JP3887107B2 - Rear suspension device for motorcycles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a rear suspension device for a motorcycle.
[0002]
[Prior art]
As a rear suspension device for a motorcycle, for example, Japanese Patent Application Laid-Open No. 64-41492 “Rear Cushion Unit” is known.
[0003]
The above technique obtains a position-dependent damping force characteristic with a simple configuration, and is interposed between the vehicle body frame 4 and the swing arm 10 as shown in FIGS. 1 and 2 of the publication. A damper cylinder 1, a piston 5 movably inserted into the damper cylinder 1, a piston rod 2 attached to the piston 5 and having a tip connected to a swing arm 10, and a piston rod 2 movably provided. A push rod 13 and a cam 25 provided on the swing arm 10 for moving the push rod 13 along with the movement of the swing arm 10 are provided. As the swing arm 10 moves to the contraction side of the damper cylinder 1, the cam 25, the push rod 13 is moved to the piston 5 side, and the flow path resistance between the oil chambers A and B formed on both sides of the piston 5 is increased. By increasing the increase the damping force generated.
[0004]
[Problems to be solved by the invention]
In the above technique, when the swing arm 10 moves to the extension side of the damper cylinder 1, the damping force is merely reduced by the action of the cam 25, and the behavior of the vehicle body on the extension side of the damper cylinder 1 is reduced. Therefore, damping force control is not considered.
[0005]
Accordingly, an object of the present invention is not only when the swing arm moves to the contraction side of the cushion unit (damper cylinder), but also when the swing arm moves to the extension side of the cushion unit, that is, the swing position of the swing arm, that is, the rear wheel axle. An object of the present invention is to provide a rear suspension device for a motorcycle that can change a damping force in accordance with a position in the vertical direction.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a cushion arm comprising a spring and a damper between a swing arm and a body frame. in motorcycle disposing the unit, the swing arm is, when moved to the extended side of the ride neutral position placed al cushion unit that rides the driver, the extension-side reduction衰力damper than the damping force of the riding neutral position damper Increased.
[0007]
Since the rear wheel damping force of the damper is small in the ride neutral position location, good ride, because the rear wheels of the damping force of the damper is increased by the extension side of the ride neutral position placed al cushion unit, a body posture changes Can be small.
[0008]
According to a second aspect of the present invention, a swing arm is attached to the body frame so as to be swingable up and down, a rear wheel is attached to the swing arm, a cushion unit including a spring and a damper between the swing arm and the body frame, and the cushion unit In a two-wheeled vehicle in which a link mechanism that increases the ratio of the cushion unit's contraction amount to the rear wheel's displacement amount as the rear wheel is retracted, the swing arm is provided with a damping force adjustment mechanism that adjusts the damping force of the damper. but when moved to the extended side of the ride neutral position placed al cushion unit that rides the driver was to increase the extension-side reduction衰力damper than the damping force of the riding neutral position damper.
[0009]
Since the rear wheel is smaller damping force than ride neutral position location, because the ride comfort is good and the rear wheel damping force increases in the contraction side of the ride neutral position placed al cushion unit, for example, prevent the bottoming of the cushion unit and, since the rear wheels of the damping force increases in the extension-side ride neutral position placed al cushion unit, it is possible to reduce the vehicle body attitude change.
[0010]
According to a third aspect of the present invention, a swing arm is attached to the body frame so as to be able to swing up and down, a rear wheel is attached to the swing arm, a cushion unit comprising a spring and a damper between the swing arm and the body frame, and the cushion unit according shrinks, the motorcycle placing the link mechanism to increase the ratio of the shrinkage amount of the cushion unit relative displacement of the rear wheel, the swing arm has moved to the extension side of the ride neutral position placed al cushion unit that ride driver time, was to increase the growth side of the reduction衰力of the damper than the damping force of the ride neutral position damper.
[0011]
Since the rear wheel damping force of the damper is small in the ride neutral position location, good ride, because the rear wheels of the damping force of the damper is increased by the extension side of the ride neutral position placed al cushion unit, a body posture changes Can be small.
[0012]
According to a fourth aspect of the present invention, a swing arm is attached to the body frame so as to be able to swing up and down, a rear wheel is attached to the swing arm, and one end of a cushion unit including a spring and a damper is attached to the body frame above the swing arm. In a two-wheeled vehicle in which a link mechanism is connected to the other end of the frame and the link mechanism is passed between the lower part of the swing arm and the lower part of the vehicle body frame, as the part of the cushion unit and part of the link mechanism move relative to each other, the damper By narrowing the damping force adjusting oil passage provided inside, the damping force on the extension side of the damper is made larger than the damping force of the damper in the neutral position where the driver gets on.
