Suspension arms

Abstract

To provide a suspension arm which can improve bush holing force while suppressing weight increase.SOLUTION: A suspension arm comprises: an arm body; and a bush press-fit part which is arranged at an end of the arm body and into which a bush is press-fitted. The bush press-fit part includes: a through hole which is formed in a plate-like part; and a vertical wall part which is formed by erecting from a peripheral edge of the through hole. A tip side of the vertical wall part includes a shape to improve rigidity of the vertical wall part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a suspension arm. [Background technology]

[0002] In recent years, with the aim of reducing the weight of automobiles, efforts have been made to thin the walls of automobile frame parts by utilizing high-tensile steel. However, thinning the walls of suspension arms, which are automobile undercarriage parts, reduces the rigidity of the suspension arm's bush press-fit portion, and the bush retention force of the suspension arm. Patent Document 1 discloses a technology for improving the rigidity of a suspension arm by attaching a separate member to the suspension arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-62675 Summary of the Invention [Problem to be solved by the invention]

[0004] The technique disclosed in Patent Document 1 increases the number of parts, which inevitably leads to increased weight and costs.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a suspension arm that can improve bush holding force while suppressing an increase in weight. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the suspension arm of the present invention is a suspension arm comprising an arm body and a bush press-fit portion provided at the end of the arm body and into which a bush is press-fitted, wherein the bush press-fit portion has a through hole formed in a plate-shaped portion and a vertical wall portion formed rising from the periphery of the through hole, and has a shape on the tip side of the vertical wall portion that increases the rigidity of the vertical wall portion.

[0007] Furthermore, the suspension arm according to the present invention is characterized in that, in the above invention, the shape of the vertical wall portion that increases the rigidity of the vertical wall portion includes a curved portion that curves in an arc shape and expands outward from the tip of the vertical wall portion in a radial direction perpendicular to the axial direction of the through hole.

[0008] Furthermore, the structure of the suspension arm according to the present invention is characterized in that, in the above invention, the shape that increases the rigidity of the vertical wall portion includes a straight portion that is formed by extending linearly from the tip of the curved portion.

[0009] Furthermore, the structure of the suspension arm according to the present invention is characterized in that, in the above invention, the shape of the vertical wall portion that increases the rigidity of the vertical wall portion includes a folded portion that is folded back from the tip of the vertical wall portion toward the outside in a radial direction perpendicular to the axial direction of the through hole.

[0010] Furthermore, the structure of the suspension arm according to the present invention is characterized in that, in the above invention, the shape that increases the rigidity of the vertical wall portion includes a straight portion that is formed by extending linearly from the tip of the folded portion. [Effects of the Invention]

[0011] The suspension arm according to the present invention has the advantage of being able to improve the bush holding force while suppressing an increase in weight. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a diagram showing a schematic configuration of a suspension arm according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a bushing press-fitting portion according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of a bushing press-fitting portion according to a reference example. [Figure 4] FIG. 4 is a cross-sectional view of a bushing press-fitting portion according to the second embodiment. [Figure 5] FIG. 5 is a cross-sectional view of a bushing press-fitting portion according to the third embodiment. [Figure 6] FIG. 6 is a cross-sectional view of a bushing press-fitting portion according to the fourth embodiment. [Figure 7] Fig. 7(a) is a plan view showing a CAE analysis model of a bushing press-fit portion according to Example 1. Fig. 7(b) is a cross-sectional view showing a CAE analysis model of a bushing press-fit portion according to Example 1. [Figure 8] Fig. 8(a) is a plan view showing a CAE analysis model of a bushing press-fit portion according to a comparative example, and Fig. 8(b) is a cross-sectional view showing a CAE analysis model of a bushing press-fit portion according to a comparative example. [Figure 9] 9(a) is a plan view showing a CAE analysis model of a bush, and FIG. 9(b) is a side view showing the CAE analysis model of a bush. [Figure 10] FIG. 10 is a diagram showing a CAE analysis model in which a bushing is press-fitted into a bushing press-fitting portion. [Figure 11] FIG. 11 is a graph showing the change in bushing extraction force during bushing extraction. [Figure 12] Fig. 12(a) is a diagram showing the range of positions within the vertical wall portion for which surface pressure calculations were performed in the bushing press-fit portion according to Invention Example 1. Fig. 12(b) is a diagram showing the range of positions within the vertical wall portion for which surface pressure calculations were performed in the bushing press-fit portion according to the comparative example. [Figure 13] FIG. 13 is a graph showing the distribution of surface pressure within the vertical wall portion. [Figure 14] FIG. 14 is a cross-sectional view showing a CAE analysis model of a bushing press-fit portion according to a second example of the present invention. [Figure 15] FIG. 15 is a cross-sectional view showing a CAE analysis model of a bushing press-fit portion according to a third example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Embodiment 1) A first embodiment of a suspension arm according to the present invention will be described below, although the present invention is not limited to this embodiment.

