Suspension arms

Abstract

To provide a suspension arm capable of improving aerodynamic characteristics.SOLUTION: A lower arm 30 includes an arm body 40 and a resin molding part 60 molded by inserting the arm body 40. The arm body 40 has a bottom wall 41, a first lateral wall 42A, a second lateral wall 42B, and a first flange 45A. The resin molding part 60 has a first lateral wall covering part 61 for covering an outward surface of the first lateral wall 42A, a first flange covering part 62 for covering the first flange 45A, and a first projection 63 projecting downward from the first flange covering part 62 and continuous to the first lateral wall covering part 61. The first flange covering part 62 is disposed with a first inclined plane 62a inclined so as to be positioned at the upper side in an opposite direction toward the base end side of the first flange 45A. The first projection 63 is disposed with a first curve surface 63a curved so as to gradually reduce a distance to the first lateral wall covering part 61 toward the lower side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Conventionally, vehicles such as automobiles are provided with suspension arms that connect the vehicle body to the wheels. The suspension arm described in Patent Document 1 includes a main body and a cover bonded to the main body by vulcanization. The main body has a bottom wall and a pair of opposing side walls that protrude from the bottom wall. The pair of side walls have flanges at their tips that protrude in opposite directions.

[0003] The cover has a front half that covers the front of the pair of side walls, which is located at the front of the vehicle. The front half covers a flange provided on the side wall located at the front of the vehicle. The cross-sectional shape of the front half is roughly triangular, which makes the cross-sectional shape of the suspension arm closer to a streamlined shape. This allows the cover to function as a straightening member that reduces air resistance of the wind coming from the front as the vehicle moves. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-56463 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 1 does not specifically mention the effect that the shape of the part of the cover that covers the flange has on the aerodynamic characteristics of the suspension arm, which means there is room for improvement in terms of improving the aerodynamic characteristics of the suspension arm. [Means for solving the problem]

[0006] A suspension arm for solving the above problem is a suspension arm comprising an arm main body and a resin molded portion formed by inserting the arm main body, wherein the arm main body has a bottom wall, a first side wall and a second side wall that protrude upward from the bottom wall and face each other, and a flange that protrudes from a tip end of the first side wall in the protruding direction to the opposite side from the second side wall in the opposing direction in which the first side wall and the second side wall face each other, and the resin molded portion has a first side wall covering portion that covers the outer surface of the first side wall, a flange covering portion that covers the flange, and a protruding portion that protrudes downward from the flange covering portion and is connected to the first side wall covering portion, and the flange covering portion has an inclined surface that is inclined so that it is positioned higher as it approaches the base end of the flange in the opposing direction, and the protruding portion has a curved surface that is curved so that the distance to the first side wall covering portion gradually decreases as it goes downward. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a lower arm as an embodiment of a suspension arm. [Figure 2] FIG. 2 is a schematic diagram showing a suspension system of a vehicle to which the lower arm of FIG. 1 is applied. [Figure 3] FIG. 3 is a perspective view showing the lower arm of FIG. [Figure 4] 4 is an exploded perspective view showing the arm body and the reinforcing member that constitute the lower arm of FIG. 1, separated from each other. [Figure 5] 5 is a perspective view showing the bottom surface of the lower arm of FIG. 1. FIG. [Figure 6] 6 is an enlarged cross-sectional view of the lower arm of FIG. 1, focusing on the first flange covering portion. [Figure 7] 7 is an enlarged cross-sectional view of the lower arm of FIG. 1, focusing on the second flange covering portion. [Figure 8] FIG. 8 is a graph showing the relationship between the inclined surface angle of the first inclined surface of the lower arm and the Cd value. [Figure 9] FIG. 9 is a graph showing the relationship between the inclined surface angle of the first inclined surface of the lower arm and the Cl value. [Figure 10] FIG. 10 is a graph showing the relationship between the inclined surface angle of the second inclined surface of the lower arm and the Cd value. [Figure 11] FIG. 11 is a graph showing the relationship between the inclined surface angle of the second inclined surface of the lower arm and the Cl value. [Figure 12] FIG. 12 is a graph showing the relationship between the radius of curvature of the first curved surface of the lower arm and the Cd value. [Figure 13] FIG. 13 is a graph showing the relationship between the radius of curvature of the first curved surface of the lower arm and the Cl value. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, with reference to FIGS. 1 to 13, an embodiment in which a suspension arm is embodied as a lower arm of a suspension system will be described. (suspension system 10) 2, the suspension system 10 is disposed between the vehicle body 100 and the wheel 110, and supports the wheel 110 so that the wheel 110 can swing freely relative to the vehicle body 100. The suspension system 10 is configured to absorb shocks transmitted from the road surface to the vehicle body 100 via the wheel 110, and to press the wheel 110 against the road surface.

