal direction, the overall lateral bending deformation of the suspension member 30 can be suppressed.

[0071] Furthermore, the suspension member 30 is integrally molded with left and right side beams 31L and 31R, which have a high vertical height and high longitudinal bending rigidity, and a first cross member 32 which has a groove-shaped structure with an open rear end and high longitudinal bending rigidity, thereby suppressing the overall longitudinal bending deformation of the suspension member 30.

[0072] Furthermore, the suspension member 30 has a groove-shaped configuration in which the upper portions 41L and 41R of the left and right side beams 31L and 31R are open on the outside in the vehicle width direction, and the first cross member 32 has a groove-shaped configuration that is open on the rear of the vehicle. In addition, the lower portions 51L and 51R of the left and right side beams 31L and 31R and the second cross member 33 have a groove-shaped configuration that is open on the underside of the vehicle. Therefore, by setting the molding direction to the outside in the vehicle width direction, the rear of the vehicle, and the underside of the vehicle, the suspension member 30 can be constructed by integral casting.

[0073] The following describes in detail the mold and demolding direction when integrally forming the suspension member 30 by casting. First, with reference to Figures 8 and 9, the mold 60 for forming the lower portion 51L of the left side beam 31L by casting and the demolding direction will be described. As shown in Figures 8 and 9, the mold 60 consists of a lower mold 61 and an upper mold 66. The lower mold 61 includes a recess 62 for forming the web 53A of the lower portion 51L, longitudinal grooves 63B and 63C for forming the inner flange 53B and outer flange 53C, and a groove set 65 for forming the rib plate 55. As shown in Figure 9, the recess 62 and the longitudinal grooves 63B and 63C extend along the longitudinal direction of the lower portion 51L. The groove set 65 consists of a plurality of transverse grooves 65A that extend in the width direction of the lower portion 51L so as to connect the longitudinal grooves 63B and 63C.

[0074] The upper mold 66 is assembled above the lower mold 61. When the upper mold 66 is assembled to the lower mold 61, the recess 62, the longitudinal grooves 63B and 63C, and the transverse groove 65A form a cavity into which molten metal flows to form the web 53A, the inner flange 53B, the outer flange 53C, and the rib plate 55.

[0075] As shown in Figures 7 and 8, once casting is complete, the lower mold 61 and the upper mold 66 are opened to remove the lower portion 51L, which has become the cast product. The lower portion 51L is constructed in a groove shape with the underside of the vehicle open, and the rib plate 55 is positioned to extend downwards towards the vehicle. Therefore, as indicated by the white arrow P51 in Figures 4, 8, and 9, the lower mold 61 can be cut downwards along the height direction of the inner flange 53B, outer flange 53C, and rib plate 55. In this way, the lower portion 51L is integrally formed by casting.

[0076] Similarly, the upper portion 41L of the left side beam 31L has a groove-shaped form that is open on the outside in the vehicle width direction (to the left of the vehicle), and the rib plate 47 is positioned to extend in the vehicle width direction. For this reason, the mold (not shown) that forms the upper portion 41L can be cut out in the outward direction in the vehicle width direction (to the left of the vehicle), which is the height direction of the upper flange 43B, lower flange 43C, and rib plate 57, as shown by the white arrow P41 in Figure 4. As a result, the upper portion 41L is integrally formed by casting.

[0077] Similarly, the first cross member 32 is composed of a web 32A, an upper flange 32B, and a lower flange 32C, and has a groove-shaped form with the rear of the vehicle open, and the rib plate 32D is positioned to extend towards the rear of the vehicle. For this reason, the mold (not shown) for forming the first cross member 32 can be demolded towards the rear of the vehicle, as indicated by the white arrow P32 in Figure 5. As a result, the first cross member 32 is integrally formed by casting.

[0078] Furthermore, the second cross member 33 is composed of a web 33A, a front flange 33B, and a rear flange 33C, and has a groove-shaped form with the underside of the vehicle open, and the rib plate 33D is positioned to extend downwards towards the vehicle. Therefore, the mold (not shown) for forming the second cross member 33 can be demolded downwards, as indicated by the white arrow P33 in Figure 5. As a result, the second cross member 33 is integrally formed by casting.