[0014] FIG. 1 is a diagram showing a schematic configuration of a suspension arm 1 according to the first embodiment.

[0015] As shown in FIG. 1, a suspension arm 1 according to the first embodiment includes an arm body 10 and a bushing press-fit portion 2 provided at the end of the arm body 10 and into which a bushing is press-fitted.

[0016] 2 is a cross-sectional view of the bushing press-fitting portion 2 according to embodiment 1. The cross section of the bushing press-fitting portion 2 shown in FIG. 2 corresponds to the AA cross section in FIG.

[0017] The bushing press-fit portion 2 according to the first embodiment has a through hole 20 formed in a top plate portion 21, which is a plate-shaped portion, and a vertical wall portion 23 formed by rising from the periphery of the through hole 20 in the axial direction of the through hole 20. In the following description, the axial direction of the through hole 20 will also be simply referred to as the axial direction. The vertical wall portion 23 is formed into a cylindrical shape by burring. The top plate portion 21 and the vertical wall portion 23 are connected by a first curved portion 22 formed by curving at 90 degrees in an arc shape from the periphery of the top plate portion 21. The bushing press-fit portion 2 according to the first embodiment has a shape on the tip side of the vertical wall portion 23 that enhances the rigidity of the vertical wall portion 23. The shape that enhances the rigidity of the vertical wall portion 23 includes a second curved portion 24 that extends from the tip of the vertical wall portion 23 in an arc shape at 90 degrees outward in a radial direction perpendicular to the axial direction of the through hole 20. The angle at which the second curved portion 24 curves and spreads in an arc shape from the tip of the vertical wall portion 23 is not limited to 90 degrees. In other words, the angle of the second curved portion 24 may be smaller or larger than 90 degrees as long as it curves and spreads in an arc shape from the tip of the vertical wall portion 23 outward in a radial direction perpendicular to the axial direction of the through hole 20.

[0018] In the bush press-fitting portion 2 of embodiment 1, the bush is pressed into the through hole 20 from the side opposite to the side where the vertical wall portion 23 rises in the axial direction, and the inner surface of the vertical wall portion 23 abuts against the side of the bush to hold the bush in place.

[0019] FIG. 3 is a cross-sectional view of a bushing press-fitting portion 2 according to a reference example.

[0020] 3, the bushing press-fitting portion 2 according to the reference example has a through hole 20 formed in a top plate portion 21 and a vertical wall portion 23 that rises from the periphery of the through hole 20. The top plate portion 21 and the vertical wall portion 23 are connected by a first curved portion 22 that is curved at an angle of 90 degrees in an arc from the periphery of the top plate portion 21. A bushing press-fitted into the bushing press-fitting portion 2 according to the reference example is held by the vertical wall portion 23.

[0021] The bushing press-fitting portion 2 according to the first embodiment has a second curved portion 24 at the tip of the vertical wall portion 23, which is a shape that increases the rigidity of the vertical wall portion 23 more than the bushing press-fitting portion 2 according to the reference example. As a result, the bushing press-fitting portion 2 according to the first embodiment can increase the rigidity of the vertical wall portion 23 and improve the bushing holding force with only a slight increase in weight compared to the bushing press-fitting portion 2 according to the reference example.