[0009] The suspension system 10 includes an upper arm 20, a lower arm 30, and a suspension spring 70. The upper arm 20 and the lower arm 30 extend in the vehicle width direction. The upper arm 20 is disposed above the lower arm 30. The upper arm 20 and the lower arm 30 connect a frame 101 of a vehicle body 100 to a support member 111 that supports a wheel 110.

[0010] The suspension spring 70 extends in the vertical direction. The lower end of the suspension spring 70 is supported by the lower arm 30. (Lower arm 30) 3, the lower arm 30 has an arm main body 40, a reinforcing member 50, and a resin molded portion 60. The reinforcing member 50 is joined to the arm main body 40. The resin molded portion 60 is molded by inserting the arm main body 40 and the reinforcing member 50 into it.

[0011] (Arm body 40) As shown in FIG. 4, the arm main body 40 has a bottom wall 41, a first side wall 42A, a second side wall 42B, a first flange 45A, and a second flange 45B. The bottom wall 41 has an elongated shape extending in the vehicle width direction. The first side wall 42A and the second side wall 42B protrude upward from both side edges of the bottom wall 41 and face each other. The first flange 45A protrudes from the tip of the first side wall 42A in the protruding direction to the opposite side from the second side wall 42B in the opposing direction in which the first side wall 42A and the second side wall 42B face each other. The second flange 45B protrudes from the tip of the second side wall 42B in the protruding direction to the opposite side from the first side wall 42A in the opposing direction. The arm main body 40 is open upward.

[0012] The arm body 40 is disposed so that the first side wall 42A and the second side wall 42B are located at the front and rear of the vehicle, respectively. Hereinafter, the direction in which the bottom wall 41 extends will be referred to as the X-axis direction. The opposing direction in which the first side wall 42A and the second side wall 42B face each other will be referred to as the Y-axis direction. The direction perpendicular to both the X-axis direction and the Y-axis direction will be referred to as the Z-axis direction. The X-axis direction is the direction that coincides with the vehicle width direction. The Y-axis direction is the direction that coincides with the front-rear direction of the vehicle. The Z-axis direction is the direction that coincides with the up-down direction.

[0013] The arm body 40 is formed by, for example, pressing a metal plate, and may be made of a metal material such as high-tensile steel. An intermediate portion 41a of the bottom wall 41 in the X-axis direction has a larger width in the Y-axis direction than the other portions. The width of the intermediate portion 41a in the Y-axis direction gradually decreases toward both ends in the X-axis direction. The intermediate portion 41a of the bottom wall 41 has a spindle shape when viewed from the Z-axis direction.

[0014] The portions of the bottom wall 41 adjacent to the middle portion 41a on both sides in the X-axis direction extend linearly in the X-axis direction. The first side wall 42A and the second side wall 42B are symmetrical in the Y-axis direction. Therefore, hereinafter, the configuration of the first side wall 42A will be described, and a description of the configuration of the second side wall 42B may be omitted.

[0015] The first side wall 42A extends over the entire X-axis direction of the bottom wall 41. One end of the first side wall 42A in the X-axis direction, which constitutes a first connecting portion 47 described later, protrudes in the X-axis direction beyond the bottom wall 41.

