Suspension arm

Abstract

A suspension arm is provided with an arm main body (40) and a resin molded part (60) which is injection molded using the arm main body (40) as an insert. The arm body (40) has a bottom wall (41), a first side wall (42A), a second side wall (42B), and a flange. The resin molded part (60) has: a first side wall covering part (61) that covers the outer surface of the first side wall (42A); a flange covering portion covering the flange; and a protruding part protruding downward from the flange covering part and connected to the first side wall covering part (61). The flange covering portion is provided with an inclined surface that is inclined so as to be positioned upward toward the base end side of the flange in the facing direction. The protruding part is provided with a curved surface which is curved so that the distance to the first side wall covering part (61) gradually decreases toward the lower side.

Description

Technical Field

[0001] The present disclosure relates to a suspension arm. Background Art

[0002] Conventionally, vehicles such as automobiles have a suspension arm that connects a wheel to a vehicle body.

[0003] The suspension arm described in Patent Document 1 includes a main body portion and a cover vulcanized and adhered to the main body portion. The main body portion has a bottom wall and a pair of side walls that project from the bottom wall and face each other. Flanges that project in opposite directions are provided at the front end portions of the pair of side walls.

[0004] The cover has a front half portion that covers the front half of the side wall disposed in front of the vehicle among the pair of side walls. The front half portion covers the flange provided on the side wall, and this flange is disposed in front of the vehicle. Since the cross-sectional shape of the front half portion is substantially triangular, the cross-sectional shape of the suspension arm is close to a streamline shape. Thus, the cover functions as a fairing member that reduces the air resistance of the oncoming traveling wind.

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-56463

[0006] However, in Patent Document 1, the influence of the shape of the portion of the cover that covers the flange on the aerodynamic characteristics of the suspension arm is not specifically mentioned. Therefore, there is room for improvement in enhancing the aerodynamic characteristics of the suspension arm. Summary of the Invention

[0007] A suspension arm according to one aspect of the present disclosure includes an arm main body and a resin molded portion that is injection molded with the arm main body as an insert. The arm main body has: a bottom wall; a first side wall and a second side wall that project upward from the bottom wall and face each other; and a flange that projects from the front end portion in the projecting direction of the first side wall. The direction in which the first side wall and the second side wall face each other is the facing direction, and the flange projects in the facing direction to the side opposite to the second side wall. 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 projecting portion that projects downward from the flange covering portion and is connected to the first side wall covering portion. An inclined surface is provided in the flange covering portion, and the inclined surface is inclined so as to be located higher as it faces the base end side of the flange in the facing direction. A curved surface is provided in the projecting portion, and the curved surface is curved so that the distance to the first side wall covering portion gradually decreases as it faces downward. Brief Description of the Drawings

[0008] Figure 1 It is a cross-sectional view of a lower arm showing one embodiment of the suspension arm.

[0009] Figure 2It represents an application Figure 1 A schematic diagram of a suspension device of a vehicle's lower arm.

[0010] Figure 3 It represents Figure 1 A perspective view of the lower arm.

[0011] Figure 4 It is an exploded perspective view showing the separation of the reinforcement member from the arm body that constitutes Figure 1 the lower arm.

[0012] Figure 5 It represents Figure 1 A perspective view of the bottom surface of the lower arm.

[0013] Figure 6 It is an enlarged cross-sectional view centered on the first flange covering portion in Figure 1 the lower arm.

[0014] Figure 7 It is an enlarged cross-sectional view centered on the second flange covering portion in Figure 1 the lower arm.

[0015] Figure 8 It represents Figure 1 A graph showing the relationship between the inclined surface angle of the first inclined surface in the lower arm and the Cd value.

[0016] Figure 9 It represents Figure 1 A graph showing the relationship between the inclined surface angle of the first inclined surface in the lower arm and the Cl value.

[0017] Figure 10 It represents Figure 1 A graph showing the relationship between the inclined surface angle of the second inclined surface in the lower arm and the Cd value.

