JP2000103380A - Rear suspension device for two-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the riding quality and reduce the attitude change in the car body by changing a damping force according to the vertical position of a rear wheel shaft of a swing ann. SOLUTION: A rear suspension device 20 for a two-wheeled vehicle is formed of a cushion unit 30 whose one end is rotatably attached to an upper bracket 2a provided in a car body frame 2, and a progressive ring mechanism 60 which is attached to the other end to change the damping force of the cushion unit 30 according to the swing of a swing arm 12. When a rear wheel shaft 13a is displaced from the getting-in neutral position to a contraction side of the cushion unit 30 the stroke quantity is so formed as to be gradually enlarged by the progressive ring mechanism 60. This constitution can enlarge the generated damping force in the maximum contraction position of the cushion unit 30 so as to prevent the bottoming of the cushion unit 30 and reduces the generated damping force near the getting-in neutral position so as to improve the riding quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a rear suspension device for a motorcycle.

[0002]

2. Description of the Related Art As a rear suspension device for a motorcycle, for example, a "rear cushion unit" disclosed in JP-A-64-41492 is known.

[0003] The above technique obtains a position-dependent damping force characteristic with a simple configuration. As shown in FIGS. 1 and 2 of the publication, the vehicle body frame 4 and the swing arm 10 are provided.
, A piston 5 movably inserted into the damper cylinder 1, and a swing arm 10 attached to the piston 5 and having a distal end.
Piston rod 2 connected to the
And a cam 25 provided on the swing arm 10 for moving the push rod 13 in accordance with the movement of the swing arm 10, and the swing arm 10 contracts the damper cylinder 1. By moving the push rod 13 to the piston 5 side by the cam 25 as it moves to the side, the flow path resistance between the oil chambers A and B formed on both sides of the piston 5 is increased.
Increase the generated damping force.

[0004]

According to the above-mentioned 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 in the opposite manner. Damping force control is not considered for the behavior of the vehicle body on the extension side of the vehicle.

Therefore, 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 it moves to the extension side of the cushion unit, that is, the swing position of the swing arm, that is, the swing position. It is an object of the present invention to provide a motorcycle rear suspension device that can change a damping force according to a position of a rear wheel axle in a vertical direction.

[0006]

To achieve the above object, a first aspect of the present invention is to mount a swing arm on a body frame so as to be able to swing up and down, mount a rear wheel to the swing arm, and connect the swing arm to the body frame. In the meantime, in a two-wheeled vehicle in which a cushion unit including a spring and a damper is arranged, the swing arm moves from the vicinity of the riding neutral position where the driver gets on to the extension side of the cushion unit, thereby increasing the extension-side damping force of the damper. did.

Since the damping force of the damper is small when the rear wheel is in the vicinity of the neutral position, the riding comfort is good, and the damping force of the damper is large when the rear wheel extends from the position near the neutral position to increase the damper force. The change can be reduced.

According to a second aspect of the present invention, a swing unit 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 a cushion unit comprising a spring and a damper is provided between the swing arm and the body frame. In a two-wheeled vehicle in which a link mechanism that increases the ratio of the amount of shrinkage of the cushion unit to the amount of displacement of the rear wheel as the cushion unit shrinks is provided, the link mechanism is provided with a damping force adjustment mechanism that adjusts the damping force of the damper. As the swing arm moves from the vicinity of the riding neutral position where the driver gets on to the extension side of the cushion unit, the extension side damping force of the damper is increased.

[0009] Since the rear wheel has a small damping force near the neutral position of the ride, the riding comfort is good, and the rear wheel has a large damping force near the neutral position of the ride on the contraction side of the cushion unit. And the damping force increases on the extension side of the cushion unit from the vicinity of the neutral position where the rear wheel is in the riding state, so that the change in the posture of the vehicle body can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view of a motorcycle provided with a motorcycle rear suspension device according to the present invention. A motorcycle 1 has a head pipe 3 attached to a front portion of a body frame 2 and a rotatable rotation of the head pipe 3. The vehicle includes a front fork 4 attached thereto, a front wheel 5 rotatably attached to a lower portion of the front fork 4, and a front fender 6 covering an upper portion of the front wheel 5.

