Suspension arm

Abstract

To provide a suspension member which does not cause torsional deformation or buckling deformation even when a large load is applied toward the rear of a vehicle, and can be reduced in weight.SOLUTION: When the suspension arm is viewed in a plan view from a side surface direction perpendicular to both an imaginary straight line connecting the ball joint section and the rear bush section and a side surface direction perpendicular to the thickness direction of the arm section, the arm section has a maximum thickness section having a maximum thickness within a range of ± 100 mm along the imaginary straight line from the position where the rear bush section is formed, and the arm section is formed so as to have a thickness smaller than that of the maximum thickness section at a portion connected to the ball joint section and at a portion connected to the rear bush section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Shock absorbers for automobile vehicles, such as strut suspensions and double wishbone suspensions, have lower arms that are suspension arms that interconnect the wheels, suspension components, and vehicle frame.

[0003] Such lower arms are the foundation of the suspension, which reduces the impact that the tires receive from the road surface while the vehicle is moving, and are components that absorb vibrations, lateral stress that occurs when cornering, and longitudinal stress that occurs when accelerating and decelerating (see, for example, Patent Documents 1 and 2).

[0004] A lower arm generally comprises a roughly L-shaped arm portion, a ball joint portion that is supported by a ball stud bolt at one end of the arm portion, a front bush portion that extends from the curved portion of the arm portion and engages with a vehicle body such as a subframe, and a rear bush portion.

[0005] Conventionally, lower arms have been made of highly rigid steel materials, but in recent years, with the trend toward lighter vehicles, they have been formed by casting or forging using aluminum alloys. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-112111 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-299663 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the suspension members disclosed in Patent Documents 1 and 2 are made of aluminum alloy, there is a concern that deformation such as twisting or buckling may occur when a large load is applied, particularly toward the rear of the vehicle.

[0008] The present invention has been made in view of the above technical background, and aims to provide a suspension member that does not undergo torsional deformation or buckling deformation even when a large load is applied toward the rear of the vehicle, and that can be made lighter. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following means.

[0010] (1) A suspension arm for a vehicle, comprising: an L-shaped bent arm portion; a ball joint portion formed at one end of the arm portion; a rear bush portion formed at the other end of the arm portion; and a front bush portion formed to protrude from the bent portion of the arm portion into the vehicle body, all of which are integrally formed from an aluminum alloy; when the suspension arm is viewed in plan from above perpendicular to the thickness direction of the arm portion, a maximum width portion where the arm portion has a maximum width is at the bent portion, and the width of the arm portion gradually decreases from the maximum width portion toward the ball joint portion and toward the rear bush portion, respectively; when the suspension arm is viewed in plan from a side direction perpendicular to an imaginary line connecting the ball joint portion and the rear bush portion and to the thickness direction of the arm portion, the arm portion has a maximum thickness portion where the thickness is maximum within a range of ±100 mm along the imaginary line from the position where the front bush portion is formed; and the suspension arm is formed so that the thickness at the connection portion with the ball joint portion and the connection portion with the rear bush portion is smaller than the maximum thickness portion.

[0011] (2) A suspension arm according to (1), wherein the cross section perpendicular to the extension direction of the arm portion is H-shaped or concave.

[0012] (3) A suspension arm according to (3), wherein the two rib-like portions protruding along the thickness direction on both sides of the central portion in a cross section perpendicular to the extension direction of the arm portion have different thicknesses.

[0013] (4) The suspension arm according to (1), wherein a cross section perpendicular to the extension direction of the arm portion is rectangular.

[0014] (5) A suspension arm according to any one of (1) to (4), wherein the maximum thickness portion is within a range of ±70 mm along the imaginary line from the position where the rear bush portion is formed.

