JPH06107263A - Rear wheel suspension device for motorcycle - Google Patents

Abstract

PURPOSE:To exhibit damping characteristics of a damper smoothly in a transient time of a rear wheel oscillation by providing two dampers having check valves displaying special damping function, when a swing arm suspending a rear wheel is oscillated in one direction and the other direction. CONSTITUTION:In a rear wheel suspension device 30 pivotally mounted on a body frame 1 via swing arm 5 so as to roll a rear wheel 2 freely, first damper 40 is installed in a cushion unit 31 having a coil spring 20. Namely, a bell crank 41 which is pivotally supported 6 by the rear lower end 1a of the body frame 1 is formed into a Y shape and the rear end of the first damper 40 is pivotally supported 11 by one end 41a. The rear end of a damper 12 is pivotally supported by the other end 41b at a point 43 and the front end of the damper 42 is pivotally supported by the body frame 1 via a bracket 44. Respective dampers 40, 42 are provided with a check valve 53 and a throttle valve 54, which allowed only oil to flow from B chamber into A chamber, in a piston 51 paralell to each other so as to exhibit one-directional damping action.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 7 is a conceptual diagram of a motorcycle equipped with a conventional rear wheel suspension system.

In this motorcycle, a rear wheel suspension device 3 using a so-called single cushion unit for swingably supporting a rear wheel 2 is mounted behind a vehicle body frame 1. The rear wheel suspension device 3 includes a swing arm 5 rotatably supported by a swing arm pivot 4 about a shaft 5a, and a bell rotatably supported by a rear lower end 1a of a frame 1 about a shaft 6. A compression rod 1 that connects a crank 7 and a substantially central portion of the bell crank 7 and the swing arm 5 via shafts 8 and 9.
0, and one cushion unit 13 supported via shafts 11 and 12 between the front end portion 7a of the bell crank 7 and the rear upper end 1b of the frame 1.
In FIG. 7, reference numeral 14 is a rear axle.

According to the rear wheel suspension device 3 described above, the rear wheel 2
Is rotated counterclockwise about the swing arm pivot 4 as shown by an arrow A, the bell crank 7 is rotated counterclockwise about the shaft 6 by the compression rod 10, so that the cushion unit 13 has both ends thereof. When the rear wheel 2 rotates clockwise around the swing arm pivot 4 as indicated by arrow B, the compression rod 10 causes the bell crank 7 to move.
Rotates around the shaft 6 in the clockwise direction, so that the cushion unit 13 receives a pulling force for stretching both ends thereof.

On the other hand, the cushion unit 13 used in the above-mentioned conventional rear wheel suspension system 3 includes a coil spring 20 for absorbing a shock from the road surface, and an oil type damper 21 for controlling the vibration of the coil spring 20. It consists of

Of these, the damper 21 is a cylinder 22 filled with oil, as shown in the enlarged view of the main part of FIG.
And a piston 23 for separating the cylinder 22 into A and B chambers, and a piston rod 24 connected to the lower surface of the piston 23.

On the other hand, the piston 23 constituting the above-mentioned damper 21 has a first check valve 24 and a throttle valve 25 connected in series which allow only the inflow of oil from the A chamber to the B chamber.
And a second fluid movement direction control means 26 consisting of a second check valve 27 and a throttle valve 28 connected in series that allow only the inflow of oil from the B chamber to the A chamber. A control means 29 is provided.

Therefore, as shown in FIG. 7, when the rear wheel 2 rotates counterclockwise about the swing arm pivot 4 as shown by the arrow A, a compressive force for compressing both ends of the cushion unit 13 acts. As shown in FIG. 9, the piston 23 of the damper 21 is moved upward by the piston rod 24, thereby compressing the chamber B and causing the oil filled in the chamber B to move to the second fluid movement direction control means 29. Although it is attempted to flow into the chamber A through the arrow through the arrow, the throttle valve 28 of the second fluid movement direction control means 29 acts as a flow path resistance to increase the pressure in the chamber B to move the piston 23 upward. It will be controlled and the dump action will be activated.

Further, as shown in FIG. 7, when the rear wheel 2 rotates clockwise about the swing arm pivot 4 as shown by arrow B, a tensile force pulling both ends of the cushion unit 13 acts. As shown in FIG. 10, the piston 23 of the damper 21 is moved downward by the piston rod 24, whereby the chamber A is compressed and the oil filled in the chamber A is passed through the first fluid movement direction control means 26. Attempt is made to flow into the chamber B as indicated by the arrow. At this time, the throttle valve 25 of the first fluid movement direction control means 26 becomes a resistance of the flow passage to increase the pressure in the chamber A and control the downward movement of the piston 23. The dump action will be activated.

That is, in the cushion unit 13 used in the above-mentioned conventional rear wheel suspension device 3, even if both compressive force and tensile force act on the cushion unit 13, the damper 21 functions to the coil spring 20. The damping force will act.

[0011]

According to the above-mentioned conventional rear wheel suspension device 3, both the compressive force and the tensile force act on the damper 21 of the cushion unit 13 used in the rear wheel suspension device 3. Even so, in order to apply the damping force to the coil spring 20, the first and second fluid movement direction control means 26 and 29 in which the check valve and the throttle valve are connected in series are arranged side by side. In the so-called transitional period when the moving direction of the piston 23 changes, both check valves 24 and 27 have to be operated, so that there is a drawback that the responsiveness of the damper 21 is poor.

