Suspension device

Abstract

Suspension device comprising: a lower control arm connected to a wheel carrier and adapted to be rotatable upward and downward in accordance with a movement of the wheel carrier; a frame member connected to the lower control arm and adapted to accommodate the movement of the wheel carrier; and a retaining member disposed on the frame member and configured to restrict a range of rotation of the lower arm.

Description

Background1. Area

[0001] Exemplary embodiments of the present disclosure relate to suspension devices, and more particularly to suspension devices installed to improve ride comfort by absorbing vibrations or shocks generated between an axle and a road surface during travel of a vehicle. 2. Description of the state of the art

[0002] In general, a vehicle suspension is a device connected to the axle to control vibrations or shocks from a road surface during driving, preventing vibrations or shocks from being directly transmitted to the body, and improving ride comfort. The suspension device includes coil springs, shock absorbers that control the free oscillation of the coil springs, and stabilizer bars that suppress the vehicle's roll phenomenon.

[0003] Conventional shock absorbers are installed between the car body and the wheel to absorb the natural vibrations caused by the coil spring during driving. Shock absorbers can have different connecting part structures depending on the positions of the shock absorbers mounted on the car body and the movement characteristics.

[0004] However, many parts, such as washers and bushings, are required to assemble shock absorbers. A rubber bushing in a shock absorber can constantly contract and expand. In this case, the rubber bushing can tear or wear out due to the constant, repetitive movement.

[0005] The background technology of the present disclosure is disclosed in Korean Patent Publication No. 10-2024-0002483 (published on March 11, 2024, entitled “Rear Shock Absorber for Vehicle”). Summary

[0006] Various embodiments of the present disclosure relate to a suspension device that can reduce the weight of a vehicle and create space between internal vehicle parts by omitting a shock absorber.

[0007] In one embodiment of the present disclosure, a suspension device includes a lower arm connected to a wheel carrier and configured to be rotatable according to an up and down movement of the wheel carrier, a frame member connected to the lower arm and configured to receive the movement of the wheel carrier, and a retaining member arranged on the frame member and configured to restrict a rotation range of the lower arm.

[0008] The lower arm may include a first mounting hole disposed opposite the wheel carrier, the frame member including a second mounting hole disposed opposite the first mounting hole, and the suspension device may further include a mounting member passing through the first mounting hole and the second mounting hole and serving as a rotational center axis of the lower arm.

[0009] The frame part may comprise a guide hole arranged opposite the wheel carrier with respect to the second fastening hole and adapted to guide the movement of the retaining part on the frame part.

[0010] The retaining member may include a shaft member inserted into the guide hole, a step member connected to the shaft member and arranged to protrude outwardly with a larger diameter than the guide hole to prevent movement of the shaft member, and a guide fixing member connected to the step member and configured to restrict movement of the shaft member.

[0011] The lower link may include a retaining hole having the same diameter as the stem portion.

[0012] The retaining member can be inserted into the retaining hole without being spaced from it, so that the lower arm can be fixed without moving in the longitudinal direction of the lower arm.

[0013] The guide hole may have a curved surface that is in vertical contact with the shaft portion.

[0014] The guide hole may have a surface that contacts the shaft part on the left and right sides and has an equal curvature with respect to the rotational center axis of the lower arm.

[0015] The guide hole may have a vertically elongated shape and limit the range in which the lower arm connected to the wheel carrier rises or falls when the wheel carrier rotates up or down.

[0016] The shaft member may include an insulator disposed between the lower arm and the frame member to prevent longitudinal movement of the shaft member.

[0017] The insulator may comprise a material of lower hardness than the lower arm and the frame member to reduce friction that occurs at a contact surface with the lower arm when the lower arm rotates up or down. Brief description of the drawings Fig. 1 is a perspective view schematically illustrating a suspension device according to an embodiment of the present disclosure. Fig. 2 schematically shows a suspension device according to an embodiment of the present disclosure. Fig. 3 schematically shows a lower arm of a suspension device according to an embodiment of the present disclosure. Fig. 4 schematically shows a frame part of a suspension device according to an embodiment of the present disclosure. Fig. 5 schematically shows a fastening element of a suspension device according to an embodiment of the present disclosure. Fig. 6 schematically shows a mounting shaft of a suspension device according to an embodiment of the present disclosure. Fig. 7 schematically shows a coupling element of a suspension device according to an embodiment of the present disclosure. Fig. 8 schematically shows a retaining part of a suspension device according to an embodiment of the present disclosure. Fig. 9 schematically shows a coupling of a lower arm and a retaining part of a suspension device according to an embodiment of the present disclosure. Fig. 10 schematically shows a guide hole of a suspension device according to an embodiment of the present disclosure. Fig. 11 schematically shows a rotational state of a lower arm of a suspension device according to an embodiment of the present disclosure. Fig. 12A schematically illustrates a rebound state of a suspension device according to an embodiment of the present disclosure. Fig. 12B schematically shows a shock state of a suspension device according to an embodiment of the present disclosure. Fig. 13 schematically shows an isolator of a suspension device according to an embodiment of the present disclosure. Detailed description