[0013]
When a part of the cushion unit and a part of the link mechanism move relative to each other, the damping force adjusting oil passage provided in the damper is narrowed, and the damping force on the extension side of the damper is adjusted to the neutral position where the driver has boarded. It is possible to reduce the posture change of the vehicle body by making it larger than the damping force of the damper.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a side view of a motorcycle equipped with a rear suspension device for a motorcycle according to the present invention. The motorcycle 1 has a head pipe 3 attached to a front portion of a body frame 2 and is rotatable on the head pipe 3. The front fork 4 is attached, the front wheel 5 is rotatably attached to the lower part of the front fork 4, and the front fender 6 covers the upper part of the front wheel 5.
[0015]
The motorcycle 1 includes a fuel tank 7 provided at the upper part of the vehicle body frame 2, a seat 8 disposed behind the fuel tank 7, an engine and a transmission disposed below the fuel tank 7 and the seat 8. A power unit 11, a swing arm 12 swingably attached to the vehicle body frame 2 behind the power unit 11, a rear wheel 13 rotatably attached to the rear end of the swing arm 12 and driven by the power unit 11, A rear fender 14 covering the upper part of the wheel 13 and a rear suspension device 20 interposed between the vehicle body frame 2 and the swing arm 12 are included.
Here, 13a is a rear wheel shaft provided at the rear end of the swing arm 12 and serving as a rotation center of the rear wheel 13, 15 is a radiator shroud, 16 is a rear cowl, 17 is an exhaust pipe, and 18 is a muffler.
[0016]
FIG. 2 is a side view of a main part of the rear suspension device for a motorcycle according to the present invention. The rear suspension device 20 includes a cushion unit 30 having one end rotatably attached to an upper bracket 2a provided on the vehicle body frame 2, and the cushion. It comprises a progressive link mechanism 60 attached to the other end of the unit 30 in order to change the damping force of the cushion unit 30 as the swing arm 12 swings. Here, 12a is a bolt that serves as an axis on which the swing arm 12 swings with respect to the vehicle body frame 2.
[0017]
The cushion unit 30 is attached to a cylinder part 32 having an upper spring seat 31 screwed to the outer surface, a reservoir tank 33 communicated with the cylinder part 32, and a piston (described later) housed in the cylinder part 32. The piston rod 34 includes a lower spring seat 35 and an extension rod 36 attached to the tip of the piston rod 34, and a coil spring 37 sandwiched between the upper spring seat 31 and the lower spring seat 35. Reference numeral 38 denotes a lock nut for fixing the upper spring seat 31, and 39 denotes a bump stopper rubber.
[0018]
The reservoir tank 33 is a volume compensation chamber that compensates for a volume change in the cylinder portion 32 when hydraulic oil enters and exits when the piston rod 34 enters or leaves the cylinder portion 32.
The extension rod 36 has a distal end rotatably connected to the progressive link mechanism 60, and includes a push rod 41 that can be pushed into the outer surface.
[0019]
The progressive link mechanism 60 is rotatably attached to a first link 61 rotatably attached to a mounting bracket 12 b provided on the swing arm 12, and can be rotated to a lower bracket 2 b provided on the body frame 2 while being rotatably attached to the first link 61. And a second link 62 attached to the.
[0020]
The first link 61 includes a first fulcrum part 61a, a second fulcrum part 61b, and a third fulcrum part 61c. The first fulcrum part 61a is attached to the mounting bracket 12b of the swing arm 12 with a bolt 63, and the second fulcrum part 61b. Is attached to one end portions 62a, 62a (the rear side is not shown) of the second link 62 with a bolt 64, and the third fulcrum portion 61c is attached to the extension rod 36 of the cushion unit 30 with a bolt 65.
The second link 62 includes one end portions 62 a and 62 a and the other end portion 62 b, and the other end portion 62 b is attached to the lower bracket 2 b of the vehicle body frame 2 with a bolt 66.
[0021]
FIG. 3 is a perspective view of the second link according to the present invention. The second link 62 has a U-shape in plan view in which a pair of arms is extended from the other end 62b, and a small diameter portion is formed on the other end 62b. 62c is formed, and an upper protruding portion 62d and a lower protruding portion 62e are provided on the small diameter portion 62c.