[0022] (Embodiment 2) Hereinafter, a second embodiment of the suspension arm structure according to the present invention will be described. Note that in this embodiment, the same explanation as in the first embodiment will be omitted as appropriate.

[0023] 4 is a cross-sectional view of the bushing press-fitting portion 2 according to embodiment 2. The cross section of the bushing press-fitting portion 2 shown in FIG. 4 corresponds to the AA cross section in FIG.

[0024] 4, the bushing press-fit portion 2 according to the second embodiment has a through hole 20, a top plate portion 21, a first curved portion 22, a vertical wall portion 23, a second curved portion 24, and a straight portion 25. The through hole 20, top plate portion 21, first curved portion 22, vertical wall portion 23, and second curved portion 24 of the bushing press-fit portion 2 according to the second embodiment are similar to the top plate portion 21, first curved portion 22, vertical wall portion 23, and second curved portion 24 of the bushing press-fit portion 2 according to the first embodiment. The straight portion 25 is formed by extending linearly from the tip of the second curved portion 24 along the top plate portion 21 in a direction perpendicular to the axis of the through hole 20.

[0025] In the bush press-fitting portion 2 of embodiment 2, by providing a straight portion 25 at the tip of the second curved portion 24, the rigidity of the bush press-fitting portion 2 can be further increased and the bush holding force can be improved with only a slight increase in weight compared to the bush press-fitting portion 2 of embodiment 1.

[0026] (Embodiment 3) Hereinafter, a suspension arm structure according to a third embodiment of the present invention will be described. Note that in this embodiment, the same explanation as in the first embodiment will be omitted as appropriate.

[0027] 5 is a cross-sectional view of the bushing press-fitting portion 2 according to embodiment 3. The cross section of the bushing press-fitting portion 2 shown in FIG. 5 corresponds to the AA cross section in FIG.

[0028] 5, the bushing press-fitting portion 2 according to the third embodiment has a through hole 20, a top plate portion 21, a first curved portion 22, a vertical wall portion 23, and a second curved portion 26. The through hole 20, top plate portion 21, first curved portion 22, and vertical wall portion 23 of the bushing press-fitting portion 2 according to the third embodiment are similar to the through hole 20, top plate portion 21, first curved portion 22, and vertical wall portion 23 of the bushing press-fitting portion 2 according to the first embodiment. The second curved portion 26 is a folded portion that is curved 180 degrees in an arc shape and folded back from the tip of the vertical wall portion 23 toward the outside in the radial direction relative to the through hole 20.

[0029] In the bush press-fitting portion 2 of embodiment 3, by providing a second curved portion 26 at the tip of the vertical wall portion 23, the rigidity of the bush press-fitting portion 2 can be further increased and the bush holding force can be improved with only a slight increase in weight compared to the bush press-fitting portion 2 of embodiment 1.

[0030] (Embodiment 4) Hereinafter, a fourth embodiment of the suspension arm structure according to the present invention will be described. Note that in this embodiment, the same explanation as in the third embodiment will be omitted as appropriate.

[0031] 6 is a cross-sectional view of the bushing press-fitting portion 2 according to embodiment 4. The cross section of the bushing press-fitting portion 2 shown in FIG. 6 corresponds to the AA cross section in FIG.

[0032] 6, the bushing press-fitting portion 2 according to the fourth embodiment has a through hole 20, a top plate portion 21, a first curved portion 22, a vertical wall portion 23, a second curved portion 26, and a straight portion 27. The through hole 20, top plate portion 21, first curved portion 22, vertical wall portion 23, and second curved portion 26 of the bushing press-fitting portion 2 according to the fourth embodiment are similar to the through hole 20, top plate portion 21, first curved portion 22, vertical wall portion 23, and second curved portion 26 of the bushing press-fitting portion 2 according to the third embodiment. The straight portion 27 is formed by extending linearly from the tip of the second curved portion 26 toward the top plate portion 21 in the axial direction along the vertical wall portion 23.

