Suspension arm

Abstract

An arm part (11) of this suspension arm is formed such that when the suspension arm is viewed in a plan view from a side surface direction perpendicular to both a virtual straight line connecting a ball joint part (12) and a rear bush part (13) and the thickness direction of the arm part (11), the arm part (11) has a maximum thickness part at which the thickness is maximum within a range of ± 100 mm from the rear bush part (13) formation position along the virtual straight line, and said thickness is smaller than the maximum thickness part at the connection part with the ball joint part (12) and the connection part with the rear bush part (13).

Description

Suspension arms

[0001] This application claims priority to Japanese Patent Application No. 2024-127877, filed on August 2, 2024, the contents of which are incorporated herein by reference.

[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 base components of the suspension that absorbs the impact that the tires receive from the road surface while the vehicle is moving, and are components that absorb vibrations, and absorb lateral stress that occurs when cornering, and longitudinal stress that occurs when accelerating and decelerating (see, for example, Patent Documents 1 and 2).

[0004] The lower arm generally comprises a generally 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.

[0006] Japanese Unexamined Patent Publication No. 5-112111 (A) Japanese Unexamined Patent Publication No. 2004-299663 (A)

[0007] However, with the suspension members disclosed in Patent Documents 1 and 2, if they are made of an 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.

[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, and the arm portion having a maximum width portion at the bent portion when viewed in plan from above perpendicular to the thickness direction of the arm portion, the arm portion has a maximum width portion 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 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 at which 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 arm portion is formed so that the thickness at a connection portion with the ball joint portion and a connection portion with the rear bush portion is smaller than the maximum thickness portion.

[0011] (2) The suspension arm according to (1), wherein a 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.

[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.

[0017] FIG. 1 is an external perspective view showing a lower arm which is a suspension member of an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a cross section perpendicular to the extension direction of the arm portion. FIG. 2 is another cross-sectional view showing a cross section perpendicular to the extension direction of the arm portion. FIG. 3 is a plan view of the suspension arm when viewed from above perpendicular to the thickness direction of the arm portion. FIG. 4 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 bush portion and to the thickness direction of the arm portion. FIG. 5 is a plan view of the lower arm of Conventional Example 1 in Verification Example 1. FIG. 6 is a graph showing the results of Verification Example 2. FIG. 7 is a graph showing the results of Verification Example 3. FIG. 8 is a graph showing the results of Verification Example 4. FIG. 9 is a graph showing the results of Verification Example 5. FIG. 10 is an external perspective view of the lower arm used in Verification Example 6. FIG. 11 is an external perspective view of the lower arm used in Verification Example 6.

[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] 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 bushing portion 13 formed at the other end of the arm portion 11, and a front bushing portion 14 formed 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 direction of the large arrow at point A pointing to the rear of the vehicle, but in some vehicle models the lower arm is mounted so that the direction of the large arrow at point A points to the front of the vehicle (point B is the rear bush, point C is the FR bush). Even in this case, the objective is to provide a suspension member that does not undergo torsional deformation or buckling deformation due to a load in the direction of the large arrow and that can be made lighter. Furthermore, the direction of the large arrow is at a slight angle to the plane connecting points A, B, and C.

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

[0022] In this embodiment, the heights of the ribs 18, 18 along the thickness direction HD, i.e., the thickness H of the arm portion 11 described below, are formed to be the same for the rib 18 on one side and the rib 18 on the other side, but they can also be formed to be different from each other. Although not particularly limited, when the thicknesses of the two ribs are formed to be different from each other, when the thickness of the rib 18 on one side is H1 and the thickness of the rib 18 on the other side is H2, H1 / H2 may be 1.2 to 10, 1.5 to 8, or 2 to 6.

[0023] 3, the arm portion 11 may have a concave cross section perpendicular to the extension direction. Alternatively, the arm portion 11 may have a rectangular cross section perpendicular to the extension direction. If the cross section of the arm portion 11 is rectangular, the overall mass increases, but the 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.

[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 12, point B of front bush 14, and point C of rear bush 13 shown in Figure 1 are defined as points indicating the centers of the cylindrical central axes of the respective members. Also, an imaginary line Q connecting ball joint 12 and rear bush 13 is defined as a line connecting point A and point C.

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

[0029] 5 is a plan view of the suspension arm as viewed from a side direction perpendicular to an imaginary line connecting the ball joint and the rear bushing and to the thickness direction of the arm portion. That is, Fig. 5 is a plan view of lower arm (suspension member) 10 as 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] 5, the thickness H of the arm portion 11 along the thickness direction HD (i.e., the height of the rib 18 in FIG. 2) of the lower arm (suspension member) 10 of this embodiment has a maximum thickness portion Hm at a position corresponding to a range of ±100 mm, or ±70 mm in this embodiment, from point B on the imaginary line Q, where the front bush portion 14 is formed, along this imaginary line Q. Note that in this embodiment, the direction from point B to point A along the imaginary line Q in FIG. 5 is represented as − (minus), and the direction from point B to point C is represented as + (plus).

