JP2018203137A - Trailing arm - Google Patents

Abstract

To reduce a wall thickness of a hub attachment face while securing required rigidity even if thinning a plate thickness of the hub attachment face by enhancing durability and stiffness performance with respect to inputs in a variety of directions from tires, and to secure light weight and favorable internal quality even if trailing arms are molded by a die-cast method.SOLUTION: In trailing arms 3 arranged at left-and-right both sides of a vehicle width direction, and having at least hub attachment parts 32, a hub attachment part 32A has a hub attachment face 32b at which an attachment hole 32a is formed, and a first reinforcing structure 36 extending to a vertical direction with respect to the hub attachment face 32b, and continuously arranged so as to surround the attachment hole 32a is arranged at a periphery of the attachment hole 32a.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a trailing arm of a torsion beam suspension.

In conventional vehicles, a pair of left and right trailing arms are joined to the left and right end portions of the torsion beam arranged along the vehicle width direction in order to achieve vehicle weight reduction, space saving, and cost reduction. Some use a torsion beam suspension.
Among the trailing arms of such a torsion beam type suspension, it is made of aluminum die casting, and is pivotally supported by the vehicle body, the wheel suspension for suspending the wheel, the spring support for supporting the coil spring, and There is one in which a shock attachment portion to which one end of a shock absorber is attached is integrally formed (for example, see Patent Document 1). In general, the touring / camber stiffness that determines the tire posture with respect to the input lateral force and longitudinal force is required for the trailing arm. Therefore, in the conventional trailing arm, the plate thickness of the back plate mounting seat on which the hub is mounted is extremely increased to ensure toe rigidity and camber rigidity.

  By the way, in a trailing arm having a hub mounting portion having an open cross-sectional structure, if the thickness of the hub mounting portion is the same as that of the trailing arm other than the hub mounting portion, the rigidity of the hub mounting portion is locally increased. The required toe rigidity and camber rigidity cannot be ensured. Therefore, in the conventional trailing arm, the toe rigidity and the camber rigidity are ensured by increasing the thickness of the hub mounting portion.

JP 2010-69963 A

However, increasing the plate thickness of the hub mounting portion as in the above-described conventional trailing arm increases the weight of the vehicle body, which is not preferable from the viewpoint of realizing the weight reduction of the entire vehicle.
Also, generally in casting, especially die casting, a casting defect is likely to occur inside the thick wall part, and in particular, if a casting defect occurs inside the hub mounting part, there is a risk of reducing the strength. It was not preferable in ensuring the quality of the.

  The present invention has been made in view of such circumstances, and its purpose is to increase durability performance and rigidity performance against input in various directions from the tire, and to reduce the thickness of the hub mounting surface. It is possible to reduce the wall thickness of the hub mounting surface while ensuring the required rigidity, and even if it is molded by the die casting method, a trailing arm that is lightweight and can ensure good internal quality It is to provide.

  In order to solve the above-described problems of the prior art, the present invention provides a trailing arm that is disposed on both the left and right sides in the vehicle width direction and has at least a hub mounting portion. The hub mounting portion is a hub provided with a mounting hole. A first reinforcing structure portion having a mounting surface and extending in a vertical direction with respect to the hub mounting surface and continuously arranged so as to surround the mounting hole is provided around the mounting hole. Yes.

As described above, the trailing arm according to the present invention is disposed on both the left and right sides in the vehicle width direction and has at least a hub mounting portion, and the hub mounting portion has a hub mounting surface provided with a mounting hole. Since the first reinforcing structure portion is provided around the mounting hole so as to extend in the vertical direction with respect to the hub mounting surface and to continuously surround the mounting hole. Durability and rigidity performance can be improved with respect to input in various directions from the tire without providing a meat part.
Therefore, in the trailing arm of the present invention, the thickness of the hub mounting surface can be reduced while ensuring the required rigidity even if the thickness of the hub mounting surface to which a load is input is reduced. Can be achieved.
Also, in the trailing arm of the present invention, it is not necessary to provide a thick portion where die defects are likely to occur in die casting, so that it is possible to improve the casting quality of the hub mounting portion and ensure good internal quality at a light weight. it can.