[0033] In the bush press-fitting portion 2 of embodiment 4, by providing a straight portion 27 at the tip of the second curved portion 26, the rigidity of the bush press-fitting portion 2 can be further increased and the bush holding force can be improved with only a slight increase in weight compared to the bush press-fitting portion 2 of embodiment 3.

[0034] The configuration of the bushing press-fit portion 2 of the suspension arm 1 according to the present invention is not limited to the configurations shown in the first to fourth embodiments. For example, the angle at which the second curved portions 24, 26 are curved and the length of the straight portions 25, 27 are not particularly limited as long as the rigidity of the vertical wall portion 23 (rigidity of the bushing press-fit portion 2) can be increased so as to obtain the required bushing holding force. In other words, the bushing press-fit portion 2 may have a shape that increases the rigidity of the vertical wall portion 23 (rigidity of the bushing press-fit portion 2) so as to obtain the required bushing holding force while suppressing an increase in weight, without adding any additional parts in addition to the bushing press-fit portion 2. [Example]

[0035] In order to confirm the advantages of the structure of the bushing press-fit portion 2 according to the present invention, a CAE analysis was carried out on the press-fitting and drawing of the bushing 3 into the bushing press-fit portion 2. Note that the material of the bushing press-fit portion 2 was assumed to be a 590 MPa class hot-rolled steel plate.

[0036] Example 1 In Example 1, a bushing press-fit portion 2 according to Present Invention Example 1 and a bushing press-fit portion 2 according to a Comparative Example were used to carry out a CAE analysis of press-fitting the bushing 3 into the bushing press-fit portion 2 and a CAE analysis of pulling out the bushing 3 from the bushing press-fit portion 2. When there is no need to particularly distinguish between the bushing press-fit portion 2 according to Present Invention Example 1 and the bushing press-fit portion 2 according to the Comparative Example, they will simply be referred to as the bushing press-fit portion 2.

[0037] Fig. 7(a) is a plan view showing a CAE analysis model of the bushing press-fit portion 2 according to Present Invention Example 1. Fig. 7(b) is a cross-sectional view showing the CAE analysis model of the bushing press-fit portion 2 according to Present Invention Example 1. The cross section of the bushing press-fit portion 2 shown in Fig. 7(b) corresponds to the BB cross section in Fig. 7(a).

[0038] In the CAE analysis model of the bushing press-fit portion 2 according to Example 1, the top plate portion 21 is disk-shaped with a radius of 58 mm, and the radius of the through-hole 20, which is concentric with the top plate portion 21, is 25 mm. In the CAE analysis model of the bushing press-fit portion 2 according to Example 1, the plate thickness t1 is 2 mm, the radial length L1 of the top plate portion 21 is 30 mm, the inner radius R1 of the first curved portion 22 is 1 mm, and the outer radius R2 of the first curved portion 22 is 3 mm. In the CAE analysis model of the bushing press-fit portion 2 according to Example 1, the axial length L2 of the vertical wall portion 23 is 8 mm, the inner radius R3 of the second curved portion 24 is 1 mm, and the outer radius R4 of the second curved portion 24 is 3 mm. In the CAE analysis model of the bushing press-fit portion 2 according to the present invention example 1, the bushing press-fit portion 2 according to the present invention example 1 was modeled using solid elements of 0.4 mm each, which were divided into five parts in the plate thickness direction.

[0039] Fig. 8(a) is a plan view showing a CAE analysis model of the bushing press-fit portion 2 according to a comparative example. Fig. 8(b) is a cross-sectional view showing the CAE analysis model of the bushing press-fit portion 2 according to the comparative example. The cross section of the bushing press-fit portion 2 shown in Fig. 8(b) corresponds to the CC cross section of Fig. 8(a).