[0016] As shown in FIG. 1, the portion of the first side wall 42A that protrudes from the middle portion 41a has an inclined portion 43 that continues to the bottom wall 41 and a straight portion 44 that continues to the inclined portion 43. The inclined portion 43 is inclined so as to move away from the second side wall 42B in the Y-axis direction as it goes upward.

[0017] The straight portion 44 extends linearly in the Z-axis direction. The straight portion 44 of the first side wall 42A and the straight portion 44 of the second side wall 42B extend parallel to each other. 4, the first flange 45A extends over the entire first side wall 42A in the X-axis direction, and the second flange 45B extends over the entire second side wall 42B in the X-axis direction.

[0018] The arm main body 40 has a spring accommodating portion 46, a first connecting portion 47, and a second connecting portion 48. The spring accommodating portion 46 forms the center portion in the X-axis direction of the arm main body 40. The first connecting portion 47 and the second connecting portion 48 are connected to both ends of the spring accommodating portion 46 in the X-axis direction, respectively.

[0019] (Spring housing 46) The spring accommodating portion 46 defines an accommodating space for accommodating the lower end of the suspension spring 70 by the middle portion 41a, the first side wall 42A, and the second side wall 42B.

[0020] The first side wall 42A and the second side wall 42B of the spring accommodating portion 46 bulge out in opposite directions in the Y-axis direction. A through-hole 46a that penetrates in the Z-axis direction is provided in the bottom of the spring accommodating portion 46, that is, the intermediate portion 41a. The through-hole 46a has a circular shape.

[0021] (1st connection part 47) The first connecting portion 47 is a portion of the arm main body 40 that is connected to the vehicle body 100. The first side wall 42A and the second side wall 42B of the first connecting portion 47 extend parallel to each other in the X-axis direction. The first side wall 42A and the second side wall 42B of the first connecting portion 47 protrude in the X-axis direction beyond the edge of the bottom wall 41 in the X-axis direction.

[0022] A first connecting hole 47a penetrating in the Y-axis direction is provided in each of the first side wall 42A and the second side wall 42B of the first connecting portion 47. The first connecting portion 47 is rotatably connected to the frame 101 of the vehicle body 100 via a rotation shaft (not shown) inserted into the first connecting hole 47a.

[0023] (Second connection part 48) The second connecting portion 48 is a portion of the arm body 40 that is connected to the wheel 110. The first side wall 42A and the second side wall 42B of the second connecting portion 48 extend parallel to each other in the X-axis direction.

[0024] A second connecting hole 48a penetrating in the Y-axis direction is provided in each of the first side wall 42A and the second side wall 42B of the second connecting portion 48. The second connecting portion 48 is rotatably connected to the support member 111 of the wheel 110 via a rotating shaft (not shown) inserted into the second connecting hole 48a.

[0025] (reinforcing member 50) The reinforcing member 50 has a flat plate shape. The reinforcing member 50 covers the spring accommodating portion 46 from above. The reinforcing member 50 has a spindle shape when viewed from the Z-axis direction.

[0026] The reinforcing member 50 may be made of a metal material such as high-tensile steel. The reinforcing member 50 is joined to the upper surfaces of the first flange 45A and the second flange 45B in the spring accommodating portion 46 by, for example, welding.

[0027] Both end edges of the reinforcing member 50 in the Y axis direction are located inside the end edges of the first flange 45A and the second flange 45B of the spring accommodating portion 46 in the Y axis direction. The reinforcing member 50 is provided with an insertion hole 50a into which the suspension spring 70 is inserted. The insertion hole 50a communicates with the accommodation space of the spring accommodation portion 46.

[0028] (Resin molding part 60) As shown in FIG. 1, the resin molded portion 60 has a first side wall covering portion 61, a first flange covering portion 62, a plurality of first protrusions 63, a second side wall covering portion 64, a second flange covering portion 65, a plurality of second protrusions 66, and a bottom wall covering portion 67.

[0029] The resin molded portion 60 is formed by placing the arm main body 40 to which the reinforcing member 50 is joined as an insert inside a mold device (not shown), and then filling the inside of the mold device with resin.