[0018] Figure 11 It represents Figure 1 A graph showing the relationship between the inclined surface angle of the second inclined surface in the lower arm and the Cl value.

[0019] Figure 12 It represents Figure 1 A graph showing the relationship between the radius of curvature of the first curved surface in the lower arm and the Cd value.

[0020] Figure 13 It represents Figure 1 A graph showing the relationship between the radius of curvature of the first curved surface in the lower arm and the Cl value. Detailed implementation mode

[0021] Hereinafter, with reference to Figures 1 to 13 one implementation mode in which the suspension arm is embodied as the lower arm of the suspension device will be described.

[0022] (Suspension device 10)

[0023] As shown Figure 2 in FIG. 1, the suspension device 10 is disposed between the vehicle body 100 and the wheel 110, and swingably supports the wheel 110 on the vehicle body 100. The suspension device 10 is configured to mitigate the impact transmitted from the road surface to the vehicle body 100 via the wheel 110 and press the wheel 110 against the road surface.

[0024] The suspension device 10 includes an upper arm 20, a lower arm 30, and a suspension spring 70.

[0025] 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 the support member 111 that supports the wheel 110 to the frame 101 of the vehicle body 100.

[0026] The suspension spring 70 extends in the vertical direction. The lower end portion of the suspension spring 70 is supported by the lower arm 30.

[0027] (Lower arm 30)

[0028] As shown Figure 3 in FIG. 2, 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 injection molded with the arm main body 40 and the reinforcing member 50 as inserts.

[0029] (Arm main body 40)

[0030] As shown Figure 4 in FIG. 3, 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 is in a long strip shape extending in the vehicle width direction. The first side wall 42A and the second side wall 42B project upward from both side edges of the bottom wall 41 and face each other. The direction in which the first side wall 42A and the second side wall 42B project from the bottom wall 41 is referred to as the protruding direction, and the direction in which the first side wall 42A and the second side wall 42B face each other is referred to as the opposing direction. The first flange 45A projects from the front end portion in the protruding direction of the first side wall 42A in the opposing direction to the side opposite to the second side wall 42B. The second flange 45B projects from the front end portion in the protruding direction of the second side wall 42B in the opposing direction to the side opposite to the first side wall 42A. The arm main body 40 is open upward.

[0031] The arm main body 40 is arranged such that the first side wall 42A and the second side wall 42B are respectively located in the front and rear of the vehicle.

[0032] Hereinafter, the long side direction of the bottom wall 41 is referred to as the X-axis direction. The facing direction is referred to as the Y-axis direction. The direction (protrusion direction) orthogonal to both the X-axis direction and the Y-axis direction is referred to as the Z-axis direction. The X-axis direction is the same as the vehicle width direction. The Y-axis direction is the same as the vehicle front-rear direction. The Z-axis direction is the same as the up-down direction.

[0033] The arm main body 40 is formed, for example, by stamping a metal plate. The material of the arm main body 40 is, for example, a metal material such as high-tensile steel.

[0034] The width in the Y-axis direction of the middle portion 41a in the X-axis direction of the bottom wall 41 is larger than that of other portions. The width in the Y-axis direction of the middle portion 41a gradually decreases toward both sides in the X-axis direction. The middle portion 41a of the bottom wall 41 has a spindle shape when viewed from the Z-axis direction.

[0035] On both sides of the bottom wall 41 in the X-axis direction, the portions adjacent to the middle portion 41a extend linearly in the X-axis direction.

[0036] The first side wall 42A and the second side wall 42B have symmetric shapes in the Y-axis direction. Therefore, hereinafter, when explaining the structure of the first side wall 42A, the explanation of the structure of the second side wall 42B may sometimes be omitted.

[0037] The first side wall 42A extends over the entire X-axis direction of the bottom wall 41. One end portion of the first side wall 42A in the X-axis direction and the portion constituting the first connecting portion 47 to be described later protrude from the bottom wall 41 in the X-axis direction.