It is the perspective view which looked at the state before joining the trailing arm of the torsion beam type suspension concerning the embodiment of the present invention to the torsion beam from the upper part. It is a disassembled perspective view which shows the torsion beam type suspension provided with the trailing arm which concerns on embodiment of this invention. FIG. 3 is an enlarged view of a portion Z in FIG. 2, and is a perspective view for explaining an input load to a torsion beam. It is the top view which looked at the trailing arm concerning a 1st embodiment of the present invention from the lower part. It is the sectional view on the AA line in FIG. FIG. 5 shows a trailing arm according to a second embodiment of the present invention, and is a cross-sectional view of the same place as the cross section along line AA in FIG. 4. FIG. 5 is a sectional view showing a trailing arm according to a third embodiment of the present invention, which is the same as the section taken along line AA in FIG. 4. FIG. 10 is a cross-sectional view of a trailing arm according to a fourth embodiment of the present invention, taken along the line AA in FIG. 4. It is the perspective view which looked at the trailing arm which concerns on 5th Embodiment of this invention from the downward direction. It is the BB sectional view taken on the line in FIG. It is CC sectional view taken on the line in FIG.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
1 to 11 show a trailing arm according to an embodiment of the present invention and a torsion beam suspension provided with the trailing arm. In the figure, the arrow Fr indicates the front of the vehicle, the arrow O indicates the vehicle outer direction, and the arrow U indicates the vehicle upper direction. In FIG. 3, the arrow F1 indicates the vertical force (vertical load) of the tire contact point G, the arrow F2 indicates the longitudinal force (front / rear load) of the tire contact point G, and the arrow F3 indicates the lateral force (lateral load) of the tire contact point G. Each direction is shown.

  As shown in FIGS. 1 to 3, a torsion beam type suspension 1 having a trailing arm according to an embodiment of the present invention is mounted on a four-wheel type automobile or the like as a rear suspension. Each is suspended on a vehicle body (not shown) via a torsion beam suspension 1. Such a torsion beam suspension 1 is arranged along a vehicle width direction with a pair of left and right trailing arms 3 arranged on both left and right sides in the vehicle width direction, and connects the left and right trailing arms 3 in the vehicle width direction. A long torsion beam 4 is provided. A spring 5 and a shock absorber 6 are attached to the trailing arm 3 and are suspended from the vehicle body.

  As shown in FIGS. 1 to 3, the trailing arm 3 of the present embodiment is made of an aluminum die casting using a non-ferrous alloy such as a light metal alloy and has an open cross-sectional structure. A beam joint portion 3a extending in the vehicle width direction is provided at the vehicle inner side intermediate portion of the trailing arm 3 in the vehicle front-rear direction, and a front arm portion extending in the vehicle front-rear direction on the opposite side of the beam joint portion 3a. 3b and a rear arm portion 3c are provided. The trailing arm 3 is not limited to die casting but may be casting. Moreover, what was press-molded an aluminum plate, an aluminum extrusion material, and aluminum forging may be used, and what was joined using two or more types of these manufacturing methods may be sufficient, and according to this, the thickness of the hub attachment part mentioned later Can be reduced. Furthermore, the material of the trailing arm 3 is not limited to aluminum, but may be a light metal material such as magnesium or a resin material. When the trailing arm 3 is manufactured by casting a light metal material or molding a resin material, a casting defect or the like is likely to occur inside the thick wall portion. 3 is particularly effective.

  As shown in FIGS. 1 to 3, the beam joint portion 3 a of the trailing arm 3 is a joint portion with the torsion beam 4 to be abutted, and is provided with a step corresponding to the thickness of the torsion beam 4. Yes. And the cross-sectional outer periphery shape of the beam junction part 3a is substantially the same as the cross-sectional inner periphery shape of the torsion beam 4, and is formed in the vertical cross-section substantially U shape which the vehicle lower side opened by the vehicle side view. Moreover, the arm joints 4a at the left and right ends of the torsion beam 4 are overlapped from the top of the vehicle on the tip side located on the vehicle inner side of the beam joint 3a. The cross-sectional area of the beam joint portion 3a becomes smaller toward the vehicle center side. Therefore, in a state where the beam joint portion 3a of the trailing arm 3 and the arm joint portion 4a of the torsion beam 4 are overlapped, the outer peripheral portion of the trailing arm 3 and the outer peripheral portion of the torsion beam 4 are substantially flat (flat). It is comprised so that it may become.