[0040] In the CAE analysis model of the bushing press-fit portion 2 according to the comparative example, the top plate portion 21 is disk-shaped with a radius of 58 mm, and the radius of the through-hole 20, which is concentric with the top plate portion 21, is 25 mm. In the CAE analysis model of the bushing press-fit portion 2 according to the comparative example, the plate thickness t1 is 2 mm, the radial length L1 of the top plate portion 21 is 30 mm, the inner radius R1 of the first curved portion 22 is 1 mm, and the outer radius R2 of the first curved portion 22 is 3 mm. In the CAE analysis model of the bushing press-fit portion 2 according to the comparative example, the axial length L2 of the vertical wall portion 23 is 8 mm. In the CAE analysis model of the bushing press-fit portion 2 according to the comparative example, the bushing press-fit portion 2 according to the comparative example is modeled using solid elements with a size of 0.4 mm, which are obtained by dividing the bushing press-fit portion 2 according to the comparative example into five parts in the plate thickness direction.

[0041] 9(a) is a plan view showing the CAE analysis model of the bush 3. FIG. 9(b) is a side view showing the CAE analysis model of the bush 3.

[0042] In the CAE analysis model of the bushing 3, the outer peripheral surface of the bushing 3 is tapered so that the diameter increases linearly from the tip end 31 side to the base end 32 side in the height direction of the bushing 3. In other words, within a distance of 50 mm from the base end 32 to the tip end 31 in the height direction of the bushing 3, the radius of the bushing 3 increases linearly from the tip end 31 side at a radius of 25.0 mm to the base end 32 side at a radius of 25.5 mm. In addition, the CAE analysis model of the bushing 3 was modeled using shell elements with the bushing 3 as a rigid body.

[0043] Fig. 10 is a diagram showing a CAE analysis model of a state in which a bushing 3 is press-fitted into a bushing press-fit portion 2. Note that Fig. 10 shows a case in which a bushing press-fit portion 2 according to a comparative example is used as a representative example, but the case in which a bushing press-fit portion 2 according to invention example 1 is used is similar except for the presence of the second curved portion 24, and therefore is not shown in the figure.

[0044] First, in the CAE analysis of press-fitting the bushing 3 into the bushing press-fit portion 2, the bushing 3 was press-fitted into the bushing press-fit portion 2 while the top plate portion 21 of the bushing press-fit portion 2 was restrained by a holder (not shown) so as to prevent movement of the top plate portion 21. At this time, as shown in Fig. 10, the bushing 3 was press-fitted into the bushing press-fit portion 2 until the distance from the tip 31 of the bushing 3 to the top plate portion 21 of the bushing press-fit portion 2 in the axial direction of the bushing press-fit portion 2 was 35 mm.

[0045] Next, in the CAE analysis of pulling out the bushing 3 from the bushing press-fit portion 2, the top plate portion 21 of the bushing press-fit portion 2 was restrained by a holder (not shown) to prevent movement, and the bushing 3 was pulled out from the bushing press-fit portion 2 toward the base end 32 (downward in Figure 10).

[0046] Figure 11 is a graph showing changes in bushing extraction force during bushing extraction. The horizontal axis in Figure 11 represents bushing displacement, which is the amount of change in the position of the bushing 3 when it is extracted axially from the bushing press-fit portion 2, starting from the position of the bushing 3 press-fitted into the bushing press-fit portion 2. The vertical axis in Figure 11 represents bushing extraction force, which is the force required to extract the bushing 3 from the bushing press-fit portion 2.

[0047] As can be seen from Figure 11, in both Inventive Example 1 and the Comparative Example, the bushing pull-out force increases rapidly immediately after the bushing 3 begins to displace. Then, in both Inventive Example 1 and the Comparative Example, after the bushing pull-out force reaches its peak, the bushing pull-out force decreases as the bushing 3 and the bushing press-fit portion 2 begin to slide relative to each other. The peak value of the bushing pull-out force was 18.8 kN for the Comparative Example and 22.9 kN for Inventive Example 1. This indicates that the peak value of the bushing pull-out force in Inventive Example 1 is 21.8% higher than that in the Comparative Example. Furthermore, the higher the peak value of the bushing pull-out force, the more difficult it is for the bushing 3 to be removed from the bushing press-fit portion 2. Therefore, it can be seen that the bushing press-fit portion 2 in Inventive Example 1 has improved bushing retention force compared to the bushing press-fit portion 2 in the Comparative Example.