[0038] As Figure 1 shown, the portion of the first side wall 42A protruding upward from the middle portion 41a has an inclined portion 43 connected to the bottom wall 41 and a straight portion 44 connected to the inclined portion 43.

[0039] The inclined portion 43 is inclined so as to be farther away from the second side wall 42B in the Y-axis direction as it goes upward.

[0040] 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 in parallel with each other.

[0041] As Figure 4 shown, the first flange 45A extends over the entire X-axis direction of the first side wall 42A. The second flange 45B extends over the entire X-axis direction of the second side wall 42B.

[0042] The arm main body 40 has a spring housing portion 46, a first connecting portion 47, and a second connecting portion 48. The spring housing portion 46 constitutes the central portion of the arm main body 40 in the X-axis direction. The first connecting portion 47 and the second connecting portion 48 are provided on both sides of the spring housing portion 46 in the X-axis direction.

[0043] (Spring housing portion 46)

[0044] The spring housing portion 46 includes an intermediate portion 41a, a portion of the first side wall 42A protruding from the intermediate portion 41a, and a portion of the second side wall 42B protruding from the intermediate portion 41a. The spring housing portion 46 forms a housing space for housing the lower end portion of the suspension spring 70.

[0045] The portions of the first side wall 42A and the second side wall 42B that constitute the spring housing portion 46 bulge in opposite directions from each other in the Y-axis direction.

[0046] A through hole 46a penetrating in the Z-axis direction is provided at the bottom of the spring housing portion 46, that is, the intermediate portion 41a. The through hole 46a is circular in shape.

[0047] (First connecting portion 47)

[0048] The first connecting portion 47 is the portion of the arm main body 40 connected to the vehicle body 100. The first connecting portion 47 includes a portion of the first side wall 42A protruding in the X-axis direction from the bottom wall 41 and a portion of the second side wall 42B protruding in the X-axis direction from the bottom wall 41. The portions of the first side wall 42A and the second side wall 42B that constitute the first connecting portion 47 extend parallel to each other in the X-axis direction. The portions of the first side wall 42A and the second side wall 42B that constitute the first connecting portion 47 protrude in the X-axis direction from the end edges of the bottom wall 41 in the X-axis direction.

[0049] First connecting holes 47a penetrating in the Y-axis direction are respectively provided in the portions of the first side wall 42A and the second side wall 42B that constitute 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 holes 47a.

[0050] (Second connecting portion 48)

[0051] The second connecting portion 48 is the portion of the arm main body 40 connected to the wheel 110. The portions of the first side wall 42A and the second side wall 42B that constitute the second connecting portion 48 extend parallel to each other in the X-axis direction.

[0052] Second connection holes 48a penetrating in the Y-axis direction are respectively provided in portions of the first side wall 42A and the second side wall 42B that constitute the second connection portion 48. The second connection portion 48 is rotatably connected to the support member 111 of the wheel 110 via a rotation shaft (not shown) inserted into the second connection hole 48a.

[0053] (Reinforcement member 50)

[0054] The reinforcement member 50 is in a flat plate shape. The reinforcement member 50 covers the spring housing portion 46 from above. The reinforcement member 50 is spindle-shaped when viewed from the Z-axis direction.

[0055] The material of the reinforcement member 50 is, for example, a metal material such as high-tensile steel.

[0056] The reinforcement member 50 is joined, for example, by welding to the upper surfaces of portions of the first flange 45A and the second flange 45B that constitute the spring housing portion 46.

[0057] Both end edges of the reinforcement member 50 in the Y-axis direction are located at positions closer to the inside than the end edges of portions of the first flange 45A and the second flange 45B that constitute the spring housing portion 46 in the Y-axis direction.

[0058] An insertion hole 50a for inserting the suspension spring 70 is provided in the reinforcement member 50. The insertion hole 50a communicates with the accommodation space of the spring housing portion 46.

[0059] (Resin molding portion 60)

[0060] As Figure 1 shown, the resin molding portion 60 includes a first side wall covering portion 61, a first flange covering portion 62, a plurality of first protruding portions 63, a second side wall covering portion 64, a second flange covering portion 65, a plurality of second protruding portions 66, and a bottom wall covering portion 67.