  Further, as shown in FIGS. 2 and 3, a cylindrical bush 31 that is an elastic member is press-fitted into the front arm portion 3 b of the trailing arm 3, and the trailing arm 3 and the vehicle body frame ( (Not shown) is fastened with a bolt, and is configured to swing around the bolt as a central axis. Further, the rear arm portion 3 c of the trailing arm 3 is provided with a hub attachment portion 32, a spring attachment portion 33 having high rigidity, and an absorber attachment portion 34. The hub mounting portion 32 supports the wheel 2 in a rotatable manner, and the outer surface of the hub mounting portion 32 in the vehicle width direction is configured as a hub mounting surface 32b provided with a mounting hole 32a. The hub 7 and the brake drum 8 are attached to the hub attachment surface 32b via the attachment holes 32a. Further, the spring attachment portion 33 supports the lower end of the spring 5 whose upper end is attached to a vehicle body frame (not shown), and is arranged inside the trailing arm 3 in the vehicle width direction. And the absorber attachment part 34 is located in the vehicle back of the spring attachment part 33, and is comprised so that rocking | fluctuation motion may be made by using this bolt as a central axis by fastening the shock absorber 6 with a bolt. The upper end of the shock absorber 6 is supported by a vehicle body frame (not shown).

In the torsion beam suspension 1 of the present embodiment, the load input to the torsion beam 4 is applied to the tire ground contact point G in addition to the vertical force, the longitudinal force and the lateral force indicated by arrows F1, F2 and F3 in FIG. There is a roll load that applies a reverse phase displacement to the wheel 2 in the vertical direction of the vehicle. The vertical position of the torsion beam suspension 1 with respect to the vehicle body is freely restricted by a bush 31 disposed on the vehicle front side of the torsion beam 4, and is determined by a spring 5 and a shock absorber 6.
The torsion beam 4 has high rigidity with respect to the lateral force, the longitudinal force, and the vertical force input to the trailing arm 3, but when the roll load is applied (when the left and right wheels 2 stroke in the opposite phase). Since the torsion beam 4 is stroked while twisting, an appropriate rigidity is required. Mainly, the stiffness of the trailing arm 3 is governed by the lateral force, the longitudinal force, and the vertical force, and the stiffness of the torsion beam 4 is governed by the stiffness of the roll load. In addition, the torsion beam 4 is required to have durability against repeated loads and static strength against large loads.

As shown in FIGS. 1 to 3, the torsion beam 4 of the present embodiment has a substantially U-shaped vertical cross section in which a vehicle lower side is opened in a vehicle side view by bending and bending a plate-like member having a predetermined thickness. It is a long molded article having The left and right end portions of the torsion beam 4 in the vehicle width direction are respectively formed as arm joint portions 4a that are joint portions with the trailing arm 3 to be abutted. The torsion beam 4 having the arm joint 4 a is formed in a substantially U-shaped vertical cross section corresponding to the beam joint 3 a of the trailing arm 3.
Such a torsion beam 4 is not limited to an aluminum extruded material, and may be made of die casting or casting. Moreover, the material of the torsion beam 4 is not limited to aluminum as in the case of the trailing arm 3, but may be a light metal material such as magnesium or a resin material. The vertical cross-sectional shapes of the beam joint 3a of the trailing arm 3 and the arm joint 4a of the torsion beam 4 may be substantially V-shaped or substantially C-shaped.

[First Embodiment]
4 and 5 show the trailing arm according to the first embodiment of the present invention. FIG. 4 is a plan view of the trailing arm as viewed from below. FIG. 5 is a cross-sectional view taken along line AA in FIG. FIG. In addition, about the part similar to what was demonstrated with the torsion beam type suspension of the said embodiment shown in FIGS. 1-3, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