[0030] The resin molded portion 60 may be made of, for example, a thermoplastic resin material. (First side wall covering part 61) The first sidewall covering portion 61 covers the outer surface of the first sidewall 42A. More specifically, the first sidewall covering portion 61 covers a portion of the outer surface of the first sidewall 42A excluding the peripheries of the first connecting hole 47a and the second connecting hole 48a. The outer surface of the first sidewall 42A is the surface of the first sidewall 42A opposite to the surface facing the second sidewall 42B.

[0031] The first sidewall covering portion 61 has an inclined covering portion 61a that covers the inclined portion 43 of the first sidewall 42A and a straight covering portion 61b that covers the straight portion 44 of the first sidewall 42A. The inclined covering portion 61a extends along the outer surface of the inclined portion 43 of the first sidewall 42A. The straight covering portion 61b extends along the outer surface of the straight portion 44 of the first sidewall 42A.

[0032] The first sidewall covering portion 61 covers both ends of the first sidewall 42A in the X-axis direction from both sides in the Y-axis direction and one side in the X-axis direction. (First flange covering portion 62) The first flange covering portion 62 covers the first flange 45A. The first flange covering portion 62 covers both sides of the first flange 45A in the Z-axis direction and one side in the Y-axis direction. The first flange covering portion 62 covers the entire first flange 45A in the X-axis direction.

[0033] In the spring accommodating portion 46, the first flange covering portion 62 covers the first flange 45A as well as the joint portion between the first flange 45A and the reinforcing member 50. 6, a first inclined surface 62a is provided on the upper part of the first flange covering portion 62. The first inclined surface 62a is inclined so as to be positioned higher in the Y-axis direction toward the base end side of the first flange 45A, i.e., toward the rear.

[0034] The first inclined surface 62a is provided, for example, over the entire first flange covering portion 62 in the X-axis direction. The first inclined surface 62a extends from above the tip end to above the base end of the first flange 45A. The upper surface of the first flange covering portion 62 is, for example, formed solely by the first inclined surface 62a.

[0035] (First protrusion 63) 5, a plurality of first protrusions 63 are provided at intervals in the X-axis direction on the lower part of the first flange covering portion 62. The plurality of first protrusions 63 are provided on a portion of the resin molded portion 60 that covers the spring accommodating portion 46.

[0036] The first protrusion 63 is formed in a thin plate shape with the thickness direction being in the X-axis direction. 6, the first protruding portion 63 protrudes downward and is connected to the linear covering portion 61b of the first sidewall covering portion 61. Therefore, the first protruding portion 63 connects the first flange covering portion 62 and the linear covering portion 61b.

[0037] The first protruding portion 63 is provided with a first curved surface 63a that is curved so that the distance to the linear covering portion 61b gradually decreases with increasing distance from the first flange covering portion 62. More specifically, the first curved surface 63a is curved so that the distance to the linear covering portion 61b in the Y-axis direction gradually decreases with increasing downward movement. The first curved surface 63a has an arc shape when viewed from the X-axis direction. The lower end of the first curved surface 63a is seamlessly connected to the linear covering portion 61b.

[0038] (Second side wall covering part 64) 1, the second sidewall covering portion 64 covers the outer surface of the second sidewall 42B. More specifically, the second sidewall covering portion 64 covers a portion of the outer surface of the second sidewall 42B excluding the peripheries of the first connecting hole 47a and the second connecting hole 48a. The outer surface of the second sidewall 42B is the surface of the second sidewall 42B opposite to the surface facing the first sidewall 42A.

[0039] The second sidewall covering portion 64 has an inclined covering portion 64a that covers the inclined portion 43 of the second sidewall 42B and a straight covering portion 64b that covers the straight portion 44 of the second sidewall 42B. The inclined covering portion 64a extends along the outer surface of the inclined portion 43 of the second sidewall 42B. The straight covering portion 64b extends along the outer surface of the straight portion 44 of the second sidewall 42B.