[0079] Furthermore, the front cross member 34 is cast using a mold 60A that includes a lower mold 67 having a recess 69A for forming the transverse rib 34B as shown in Figure 10 and a longitudinal groove 69B for forming the lower part of the flat plate 34A, and an upper mold 68 having a longitudinal groove 69C for forming the upper part of the flat plate 34A. In this case as well, the lower mold 67 can be demolded downward along the height direction of the flat plate 34A, as shown by the white arrow P34 in Figures 5 and 10. As a result, the front cross member 34 is integrally formed by casting.

[0080] As explained above, by setting the demolding directions of the molds 60 and 60A to the outward side in the vehicle width direction, the rear of the vehicle, and the downward direction of the vehicle, the left and right side beams 31L and 31R, the first cross member 32, the second cross member 33, and the front cross member 34 can be constructed by integral casting.

[0081] Furthermore, since the suspension member assembly 70 described above integrally connects the first cross member 32 and the second cross member 33 by the dynamic rear steering 25, the overall rigidity of the suspension member assembly 70 can be improved. In addition, this can increase the torsional rigidity of the suspension member 30 and suppress the overall deformation of the suspension member 30.

[0082] In the above explanation, the assembly members of the suspension member assembly 70 were described as the dynamic rear steering 25, but they are not limited to this. They may be composed of other on-board parts, not just the dynamic rear steering 25. Furthermore, the assembly members may be made of plate-shaped members. This makes it possible to increase the rigidity of the suspension member assembly 70 while reducing the number of parts.

[0083] Furthermore, the assembly member may consist of multiple brace members that intersect and connect both ends of the first and second cross members 32 and 33 in the vehicle width direction. Specifically, the assembly member may consist of a first brace member connecting the left end of the first cross member 32 to the right end of the horizontal portion 33H of the second cross member 33, and a second brace member connecting the right end of the first cross member 32 to the left end of the horizontal portion 33H of the second cross member 33.

[0084] Furthermore, in the vehicle rear structure 80, the left and right rear ends 37L and 37R of the left and right side beams 31L and 31R are located further rearward than the front ends of the left and right crash boxes 14L and 14R. As a result, in the event of a rear-end collision, the left and right rear ends 37L and 37R absorb the impact force together with the left and right crash boxes 14L and 14R, thereby improving the impact load absorption performance.

[0085] Furthermore, in the vehicle rear structure 80, left and right stabilizer support parts 38L and 38R are provided on the lower surfaces of the left and right rear ends 37L and 37R of the vehicle, so there is no need to provide any other members to support the stabilizer 26, and the number of parts can be reduced.

[0086] Next, a suspension member assembly 170 of another embodiment will be described with reference to Figure 11. The suspension member assembly 170 includes a suspension member 130 and a dynamic rear steering 25. The suspension member assembly 170 is mounted on a vehicle 110. In the following description, the same reference numerals are used for parts identical to those of the suspension member assembly 70 and suspension member 30 described with reference to Figures 1 to 9, and their descriptions are omitted.

[0087] As shown in Figure 11, the suspension member 130 is constructed by modifying the first cross member 32 of the suspension member 30 described with reference to Figures 1 to 9, with a V-shaped cross section including a horizontal plate 32F extending to the rear of the vehicle and a vertical plate 32G extending to the underside of the vehicle. The vertical plate 32G is provided with a triangular rib plate 32H extending from the vertical plate 32G toward the rear of the vehicle.

[0088] Thus, the first cross member 132 is composed of a V-shaped structure including a horizontal plate 32F and a vertical plate 32G, and the rib plate 32H is arranged to extend toward the rear of the vehicle. For this reason, the mold (not shown) for forming the first cross member 132 is integrally formed by casting by cutting out the mold toward the rear of the vehicle, as indicated by the white arrow P132 in Figure 11.

[0089] Therefore, the suspension member 130, like the suspension member 30, can be constructed by integral casting by setting the mold-cutting direction to the outward side in the vehicle width direction, the rear of the vehicle, and the underside of the vehicle.