[0015] (6) A suspension arm according to any one of (1) to (5), wherein the maximum thickness portion is formed so as to extend along the imaginary straight line with a predetermined width. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a suspension member that does not undergo torsional deformation or buckling deformation even when a large load is applied toward the rear of the vehicle, and that can be made lighter. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an external perspective view showing a lower arm, which is a suspension member according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a cross section perpendicular to the extension direction of the arm portion. [Figure 3] FIG. 10 is another cross-sectional view showing a cross section perpendicular to the extension direction of the arm portion. [Figure 4] FIG. 2 is a plan view of the suspension arm when viewed from above perpendicular to the thickness direction of the arm portion. [Figure 5]1 is a plan view of a suspension arm as viewed from a side direction perpendicular to an imaginary line connecting a ball joint portion and a rear bush portion and to the thickness direction of the arm portion. FIG. [Figure 6] FIG. 1 is a plan view showing a lower arm of Conventional Example 1 in Verification Example 1. [Figure 7] 10 is a graph showing the results of verification example 2. [Figure 8] 10 is a graph showing the results of Verification Example 3. [Figure 9] 10 is a graph showing the results of Verification Example 4. [Figure 10] 10 is a graph showing the results of Verification Example 5. [Figure 11] FIG. 10 is an external perspective view showing a lower arm used in verification example 6. [Figure 12] FIG. 10 is an external perspective view showing a lower arm used in verification example 6. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited thereto. Appropriate changes can be made within the scope that does not change the effects of the present invention.

[0019] FIG. 1 is an external perspective view showing a lower arm, which is a suspension member according to one embodiment of the present invention. The lower arm (suspension member) 10 has an arm portion 11 having an L-shaped bent portion 19, a ball joint portion 12 formed at one end of the arm portion 11, a rear bush portion 13 formed at the other end of the arm portion 11, and a front bush portion 14 formed so as to protrude into the vehicle body from the bent portion 19 of the arm portion 11. The lower arm 10 may be integrally formed from an aluminum alloy.

[0020] Note that Figure 1 is a top view of the lower arm on the left side of the vehicle, with the large arrow at point A pointing towards the rear of the vehicle, but in some vehicle models the lower arm is mounted so that the large arrow at point A points towards the front of the vehicle (point B is the rear bush, point C is the FR bush). In this case too, the objective is to provide a suspension member that does not undergo torsional or buckling deformation due to the load in the direction of the large arrow and that can be made lighter. The direction of the large arrow is also at a slight angle to the plane connecting points A, B, and C.

[0021] 2, the cross section of arm portion 11 perpendicular to the extension direction is H-shaped. In the following description, the portions of arm portion 11 that protrude in the thickness direction HD on both sides of the width direction WD are referred to as ribs 18, 18.

[0022] In this embodiment, the height of these ribs 18, 18 along the thickness direction HD, i.e., the thickness H of the arm portion 11 described later, is formed to be the same for the ribs 18 on one side and the ribs 18 on the other side, but they can also be formed to be different from each other.

[0023] 3, arm portion 11 may have a cross section perpendicular to the extension direction that is concave. Alternatively, arm portion 11 may have a cross section perpendicular to the extension direction that is rectangular. If arm portion 11 has a rectangular cross section, the overall mass increases, but strength can be increased compared to an H-shaped cross section or a concave cross section.

[0024] When used as a vehicle suspension, the ball joint 12 has a cylindrical shape with a hemispherical bottom, into which a ball stud of the vehicle is rotatably inserted, thereby connecting the ball joint 12 to the wheel support body in a rotatable manner.

[0025] The rear bush portion 13 has a hollow cylindrical shape. The rear bush portion 13 is engaged with, for example, a subframe.

[0026] The front bush portion 14 is made up of a rod-shaped portion 14a that protrudes outward from the outside 19a of the bent portion 19 of the arm portion 11, and a hollow cylindrical portion 14b formed at the tip of the rod-shaped portion 14a. The front bush portion 14 is engaged with, for example, a subframe.

[0027] In the following description, point A of ball joint portion 12, point B of front bush portion 14, and point C of rear bush portion 13 shown in Fig. 1 are points that indicate the centers of the cylindrical central axes of the respective members. Also, an imaginary line Q connecting ball joint portion 12 and rear bush portion 13 is a line connecting point A and point C.

[0028] Figure 4 is a plan view of the suspension arm when viewed from above, perpendicular to the thickness direction of the arm portion. In the plan view shown in Figure 4, the arm portion 11 is formed so that the overall width WA of the arm portion 11, which is perpendicular to the center line L along the extension direction, is greatest near the protruding portion of the front bush portion 14 at the bent portion 19 (maximum width portion), and the overall width WA of the arm portion 11 gradually decreases from this maximum width portion toward the ball joint portion 12 and the rear bush portion 13, respectively.