[0018] An embodiment of a suspension device according to the present disclosure will be described in detail below using various exemplary embodiments with reference to the accompanying drawings. It should be noted that the thickness of individual lines or the size of individual components may be exaggerated in the drawings for clarity and simplicity.

[0019] In this case, the thickness of a line or the size of an element depicted in the drawings may be exaggerated for clarity. The terms described below have been defined with their functions in mind in this disclosure and may vary depending on the intention or approach of the user or operator. Accordingly, these terms should be interpreted within the scope of this description.

[0020] Furthermore, in this specification, when a part is "connected (or joined)" to another part, it means not only that it is "directly connected (or joined)" to another part, but also that it is "indirectly connected (or joined)" to another intervening element. In this specification, when a part "includes (or has)" a component, it means that it may "include (or have)" additional components, rather than excluding other components, unless expressly stated otherwise.

[0021] The object and effect of the present disclosure will become clearer from the following description and are not limited solely by this description. If the description of the known technology unnecessarily obscures the essence of the present disclosure, a detailed description will be omitted.

[0022] Fig. 1 is a perspective view schematically illustrating a suspension device 1 according to an embodiment of the present disclosure. Fig. 2 schematically shows the suspension device 1 according to an embodiment of the present disclosure. Fig. 3 schematically shows a lower arm 100 of the suspension device 1 according to an embodiment of the present disclosure.

[0023] With reference to Fig. 1, the suspension device 1 according to an embodiment of the present disclosure includes the lower arm 100, a frame part 200, and a retaining part 300.

[0024] The lower arm 100 is connected to a wheel carrier 400 so that it can be rotated up and down according to the movement of the wheel carrier 400.

[0025] The suspension device 1 is a device mounted between an axle and a vehicle frame. It absorbs vibrations and shocks transmitted from the road surface during travel, thereby improving the ride comfort and stability of the vehicle. The suspension device 1 includes the wheel carrier 400, which rotatably supports a wheel, and the lower arm 100 and an upper arm (not shown) arranged in a vehicle width direction and connected to the wheel carrier 400 to enable rotation of the vehicle body.

[0026] The suspension device 1 according to an embodiment of the present disclosure includes the lower arm 100 arranged on one side and an elastic member 700 supporting the vehicle body and arranged on the other side.

[0027] With reference to Fig. 1, the elastic member 700 supporting the vehicle body is mounted on the lower arm 100. Since the elastic member 700 supports bending caused by irregularly repeated up and down movements, twisting caused by centrifugal force during turning, and the vehicle load, durability and rigidity are required for the lower arm 100.

[0028] In this embodiment, the elastic member 700 is described as an example of an elastically deformable coil spring, but the present disclosure is not limited thereto, and various modifications are possible.

[0029] With reference to Fig. 2, the coil spring is arranged so that one end is connected to the vehicle body and the other end is connected to the lower arm 100 to absorb the shocks transmitted from the road surface.

[0030] With reference to Fig. 3, the lower arm 100 is provided with an elastic member attachment portion 130 for attaching the spring, and a mounting protrusion 131 is provided on an edge of the elastic member attachment portion 130 for attaching the spring to the lower arm 100 without detaching. The lower arm 100 can be manufactured by aluminum forging or aluminum extrusion for weight reduction.

[0031] The lower arm 100 is connected to a stabilizer so that the movement of the vehicle can be transferred to a stabilizer 500 when the vehicle turns.