[0061] The resin molding portion 60 is formed by filling resin inside a mold device (not shown) after disposing the arm main body 40 joined with the reinforcement member 50 as an insert.

[0062] The material of the resin molding portion 60 is, for example, a thermoplastic resin material.

[0063] (First side wall covering portion 61)

[0064] The first side wall covering portion 61 covers the outer surface of the first side wall 42A. More specifically, the first side wall covering portion 61 covers a portion of the outer surface of the first side wall 42A except for the peripheries of the first connection hole 47a and the second connection hole 48a. The outer surface of the first side wall 42A is the surface on the opposite side of the surface of the first side wall 42A that faces the second side wall 42B.

[0065] The first side wall covering portion 61 has an inclined covering portion 61a that covers the inclined portion 43 of the first side wall 42A and a linear covering portion 61b that covers the linear portion 44 of the first side wall 42A. The inclined covering portion 61a extends along the outer surface of the inclined portion 43 of the first side wall 42A. The linear covering portion 61b extends along the outer surface of the linear portion 44 of the first side wall 42A.

[0066] The first side wall covering portion 61 covers both ends of the first side wall 42A in the X-axis direction from both sides in the Y-axis direction and the corresponding side in the X-axis direction.

[0067] (The first flange covering portion 62)

[0068] The first flange covering portion 62 covers the first flange 45A. The first flange covering portion 62 covers the first flange 45A from both sides in the Z-axis direction and the first side in the Y-axis direction. The first flange covering portion 62 covers the entire first flange 45A in the X-axis direction.

[0069] In the spring housing portion 46, the first flange covering portion 62 covers the joint portion between the first flange 45A and the reinforcing member 50 in addition to the first flange 45A.

[0070] As Figure 6 shown, a first inclined surface 62a is provided on the upper portion of the first flange covering portion 62. The first inclined surface 62a is inclined such that it is located higher as it approaches the base end side, i.e., the rear, of the first flange 45A in the Y-axis direction.

[0071] The first inclined surface 62a is provided, for example, over the entire first flange covering portion 62 in the X-axis direction.

[0072] The first inclined surface 62a extends from above the front end portion of the first flange 45A to above the base end portion. The upper surface of the first flange covering portion 62 is constituted only by the first inclined surface 62a, for example.

[0073] (The first protrusion 63)

[0074] As Figure 5 shown, a plurality of first protrusions 63 are provided at intervals in the X-axis direction on the lower portion of the first flange covering portion 62. The plurality of first protrusions 63 are provided on the portion of the resin molding portion 60 that covers the spring housing portion 46.

[0075] The first protrusion 63 is in the shape of a thin plate. The first protrusion 63 is provided on the lower portion of the first flange covering portion 62 such that its thickness direction is parallel to the X-axis direction.

[0076] As Figure 6As shown, the first protruding portion 63 protrudes downward from the first flange covering portion 62 and is connected to the linear covering portion 61b of the first side wall covering portion 61. Therefore, the first protruding portion 63 connects the linear covering portion 61b and the first flange covering portion 62.

[0077] The first bending surface 63a is provided on the first protruding portion 63, and the first bending surface 63a bends in such a manner that the distance to the linear covering portion 61b gradually decreases as it is farther from the first flange covering portion 62. More specifically, the first bending surface 63a bends in such a manner that the distance to the linear covering portion 61b in the Y-axis direction gradually decreases as it faces downward. The first bending surface 63a is circular arc-shaped when viewed from the X-axis direction. The lower end of the first bending surface 63a is connected to the linear covering portion 61b without a step difference.

[0078] (Second side wall covering portion 64)

[0079] As Figure 1 shown, the second side wall covering portion 64 covers the outer surface of the second side wall 42B. More specifically, the second side wall covering portion 64 covers the portion of the outer surface of the second side wall 42B except for the peripheries of the first connection hole 47a and the second connection hole 48a. The outer surface of the second side wall 42B is the surface on the side opposite to the surface of the second side wall 42B that faces the first side wall 42A.