[0029] Fig. 5 is a plan view of the suspension arm when viewed from a side direction perpendicular to an imaginary line connecting the ball joint portion and the rear bushing portion and to the thickness direction of the arm portion. That is, Fig. 4 is a plan view of lower arm (suspension member) 10 when viewed from a plane that includes imaginary line Q in Fig. 1 and is parallel to the thickness direction HD of arm portion 11.

[0030] In the lower arm (suspension member) 10 of this embodiment, in Figure 4, the thickness H of the arm portion 11 along the thickness direction HD (i.e., the height of the rib 18 in Figure 2) has a maximum thickness portion Hm where the thickness H is greatest at a position corresponding to a range of ±100 mm, or in this embodiment ±70 mm, along the imaginary line Q from point B, which is the formation position of the front bush portion 14 on the imaginary line Q. In this embodiment, the direction from point B to point A along the imaginary straight line Q in FIG. 4 is represented as - (minus), and the direction from point B to point C is represented as + (plus).

[0031] The arm portion 11 is formed such that the thicknesses Hs1 and Hs2 of the arm portion 11 are smaller than the maximum thickness Hm at the connection portion with the ball joint portion 12 and the connection portion with the rear bush portion 13, respectively.

[0032] That is, in the lower arm (suspension member) 10 of this embodiment, the thickness H of the arm portion 11 is greatest at the maximum thickness portion Hm, and the thickness H of the arm portion 11 is gradually reduced from this maximum thickness portion Hm toward the connection portion with the ball joint portion 12 and the connection portion with the rear bush portion 13.

[0033] In addition, the thickness H of the arm portion 11 of the lower arm (suspension member) 10 can be configured to gradually decrease from the maximum thickness part Hm toward one end and the other end of the arm portion 11. Alternatively, the maximum thickness part Hm can be formed with a predetermined width along the imaginary line Q within a range of ±100 mm from point B along the imaginary line Q, or two maximum thickness parts Hm can be provided and the thickness H of the arm portion 11 between these two maximum thickness parts Hm can be formed to be smaller than the maximum thickness part Hm. Furthermore, the thickness H of the arm portion 11 may decrease not only uniformly from the maximum thickness portion Hm toward one end side and the other end side of the arm portion 11, but also non-linearly.

[0034] With the lower arm (suspension member) 10 of this embodiment configured as described above, a maximum thickness portion Hm is formed where the thickness is greatest within a range of ±100 mm along the imaginary line Q from the formation (equivalent) position of the front bush portion on the imaginary line Q connecting point A of the ball joint portion 12 and point C of the rear bush portion 13, and the arm portion 11 is formed so that the thickness at the connection portion with the ball joint portion 12 and the connection portion with the rear bush portion 13 is smaller than the maximum thickness portion, thereby making it possible to increase the maximum deformation load against the rear load F shown in Figure 1 without increasing the mass of the lower arm (suspension member) 10.

[0035] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Example]

[0036] Hereinafter, several embodiments of the lower arm (suspension member) of the present invention will be described. (Verification example 1) As in the lower arm (suspension member) shown in Figure 1 described as an embodiment of the present invention, Example 1 of the present invention was used, in which the thickness H of the arm portion 11 was varied when viewed in plan as shown in Figure 5, and Comparative Example 1 was used, in which the thickness H of the arm portion 11 was made uniform when viewed in plan from the same perspective as Figure 5, as shown in Figure 6.

[0037] Table 1 shows the dimensions of each part in the cross section of arm portion 11, which has an H-shaped cross section as shown in Figure 2. Note that H and h in Table 1 are for Comparative Example 1. Also, W1 is a value within a range that varies along the extension direction of arm portion 11. Also, Table 2 shows H and h for Invention Example 1.

[0038] [Table 1] [Table 2]

[0039] The forged product weight of the lower arm of Comparative Example 1 described above was 2.208 kg, and the forged product weight of Inventive Example 1 was 2.183 kg. The maximum deformation load in response to a rear load F (see FIG. 1) was measured for each of the lower arms of Comparative Example 1 and Inventive Example 1. As a result, Comparative Example 1 had F = 29.94 (kN), while Inventive Example 1 reached F = 34.04 (kN).