[0022]
The second link 62 has a cam 67 shown in FIG. 3 attached to the tip of the push rod 41 of the cushion unit 30 shown in FIG. 2 with screws 68 and 68 on the upper protrusion 62d and the lower protrusion 62e. It is.
The cam 67 includes an attachment portion 67 a formed in a shape along the outer peripheral surface of the small diameter portion 62 c of the other end portion 62 b for attachment to the second link 62, and a cam surface 67 b that contacts the push rod 41.
[0023]
FIG. 4 is a cross-sectional view of the cushion unit according to the present invention. The cushion unit 30 includes a damper 30a and a coil spring 37. The damper 30a is inserted into the cylinder part 32 so as to be movable. A piston 42, a hollow piston rod 34 attached to the piston 42, and an opening / closing rod 43 and a push rod 41 movably housed in the piston rod 34 to open and close an oil passage in the piston 42 are provided. S1 and S2 are upper and lower oil chambers formed on both sides of the piston 42 in the cylinder part 32.
[0024]
The piston rod 34 includes a hollow portion 34a, an upper oil passage 34b that communicates from the hollow portion 34a to the upper oil chamber S1, and horizontal oil passages 34c and 34c that communicate from the upper end portion of the hollow portion 34a to the lower oil chamber S2. A taper hole 34d as an orifice hole serving as a valve seat formed between the upper oil passage 34b and the lateral oil passages 34c, 34c, and a threaded portion 34e for forming on the inner surface of the lower end portion of the hollow portion 34a.
The push rod 41 includes a rack portion 41 a with teeth cut on the outer surface and a flange portion 41 b that holds a spring 44 at the end, and the push rod 41 is biased to the outside of the extension rod 36 by the spring 44.
[0025]
The piston 42 includes a piston body 45, an extension side oil passage 46 and a contraction side oil passage 47 opened in the piston body 45, an extension side valve 48 provided at the outlet of the extension side oil passage 46, and a contraction side oil passage 47. And a contraction side valve 49 provided at the outlet. In addition, 51 and 52 are washers, 53 is a nut.
[0026]
The open / close rod 43 includes a valve body 43 a provided at the tip, a pinion portion 43 b meshed with the rack portion 41 a of the push rod 41, and a male screw portion 43 c fitted to the female screw portion 34 e of the piston rod 34. .
The valve body 43a is separated from the tapered hole 34d of the hollow portion 34a, thereby increasing the cross-sectional area of the oil passage P between the upper oil passage 34b and the lateral oil passages 34c, 34c, and the upper oil chamber S1 and the lower oil. This makes it easier for hydraulic oil to flow through the chamber S2. Further, the valve body 43a approaches the tapered hole 34d of the hollow portion 34a, thereby reducing the cross-sectional area of the oil passage P between the upper oil passage 34b and the lateral oil passages 34c, 34c, and the upper oil chamber S1 and the lower oil passage S1. This makes it difficult for hydraulic oil to flow through the oil chamber S2.
[0027]
The pinion portion 43b meshes with the rack portion 41a to rotate the opening / closing rod 43 when the push rod 41 moves in the axial direction.
The male screw portion 43c is engaged with the female screw portion 34e to move the open / close rod 43 in the axial direction when the open / close rod 43 rotates.
A damping force adjusting mechanism 40 is constituted by the hollow portion 34a, the upper oil passage 34b, the lateral oil passages 34c and 34c, the taper hole 34d, the female thread portion 34e, the open / close rod 43, the push rod 41, and the spring 44 of the piston rod 34 described above. To do.
[0028]
With the above configuration, when the push rod 41 enters the extension rod 36, the opening / closing rod 43 is rotated by the engagement of the rack portion 41a and the pinion portion 43b, and the opening / closing rod is engaged by the fitting of the female thread portion 34e and the external thread portion 43c. 43 rises, the valve body 43a approaches the tapered hole 34d, the cross-sectional area of the oil passage P becomes smaller, and the hydraulic oil hardly flows between the upper oil chamber S1 and the lower oil chamber S2.
Therefore, the damping force generated in the oil passage P can be increased.
[0029]
Further, when the push rod 41 is retracted from the extension rod 36 by the urging force of the spring 44, the opening / closing rod 43 rotates reversely with respect to when the push rod 41 enters due to the engagement of the rack portion 41a and the pinion portion 43b, The fitting of the female thread part 34e and the male thread part 43c lowers the opening / closing rod 43, the valve body 43a is separated from the tapered hole 34d, the cross-sectional area of the oil passage P gradually increases, and the upper oil chamber S1 and the lower oil chamber It becomes easy for hydraulic oil to circulate between S2.