[0080] The second side wall covering portion 64 has an inclined covering portion 64a that covers the inclined portion 43 of the second side wall 42B and a linear covering portion 64b that covers the linear portion 44 of the second side wall 42B. The inclined covering portion 64a extends along the outer surface of the inclined portion 43 of the second side wall 42B. The linear covering portion 64b extends along the outer surface of the linear portion 44 of the second side wall 42B.

[0081] The second side wall covering portion 64 covers both ends of the second side wall 42B in the X-axis direction from both sides in the Y-axis direction and the corresponding side in the X-axis direction.

[0082] (Second flange covering portion 65)

[0083] The second flange covering portion 65 covers the second flange 45B. The second flange covering portion 65 covers the second flange 45B from both sides in the Z-axis direction and the second side opposite to the first side in the Y-axis direction. The second flange covering portion 65 covers the entire second flange 45B in the X-axis direction.

[0084] In the spring housing 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.

[0085] A second inclined surface 65a is provided at the rear end portion in the upper part of the second flange covering portion 65. The second inclined surface 65a is located above the front end portion of the second flange 45B. The second inclined surface 65a is inclined such that in the Y-axis direction, the more it faces the front end side of the second flange 45B, that is, the rear side of the vehicle, the lower it is located. The second inclined surface 65a is provided, for example, over the entire X-axis direction of the second flange covering portion 65.

[0086] A third inclined surface 65b is provided at the front end portion in the upper part 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 such that in the Y-axis direction, the more it faces the front end side of the second flange 45B, that is, the rear side of the vehicle, the higher it is located. The third inclined surface 65b is provided, for example, over the entire X-axis direction of the second flange covering portion 65.

[0087] The second inclined surface 65a and the third inclined surface 65b are adjacent to each other in the Y-axis direction. The boundary portion between the second inclined surface 65a and the third inclined surface 65b is located at the center in the Y-axis direction of the second flange covering portion 65. The upper surface of the second flange covering portion 65 is constituted, for example, only by the second inclined surface 65a and the third inclined surface 65b.

[0088] (Second protruding portion 66)

[0089] A plurality of second protruding portions 66 are provided at intervals in the X-axis direction in the lower part of the second flange covering portion 65. The plurality of second protruding portions 66 are provided at a portion of the resin molding portion 60 that covers the spring housing portion 46. The plurality of second protruding portions 66 are provided at positions that are respectively the same as the plurality of first protruding portions 63 in the Y-axis direction.

[0090] The second protruding portion 66 is in a thin plate shape. The second protruding portion 66 is provided at the lower part of the second flange covering portion 65 such that its thickness direction is parallel to the X-axis direction.

[0091] As Figure 7 shown, the second protruding portion 66 protrudes downward from the second flange covering portion 65 and is connected to the straight covering portion 64b of the second side wall covering portion 64. Therefore, the second protruding portion 66 connects the straight covering portion 64b and the second flange covering portion 65.

[0092] The second bending surface 66a is provided at the second protruding portion 66, and the second bending surface 66a is bent in such a manner that the distance to the straight covering portion 64b gradually decreases as it moves farther away from the second flange covering portion 65. More specifically, the second bending surface 66a is bent in such a manner that the distance to the straight covering portion 64b in the Y-axis direction gradually decreases as it faces downward. The second bending surface 66a is circular arc-shaped when viewed from the X-axis direction. The lower end of the second bending surface 66a is connected to the straight covering portion 64b without a step.

[0093] (Bottom wall covering portion 67)

[0094] As Figure 1 and Figure 5 shown, 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.

[0095] The bottom wall covering portion 67 covers the two end portions of the bottom wall 41 in the X-axis direction from both sides in the Z-axis direction and the corresponding side in the X-axis direction.

[0096] As Figure 1 shown, the bottom wall covering portion 67 covers the peripheral portion of the through hole 46a from both sides in the Z-axis direction and the inner surface side of the through hole 46a.