[0040] These results show that the lower arm of Inventive Example 1 had a maximum deformation load that was increased by 13.7%, despite the fact that the forged product weight was 25 g lighter than the lower arm of Comparative Example 1. Therefore, it was confirmed that by forming the maximum thickness portion Hm in the range of ±100 mm from point B along the imaginary line Q shown in Figure 5, and forming an arm portion with a shape in which the thickness H gradually decreases from there toward points A and C, a lower arm (suspension member) that achieved both weight reduction and a maximum deformation load could be obtained.

[0041] (Verification example 2) In the lower arm (suspension member) shown in FIG. 1, which is described as an embodiment of the present invention, when viewed in plan as shown in FIG. 5, we verified how far the position of the maximum thickness part Hm should be moved from point B to maximize the load ratio relative to ±0 mm (point B). The results are shown in Table 3. In Table 3, the direction from point B to point A along the virtual line Q in Figure 4 is represented as - (minus), and the direction from point B to point C is represented as + (plus). Figure 7 shows a graph showing the relationship between the distance from point B of the maximum thickness part and the load ratio, based on the results in Table 3.

[0042] [Table 3]

[0043] According to the results shown in Table 3 and Fig. 7, by setting the maximum thickness part Hm at a position of -28.3 mm from point B toward point A, the maximum deformation load ratio to ±0 mm (point B) was maximized at 1.0132. Note that even when the position of the maximum thickness part Hm was changed within the range shown in Table 3, there was almost no change in the forged product mass of the lower arm.

[0044] (Verification example 3) In the lower arm (suspension member) shown in FIG. 1 described as an embodiment of the present invention, when the width W of the rib 18 of the arm portion 11 with an H-shaped cross section shown in FIG. 2 is set to 15 mm, we investigated how far the position of the maximum thickness part Hm should be separated from point B to maximize the maximum deformation load. H and h (see FIG. 2) in this verification example 3 are shown in Table 4. The results of verification example 3 are shown in Table 5. In Table 5, the direction from point B to point A along the imaginary line Q in FIG. 4 is represented as - (minus), and the direction from point B to point C is represented as + (plus). FIG. 8 is a graph showing the relationship between the distance from point B of the maximum thickness part and the load ratio based on the results of Table 5.

[0045] [Table 4] [Table 5]

[0046] According to the results shown in Table 5 and Fig. 8, by setting the maximum thickness part Hm at a position between -48.3 mm and -28.3 mm from point B toward point A, the maximum deformation load ratio to ±0 mm (point B) was maximized at 1.02. Note that even when the position of the maximum thickness part Hm was changed within the range shown in Table 5, there was almost no change in the forged product mass of the lower arm.

[0047] (Verification example 4) In the lower arm (suspension member) shown in FIG. 1 described as an embodiment of the present invention, the width W of rib 18 of arm portion 11 with an H-shaped cross section shown in FIG. 2 was set to 10 mm, and the distances between points A and C and between points B and C were increased to verify how far the position of the maximum thickness portion Hm should be separated from point B to maximize the maximum deformation load. H and h (see FIG. 2) in this verification example 4 are shown in Table 6. The results of verification example 4 are shown in Table 7. In Table 7, the direction from point B to point A along the imaginary line Q in FIG. 4 is indicated as - (minus), and the direction from point B to point C is indicated as + (plus). FIG. 9 is a graph showing the relationship between the distance from point B of the maximum thickness portion and the load ratio based on the results of Table 7.

[0048] [Table 6] [Table 7]

[0049] According to the results shown in Table 7 and Fig. 9, by setting the maximum thickness part Hm at a position of -16.4 mm from point B toward point A, the maximum deformation load ratio to ±0 mm (point B) was maximized at 1.0034. Note that even when the position of the maximum thickness part Hm was changed within the range shown in Table 7, there was almost no change in the forged product mass of the lower arm.

[0050] (Verification example 5) In the lower arm (suspension member) shown in FIG. 1 described as an embodiment of the present invention, we investigated how far the position of the maximum thickness part Hm should be separated from point B to maximize the maximum deformation load (stress resistance) when the length of the rod-shaped portion 14a of the front bushing 14 was shortened. Table 8 shows H and h (see FIG. 2) in this verification example 5. Table 9 shows the results of verification example 5. In Table 9, the direction from point B to point A along the imaginary line Q in FIG. 4 is indicated as - (minus), and the direction from point B to point C is indicated as + (plus). FIG. 10 is a graph showing the relationship between the distance from point B of the maximum thickness part and the load ratio based on the results of Table 9.