As shown in FIGS. 4 and 5, the trailing arm 3 </ b> A of the first embodiment includes a highly rigid spring mounting portion 33 and absorber mounting from the vehicle upper side of the hub mounting surface 32 b located on the vehicle outer side of the hub mounting portion 32 </ b> A. A wall-shaped upper wall 32c that extends in the vehicle width direction and the vehicle front-rear direction toward the portion 34 and connects the hub attachment portion 32A, the spring attachment portion 33, and the absorber attachment portion 34, and the vehicle front-rear portion of the upper wall 32c A front wall 32d and a rear wall 32e extending downward from the vehicle. That is, the hub attachment portion 32A has a box shape with an open bottom surface.
Further, the trailing arm 3A extends in the vehicle width direction from the vehicle lower side of the hub mounting portion 32A toward the front and rear substantially central position on the vehicle outer surface lower side of the spring mounting portion 33, and the hub mounting portion 32A and the spring mounting portion. 33 has a connecting portion 35 that connects 33. The connecting portion 35 is formed in a rib shape extending substantially linearly when viewed from below the vehicle, and is provided at a substantially central position in the vehicle front-rear direction of the hub attachment portion 32A.

  As shown in FIG. 5, the hub attachment portion 32A of the present embodiment has a hub attachment surface 32b in which a circular attachment hole 32a is provided in the center portion. In addition, the first reinforcing structure 36 that extends in the vertical direction with respect to the hub mounting surface 32b and is continuously arranged so as to surround the mounting hole 32a is like a vertical wall rib around the mounting hole 32a. It is provided to stand up. That is, the 1st reinforcement structure part 36 makes one round in the state away from the peripheral part of the attachment hole 32a, and is formed as a polygonal cylindrical structure in planar view.

  Further, the hub attachment portion 32A of the present embodiment is disposed outside the vehicle width direction in the trailing arm 3A, and the spring attachment portion 33 and the absorber attachment portion 34 are disposed inside the vehicle width direction in the trailing arm 3A. The hub mounting portion 32A, the spring mounting portion 33, and the absorber mounting portion 34 are arranged to face each other with a gap in the vehicle width direction. Moreover, the thickness of the hub mounting portion 32A is substantially equal to the thickness of the base plate of the trailing arm 3A. Therefore, in the trailing arm 3A of the present embodiment, it is possible to reduce the thickness of the hub attachment portion 32A compared to the conventional case. On the other hand, in the trailing arm 3A of the present embodiment, even if the hub mounting portion 32A is cast and machined by the solid portion, the machining portion is very short, so that the number of man-hours required for machining is small and high. It has a structure with productivity.

  Furthermore, in the trailing arm 3A of the first embodiment, at least at a position located on the hub attachment portion 32A side (and the spring attachment portion 33 side), as shown in FIGS. 4 and 5, the upper wall 32c and the connecting portion 35 are provided. Are spaced apart in the vehicle vertical direction. Moreover, the 1st reinforcement structure part 36 is arrange | positioned away from the peripheral part of the attachment hole 32a. For this reason, the hub mounting surface portion 32b side where the mounting hole 32a is provided has a U-shaped concave portion opened on the outer side of the vehicle, and the hub 7 is attached to the hub while being partially inserted into the concave portion. It is configured to be attached to the portion 32A. The upper wall 32c and the connecting portion 35 are connected to each other on the vehicle inner side on the hub mounting portion 32A side (and the vehicle outer side on the spring mounting portion 33 side).

As described above, the trailing arm 3A according to the first embodiment of the present invention has the hub attachment portion 32A, and the hub attachment portion 32A has the hub attachment surface 32b provided with the attachment holes 32a. . Around the mounting hole 32a, there is provided a first reinforcing structure 36 that extends in the vertical direction with respect to the hub mounting surface 32b to which a load is input and is continuously arranged so as to surround the mounting hole 32a. ing. Therefore, in the trailing arm 3A of the present embodiment, it is possible to improve durability performance and rigidity performance with respect to input in various directions from the tire 2 without providing a thick portion.
That is, in the trailing arm 3A of the present embodiment, required rigidity such as toe rigidity and camber rigidity of the hub mounting portion 32A is ensured even if the thickness of the hub mounting surface 32b to which a load is input is reduced. Therefore, the thickness of the hub mounting surface 32b can be reduced and the weight can be reduced.
Further, in the trailing arm 3A of the present embodiment, since it is not necessary to provide a thick portion where casting defects are likely to occur in die casting, the casting quality of the hub mounting portion 32A is improved, and a light weight and good internal quality are ensured. can do.