The motorcycle 1 has a fuel tank 7 provided above the vehicle body frame 2, a seat 8 provided behind the fuel tank 7, an engine provided below the fuel tank 7 and the seat 8, and A power unit 11 composed of a transmission, and a swing arm 12 attached to the vehicle body frame 2 behind the power unit 11 so as to swing.
And a rear wheel 13 rotatably attached to the rear end of the swing arm 12 and driven by the power unit 11.
And a rear fender 14 that covers an upper portion of the rear wheel 13 and a rear suspension device 20 interposed between the vehicle body frame 2 and the swing arm 12. here,
A rear wheel shaft 13a is provided at the rear end of the swing arm 12 and serves as a rotation center of the rear wheel 13, a radiator shroud 15, a rear cowl 16, an exhaust pipe 17, and a muffler 18.

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 an upper bracket 2a provided on the body frame 2.
Unit 30 with one end rotatably attached to
And a progressive link mechanism 60 attached to the other end of the cushion unit 30 to change the damping force of the cushion unit 30 with the swing of the swing arm 12. Here, reference numeral 12 a denotes a bolt serving as an axis on which the swing arm 12 swings with respect to the vehicle body frame 2.

The cushion unit 30 has a cylinder portion 32 having an upper spring seat 31 screwed to the outer surface.
And a reservoir tank 33 communicated with the cylinder portion 32, a piston rod 34 attached to a piston (described later) housed in the cylinder portion 32, and a lower spring seat 35 attached to a tip of the piston rod 34.
And the extension rod 36 and the upper spring seat 3
1 and a coil spring 37 sandwiched between the lower spring seat 35. Reference numeral 38 denotes a lock nut for fixing the upper spring seat 31, and reference numeral 39 denotes a bump stopper rubber.

The reservoir tank 33 is a volume compensation chamber in which hydraulic oil enters and exits when the piston rod 34 enters and exits the cylinder portion 32 to compensate for a change in volume in 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 in on the outer surface.

The progressive link mechanism 60 includes a first link 61 rotatably mounted on a mounting bracket 12b provided on the swing arm 12, and a lower bracket 2b mounted rotatably on the first link 61 and provided on the vehicle body frame 2. And a second link 62 rotatably mounted on the second link 62.

The first link 61 includes a first fulcrum 61a, a second fulcrum 61b, and a third fulcrum 61c, and the first fulcrum 61a is attached to the mounting bracket 12b of the swing arm 12.
And the second fulcrum 61b is attached to one end 62a of the second link 62 (not shown) with a bolt 64, and the third fulcrum 61c is attached to the extension rod 36 of the cushion unit 30 with a bolt 63. It is attached at 65. The second link 62 has one end portions 62a, 62a and the other end portion 62b, and the other end portion 62b is attached to the lower bracket 2b of the vehicle body frame 2 with a bolt 66.

FIG. 3 is a perspective view of a second link according to the present invention. The second link 62 has a U-shape in plan view in which a pair of arms extend from the other end 62b.
b, a small diameter portion 62c is formed, and the small diameter portion 62c is provided with an upper projecting portion 62d and a lower projecting portion 62e.

The second link 62 has an upper projecting portion 62
A cam 67 shown in FIG. 3 which is applied to the tip of the push rod 41 of the cushion unit 30 shown in FIG.
The cam 67 is attached to the other end 6 for attaching to the second link 62.
A mounting portion 67a formed into a shape along the outer peripheral surface of the small-diameter portion 62c of 2b, and a cam surface 67b abutting on the push rod 41 are provided.

FIG. 4 is a sectional view of a cushion unit according to the present invention.
a and a coil spring 37, and a damper 30a
Is a cylinder part 32, a piston 42 movably inserted into the cylinder part 32, a hollow piston rod 34 attached to the piston 42, and opens and closes an oil passage in the piston 42 in the piston rod 34. For this purpose, an opening / closing rod 43 and a push rod 41 movably housed are provided. S1 and S2 are upper and lower oil chambers formed on both sides of the piston 42 in the cylinder portion 32.