[0040] The second sidewall covering portion 64 covers both ends of the second sidewall 42B in the X-axis direction from both sides in the Y-axis direction and one side in the X-axis direction. (Second flange covering portion 65) The second flange covering portion 65 covers the second flange 45B. The second flange covering portion 65 covers both sides of the second flange 45B in the Z-axis direction and one side in the Y-axis direction. The second flange covering portion 65 covers the entire second flange 45B in the X-axis direction.

[0041] In the spring accommodating portion 46, the second flange covering portion 65 covers the joint portion between the second flange 45B and the reinforcing member 50 in addition to the second flange 45B. A second inclined surface 65a is provided at the rear end of the upper part of the second flange covering portion 65. The second inclined surface 65a is located above the tip end of the second flange 45B. The second inclined surface 65a is inclined in the Y-axis direction so that it is positioned lower toward the tip end of the second flange 45B, i.e., toward the rear of the vehicle. The second inclined surface 65a is provided, for example, over the entire second flange covering portion 65 in the X-axis direction.

[0042] A third inclined surface 65b is provided at the front end portion of the upper portion of the second flange covering portion 65. The third inclined surface 65b is located above the base end portion of the second flange 45B. The third inclined surface 65b is provided at a position closer to the first side wall 42A in the Y-axis direction than the second inclined surface 65a. The third inclined surface 65b is inclined so as to be positioned higher in the Y-axis direction toward the tip end side of the second flange 45B, i.e., toward the rear of the vehicle. The third inclined surface 65b is provided, for example, over the entire second flange covering portion 65 in the X-axis direction.

[0043] The second inclined surface 65a and the third inclined surface 65b are adjacent to each other in the Y-axis direction. The boundary between the second inclined surface 65a and the third inclined surface 65b is located at the center of the second flange covering portion 65 in the Y-axis direction. The upper surface of the second flange covering portion 65 is formed, for example, only by the second inclined surface 65a and the third inclined surface 65b.

[0044] (Second protrusion 66) A plurality of second protrusions 66 are provided at intervals in the X-axis direction on the lower part of the second flange covering portion 65. The plurality of second protrusions 66 are provided on a portion of the resin molded portion 60 that covers the spring accommodating portion 46. The plurality of second protrusions 66 are provided at the same positions as the plurality of first protrusions 63 in the Y-axis direction.

[0045] 7, the second protruding portion 66 protrudes downward and is connected to the linear covering portion 64b of the second sidewall covering portion 64. Therefore, the second protruding portion 66 connects the second flange covering portion 65 and the linear covering portion 64b.

[0046] The second protrusion 66 is provided with a second curved surface 66a that is curved so that the distance to the linear covering portion 64b gradually decreases with increasing distance from the second flange covering portion 65. More specifically, the second curved surface 66a is curved so that the distance to the linear covering portion 64b in the Y-axis direction gradually decreases with increasing downward movement. The second curved surface 66a has an arc shape when viewed from the X-axis direction. The lower end of the second curved surface 66a is seamlessly connected to the linear covering portion 64b.

[0047] (Bottom wall covering part 67) 1 and 5, the bottom wall covering portion 67 covers the entire outer surface of the bottom wall 41. The outer surface of the bottom wall 41 is the lower surface of the bottom wall 41.

[0048] The bottom wall covering portion 67 covers both ends of the bottom wall 41 in the X-axis direction from both sides in the Z-axis direction and from one side in the X-axis direction. As shown in FIG. 1, the bottom wall covering portion 67 covers the periphery of the through-hole 46a from both sides in the Z-axis direction and from the inner surface side of the through-hole 46a.

[0049] (Simulation results) The aerodynamic characteristics of the lower arm 30 when the inclined surface angle θ1 of the first inclined surface 62a, the inclined surface angle θ2 of the second inclined surface 65a, and the curvature radius R1 of the first curved surface 63a are changed will be described using simulation results. In this simulation, the aerodynamic characteristics of the lower arm 30 were evaluated when air flows from the first side wall 42A side to the second side wall 42B side while the vehicle is traveling.

[0050] As shown in Fig. 6, the inclined surface angle θ1 in this simulation is the angle between the virtual axis V extending in the Y-axis direction and the first inclined surface 62a when the first flange covering portion 62 is viewed from the X-axis direction. As shown in Fig. 7, the inclined surface angle θ2 is the angle between the virtual axis V and the second inclined surface 65a when the second flange covering portion 65 is viewed from the X-axis direction.