[0090] Furthermore, the suspension member 130, like the suspension member 30, has a groove-shaped design with an open underside and is equipped with a second cross member 33 that has high lateral bending rigidity in the longitudinal direction of the vehicle. This allows for increased overall rigidity of the suspension member 130 and suppresses deformation modes that cause the entire suspension member 130 to flex.

[0091] [Note] The suspension member 30 of this disclosure may be configured as follows: [1] A suspension member 30 which is integrally formed by casting and attached to the rear of the vehicle body 200, The left and right side beams 31L and 31R are positioned on both sides of the vehicle and extend in the front-to-rear direction, It includes a plurality of cross members 32, 33, 34 that connect the left and right side beams 31L, 31R in the vehicle width direction, The aforementioned left and right side beams 31L and 31R include upper portions 41L and 41R and lower portions 51L and 51R. The lower portions 51L and 51R are curved downwards in a convex shape such that there is a space 50L and 50R between them and the upper portions 41L and 41R. A suspension member 30 characterized by the following. [2] The suspension member 30 described in [1], The aforementioned upper portion is configured with a groove-shaped form that is open on the outer side in the vehicle width direction. A suspension member 30 characterized by the following. [3] [2] The suspension member 30 described above, The aforementioned lower portions 51L and 51R are configured in a groove-shaped form with the underside of the vehicle open. A suspension member 30 characterized by the following.

[0092] Furthermore, in the suspension member 30 described above, the multiple cross members 32, 33, and 34 may be configured in a groove shape, a V-shape shape, or a T-shape.

[0093] Furthermore, the vehicle rear structure 80 of this disclosure may be configured as follows. [4] A rear unit 10 including left and right rear side member sections 11L and 11R that are located on both sides of the rear of the vehicle and extend in the front-rear direction, The left and right crash boxes 14L and 14R are attached to the rear ends of the aforementioned left and right rear side member sections 11L and 11R and extend toward the rear of the vehicle, A vehicle rear structure 80 comprising a suspension member 30 attached to the lower side of the rear unit 10, The suspension member 30 is The left and right side beams 31L and 31R are positioned on both sides of the vehicle and extend in the front-to-rear direction, It includes a plurality of cross members 32, 33, 34 that connect the left and right side beams 31L, 31R in the vehicle width direction, The aforementioned left and right side beams 31L and 31R include upper portions 41L and 41R and lower portions 51L and 51R. The lower portion is curved downwards in a convex shape so that there is a space between it and the upper portion. The upper portions 41L and 41R are configured in a groove-shaped form with the outer side in the vehicle width direction open. The aforementioned lower portions 51L and 51R are configured in a groove-shaped form with the underside of the vehicle open. The rear ends 37L and 37R of the left and right side beams 31L and 31R are located further rearward than the front ends of the crash boxes 14L and 14R. A vehicle rear structure 80 characterized by the following.

[0094] Furthermore, in the above-described rear vehicle structure 80, the multiple cross members 32, 33, and 34 may be configured in a groove shape, a V-shape, or a T-shape. [Explanation of symbols]

[0095] 10 Rear unit, 11L, 11R Rear side member section, 12L, 12R Rear wheelhouse section, 13 Rear floor section, 14L, 14R Crash box, 15L, 15R Coil spring seat, 16 Rear bumper reinforcement, 17 Center unit, 18 Battery pack, 19 Drive unit, 19A Drive shaft, 20L, 20R Suspension system, 21L, 21R Suspension lower arm, 22L, 22R Coil spring, 25 Dynamic rear steering, 26 Stabilizer, 30, 130 Suspension member, 31L, 31R Side beam, 32, 132 First cross member, 32A, 33A, 43A, 53A Web, 32B, 43B Upper flange, 32C, 43C Lower flange, 32D, 33D, 47, 55 Rib plate, 32E, 33E Mounting base, 32F; Horizontal plate, 32G; Vertical plate, 33; Second cross member, 33B; Front flange, 33C; Rear flange, 33H; Horizontal section, 33L; Left end, 33R; Right end, 34; Front cross member, 34A; Flat plate, 34B; Transverse rib, 35L, 35R; Front body mounting section, 36L, 36R; Rear body mounting section, 37L, 37R; Rear end of vehicle, 38L, 38R; Stabilizer support section, 39L, 39R; Lower arm mounting section, 41L, 41R; Upper section, 42L, 42R; Front section, 43L, 43R; Center section, 44L, 44R; Rear section, 45L, 45R, 46L, 46R; Arm connection section, 50L, 50R; Space, 51L, 51R; Lower section, 52L, 52R Front end, 53B Inner flange, 53C Outer flange, 53L, 53R Curved section, 54L, 54R Rear end, 58L, 58R Mount attachment section, 60, 60A Mold, 61, 67 Lower mold, 62, 69A Recess, 63B, 63C, 69B, 69C Longitudinal groove, 65 Groove set, 65A Lateral groove, 66, 68 Upper mold, 70, 170 Suspension member assembly, 80 Rear vehicle structure, 100, 110 Vehicle, 200 Body.