The piston rod 34 has a hollow portion 34a,
An upper oil passage 34b communicating from the hollow portion 34a to the upper oil chamber S1, a horizontal oil passage 34c communicating from the upper end of the hollow portion 34a to the lower oil chamber S2, and an upper oil passage 34
b, a tapered hole 34d as an orifice hole serving as a valve seat formed between the horizontal oil passages 34c and 34c, and a threaded portion 34e formed on the inner surface of the lower end of the hollow portion 34a. The push rod 41 includes a rack portion 41a having teeth cut on an outer surface thereof,
A flange portion 41b for holding a spring 44 is provided at the end, and the push rod 41 is urged to the outside of the extension rod 36 by the spring 44.

The piston 42 includes a piston body 45, an extension oil passage 46 and a contraction oil passage 47 opened in the piston body 45, an extension valve 48 provided at an outlet of the extension oil passage 46, It comprises a contraction side valve 49 provided at the outlet of the oil passage 47. In addition, 51 and 52 are washers, and 53 is a nut.

The opening / closing rod 43 is provided with a valve body 43 provided at the tip.
a, a pinion portion 43b meshed with the rack portion 41a of the push rod 41, and a male thread portion 43c fitted to the female thread portion 34e of the piston rod 34. By separating the valve body 43a from the tapered hole 34d of the hollow portion 34a, the sectional area of the oil passage P between the upper oil passage 34b and the horizontal oil passages 34c, 34c is increased, and the upper oil chamber S1 and the lower oil passage S1 are separated from each other. Room S
2 facilitates the distribution of hydraulic oil. Further, the valve body 43a makes the cross-sectional area of the oil passage P between the upper oil passage 34b and the horizontal oil passages 34c, 34c smaller by approaching the tapered hole 34d of the hollow portion 34a, and makes the upper oil chamber S1 and the lower oil passage S1 closer to each other. This makes it difficult for hydraulic oil to flow through the oil chamber S2.

The pinion portion 43b rotates the opening / closing rod 43 when the push rod 41 moves in the axial direction by engaging with the rack portion 41a.
The external thread portion 43c is to move the opening / closing rod 43 in the axial direction when the opening / closing rod 43 is rotated by fitting with the female thread portion 34e. The hollow portion 34a, the upper oil passage 34b, and the horizontal oil passage 34 of the piston rod 34 described above.
The damping force adjusting mechanism 40 is composed of c, 34c, a tapered hole 34d, a female thread portion 34e, an opening / closing rod 43, a push rod 41, and a spring 44.

With the above configuration, when the push rod 41 enters the extension rod 36, the opening / closing rod 43 is rotated by the engagement between the rack portion 41a and the pinion portion 43b, and the fitting between the female thread portion 34e and the male thread portion 43c is performed. As a result, the opening / closing rod 43 is raised, and the valve body 43a is
d, the cross-sectional area of the oil passage P becomes smaller, and it becomes difficult for hydraulic oil to flow 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.

The push rod 41 is connected to the spring 4
When the push rod 41 retreats from the inside of the extension rod 36 due to the urging force of 4, the opening / closing rod 43 rotates counter to the push rod 41 when the rack 41a and the pinion 43b mesh with each other. The opening / closing rod 43 is lowered by fitting with 43c, the valve element 43a is separated from the tapered hole 34d, the sectional area of the oil passage P gradually increases, and the hydraulic oil flows between the upper oil chamber S1 and the lower oil chamber S2. Is easier to distribute. Therefore, the damping force generated in the oil passage P can be reduced.

The progressive link mechanism 60 described above
The operation of will be described below. FIG. 5 is an operation diagram for explaining the operation of the progressive link mechanism according to the present invention, and shows 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). FIG. In the figure, large ◎
The mark indicates the rear wheel axle 13a, and the small circle mark indicates the bolt 65. The position where the rear wheel axle 13a is indicated by the mark ◎, that is, the position when the driver is riding on the motorcycle and stopped (without applying the acceleration / deceleration force to the vehicle body) to stand upright (“riding” 1G
Also referred to as "state position." This position is hereinafter referred to as a “boarding neutral position”. This is also the riding neutral position of the swing arm 12 and the rear wheel 13. In the case of (1), the bolt 65 serving as a connecting shaft between the progressive link mechanism 60 and the cushion unit is located at the position indicated by the mark ◎.