[0051] FIG. 8 is a graph showing the change in the Cd value (hereinafter simply referred to as the Cd value) which is the drag coefficient of the lower arm 30 when the inclined surface angle θ1 is changed from 0° to 10°. As shown in Fig. 8, it was confirmed that the Cd value decreases as the inclined surface angle θ1 increases. In this simulation, the Cd value was smallest when the inclined surface angle θ1 was 10°.

[0052] FIG. 9 is a graph showing the change in the Cl value, which is the lift coefficient of the lower arm 30 (hereinafter simply referred to as the Cl value), when the inclined surface angle θ1 is changed from 0° to 10°. As shown in Figure 9, it was confirmed that the Cl value decreases as the inclined surface angle θ1 approaches 5° from 0°, and increases as the inclined surface angle θ1 increases beyond 5°. In this simulation, the Cl value was smallest when the inclined surface angle θ1 was 5°. Note that the Cl value when the inclined surface angle θ1 was 10° was larger than when the inclined surface angle θ1 was 0°.

[0053] FIG. 10 is a graph showing the change in the Cd value when the inclined surface angle θ2 is changed from 0° to 10°. As shown in Fig. 10, it was confirmed that the Cd value decreases as the inclined surface angle θ2 increases. In this simulation, the Cd value was smallest when the inclined surface angle θ2 was 10°.

[0054] FIG. 11 is a graph showing the change in Cl value when the inclined surface angle θ2 is changed from 0° to 10°. 11, it was confirmed that the Cl value decreases as the inclined surface angle θ2 approaches 10°. In this simulation, the Cl value was smallest when the inclined surface angle θ2 was 10°.

[0055] FIG. 12 is a graph showing the change in the Cd value when the radius of curvature R1 is changed from 10 mm to 50 mm. As shown in Fig. 12, it was confirmed that the Cd value decreases as the radius of curvature R1 increases. In this simulation, the Cd value was smallest when the radius of curvature R1 was 50 mm.

[0056] FIG. 13 is a graph showing the change in Cl value when the radius of curvature R1 is changed from 10 mm to 50 mm. As shown in FIG. 13, it was confirmed that the Cl value increased as the radius of curvature R1 increased.

[0057] If the Cl value becomes an excessively negative value, it will cause an increase in the rolling resistance of the vehicle, so it is preferable that the Cl value be approximately 0. In this simulation, when the radius of curvature R1 was 10 mm, the Cl value was smaller than 0, and when the radius of curvature R1 was 50 mm, the Cl value was larger than 0. Furthermore, when the radius of curvature R1 was about 30 mm, the Cl value was approximately 0.

[0058] From the above, it can be seen that the aerodynamic characteristics of the lower arm 30 can be effectively improved by setting the inclined surface angle θ1 to 5°, the inclined surface angle θ2 to 10°, and the curvature radius R1 to 30 mm.

[0059] Note that an air flow that tries to push the first flange covering portion 62 upward occurs below the first flange covering portion 62. For this reason, in order to reduce the Cl value, it is preferable that the length of the first flange covering portion 62 in the Y-axis direction be short within a range that ensures a welding allowance between the first flange 45A and the reinforcing member 50. The same applies to the second flange covering portion 65.

[0060] The operation and effects of this embodiment will be described. (1) The lower arm 30 includes an arm main body 40 and a resin molded portion 60 molded by inserting the arm main body 40. The arm main body 40 includes a bottom wall 41, a first side wall 42A and a second side wall 42B that protrude upward from the bottom wall 41 and face each other, and a first flange 45A that protrudes from a tip end of the first side wall 42A in the protruding direction to a side opposite the second side wall 42B in the opposing direction. The resin molded portion 60 includes a first side wall covering portion 61 that covers the outer surface of the first side wall 42A, a first flange covering portion 62 that covers the first flange 45A, and a first protruding portion 63 that protrudes downward from the first flange covering portion 62 and is continuous with the first side wall covering portion 61. The first flange covering portion 62 is provided with a first inclined surface 62a that is inclined upward toward the base end of the first flange 45A in the opposing direction. The first protruding portion 63 is provided with a first curved surface 63a that is curved so that the distance to the first sidewall covering portion 61 gradually decreases as it goes downward.