[0032] When the vehicle body is unbalanced, the stabilizer bar 500 is controlled to reduce the inclination of the vehicle body and restore the position of the vehicle body to a state of balance. The stabilizer bar 500 is arranged across the left and right directions of the vehicle. Both ends of the stabilizer bar 500 are connected to the stabilizer bar (not shown), and the stabilizer bar is rotatably coupled to the lower arm 100. Thus, the movement of the lower arm 100 can be transmitted to the stabilizer bar 500 and the frame member 200.

[0033] In the following drawings, the X-axis direction represents a direction parallel to a longitudinal direction of the lower arm 100, and the Y-axis direction represents a direction perpendicular to the longitudinal direction of the lower arm 100 and parallel to the longitudinal direction of the retaining part 300. The X-axis direction and the Y-axis direction may be mutually perpendicular directions. The Z-axis direction represents a direction perpendicular to the longitudinal direction of the lower arm 100 and the longitudinal direction of the retaining part 300. In other words, the Z-axis direction may be a direction perpendicular to the XY plane.

[0034] Furthermore, in the following drawings, a first horizontal direction, a second horizontal direction, and a vertical direction can be understood as follows. The first horizontal direction can be understood as the X-axis direction, the second horizontal direction as the Y-axis direction, and the vertical direction as the Z-axis direction.

[0035] With reference to Fig. 2 and Fig. 3, the lower arm 100 has first mounting holes 110 located on an opposite side of the wheel carrier 400 and rotatable according to the movement of the wheel carrier 400. A later-described mounting member 600 passes through the first mounting holes 110, allowing the lower arm 100 to rotate in the vertical direction (Z-axis direction), with the mounting member 600 serving as a rotation axis.

[0036] The lower link 100 is provided with a retaining hole 120 having the same diameter as a shaft part 310 described below. Since the retaining hole 120 of the lower link 100 has the same diameter as the shaft part 310, the movement of the lower link 100 in the vertical direction (Z-axis direction) can be transmitted to the holding part 300.

[0037] Fig. 4 schematically shows the frame part 200 of the suspension device according to an embodiment of the present disclosure.

[0038] With reference to Fig. 2 and Fig. 4, the frame part 200 is rotatably connected to the lower link 100 so that the movement of the wheel carrier 400 is transmitted.

[0039] The frame part 200 is connected to the lower control arm 100 so that the movement of the wheel carrier 400 is transmitted.

[0040] The frame part 200 includes second mounting holes 210 arranged so as to be opposite to the first mounting holes 110. The second mounting holes 210 are arranged in an oval shape with a long extension in the first horizontal direction (X-axis direction). The second mounting holes 210 are formed on both sides of the frame part 200 with reference to Fig. 4 provided.

[0041] The second mounting holes 210 are provided on the same line as the first mounting hole 110. The fastening element 600 penetrates the first mounting hole 110 and the second mounting holes 210, allowing the lower arm 100 to rotate up and down with the fastening element 600 as a rotation axis. The frame part 200 includes guide holes 220 arranged on the opposite side of the wheel carrier 400 with respect to the second mounting holes 210 to guide the movement of the retaining part 300 on the frame part 200. The guide holes 220 are arranged spaced apart from the second mounting holes 210.

[0042] The guide holes 220 are provided with a vertical length. The retaining part 300 is inserted into the guide holes 220 and rotated vertically, that is, in the vertical direction (Z-axis direction). In particular, the guide holes 220 can restrict the movement of the shaft part 310 described below.

[0043] Fig. 5 schematically shows the fastening element 600 of the suspension device according to an embodiment of the present disclosure.

[0044] With reference to Fig. 5, the fastening element 600 extends through the first fastening holes 110 and the second fastening holes 210 and forms the rotation axis of the lower arm 100. In this case, the first fastening holes 110, the second fastening holes 210, and the fastening element 600 are arranged on the same line and have the same rotation axis. Accordingly, the lower arm 100 can rotate around the fastening element 600.

[0045] The fastening element 600 comprises a fastening shaft 610 and a coupling element 620.

[0046] Fig. 6 schematically shows the attachment shaft 610 of the suspension device according to an embodiment of the present disclosure.

[0047] With reference to Fig. 6, the fastening shaft 610 refers to a shaft that penetrates the first fastening holes 110 and the second fastening holes 210. In this embodiment, the fastening shaft 610 is exemplified as a cylindrical shaft, but the present disclosure is not limited thereto, and various modifications are possible.