First, when the swing arm 12 swings from the riding neutral position to the extension side of the cushion unit 30 (see FIG. 4), the swing arm 12 and the rear wheel shaft 13
a, the progressive link mechanism 60, the extension rod 36 of the cushion unit, and the bolt 65 (indicated by a circle) are at the positions shown by solid lines, and the amount of movement of the rear wheel shaft 13a toward the extension side of the cushion unit at this time is Da, Bolt 6
5, the extension amount of the cushion unit is Eb.
And

When the swing arm 12 swings from the riding 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 extension rod 36 of the cushion unit,
And the bolt 65 at the position shown by the two-dot chain line. At this time, the amount of movement of the rear wheel axle 13a to the contraction side of the cushion unit is set to Da which is the same as the above-mentioned amount of movement, and the amount of movement of the bolt 65, If the amount of unit contraction is Sb, then Sb> Eb.

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. Thereby, the moving speed of the piston 42 (see FIG. 4) of the cushion unit 30 shown in FIG.
Further, the resistance when the contraction side valve 49 is pushed open to flow increases, and the damping force generated in the cushion unit 30 increases.

FIG. 6 is a graph showing the relationship between the displacement of the rear wheel axle and the stroke of the cushion unit in the progressive link mechanism according to the present invention, wherein the vertical axis represents the stroke of the cushion unit, and the horizontal axis represents the vertical direction of the rear wheel axle. Indicates the amount of displacement in the direction. (Refer to FIG. 5 for the sign.) When the vertical displacement of the rear wheel axle 13a is 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 stroke amount of the cushion unit increases substantially linearly with an increase in the amount of vertical displacement of the rear wheel shaft 13a.

In the range of the vertical displacement of the rear wheel axle 13a from the riding neutral position point B to the maximum contraction position C of the cushion unit, the vertical wheel displacement of the rear wheel axle 13a increases. On the other hand, the rate of increase in the stroke amount of the cushion unit gradually increases.

As described above, the progressive link mechanism 60
Accordingly, when the rear wheel axle 13a is displaced from the riding neutral position to the contraction side of the cushion unit, the stroke amount of the cushion unit is gradually increased, that is, by increasing the stroke speed of the cushion unit, the maximum contraction of the cushion unit is achieved. At the position, the damping force generated by the cushion unit is increased to prevent the cushion unit from bottoming, and near the riding neutral position, the damping force generated by the cushion unit is reduced to improve the riding comfort.

The above-described rear suspension device 20
The operation of will be described below. FIGS. 7A to 7C are operation diagrams for explaining the operation of the rear suspension device according to the present invention, and FIG. 7A shows a state in which 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 of (a) to the extension side of the cushion unit, and (c) shows a state in which the swing arm swings from the state of (a) to the contraction side of the cushion unit. In (a), the inclination angle of the swing arm 12 with respect to the horizontal line HL at the riding neutral position is defined as θ. At this time, the tip of the push rod 41 is
The protrusion amount of the push rod 41 from the surface of the extension rod 36 at the upper end of b is t1.

In (b), for example, during braking, the body of the motorcycle leans forward and rises rearward, so that the swing arm 12 is tilted 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 extension rod 36
The amount of protrusion of the push rod 41 from the surface is t in FIG.
It becomes t2 smaller than 1. Therefore, 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. The damping force increases.

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 pushes and opens the extension-side valve 48. Therefore, pitching, which is a roll in the front-rear direction of the motorcycle, is reduced, and a change in the posture of the vehicle body can be reduced.

In (c), for example, when the vehicle body is sinking, the swing arm 12 is inclined 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 67b of the cam 67. Therefore,
The damping force of the cushion unit 30 does not change.

The cam 67 has a cam surface so as to operate the damping force adjusting mechanism when the swing arm 12 swings from the riding neutral position where the driver is riding to a certain position on the extension side of the cushion unit 30. The position of 67b and the position of the push rod 41 are set.

As described above, the push rod 41 provided on the cushion unit 30 is connected to the progressive link mechanism 6.
When the push is performed by the cam 67 provided at 0, the relative movement amount between the progressive link mechanism 60 and the cushion unit 30 is large, so that the movement amount of the push rod 41 can be increased, and the damping force of the cushion unit 30 is finely adjusted. Can be easily performed.