[0061] According to the above configuration, as shown by the arrows in Figure 6, air passing above the first flange covering portion 62 from the first side wall 42A toward the second side wall 42B while the vehicle is traveling flows obliquely upward along the first inclined surface 62a. This straightens the air flow, thereby suppressing an increase in drag generated on the lower arm 30. Furthermore, the air flowing along the first inclined surface 62a presses the first inclined surface 62a downward. This suppresses an increase in lift generated on the lower arm 30.

[0062] 6, air passing under the first flange covering portion 62 from the first side wall 42A side toward the second side wall 42B side flows obliquely downward along the first curved surface 63a. This straightens the air flow, thereby suppressing an increase in drag generated on the lower arm 30. Furthermore, because the air flows obliquely downward along the first curved surface 63a, a flow that tends to push the first flange covering portion 62 upward is less likely to be generated. This suppresses an increase in lift generated on the lower arm 30.

[0063] As a result of the above, the aerodynamic characteristics of the lower arm 30 can be improved. (2) The arm body 40 has a second flange 45B that protrudes from the tip of the second side wall 42B in the protruding direction to the opposite side from the first side wall 42A in the opposing direction. The resin molded portion 60 has a second flange covering portion 65 that covers the second flange 45B. The second flange covering portion 65 is provided with a second inclined surface 65a that is inclined downward toward the tip of the second flange 45B in the opposing direction.

[0064] According to the above configuration, as shown by the arrows in Fig. 7, air passing above the second flange covering portion 65 from the first side wall 42A side toward the second side wall 42B side while the vehicle is traveling flows obliquely downward along the second inclined surface 65a. This straightens the air flow, thereby suppressing an increase in drag generated on the lower arm 30. Furthermore, the air flowing along the second inclined surface 65a presses the second inclined surface 65a downward. This suppresses an increase in lift generated on the lower arm 30. Therefore, the aerodynamic characteristics of the lower arm 30 can be improved.

[0065] (3) The resin molded portion 60 has a second sidewall covering portion 64 that covers the outer surface of the second sidewall 42B, and a second protruding portion 66 that protrudes downward from the second flange covering portion 65 and is continuous with the second sidewall covering portion 64. The second protruding portion 66 is provided with a second curved surface 66a that is curved so that the distance to the second sidewall covering portion 64 gradually decreases as it extends downward.

[0066] According to the above configuration, as shown by the arrows in Figure 7, air passing under the second flange covering portion 65 from the bottom wall 41 side toward the top while the vehicle is running flows obliquely upward along the second curved surface 66a. This straightens the air flow, thereby suppressing an increase in drag generated on the lower arm 30. Furthermore, because the air flows obliquely upward along the second curved surface 66a, a flow that tends to push the second flange covering portion 65 upward is less likely to occur. This suppresses an increase in lift generated on the lower arm 30. This improves the aerodynamic characteristics of the lower arm 30.

[0067] (4) The second flange covering portion 65 is provided with a third inclined surface 65b that is inclined upward toward the tip end of the second flange 45B. The third inclined surface 65b is provided at a position closer to the first side wall 42A in the opposing direction than the second inclined surface 65a.

[0068] According to the above configuration, as shown by the arrows in FIG. 7, when the vehicle is traveling, air passing above the second flange covering portion 65 from the first side wall 42A side toward the second side wall 42B side flows obliquely upward along the third inclined surface 65b and then flows obliquely downward along the second inclined surface 65a. This straightens the air flow, thereby suppressing an increase in drag generated on the lower arm 30. Furthermore, the air flowing along the third inclined surface 65b presses the third inclined surface 65b downward. This suppresses an increase in lift generated on the lower arm 30. Therefore, the aerodynamic characteristics of the lower arm 30 can be improved.