[0097] (Simulation results)

[0098] Using the simulation results, the aerodynamic characteristics of the lower arm 30 are described when the inclination angle θ1 of the first inclined surface 62a, the inclination angle θ2 of the second inclined surface 65a, and the radius of curvature R1 of the first bending surface 63a are changed. In this simulation, the aerodynamic characteristics of the lower arm 30 were evaluated when air flowed from the first side wall 42A side toward the second side wall 42B side during vehicle travel.

[0099] As Figure 6 shown, the inclination angle θ1 in this simulation is the angle formed by the imaginary 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 Figure 7 shown, the inclination angle θ2 is the angle formed by the imaginary axis V and the second inclined surface 65a when the second flange covering portion 65 is viewed from the X-axis direction.

[0100] Figure 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 inclination angle θ1 is changed from 0° to 10°.

[0101] As Figure 8As shown, it can be seen that the larger the inclination angle θ1 of the inclined surface, the lower the Cd value. In this simulation, when the inclination angle θ1 of the inclined surface is 10°, the Cd value is the smallest.

[0102] Figure 9 It is a graph showing the change of the Cl value (hereinafter simply referred to as the Cl value), which is the lift coefficient of the lower arm 30, when the inclination angle θ1 changes from 0° to 10°.

[0103] As Figure 9 shown, it can be seen that as the inclination angle θ1 approaches 5° from 0°, the Cl value decreases, and the more the inclination angle θ1 is greater than 5°, the more the Cl value increases. In this simulation, when the inclination angle θ1 is 5°, the Cl value is the smallest. In addition, the Cl value when the inclination angle θ1 is 10° is greater than that when the inclination angle θ1 is 0°.

[0104] Figure 10 It is a graph showing the change of the Cd value when the inclination angle θ2 changes from 0° to 10°.

[0105] As Figure 10 shown, it can be seen that the larger the inclination angle θ2 of the inclined surface, the lower the Cd value. In this simulation, when the inclination angle θ2 is 10°, the Cd value is the smallest.

[0106] Figure 11 It is a graph showing the change of the Cl value when the inclination angle θ2 changes from 0° to 10°.

[0107] As Figure 11 shown, it can be seen that the closer the inclination angle θ2 is to 10°, the lower the Cl value. In this simulation, when the inclination angle θ2 is 10°, the Cl value is the smallest.

[0108] Figure 12 It is a graph showing the change of the Cd value when the curvature radius R1 changes from 10 mm to 50 mm.

[0109] As Figure 12 shown, it can be seen that the larger the curvature radius R1, the lower the Cd value. In this simulation, when the curvature radius R1 is 50 mm, the Cd value is the smallest.

[0110] Figure 13 It is a graph showing the change of the Cl value when the curvature radius R1 changes from 10 mm to 50 mm.

[0111] As Figure 13 shown, it can be seen that the larger the curvature radius R1, the more the Cl value increases.

[0112] When the Cl value becomes excessively negative, it becomes an important factor increasing the rolling resistance of the vehicle. Therefore, it is preferable that the Cl value is approximately 0. In this simulation, when the radius of curvature R1 is 10 mm, the Cl value is less than 0, and when the radius of curvature R1 is 50 mm, the Cl value is greater than 0. In addition, when the radius of curvature R1 is about 30 mm, the Cl value is approximately 0.

[0113] As described above, by setting the inclined surface angle θ1 to 5°, the inclined surface angle θ2 to 10°, and the radius of curvature R1 to 30 mm, the aerodynamic characteristics of the lower arm 30 can be effectively improved.

[0114] In addition, below the first flange covering portion 62, a flow of air that pushes the first flange covering portion 62 upward is generated. Therefore, 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 is short within a range where the welding amount between the first flange 45A and the reinforcing member 50 can be ensured. The same applies to the second flange covering portion 65.

[0115] The functions and effects of the present embodiment will be described.