[0031] The arm portion 11 is formed so 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 to the configuration in which the thickness H of the arm portion 11 of the lower arm (suspension member) 10 gradually decreases from the maximum thickness point Hm toward one end and the other end of the arm portion 11, the maximum thickness point 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 points Hm can be provided and the thickness H of the arm portion 11 between these two maximum thickness points Hm can be formed so as to be smaller than the maximum thickness point Hm. Furthermore, the thickness H of the arm portion 11 can decrease uniformly from the maximum thickness point Hm toward one end and the other end of the arm portion 11, or the thickness H can decrease nonlinearly.

[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 thicknesses of the connection portions with the ball joint portion 12 and with the rear bush portion 13 are smaller than the maximum thickness portion. This makes it possible to increase the maximum deformation load against the rear load F shown in FIG. 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.

[0036] Several examples of the lower arm (suspension member) of the present invention are shown below. (Verification Example 1) Like 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 uniform when viewed in plan from the same perspective as in Figure 5, as shown in Figure 6.

[0037] Table 1 shows the dimensions of each part in the cross section of the H-shaped cross section of arm portion 11 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]

[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 achieved 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 a lower arm (suspension member) that achieved both weight reduction and a maximum deformation load could be obtained 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 by forming an arm portion with a shape in which the thickness H gradually decreases from there toward points A and C.

[0041] (Verification Example 2) In the lower arm (suspension member) shown in FIG. 1 described as an embodiment of the present invention, when viewed in plan as shown in FIG. 5, verification was conducted to determine 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. Note that in Table 3, the direction from point B to point A along the imaginary line Q in FIG. 5 is represented as - (minus), and the direction from point B to point C is represented as + (plus). FIG. 7 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 3.

[0042]

[0043] 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 having an H-shaped cross section shown in FIG. 2 is set to 15 mm, verification was conducted to determine 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 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. 5 is indicated as - (minus), and the direction from point B to point C is indicated as + (plus). FIG. 8 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 5.

[0045]

[0046] According to the results shown in Table 5 and Fig. 8, the maximum deformation load ratio relative to ±0 mm (point B) was maximized at 1.02 by setting the maximum thickness part Hm at a position between -48.3 mm and -28.3 mm from point B toward point A. 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 the rib 18 of the arm portion 11 having an H-shaped cross section shown in FIG. 2 was set to 10 mm, and the distances between point A and point C and between point B and point 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. 5 is denoted as − (minus), and the direction from point B to point C is denoted as + (plus). A graph showing the relationship between the distance from point B to the maximum thickness portion and the load ratio based on the results of Table 7 is shown in FIG. 9.

[0048]

[0049] 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, verification was conducted to determine how far the position of the maximum thickness portion 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 bush portion 14 was shortened. H and h (see FIG. 2) in this verification example 5 are shown in Table 8. The results of verification example 5 are shown in Table 9. In Table 9, the direction from point B to point A along the imaginary line Q in FIG. 5 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 portion to the load ratio based on the results of Table 9.

[0051]

[0052] 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 FIGS. 11 and 12 , the ratio of maximum deformation loads was measured for a case in which two maximum thickness portions were formed within a range of ±100 mm from point B on the arm portion of a lower arm, compared to a case in which a single maximum thickness portion was formed (at a position −38.3 mm from point B). In the lower arm of FIG. 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 FIG. 5 . In addition, in the lower arm of FIG. 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 FIG. 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 FIG. 5 is denoted as − (minus), and the direction from point B to point C is denoted as + (plus).

[0054]

[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 of 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 was abrupt and the load ratio fell to about 0.8.

[0056] (Verification Example 7) In the arm portion of the lower arm, the maximum deformation load ratio was measured for the following cases: a maximum thickness portion was formed at a position −18.3 mm from point B; a maximum thickness portion was formed with a predetermined width (flat range) from this position within a range of ±10 mm, ±20 mm, ±30 mm, and ±40 mm; and a maximum thickness portion was formed at a position +20 mm from point B and with a predetermined width (flat range) from ±10 mm. 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 FIG. 5 is represented as − (minus), and the direction from point B to point C is represented as + (plus).

[0057]

[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.

[0059] 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.

[0060] 10 Lower arm (suspension member) 11 Arm portion 12 Ball joint portion 13 Rear bush portion 14 Front bush portion 18 Rib 19 Bent portion

Claims

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 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, the arm portion has a maximum width portion at the bent portion, and the width of the arm portion gradually decreases from the maximum width portion towards the ball joint portion and towards 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 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 formation position of the front bush portion, and 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.

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

3. A suspension arm as set forth in claim 2, wherein the two rib-like portions protruding in 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.

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

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

6. A suspension arm according to any one of claims 1 to 4, wherein the maximum thickness portion is formed so as to extend at a predetermined width along the imaginary straight line.

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