[0048] The fastening shaft 610 includes a fastening groove 611 that is concavely shaped inward. The suspension device 1 according to an embodiment of the present disclosure further includes a cam bolt 630 so that the fastening shaft 610 can be coupled without a gap when the fastening shaft 610 penetrates the second fastening holes 210.

[0049] The cam bolt 630 can adjust the toe angle and camber angle by changing the mounting position of the lower arm 100 according to the rotation angle. By using the cam bolt 630, the lower arm 100 can rotate around the mounting member 600 as a rotation axis.

[0050] A projection of the fastening groove 611, which corresponds to the fastening groove 611 of the fastening shaft 610, is arranged on the cam bolt 630. When the projection of the fastening groove 611 is inserted into and coupled with the fastening groove 611, it is possible to prevent the fastening shaft 610 from having play while coupling the fastening shaft 610 without a gap.

[0051] With reference to Fig. 5, by coupling the cam bolt 630 to the fixing shaft 610 and then connecting the fixed bolt 640 to the fixing shaft 610, the coupling to the fixing shaft 610, the first fixing holes 110, and the second fixing holes 210 can be stably supported.

[0052] Fig. 7 schematically shows the coupling element 620 of the suspension device according to an embodiment of the present disclosure.

[0053] With reference to Fig. 7, the coupling element 620 is provided to surround the fastening shaft 610 to prevent the fastening shaft 610 from having play. As shown in Fig. As shown in Figure 7, the coupling element 620 has a hole through which the fastening shaft 610 extends. The coupling element 620 encloses the fastening shaft 610 and penetrates the first fastening holes 110 as a unit with the fastening shaft 610.

[0054] With reference to Fig. 3 and Fig. 4, the sizes of the first mounting hole 110 and the second mounting hole 210 may be different. If the diameters of the first mounting hole 110, the second mounting hole 210, and the mounting member 600 are the same, the lower arm 100 cannot rotate freely around the mounting member 600 as a rotation axis. Accordingly, the sizes of the first mounting hole 110 and the second mounting hole 210 are different. To prevent the mounting shaft 610 passing through the first mounting holes 110 and 210 from having play in the first mounting hole 110 with a larger diameter, the coupling member 620 is provided to surround the mounting shaft 610 as it passes through the first mounting holes 110.

[0055] Fig. 8 schematically shows the retaining part 300 of the suspension device according to an embodiment of the present disclosure.

[0056] With reference to Fig. 8, the retaining part 300 comprises the shaft part 310, a step part 320 and a guide fastening part 330.

[0057] The shaft part 310 is inserted into the guide hole 220. In this embodiment, the shaft part 310 is described as a cylindrical column, but the present disclosure is not limited thereto, and various modifications are possible.

[0058] The step part 320 is connected to the shaft part 310 and protrudes outward with a larger diameter than the guide hole 220 to prevent movement of the shaft part 310. The step part 320 protrudes outward to prevent movement of the shaft part 310 in the second horizontal direction (Y-axis direction).

[0059] The step part 320 has a larger diameter than the shaft part 310 or the guide hole 220. As a result, the retaining part 300 can be fixed between the lower arm 100 and the frame part 200 without movement in the second horizontal direction (Y-axis direction).

[0060] The guide fastening part 330 is connected to the step part 320 and restricts the movement of the shaft part 310. Specifically, the guide fastening part 330 is screwed and secured to the shaft part 310 with an internal thread, with a thread formed on the outside of the shaft part 310. The guide fastening part 330 is secured to the outside of the step part 320 with a nut to further restrict and fix the movement of the retaining part 300 in the second horizontal direction (Y-axis direction).

[0061] When the fastening member 600 passes through the first fastening hole 110 and the second fastening hole 210, the lower arm 100 is rotated up and down while the fastening member 600 is inserted into the lower arm 100 and the frame member 200, and the retaining member 300 passes through the guide hole 220 which is spaced apart from the second fastening hole 210, thereby restricting the vertical rotation range of the lower arm 100.

[0062] The frame part 200 is opened downward, and the lower arm 100 is coupled to the open space of the frame part 200. Accordingly, the lower arm 100 rotates while overlapping the frame part 200, thereby improving the space utilization.

[0063] Fig. 9 schematically shows the coupling of the lower arm 100 and the retaining part 300 of the suspension device according to an embodiment of the present disclosure.