Therefore, the damping force generated in the oil passage P can be reduced.
[0030]
Next, the operation of the progressive link mechanism 60 described above will be described.
FIG. 5 is an operation diagram for explaining the operation of the progressive link mechanism according to the present invention. The relationship between the vertical stroke amount of the rear wheel shaft 13a of the swing arm 12 and the stroke amount of the cushion unit 30 (see FIG. 4) is shown. It is a figure explaining. In the drawing, large ◎ marks indicate the rear wheel shaft 13a, and small ◎ marks indicate the bolts 65.
The position at which the rear wheel axle 13a is indicated by the symbol ◎, that is, the position when the driver is riding on the motorcycle and is standing upright (without applying the acceleration / deceleration force to the vehicle body) Also referred to as “1G state position.” This position is hereinafter referred to as “a boarding neutral position. This is also a boarding neutral position of the swing arm 12 and the rear wheel 13.” The bolt 65 serving as the connecting shaft is in the position indicated by ◎.
[0031]
First, when the swing arm 12 swings from the boarding neutral position to the extension side of the cushion unit 30 (see FIG. 4), the swing arm 12, the rear wheel shaft 13a, the progressive link mechanism 60, the cushion unit extension rod 36, and the bolt 65 (○ mark) is the position indicated by the solid line, and the movement amount of the rear wheel shaft 13a to the extension side of the cushion unit at this time is Da, and the movement amount of the bolt 65, that is, the extension amount of the cushion unit is Eb. To do.
[0032]
When the swing arm 12 swings from the boarding neutral position to the contraction side of the cushion unit, the swing arm 12, the rear wheel shaft 13a, the progressive link mechanism 60, the cushion unit extension rod 36, and the bolt 65 are two-dot chain lines. The movement amount of the rear wheel shaft 13a to the contraction side of the cushion unit at this time is the same Da as the above movement amount, and the movement amount of the bolt 65, that is, the contraction amount of the cushion unit is Sb. Sb> Eb.
[0033]
That is, as the rear wheel shaft 13a strokes toward the contraction side of the cushion unit, the change in the stroke amount of the cushion unit increases.
As a result, the moving speed of the piston 42 (see FIG. 4) of the cushion unit 30 shown in FIG. 4 increases, and the resistance when the hydraulic oil flows by pushing the contraction side oil passage 47 and the contraction side valve 49 open is increased. The damping force generated in the cushion unit 30 is increased.
[0034]
FIG. 6 is a graph showing the relationship between the displacement amount of the rear wheel shaft and the stroke amount of the cushion unit in the progressive link mechanism according to the present invention, the vertical axis is the stroke amount of the cushion unit, and the horizontal axis is the vertical displacement of the rear wheel shaft. Represents an amount. (See Fig. 5 for symbols)
In the range from the point A which is the maximum extension position of the cushion unit to the point B which is the riding neutral position, the amount of stroke of the cushion unit is the amount of displacement of the rear wheel shaft 13a in the vertical direction. As it increases, it increases almost linearly.
[0035]
Further, in the range from the point B at the boarding neutral position to the point C that is the maximum contraction position of the cushion unit, the cushion of the rear wheel shaft 13a is increased against the increase in the vertical displacement of the rear wheel shaft 13a. The rate of increase of the stroke amount of the unit is gradually increased.
[0036]
As described above, when the rear wheel shaft 13a is displaced from the riding neutral position toward the contraction side of the cushion unit by the progressive link mechanism 60, the stroke amount of the cushion unit is gradually increased, that is, the stroke speed of the cushion unit is increased. Therefore, at the maximum retracted position of the cushion unit, the damping force generated by the cushion unit is increased to prevent the bottom of the cushion unit, and near the riding neutral position, the damping force generated by the cushion unit is reduced to reduce the ride comfort. Can be improved.
[0037]
Next, the operation of the rear suspension device 20 described above will be described.
FIGS. 7A to 7C are operation diagrams for explaining the operation of the rear suspension device according to the present invention, and FIG. 7A is a state when the driver gets on the motorcycle (state of the riding neutral position), (B) shows a state in which the swing arm swings from the state (a) to the extension side of the cushion unit, and (c) shows a state in which the swing arm swings from the state (a) to the contraction side of the cushion unit.