Here, the cam 67 is changed to a cam having a receiving surface of a different shape, and the damping force adjusting mechanism 40 (FIG. 4) is changed by changing the positional relationship between the cam surface and the push rod 41.
), And the stroke range of the swing arm 12 (ie, the range of the vertical displacement of the rear wheel shaft 13a) in which the change amount of the damping force or the damping force is desired to be changed is changed. can do.

The first damping mechanism of the present invention is a progressive link mechanism 60 using a plurality of links 61 and 62 shown in FIG. 2, and the second fulcrum 61b is connected to the vehicle body frame 2 by the second link 62. Although the extension rod 36 is connected to the third fulcrum 61c, the present invention is not limited to this. The second fulcrum 61b is connected to the extension rod 36, and the third fulcrum 61c is connected.
May be connected to the body frame 2 by the second link 62,
Further, the third fulcrum 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. In short, when the swing arm 12 swings downward, the push rod 4
1 may enter the extension rod 36.

[0041]

According to the present invention, the following effects are exhibited by the above configuration. The motorcycle rear suspension device of claim 1 is
As the swing arm moves from the vicinity of the riding neutral position where the driver got on to the extension side of the cushion unit,
Since the damping force on the extension side of the damper has been increased, the damping force can be reduced near the neutral position of the rear wheel to improve the ride comfort, and the damping force on the extension side of the cushion unit from the vicinity of the neutral position when the rear wheel is in the riding position. And the change in posture of the vehicle body can be reduced.

According to a second aspect of the present invention, in the motorcycle rear suspension device, the link mechanism is provided with a damping force adjusting mechanism.
As the swing arm moves from the vicinity of the riding neutral position where the driver got on to the extension side of the cushion unit,
Since the damping force on the extension side of the damper has been increased, it is possible to improve the ride comfort by reducing the damping force when the rear wheel is near the riding neutral position, and to improve the riding comfort when the rear wheel is near the riding neutral position and on the compression side of the cushion unit. For example, it is possible to prevent the bottom of the cushion unit from bumping, and to increase the damping force on the extension side of the cushion unit from near the neutral position where the rear wheel is in the riding, thereby reducing the change in the posture of the vehicle body. .

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle including a motorcycle rear suspension device 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. 3 is a perspective view of a second link according to the present invention.

FIG. 4 is a sectional view of a cushion unit according to the present invention.

FIG. 5 is an operation diagram for explaining the operation of the progressive link mechanism according to the present invention.

FIG. 6 is a graph showing a relationship between a displacement amount of a rear wheel axle and a stroke amount of a cushion unit in the progressive link mechanism according to the present invention.

FIG. 7 is an operation diagram illustrating the operation of the rear suspension device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Body frame, 12 ... Swing arm, 13 ... Rear wheel, 13a ... Rear wheel axle, 20 ... Rear suspension device, 30 ... Cushion unit, 30a ... Damper, 37 ... Spring, 40 ... Damping force adjustment mechanism , 60
... Link mechanism (progressive link mechanism).

Claims (2)

[Claims] 1. A two-wheeled vehicle having a swing arm attached to a body frame so as to be able to swing up and down, a rear wheel attached to the swing arm, and a cushion unit including a spring and a damper disposed between the swing arm and the body frame. The rear suspension device for a motorcycle according to any one of claims 1 to 4, wherein the swing arm moves from the vicinity of the riding neutral position where the driver gets on to the extension side of the cushion unit to increase the extension side damping force of the damper. 2. A cushion unit comprising a spring and a damper between the swing arm and the body frame, a cushion unit comprising a swing arm mounted on the body frame so as to be able to swing up and down, and a rear wheel attached to the swing arm. In a two-wheeled vehicle in which a link mechanism that increases the ratio of the amount of shrinkage of the cushion unit to the amount of displacement of the rear wheel as the unit shrinks is provided, a damping force adjusting mechanism that adjusts the damping force of the damper is attached to the link mechanism. A rear suspension device for a motorcycle, wherein the swing arm moves from the vicinity of the riding neutral position where the driver gets on to the extension side of the cushion unit to increase the extension side damping force of the damper.