Claims

1. A suspension member that is integrally molded by casting and attached to the rear of the vehicle body, The left and right side beams are positioned on both sides of the vehicle and extend in the front-to-rear direction, A first cross member connects the vehicle body mounting points of the left and right side beams in the vehicle width direction, The first cross member includes a second cross member that connects the left and right side beams in the vehicle width direction at the front of the vehicle, The first cross member is configured in a groove shape with the rear of the vehicle open, or in a V-shape including a horizontal plate extending to the rear of the vehicle and a vertical plate extending to the underside of the vehicle. The second cross member is configured in a groove-shaped form with the underside of the vehicle open. A suspension member characterized by the following.

2. A suspension member according to claim 1, The aforementioned left and right side beams include an upper portion and a lower portion. The lower portion is curved downwards in a convex shape so that there is a space between it and the upper portion. A suspension member characterized by the following.

3. A suspension member according to claim 2, The aforementioned upper portion is configured with a groove-shaped form that is open on the outer side in the vehicle width direction. A suspension member characterized by the following.

4. A suspension member according to claim 2, The aforementioned lower portion is configured in a groove-shaped form with the underside of the vehicle open. A suspension member characterized by the following.

5. A suspension member according to any one of claims 1 to 4, The second cross member has a lower arm mounting portion to which the suspension lower arm is attached. A suspension member characterized by the following.

6. A suspension member according to any one of claims 1 to 4, It has an assembly member that connects the first cross member and the second cross member, A suspension member assembly characterized by the following.

7. A suspension member assembly according to claim 6, The assembly member connects the front and vehicle-width ends of the first cross member to the rear and vehicle-width ends of the second cross member. A suspension member assembly characterized by the following.

8. A suspension member assembly according to claim 6, The assembly member is a plate-shaped member, or a plurality of brace members that intersect and connect both ends of the first and second cross members in the vehicle width direction. A suspension member assembly characterized by the following.

9. A suspension member assembly according to claim 6, The aforementioned assembly member is an in-vehicle component. A suspension member assembly characterized by the following.

10. A suspension member assembly according to claim 9, The aforementioned in-vehicle component is a dynamic rear steering system. A suspension member assembly characterized by the following.

11. A suspension member according to any one of claims 1 to 4, It has an assembly member that connects the first cross member and the second cross member, The second cross member extends from the lower surfaces of the left and right side beams and has a U-shaped form that is convex downwards. The assembly member connects one and the other end of the front surface of the first cross member to the other and the one end of the rear surface of the second cross member. A suspension member assembly characterized by the following.

12. A suspension member according to any one of claims 1 to 4, A rear unit including left and right rear side member sections that are located at the rear of the vehicle and extend in the front-to-rear direction, A rear vehicle structure comprising left and right crash boxes attached to the rear ends of the left and right rear side member portions and extending toward the rear of the vehicle, The rear ends of the left and right side beams are located further rearward than the front end of the crash box. A rear vehicle structure characterized by the following.

13. The vehicle rear structure according to claim 12, Stabilizer support portions are provided on the lower surface of the rear end of each of the left and right side beams of the vehicle. A rear vehicle structure characterized by the following.

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