In (a), an inclination angle with respect to the horizontal line HL of the swing arm 12 at the boarding neutral position is θ.
At this time, the tip of the push rod 41 hits the upper end of the cam surface 67b of the cam 67, and the protrusion amount of the push rod 41 from the surface of the extension rod 36 is t1.
[0038]
In (b), for example, at the time of braking, the motorcycle body tilts forward and rises rearward, so that the swing arm 12 tilts downward by an angle α with respect to (a).
At this time, the tip of the push rod 41 hits the lower end of the cam surface 67b of the cam 67, and the protruding amount of the push rod 41 from the surface of the extension rod 36 is t2 which is smaller than t1 of (a).
Accordingly, as described with reference to FIG. 4, the push rod 41 enters the extension rod 36, and the damping force adjusting mechanism functions to reduce the cross-sectional area of the oil passage P. Damping force increases.
[0039]
As a result, the damping force generated in the oil passage P is added to the damping force generated when the hydraulic oil passes through the extension-side oil passage 46 and the extension-side valve 48 is pushed open, and the damping force of the cushion unit 30 increases. Therefore, pitching, which is a roll in the front-rear direction of the motorcycle, is reduced, and the change in posture of the vehicle body can be reduced.
[0040]
In (c), for example, when the vehicle body is sinking, the swing arm 12 is tilted upward by an angle β with respect to (a).
At this time, the tip of the push rod 41 is disengaged upward from the cam surface 67 b of the cam 67.
Accordingly, the damping force of the cushion unit 30 does not change.
[0041]
The cam 67 described above is pushed with the cam surface 67b so as to operate the damping force adjusting mechanism when the swing arm 12 swings from a neutral position where the driver is riding to a certain position on the extension side of the cushion unit 30. The position with the rod 41 is set.
[0042]
As described above, the push rod 41 provided on the cushion unit 30 is pushed by the cam 67 provided on the progressive link mechanism 60, so that the relative movement amount between the progressive link mechanism 60 and the cushion unit 30 is large. The amount of movement can be increased, and the damping force of the cushion unit 30 can be easily finely adjusted.
[0043]
Here, the cam 67 is changed to a cam having a receiving surface of another shape, and the positional relationship between the cam surface and the push rod 41 is changed, whereby the operation amount of the damping force adjusting mechanism 40 (see FIG. 4) The operation timing can be changed, and the amount of change in the damping force and the stroke range of the swing arm 12 for which the damping force is to be changed (that is, the range of the vertical displacement of the rear wheel shaft 13a) can be changed.
[0044]
The first damping mechanism of the present invention is the progressive link mechanism 60 using the plurality of links 61 and 62 shown in FIG. 2, and the second fulcrum portion 61b is connected to the vehicle body frame 2 by the second link 62. Although the extension rod 36 is connected to the three fulcrum portions 61c, the present invention is not limited to this. The second fulcrum portion 61b is connected to the extension rod 36, and the third fulcrum portion 61c is connected to the vehicle body frame 2 by the second link 62. Alternatively, the third fulcrum portion 61c may be connected to the extension rod 36 and one end of the second link 62, and the other end of the second link 62 may be connected to the vehicle body frame 2. The point is that the push rod 41 may enter the extension rod 36 when the swing arm 12 swings downward.
[0045]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
A rear suspension system for a motorcycle according to claim 1, the swing arm is, when moved to the extended side of the ride neutral position placed al cushion unit that ride driver riding the neutral position of the damper than the damping force of the damper extension-side since you increase the reduction衰力, the rear wheels ride neutral position location can be used to improve the ride comfort by reducing the damping force, increasing the damping force at the rear wheels growth side of the ride neutral position placed et al cushion unit Thus, the posture change of the vehicle body can be reduced.
[0046]
A rear suspension system for a motorcycle according to claim 2, by attaching a damping force adjusting mechanism to the link mechanism, when the swing arm is moved to the extension side of the ride neutral position placed al cushion unit that ride driver riding neutral since you increase the growth side of the reduction衰力of the damper than the damping force of the position of the damper, the rear wheels ride neutral position location can be used to improve the ride comfort by reducing the damping force, the rear wheels ride neutral by increasing the damping force in the contraction-side position placed al cushion unit, for example, it is possible to prevent the bottoming of the cushion unit, the rear wheel by increasing the damping force in the extension-side ride neutral position placed al cushion unit The posture change of the vehicle body can be reduced.