[0051] [Table 8] [Table 9]

[0052] According to the results shown in Table 9 and Fig. 10, by setting the maximum thickness part Hm at a position of +12.785 mm from point B toward point A, the maximum deformation load ratio to ±0 mm (point B) was maximized at 1.0026. Note that even when the position of the maximum thickness part Hm was changed within the range shown in Table 9, there was almost no change in the forged product mass of the lower arm.

[0053] (Verification example 6) As shown in Figures 11 and 12, the ratio of maximum deformation loads was measured for a lower arm with two maximum thickness portions formed within a range of ±100 mm from point B compared to a lower arm with one maximum thickness portion (at -38.3 mm from point B). For the lower arm of Figure 11, maximum thickness portions Hm1 and Hm2 were formed at positions +38.3 mm and -38.3 mm from point B in a plan view as shown in Figure 5. For the lower arm of Figure 12, maximum thickness portions Hm1 and Hm2 were formed at positions +88.3 mm and -88.3 mm from point B in a plan view as shown in Figure 5. The results of Verification Example 6 are shown in Table 10. In Table 10, the direction from point B to point A along the imaginary line Q in Figure 4 is indicated as - (minus), and the direction from point B to point C is indicated as + (plus).

[0054] [Table 10]

[0055] According to the results shown in Table 10, when two maximum thickness portions were formed, the load ratio was lower than when there was only one maximum thickness portion, in both Figures 11 and 12. In particular, in Figure 11, where the distance from point B to the maximum thickness portions Hm1 and Hm2 is short, the thickness change became abrupt and the load ratio fell to about 0.8.

[0056] (Verification example 7) The ratio of maximum deformation loads was measured for the arm portion of the lower arm when the maximum thickness was formed at a position -18.3 mm from point B, when the maximum thickness was formed within a range of ±10 mm, ±20 mm, ±30 mm, and ±40 mm from this position, and when the maximum thickness was formed at a position +20 mm from point B and within a range of ±10 mm, the maximum thickness was measured. The results of Verification Example 7 are shown in Table 11. In Table 11, the direction from point B to point A along the imaginary line Q in Figure 4 is indicated as - (minus), and the direction from point B to point C is indicated as + (plus).

[0057] [Table 11]

[0058] According to the results shown in Table 11, when the maximum thickness portion of the arm portion was formed to have a predetermined width (flat range), the load ratio improved slightly in all cases. [Explanation of symbols]

[0059] 10...Lower arm (suspension member) 11...Arm section 12...Ball joint part 13...Rear bushing 14...Front bushing 18...Ribs 19...Bending part

Claims

1. A suspension arm for a vehicle, comprising: an arm portion bent into an L-shape; a ball joint portion formed at one end of the arm portion; a rear bush portion formed at the other end of the arm portion; and a front bush portion formed so as to protrude into a vehicle body from a bent portion of the arm portion, and the front bush portion is integrally formed from an aluminum alloy; when the suspension arm is viewed in plan from an upper surface perpendicular to a thickness direction of the arm portion, a maximum width portion where the width of the arm portion is greatest is located at the bent portion, and the width of the arm portion gradually decreases from the maximum width portion toward the ball joint portion and toward the rear bush portion, When the suspension arm is viewed in plan from a side direction perpendicular to an imaginary line connecting the ball joint portion and the rear bush portion and to a thickness direction of the arm portion, the arm portion has a maximum thickness portion within a range of ±100 mm along the imaginary line from a formation position of the front bush portion, and is formed so that the thickness is smaller than the maximum thickness portion at a connection portion with the ball joint portion and a connection portion with the rear bush portion.

2. 2. The suspension arm according to claim 1, wherein a cross section of said arm portion perpendicular to the extension direction thereof is H-shaped or concave.

3. 3. The suspension arm according to claim 2, wherein two rib-like portions protruding in the thickness direction on both sides of a central portion in a cross section perpendicular to the extension direction of said arm portion have different thicknesses.

4. 2. The suspension arm according to claim 1, wherein a cross section perpendicular to the extension direction of said arm portion is rectangular.

5. 5. The suspension arm according to claim 1, wherein the maximum thickness portion is within a range of ±70 mm along the imaginary straight line from a position where the rear bush portion is formed.

6. The suspension arm according to claim 1 , wherein the maximum thickness portion is formed so as to extend along the imaginary straight line with a predetermined width.

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