[0064] With reference to Fig. 9, the retaining part 300 is inserted into the retaining hole 120 having the same diameter as the shaft part 310 so as not to be spaced apart from each other, whereby the lower arm 100 can be fixed without moving in the first horizontal direction "a" (X-axis direction), which is the horizontal direction of the lower arm. Thus, the rotation direction of the lower arm 100 is in the vertical direction (Z-axis direction) and not in the first horizontal direction (a, X-axis direction).

[0065] Fig. 10 schematically shows the guide hole 220 of the suspension device according to an embodiment of the present disclosure.

[0066] With reference to Fig. 10, a surface of the guide hole 220 that vertically contacts the shaft part 310 is formed as a curved surface. Hereinafter, the surface of the guide hole 220 that vertically contacts the shaft part 310 is referred to as a first surface 221. The first surface 221, in which the guide hole 220 and the shaft part 310 vertically contact, is formed as a curved surface by molding.

[0067] Since the first surface 221 is provided as a curved surface, the retaining member 300 cannot be damaged when the retaining member 300 reciprocates in the vertical direction (Z-axis direction).

[0068] The guide hole 220 is formed with the same curvature on the surface that contacts the shaft part 310 on the left and right sides relative to the rotation axis of the lower arm 100. Hereinafter, the surface where the guide hole 220 contacts the shaft part 310 on the left and right sides is referred to as the second surface 222. The second surface 222 is formed as a curved surface along the path c of the rotating lower arm 100.

[0069] With reference to Fig. 10, since the lower arm 100 rotates vertically (Z-axis direction) relative to the fastening member 600 passing through the second fastening hole 210, the lower arm 100 reciprocates in a curved manner in the guide hole 220 spaced apart from the second fastening hole 210. Since the second surface 222 is shaped as a curved surface, the rotating lower arm 100 can reciprocate more easily.

[0070] Fig. 11 schematically shows a rotational state of the lower arm 100 of the suspension device according to an embodiment of the present disclosure.

[0071] With reference to Fig. 11, the distance “d” from the first mounting hole 110 to the wheel carrier 400 is greater than the distance “d” to the retaining hole 120, so that the vertical movement of the wheel carrier 400 can be easily transmitted from the retaining hole 120 to the moving retaining part 300.

[0072] When the wheel carrier 400 rotates clockwise, the retaining member 300 also rotates counterclockwise, ie, downward, since the retaining hole 120 also rotates clockwise.

[0073] As in Fig. As shown in Figure 10, the retaining member 300 rotates clockwise, i.e., upward, when the wheel carrier 400 rotates counterclockwise, because the retaining hole 120 also rotates counterclockwise. As a result, the retaining member 300 can restrict the rotation radius of the lower arm 100.

[0074] When the vehicle travels on a bumpy road, the vehicle body vibrates, and the wheel also vibrates up and down. In this case, it is called a shock condition when the wheel rises, and a rebound condition when the wheel falls.

[0075] Fig. 12A schematically illustrates a rebound state of the suspension device according to an embodiment of the present disclosure.

[0076] As in Fig. As shown in Figure 12A, the position of the retaining hole 120 on the side of the wheel carrier 400 opposite the lower arm 100 increases as the wheel is lowered (counterclockwise) and the wheel carrier 400 rotates downward. The guide hole 220 can limit the range in which the lower arm 100 connected to the wheel carrier 400 rises as the wheel carrier 400 rotates downward.

[0077] Fig. 12B schematically shows a shock state of the suspension device according to an embodiment of the present disclosure.

[0078] With reference to Fig. 12B, the position of the retaining hole 120 on the side of the wheel carrier 400 opposite the lower arm 100 lowers as the wheel moves upward (clockwise) and the wheel carrier 400 rotates upward. The guide hole 220 is provided in a vertically elongated shape and restricts the lowering range of the lower arm 100 connected to the wheel carrier 400 during the upward rotation of the wheel carrier 400.

[0079] Accordingly, the lower arm 100 is installed between the wheel carrier 400 and the vehicle body, and the range of rise or fall of the lower arm 100 is restricted, thereby mitigating the shocks applied to the driver and improving driving comfort and driving stability.

[0080] Fig. 13 schematically shows an insulator 311 of the suspension device according to an embodiment of the present disclosure.