[0069] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0070] The third inclined surface 65b may be provided on a portion of the second flange covering portion 65 in the X-axis direction. The third inclined surface 65b may be omitted from the second flange covering portion 65.

[0071] The second protrusion 66 may be omitted from the resin molded portion 60. The second inclined surface 65a may be provided on a portion of the second flange covering portion 65 in the X-axis direction.

[0072] The second inclined surface 65a may be omitted from the second flange covering portion 65. The second flange covering portion 65 may be omitted from the resin molded portion 60. In this case, the second flange 45B may be omitted from the arm main body 40.

[0073] The first inclined surface 62a may be provided on a portion of the first flange covering portion 62 in the X-axis direction. The resin molded portion 60 may have a single first protruding portion 63 that extends continuously in the X-axis direction.

[0074] The resin molded portion 60 may have a single second protruding portion 66 that extends continuously in the X-axis direction. The reinforcing member 50 may be omitted from the lower arm 30.

[0075] The lower arm 30 may be applied to the upper arm 20 of the suspension system 10 . [Explanation of symbols]

[0076] V: Virtual axis θ1, θ2…Slope angle R1…curvature radius 10…Suspension device 20...Upper arm 30...Lower arm 40...Arm body 41...Bottom wall 41a...middle part 42A…1st side wall 42B…Second side wall 43…Slope part 44...Straight section 45A...First flange 45B...Second flange 46...Spring housing 46a...Through hole 47...1st connection part 47a...1st connection hole 48…Second connection part 48a…Second connection hole 50...Reinforcing member 50a...insertion hole 60…Resin molding part 61...First side wall covering part 61a, 64a...Sloped covering portion 61b, 64b...Straight coated section 62...First flange covering part 62a...first slope 63...first protrusion 63a...First curved surface 64…Second side wall covering part 65...Second flange covering part 65a…Second slope 65b…Third slope 66...Second protrusion 66a...Second curved surface 67...Bottom wall covering part 70...Suspension spring 100...Body 101...Frame 110...Wheel 111...Support member

Claims

1. A suspension arm comprising: an arm body; and a resin molded portion molded by inserting the arm body, the arm body has a bottom wall, a first side wall and a second side wall that protrude upward from the bottom wall and face each other, and a flange that protrudes from a tip end of the first side wall in a protruding direction to a side opposite the second side wall in an opposing direction in which the first side wall and the second side wall face each other, The resin molded portion is a first sidewall covering portion that covers an outer surface of the first sidewall; a flange covering portion that covers the flange; a protruding portion that protrudes downward from the flange covering portion and is connected to the first sidewall covering portion, The flange covering portion is provided with an inclined surface that is inclined so as to be positioned upward as it approaches the base end side of the flange in the opposing direction, The protruding portion is provided with a curved surface that is curved such that the distance to the first sidewall covering portion gradually decreases downward. Suspension arm.

2. When the flange is a first flange, the flange covering portion is a first flange covering portion, and the inclined surface is a first inclined surface, the arm body has a second flange that protrudes from a tip end of the second side wall in a protruding direction to a side opposite to the first side wall in the opposing direction, the resin molded portion has a second flange covering portion that covers the second flange, The second flange covering portion is provided with a second inclined surface that is inclined downward toward the tip end of the second flange in the opposing direction.

2. The suspension arm according to claim 1.

3. When the protruding portion is a first protruding portion and the curved surface is a first curved surface, the resin molding portion includes a second sidewall covering portion that covers an outer surface of the second sidewall, and a second protruding portion that protrudes downward from the second flange covering portion and is connected to the second sidewall covering portion; It has The second protruding portion is provided with a second curved surface that is curved so that the distance to the second sidewall covering portion gradually decreases as the second protruding portion extends downward.

3. The suspension arm according to claim 2.

4. The second flange covering portion is provided with a third inclined surface that is inclined so as to be positioned upward toward the tip end side of the second flange, the third inclined surface is provided at a position closer to the first side wall in the opposing direction than the second inclined surface; 4. The suspension arm according to claim 2 or 3.

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