[0048] Furthermore, the surface pressure that the vertical wall portion 23 of the bushing press-fitting portion 2 receives from the bushing 3 after the bushing is press-fitted into the bushing press-fitting portion 2 was calculated by simulation. Fig. 12(a) is a diagram showing the range of positions within the vertical wall portion 23 for which the surface pressure calculation was performed in the bushing press-fitting portion 2 according to Example 1 of the present invention. Fig. 12(b) is a diagram showing the range of positions within the vertical wall portion 23 for which the surface pressure calculation was performed in the bushing press-fitting portion 2 according to the comparative example.

[0049] The surface pressure calculations were performed on each mesh in Figures 12(a) and 12(b) that was located between 0 [mm] and 8 [mm] in the axial direction within the vertical wall portion 23, starting from the end of the vertical wall portion 23 on the side of the first curved portion 22.

[0050] Fig. 13 is a graph showing the distribution of surface pressure within the vertical wall portion 23. The horizontal axis in Fig. 13 represents the position in the axial direction within the vertical wall portion 23. The vertical axis in Fig. 13 represents the surface pressure that the vertical wall portion 23 receives from the bushing 3.

[0051] In both Inventive Example 1 and the Comparative Example, the surface pressure is concentrated in the lower part (0 mm to 2 mm) and upper part (6 mm to 8 mm) of the vertical wall portion 23. There is almost no difference in the surface pressure distribution in the lower part of the vertical wall portion 23 between Inventive Example 1 and the Comparative Example, but the surface pressure in the upper part of the vertical wall portion 23 is higher in Inventive Example 1 than in the Comparative Example due to the increased rigidity caused by the addition of the second curved portion 24. It is believed that the difference in surface pressure in this area contributes to the improvement of the bushing pull-out force in the bushing press-fit portion 2 of Inventive Example 1.

[0052] Example 2 In Example 2, a CAE analysis of pressing a bush 3 into the bush press-fit portion 2 and a CAE analysis of pulling out the bush 3 from the bush press-fit portion 2 were performed using the bush press-fit portion 2 according to Example 2 of the present invention and the bush press-fit portion 2 according to Example 3 of the present invention, respectively.

[0053] FIG. 14 is a cross-sectional view showing a CAE analysis model of the bushing press-fitting portion 2 according to the second example of the present invention.

[0054] The CAE analysis model of the bushing press-fit portion 2 according to Example 2 of the present invention corresponds to the bushing press-fit portion 2 according to embodiment 2. The top plate portion 21, first curved portion 22, vertical wall portion 23, and second curved portion 24 of the bushing press-fit portion 2 according to Example 2 of the present invention are the same as those of the bushing press-fit portion 2 according to Example 1 of the present invention. The straight portion 25 is formed by extending linearly from the tip of the second curved portion 24 along the top plate portion 21 in a direction perpendicular to the axial direction, with a length L3 of 5 mm. In the CAE analysis model of the bushing press-fit portion 2 according to Example 2 of the present invention, the bushing press-fit portion 2 according to Example 2 of the present invention was modeled using solid elements with a size of 0.4 mm, which were obtained by dividing the bushing press-fit portion 2 according to Example 2 of the present invention into five parts in the plate thickness direction.

[0055] FIG. 15 is a cross-sectional view showing a CAE analysis model of the bushing press-fitting portion 2 according to the third example of the present invention.