[0047]
A rear suspension system for a motorcycle according to claim 3, the swing arm is, when moved to the extended side of the ride neutral position placed al cushion unit that ride driver riding the neutral position of the damper than the damping force of the damper extension-side since you increase the reduction衰力, the rear wheels ride neutral position location can be used to improve the ride comfort by reducing the damping force, increasing the damping force at the rear wheels growth side of the ride neutral position placed et al cushion unit Thus, the posture change of the vehicle body can be reduced.
[0048]
In the rear suspension device for a motorcycle according to claim 4, as a part of the cushion unit and a part of the link mechanism move relative to each other, the damping force adjusting oil passage provided in the damper is narrowed, thereby Because the damping force on the extension side of the damper is made larger than the damping force of the damper at the boarding neutral position, the damping on the extension side of the damper is utilized by using the relative movement between part of the cushion unit and part of the link mechanism. The posture change of the vehicle body can be reduced by making the force larger than the damping force of the damper at the boarding neutral position where the driver has boarded.
[Brief description of the drawings]
FIG. 1 is a side view of a motorcycle provided with a rear suspension device for a motorcycle according to the present invention. FIG. 2 is a side view of a main part of a rear suspension device for a motorcycle according to the present invention. FIG. 4 is a cross-sectional view of the cushion unit according to the present invention. FIG. 5 is an operation diagram illustrating the operation of the progressive link mechanism according to the present invention. FIG. 6 is a displacement of the rear wheel shaft in the progressive link mechanism according to the present invention. FIG. 7 is a graph showing the relationship between the amount of stroke and the stroke amount of the cushion unit. FIG. 7 is an operation diagram for explaining the operation of the rear suspension device according to the present invention.
DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Body frame, 12 ... Swing arm, 13 ... Rear wheel, 13a ... Rear-wheel axle, 20 ... Rear suspension apparatus, 30 ... Cushion unit, 30a ... Damper, 37 ... Spring, 40 ... Damping force adjustment mechanism , 60 ... Link mechanism (progressive link mechanism) , P ... Damping force adjusting oil passage (oil passage) .

Claims (4)

In a two-wheeled vehicle in which a swing arm is attached to the body frame so that it can swing up and down, a rear wheel is attached to the swing arm, and a cushion unit including a spring and a damper is disposed between the swing arm and the body frame .
Before SL swing arm, when moved to the extended side of the ride neutral position placed al cushion unit that rides the driver was to increase the reduced衰力the extension side of the damper than the damping force of the damper of the riding neutral position A rear suspension device for a two-wheeled vehicle. A swing arm is attached to the body frame so that it can swing up and down, a rear wheel is attached to the swing arm, a cushion unit comprising a spring and a damper between the swing arm and the body frame, and as the cushion unit shrinks, In a two-wheeled vehicle in which a link mechanism that increases the ratio of the amount of contraction of the cushion unit to the amount of displacement of the rear wheel is arranged ,
By attaching a damping force adjusting mechanism for adjusting the damping force of the damper prior Symbol linkage, when the swing arm is moved to the extension side of the ride neutral position placed al cushion unit that rides the driver, the passenger a rear suspension system for a motorcycle, wherein a is made larger extension-side reduction衰力of said damper than the damping force of the damper of the neutral position. A swing arm is attached to the body frame so that it can swing up and down, a rear wheel is attached to the swing arm, a cushion unit comprising a spring and a damper between the swing arm and the body frame, and as the cushion unit shrinks, in motorcycles placed a link mechanism to increase the ratio of the shrinkage amount of the cushion unit relative to the displacement amount of the rear wheel, when the swing arm is moved to the extension side of the ride neutral position placed al cushion unit that ride driver the boarding neutral position of the damper of the damping force rear suspension system for a motorcycle being characterized in that a larger reduction衰力the extension side of the damper than. A swing arm is attached to the body frame so that it can swing up and down, a rear wheel is attached to the swing arm, one end of a cushion unit consisting of a spring and a damper is attached to the body frame above the swing arm, and the other end of the cushion unit is attached. In a motorcycle that connects a link mechanism and passes the link mechanism to a lower part of the swing arm and a lower part of the body frame,
  As the part of the cushion unit and the part of the link mechanism move relative to each other, the damping force adjusting oil path provided in the damper is narrowed, so that the damper in the neutral position where the driver has boarded is placed. A rear suspension device for a motorcycle, wherein the damping force on the extension side of the damper is made larger than the damping force of the motorcycle.

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