[0116] (1) The lower arm 30 includes an arm main body 40 and a resin molding portion 60 that is injection-molded with the arm main body 40 as an insert. The arm main body 40 has: a bottom wall 41; a first side wall 42A and a second side wall 42B that project upward from the bottom wall 41 and face each other; and a first flange 45A that projects from the front end portion in the projecting direction of the first side wall 42A in the facing direction to the side opposite to the second side wall 42B. The resin molding portion 60 has: 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 projecting portion 63 that projects downward from the first flange covering portion 62 and is connected to the first side wall covering portion 61. A first inclined surface 62a is provided on the first flange covering portion 62, and the first inclined surface 62a is inclined so as to be located higher as it faces the base end side of the first flange 45A in the facing direction. A first curved surface 63a is provided on the first projecting portion 63, and the first curved surface 63a is curved so that the distance to the first side wall covering portion 61 gradually decreases as it faces downward.

[0117] According to the above structure, as Figure 6 indicated by the arrow in the figure, when the vehicle is traveling, the air passing above the first flange covering portion 62 from the front to the rear flows obliquely upward along the first inclined surface 62a. As a result, since the air is rectified, an increase in the resistance generated in the lower arm 30 can be suppressed. And due to the air flowing along the first inclined surface 62a, the first inclined surface 62a is pressed downward. Thus, an increase in the lift force generated in the lower arm 30 can be suppressed.

[0118] In addition, as Figure 6 indicated by the arrow in the figure, the air passing under the first flange covering portion 62 from the front toward the rear flows obliquely downward along the first curved surface 63a. Thus, since the air is rectified, an increase in the drag generated in the lower arm 30 can be suppressed. Also, since the air flows obliquely downward along the first curved surface 63a, a flow that pushes the first flange covering portion 62 upward is less likely to occur. Thus, an increase in the lift generated in the lower arm 30 can be suppressed.

[0119] Based on the above, the aerodynamic characteristics of the lower arm 30 can be improved.

[0120] (2) The arm main body 40 has a second flange 45B that projects from the front end portion in the protruding direction of the second side wall 42B in the opposing direction to the side opposite to the first side wall 42A. The resin molding portion 60 has a second flange covering portion 65 that covers the second flange 45B. A second inclined surface 65a is provided on the second flange covering portion 65 and is inclined so as to be located lower as it approaches the front end side of the second flange 45B in the opposing direction.

[0121] According to the above structure, as Figure 7 indicated by the arrow in the figure, the air passing above the second flange covering portion 65 from the front toward the rear during the running of the vehicle flows obliquely downward along the second inclined surface 65a. Thus, since the air is rectified, an increase in the drag generated in the lower arm 30 can be suppressed. Also, due to the air flowing along the second inclined surface 65a, the second inclined surface 65a is pressed downward. Thus, an increase in the lift generated in the lower arm 30 can be suppressed. Therefore, the aerodynamic characteristics of the lower arm 30 can be improved.

[0122] (3) The resin molding portion 60 has: a second side wall covering portion that covers the outer surface of the second side wall 42B; and a second protruding portion 66 that projects downward from the second flange covering portion 65 and is connected to the second side wall covering portion 64. A second curved surface 66a is provided on the second protruding portion 66 and is curved so that the distance to the second side wall covering portion 64 gradually decreases as it approaches the lower side.

[0123] According to the above structure, as Figure 7As shown by the arrow, when the vehicle is running, the air that passes from the side where the bottom wall 41 is located upward and passes under the second flange covering portion 65 flows obliquely upward along the second curved surface 66a. Thus, since the air is rectified, an increase in the resistance generated in the lower arm 30 can be suppressed. Also, since the air flows obliquely upward along the second curved surface 66a, a flow that pushes the second flange covering portion 65 upward is not likely to occur. Thus, an increase in the lift generated in the lower arm 30 can be suppressed. Therefore, the aerodynamic characteristics of the lower arm 30 can be improved.

[0124] (4) A third inclined surface 65b is provided on the second flange covering portion 65, and the third inclined surface 65b is inclined so that it is located higher as it approaches the front end side 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.