[Second Embodiment]
FIG. 6 shows a trailing arm according to a second embodiment of the present invention, and is a cross-sectional view of the same place as the cross section along line AA in FIG. In addition, about the part similar to what was demonstrated in 1st Embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
In addition to the configuration of the first embodiment described above, the hub mounting surface 32b of the trailing arm 3B according to the second embodiment has, as shown in FIG. 6, the first reinforcing structure portion 36 to the hub mounting portion 32B. A second reinforcing structure portion 37 extending toward the vehicle front side portion 32Ba is provided. The first reinforcing structure portion 36 and the vehicle front side portion 32Ba of the hub attachment portion 32B are connected to each other via the second reinforcing structure portion 37. Moreover, the 2nd reinforcement structure part 37 is extended and provided in the form of the standing vertical wall rib.
Therefore, in the trailing arm 3B of the second embodiment, the second reinforcing structure portion 37 extending from the first reinforcing structure portion 36 toward the vehicle front side portion 32Ba of the hub mounting portion 32B is provided on the hub mounting surface 32b. Since the first reinforcing structure portion 36 and the vehicle front side portion of the hub mounting portion 32B are connected via the second reinforcing structure portion 37, when receiving inputs from the tire 2 in various directions, the hub mounting surface It is possible to reinforce the vehicle front side portion 32Ba of the hub mounting portion 32B of the trailing arm 3B to which stress is particularly applied via the 32b. Therefore, the rigidity performance of the trailing arm 3B can be further improved with respect to inputs from the tire 2 in various directions, the damage of the trailing arm 3B can be prevented, and the performance of the trailing arm 3B can be maintained. A good riding comfort of a vehicle equipped with the trailing arm 3B can be secured. Other effects are the same as those of the first embodiment.

[Third Embodiment]
FIG. 7 shows a trailing arm according to a third embodiment of the present invention, and is a cross-sectional view of the same place as the cross section along line AA in FIG. In addition, about the part similar to what was demonstrated in 1st Embodiment and 2nd Embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
As in the configuration of the second embodiment described above, the hub mounting surface 32b of the trailing arm 3C of the third embodiment has a vehicle from the first reinforcing structure portion 36 to the hub mounting portion 32C as shown in FIG. A second reinforcing structure portion 37C extending toward the front portion 32Ca is provided. And the 1st reinforcement structure part 36 and the vehicle front side part 32Ca of the hub attachment part 32C are mutually connected via the 2nd reinforcement structure part 37C. The second reinforcing structure portion 37C is provided so as to extend linearly in the form of an upright vertical wall rib. Moreover, the second reinforcement structure portion 37C is provided at a position where the distance between the first reinforcement structure portion 36 and the vehicle front side portion 32Ca of the hub attachment portion 32C is the shortest.
Therefore, in the trailing arm 3C of the third embodiment, the second reinforcement structure portion 37C extending from the first reinforcement structure portion 36 toward the vehicle front side portion 32Ca of the hub attachment portion 32C is provided on the hub attachment surface 32b. The first reinforcing structure portion 36 and the vehicle front side portion 32Ca of the hub attachment portion 32C are connected via the second reinforcing structure portion 37C, and the second reinforcing structure portion 37C is connected to the first reinforcing structure. Since the distance between the portion 36 and the vehicle front side portion 32Ca of the hub attachment portion 32C is provided at the shortest position, the trailing arm 3C can be most efficiently input from the tire 2 in various directions. Rigidity performance can be improved and damage to the trailing arm 3B can be prevented. Further, since the amount of the second reinforcing structure portion 37C to be provided is small, it can contribute to weight reduction. Other effects are the same as those of the first embodiment and the second embodiment.

[Fourth Embodiment]
FIG. 8 shows a trailing arm according to a fourth embodiment of the present invention, and is a cross-sectional view of the same place as the cross section along line AA in FIG. In addition, about the part similar to what was demonstrated in 1st Embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
As shown in FIG. 8, the first reinforcing structure portion 36D of the hub mounting portion 32D of the trailing arm 3D of the fourth embodiment is formed in an annular shape concentric with the center C of the mounting hole 32a. That is, the first reinforcing structure portion 36D in the fourth embodiment is provided at a position away from the peripheral edge portion of the mounting hole 32a by a certain distance, and is continuously disposed so as to surround the mounting hole 32a. .
Therefore, in the trailing arm 3D of the fourth embodiment, the first reinforcing structure portion 36D is formed in an annular shape concentric with the center C of the mounting hole 32a. It can be uniformly dispersed in one reinforcing structure 36D. Therefore, the effect of the first embodiment can be further enhanced.