[0081] With reference to Fig. 13, the shaft portion 310 includes the insulator 311 positioned between the lower arm 100 and the frame portion 200, preventing movement of the shaft portion 310 in the longitudinal direction. That is, the shaft portion 310 includes the insulator 311 to prevent movement of the shaft portion 310 in the second horizontal direction "b."

[0082] The insulator 311 is made of a material having a lower hardness than the lower arm 100 and the frame member 200 in order to reduce the friction that occurs at the contact surface with the lower arm 100 when the lower arm 100 rotates up and down.

[0083] The insulator 311 is provided to surround the shaft part 310 and comes into contact with the lower arm 100. In this case, friction occurs on a contact surface when the lower arm 100 rotates up and down, and therefore, a low-hardness material can be used to reduce friction.

[0084] In particular, the insulator 311 comprises an elastically deformable material. Since the insulator 311 comprises the elastically deformable material, the lower arm 100 is fixed so as not to move in the second horizontal direction "b" (Y-axis direction), and the friction generated when the lower arm 100 and the frame member 200 contact the insulator 311 can be minimized.

[0085] In this embodiment, the insulator 311 is described as an example of a rubber material, but the present disclosure is not limited thereto and various modifications are possible.

[0086] Therefore, the suspension device according to an embodiment of the present disclosure can achieve the following effects.

[0087] The suspension device according to the present disclosure can ensure the distance and space between the parts arranged in the suspension device by omitting a shock absorber.

[0088] The suspension device according to the present disclosure can reduce the weight of the vehicle by omitting the shock absorber.

[0089] The suspension device according to the present disclosure can reduce the manufacturing cost of the shock absorber by omitting the shock absorber.

[0090] The suspension device according to the present disclosure can reduce the vehicle height and improve the ride quality by omitting the shock absorber.

[0091] The suspension device according to the present disclosure can simplify and shorten the manufacturing process by eliminating components such as rubber bushings used in the shock absorber.

[0092] The suspension device according to the present disclosure can reduce manufacturing costs by eliminating components such as rubber bushings used in the shock absorber.

[0093] The suspension device according to the present disclosure can limit the number of shocks and kickbacks by adding a guide hole structure to the frame, which is an existing part.

[0094] Although exemplary embodiments of the disclosure have been disclosed for illustrative purposes, it will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the disclosure as defined in the appended claims. The true technical scope of the disclosure is thus defined by the following claims.

Claims

[1] Suspension device comprising: a lower control arm connected to a wheel carrier and adapted to be rotatable upward and downward in accordance with a movement of the wheel carrier; a frame member connected to the lower control arm and adapted to accommodate the movement of the wheel carrier; and a retaining member disposed on the frame member and configured to restrict a range of rotation of the lower arm. [2] Suspension device according to claim 1, wherein the lower arm comprises a first mounting hole arranged opposite the wheel carrier, and wherein the frame part comprises a second fastening hole opposite the first fastening hole, further comprising a fastening member passing through the first fastening hole and the second fastening hole and serving as a rotational center axis of the lower arm. [3] Suspension device according to claim 2, wherein the frame part comprises a guide hole arranged opposite the wheel carrier with respect to the second mounting hole and adapted to guide a movement of the retaining part on the frame part. [4] Suspension device according to claim 3, wherein the retaining member comprises: a shaft part inserted into the guide hole and a step member connected to the shaft member and arranged to project outwardly with a larger diameter than the guide hole to prevent movement of the shaft member. [5] The suspension device according to claim 4, wherein the lower arm includes a retaining hole having a same diameter as the shaft part. [6] A suspension device according to claim 4 or 5, wherein the guide hole has a curved surface in vertical contact with the shaft part. [7] The suspension device according to any one of claims 4 to 6, wherein the guide hole has a surface in contact with the shaft part on the left and right sides and has an equal curvature with respect to the rotational center axis of the lower arm. [8] The suspension device according to any one of claims 4 to 7, wherein the guide hole has a vertically elongated shape and restricts a range in which the lower arm connected to the wheel carrier rises or falls when the wheel carrier rotates upward or downward. [9] The suspension device according to claim 8, wherein the shaft member comprises an insulator disposed between the lower arm and the frame member. [10] The suspension device according to claim 9, wherein the insulator comprises a material having a lower hardness than the lower arm and the frame member to reduce friction occurring at a contact surface with the lower arm when the lower arm rotates upward or downward.

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