[0125] According to the above structure, as Figure 7 shown by the arrow, when the vehicle is running, the air that passes from the front to the rear above the second flange covering portion 65 flows obliquely upward along the third inclined surface 65b and then flows obliquely downward along the second inclined surface 65a. Thus, since the air is rectified, an increase in the resistance generated in the lower arm 30 can be suppressed. Also, since the air that flows along the third inclined surface 65b, the third inclined surface 65b is pressed downward. Thus, an increase in the lift generated in the lower arm 30 can be suppressed. Therefore, the aerodynamic characteristics of the lower arm 30 can be improved.

[0126] <Modification Example>

[0127] This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a range where there is no technical contradiction.

[0128] · The third inclined surface 65b may be provided only on a part of the second flange covering portion 65 in the X-axis direction.

[0129] · The third inclined surface 65b may be omitted from the second flange covering portion 65.

[0130] · The second protrusion 66 may be omitted from the resin molding portion 60.

[0131] · The second inclined surface 65a may be provided only on a part of the second flange covering portion 65 in the X-axis direction.

[0132] · The second inclined surface 65a may be omitted from the second flange covering portion 65.

[0133] · The second flange covering portion 65 may be omitted from the resin molding portion 60. In this case, the second flange 45B may also be omitted from the arm main body 40.

[0134] · The first inclined surface 62a may also be provided only on a part of the first flange covering portion 62 in the X-axis direction.

[0135] · The resin molding portion 60 may also have a single first protrusion 63 that continuously extends in the X-axis direction.

[0136] · The resin molding portion 60 may also have a single second protrusion 66 that continuously extends in the X-axis direction.

[0137] · The reinforcing member 50 may also be omitted from the lower arm 30.

[0138] · The lower arm 30 may also be applied to the upper arm 20 of the suspension device 10.

Claims

1. A suspension arm, which includes an arm main body and a resin molding portion obtained by injection molding with the arm main body as an insert. Among them, the arm main body has: a bottom wall; a first side wall and a second side wall, which protrude upward from the bottom wall and face each other; and a flange, which protrudes from the front end portion in the protruding direction of the first side wall, the direction in which the first side wall and the second side wall face each other is the facing direction, the flange protrudes in the facing direction to the side opposite to the second side wall, the resin molding portion has: a first side wall covering portion, which covers the outer surface of the first side wall; a flange covering portion, which covers the flange; and a protruding portion, which protrudes downward from the flange covering portion and is connected to the first side wall covering portion, an inclined surface is provided on the flange covering portion, and the inclined surface is inclined so that it is located higher in the facing direction as it approaches the base end side of the flange, a curved surface is provided on the protruding portion, and the curved surface is curved so that the distance to the first side wall covering portion gradually becomes smaller as it approaches downward.

2. The suspension arm according to claim 1, wherein, 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 main body further has a second flange, which protrudes in the facing direction from the front end portion in the protruding direction of the second side wall to the side opposite to the first side wall, the resin molding portion further has a second flange covering portion, which covers the second flange, a second inclined surface is provided on the second flange covering portion, and the second inclined surface is inclined so that it is located lower in the facing direction as it approaches the front end side of the second flange.

3. The suspension arm according to claim 2, wherein, the protruding portion is a first protruding portion, and the curved surface is a first curved surface, the resin molding portion has: a second side wall covering portion, which covers the outer surface of the second side wall; and a second protruding portion, which protrudes downward from the second flange covering portion and is connected to the second side wall covering portion, a second curved surface is provided on the second protruding portion, and the second curved surface is curved so that the distance to the second side wall covering portion gradually becomes smaller as it approaches downward.

4. The suspension arm according to claim 2 or 3, wherein, a third inclined surface is provided on the second flange covering portion, and the third inclined surface is inclined so that it is located higher in the facing direction as it approaches the front end side of the second flange, the third inclined surface is provided at a position closer to the first side wall in the facing direction than the second inclined surface.

Images