[Fifth Embodiment]
9 to 11 show a trailing arm according to a fifth embodiment of the present invention. FIG. 9 is a perspective view of the trailing arm as viewed from below. FIG. 10 is a cross-sectional view taken along line BB in FIG. 11 and 11 are cross-sectional views taken along the line CC in the figure. In addition, about the part similar to what was demonstrated in 1st Embodiment mentioned above and 4th Embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
The first reinforcing structure portion 36E in the hub mounting portion 32E of the trailing arm 3E of the fifth embodiment is formed in an annular shape concentric with the center C of the mounting hole 32a, as shown in FIGS. At the same time, it is provided at the peripheral edge of the mounting hole 32a. That is, the first reinforcing structure portion 36E in the fifth embodiment is provided at the position of the peripheral portion of the mounting hole 32a, and is continuously arranged so as to surround the mounting hole 32a.
Therefore, in the trailing arm 3D of the fifth embodiment, the first reinforcing structure 36E is formed in an annular shape concentric with the center C of the mounting hole 32a, and is provided at the peripheral edge of the mounting hole 32a. One reinforcing structure portion 36E becomes a vertical wall portion located on the innermost side in the mounting hole 32a. Therefore, the trailing arm 3D of the fifth embodiment can uniformly distribute loads input from various directions through the tire 2 to the first reinforcing structure portion 36E while realizing weight reduction. In addition, since the inside of the first reinforcing structure portion 36E is a cylindrical cavity, it can serve as a guide that secures a clearance for inserting the hub 7 as a separate part, thereby improving the assembly workability. it can. Other effects are the same as those of the first embodiment and the fourth embodiment.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.

  For example, in the above-described embodiment, the second reinforcing structure portion 37 is provided on the hub mounting surface 32b of the trailing arms 3B and 3C of the second embodiment and the third embodiment. And it may be provided on the hub mounting surface 32b of the trailing arms 3D and 3E of the fifth embodiment. In the above-described embodiment, the torsion beam suspension 1 has a structure in which no stabilizer is attached, but may be applied to a structure in which a stabilizer is attached.

DESCRIPTION OF SYMBOLS 1 Torsion beam type suspension 2 Wheel 3, 3A, 3B, 3C, 3D, 3E Trailing arm 3a Beam joint part 3b Front side arm part 3c Rear side arm part 4 Torsion beam 4a Arm joint part 5 Spring 6 Shock absorber 7 Hub 32, 32A, 32B, 32C, 32D, 32E Hub mounting portion 32Ba, 32Ca Vehicle front side portion of hub mounting portion 32a Mounting hole 32b Hub mounting surface 33 Spring mounting portion 34 Absorber mounting portion 35 Connecting portion 36, 36D, 36E First reinforcing structure portion 37 , 37C Second reinforcing structure

Claims (5)

In the trailing arm that is disposed on both the left and right sides in the vehicle width direction and has at least a hub mounting portion,
The hub mounting portion has a hub mounting surface provided with a mounting hole, and continuously extends around the mounting hole in a direction perpendicular to the hub mounting surface and surrounds the mounting hole. A trailing arm characterized in that a first reinforcing structure portion is provided.   The hub attachment surface is provided with a second reinforcement structure portion extending from the first reinforcement structure portion toward a vehicle front side portion of the hub attachment portion, and the first reinforcement structure portion and the hub attachment portion are provided. The trailing arm according to claim 1, wherein the trailing arm is connected to the vehicle front portion via the second reinforcing structure portion.   The second reinforcing structure portion is provided at a position where a distance between the first reinforcing structure portion and a front side portion of the hub attachment portion is the shortest. The described trailing arm.   The trailing arm according to any one of claims 1 to 3, wherein the first reinforcing structure is formed in an annular shape concentric with the center of the mounting hole.   The trailing arm according to claim 4, wherein the first reinforcing structure portion is provided on a peripheral edge portion of the mounting hole.

Images