[0056] The CAE analysis model of the bushing press-fit portion 2 according to Example 3 of the present invention corresponds to the bushing press-fit portion 2 according to the fourth embodiment. The top plate portion 21, first curved portion 22, and vertical wall portion 23 of the bushing press-fit portion 2 according to Example 3 of the present invention are the same as those of the bushing press-fit portion 2 according to Example 1 of the present invention. The second curved portion 26 is a folded portion that is curved 180 degrees in an arc shape from the tip of the vertical wall portion 23 outward and folded back. The inner radius R5 of the second curved portion 26 is 1 mm, and the outer radius R6 of the second curved portion 26 is 3 mm. The straight portion 27 is formed by extending linearly from the tip of the second curved portion 26 toward the top plate portion 21 in the axial direction along the vertical wall portion 23. The length L4 of the vertical wall portion 23 is 5 mm. In the CAE analysis model of the bushing press-fit portion 2 according to Example 3 of the present invention, the bushing press-fit portion 2 according to Example 3 of the present invention is modeled using solid elements with a size of 0.4 mm, which are obtained by dividing the bushing press-fit portion 2 according to Example 3 of the present invention into five parts in the plate thickness direction.

[0057] In Example 2, CAE analysis was performed on the bushing press-fit portions 2 of Inventive Examples 2 and 3, similar to the bushing press-fit portion 2 of Inventive Example 1 in Example 1. CAE analysis was performed on the bushing press-fit portion 2 of Inventive Example 2 to determine whether the bushing 3 was press-fitted into the bushing press-fit portion 2 or whether the bushing 3 was pulled out of the bushing press-fit portion 2. The results showed that the peak bushing pull-out force during bushing pull-out was 24.2 kN for Inventive Example 2 and 24.4 kN for Inventive Example 3. This resulted in a 28.7% increase in the peak bushing pull-out force for Inventive Example 2 compared to the comparative example of Example 1. Furthermore, the peak bushing pull-out force for Inventive Example 3 compared to the comparative example of Example 1. Since the higher the peak bushing pull-out force, the more difficult it is for the bushing 3 to be pulled out of the bushing press-fit portion 2, it can be seen that the bushing press-fit portions 2 of Inventive Examples 2 and 3 have improved bushing retention force compared to the bushing press-fit portion 2 of the comparative example of Example 1. [Explanation of symbols]

[0058] 1 suspension arm 2 Bush press-fit part 3. Bush 20 through holes 21 Top plate 22 First curved section 23 Vertical wall section 24,26 Second curved section 25,27 Straight section

Claims

1. An arm body, a bushing press-fitting portion provided at an end of the arm body and into which a bushing is press-fitted; A suspension arm comprising: The bush press-fitting portion is a through hole formed in the plate-shaped portion, into which the bushing is press-fitted; a vertical wall portion that is formed to rise from a periphery of the through hole and whose inner peripheral surface abuts against a side surface of the bushing press-fitted into the through hole to hold the bushing; a first curved portion that is curved in an arc shape from the peripheral edge and connects the plate-like portion and the vertical wall portion; and a shape on a tip side of the vertical wall portion that increases the rigidity of the vertical wall portion; A suspension arm characterized in that the shape of the vertical wall portion to increase the rigidity thereof includes a second curved portion that curves in an arc shape and expands outward from the tip of the vertical wall portion in a radial direction perpendicular to the axial direction of the through hole.

2. 2. The suspension arm according to claim 1, wherein the shape of the vertical wall portion that increases the rigidity of the vertical wall portion includes a straight portion that extends linearly from a tip of the second curved portion.

3. An arm body, a bushing press-fitting portion provided at an end of the arm body and into which a bushing is press-fitted; A suspension arm comprising: The bush press-fitting portion is a through hole formed in the plate-shaped portion, into which the bushing is press-fitted; a vertical wall portion that is formed to rise from a periphery of the through hole and whose inner peripheral surface abuts against a side surface of the bushing press-fitted into the through hole to hold the bushing; a first curved portion that is curved in an arc shape from the peripheral edge and connects the plate-like portion and the vertical wall portion; and a shape on a tip side of the vertical wall portion that increases the rigidity of the vertical wall portion; A suspension arm characterized in that the shape of the vertical wall portion to increase the rigidity thereof includes a folded portion folded from the tip of the vertical wall portion toward the outside in a radial direction perpendicular to the axial direction of the through hole.

4. 4. The suspension arm according to claim 3, wherein the shape of the vertical wall portion that increases the rigidity of the vertical wall portion includes a straight portion that extends linearly from a tip of the folded portion.

Images