That is, from the state in which the tensile force shown in FIG. 10 acts on the damper 21, that is, the state in which the piston 23 moves downward, the state in which the compressive force shown in FIG. 9 acts on the damper 21. That is, in the transitional period when the piston 23 moves to the state of moving upward, or in the transitional period in the opposite case, the first and second fluid movement direction control means 26,
Both of the two check valves 24 and 27 of 29 must be operated at the same time, but since there are two check valves, their operation timings may shift, so that in the transition period, the delay of the dump function, That is, a delay in the damping characteristics occurs,
The damper 21 cannot perform a smooth dumping function. Therefore, in the motorcycle, the steering wheel is shaken, the traction (grounding) performance of the wheel is deteriorated, or hopping during engine braking occurs. Was a factor that significantly reduced the.

In view of the above-mentioned circumstances, it is an object of the present invention to provide a rear wheel suspension system for a motorcycle in which the damper exhibits a smooth damping characteristic even in the transitional period of the rear wheel swing.

[0014]

In order to solve the above-mentioned problems, the rear wheel suspension system of the present invention has one check valve, and when the swing arm swings in one direction by the check valve. The first damper having a dumping function and the second damper having one check valve and having the check valve having a dumping function only when the swing arm swings in the other direction are provided. .

[0015]

According to the above-mentioned rear wheel suspension system, in the transitional period of the damper, since only one check valve operates in one damper, it is possible to prevent the operation timing of the check valve from shifting as much as possible. Therefore, the delay of the damping characteristic is prevented as much as possible.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the rear wheel suspension system for a motorcycle according to the present invention will be described in detail below.

FIG. 1 is a conceptual view of the essential parts of a motorcycle equipped with a rear wheel suspension system according to the present invention. The same parts as those in FIG. 7 are designated by the same reference numerals.

Also in this motorcycle, the rear wheel suspension device 3 using a so-called single cushion unit for supporting the rear wheel 2 swingably behind the body frame 1 as in the conventional case.
0 is installed.

The difference between the rear wheel suspension system 30 and the conventional one is that the cushion unit 31 having the coil spring 20 has a first oil type damper 4 according to the present invention.
0 is mounted, and the bell crank 4 is rotatably supported by the rear lower end 1a of the frame 1 about a shaft 6.
1 has end portions 41a and 4 which are bifurcated like a Y-shaped tip.
1b, the rear end of the first damper 40 forming the cushion unit 31 is provided at one end 41a of the shaft 11a.
Is rotatably supported around the other end 41b.
Is the second oil-type damper 42 according to the present invention.
The rear end is rotatably supported about the shaft 43. The tip end of the second damper 42 is rotatably supported by a bracket 44 formed on the lower portion 1c of the vehicle body frame 1 about a shaft 45.

According to the rear wheel suspension device 3 described above, the rear wheel 2
When the swing arm pivot 4 rotates counterclockwise as indicated by arrow A, the compression rod 10 causes the bell crank 41 to rotate counterclockwise around the shaft 6, so that the first damper of the cushion unit 31 is rotated. 40
Compressive force that contracts both ends of the
A tensile force for stretching both ends of the damper 42 is applied.

Further, the rear wheel 2 is a swing arm pivot 4
When it is rotated clockwise about the axis as indicated by arrow B, the bell crank 41 is rotated clockwise around the shaft 6 by the compression rod 10, so that the cushion unit 31 is rotated.
The first damper 40 is subjected to a tensile force for stretching both ends thereof, and the second damper 42 is subjected to a compressive force for contracting both ends thereof.

On the other hand, the above-mentioned first and second dampers 4
0 and 42 have the same structure, and as shown in the enlarged view of the main part of FIG. 2, a cylinder 50 filled with oil and a piston 51 for separating the cylinder 50 into two chambers A and B.
And a piston rod 52 connected to the lower surface of the piston 51. Among them, the piston 51 is connected to one check valve 53 which allows only the inflow of oil from the B chamber to the A chamber, and is connected in parallel with the one check valve 53, and is connected to either the A chamber or the B chamber. A throttle valve 54 that allows a constant flow of oil from the direction is provided.

Therefore, according to the above-mentioned first and second dampers 40 and 42, when a compressive force for contracting both ends of the first and second dampers 40 and 42 is applied to the piston, as shown in FIG. Although the rod 52 moves upward and tries to compress the chamber B by this, the oil filled in the chamber B quickly flows into the chamber A through the check valve 53, and in this case, the first and second chambers are used. The damper function, that is, the damping function, does not work on the dampers 40 and 42 of FIG.

On the other hand, as shown in FIG. 4, when a pulling force for pulling both ends of the first and second dampers 40, 42 acts, the piston 51 moves downward by the piston rod 52, whereby A The chamber is compressed so that the oil filled in the chamber A is allowed to flow into the chamber B. At that time, the check valve 5
Since 3 allows only the inflow of oil from the B chamber to the A chamber, the oil cannot pass through the check valve 53, so that the oil filled in the A chamber only through the throttle valve 54. It flows into room B. Therefore, the throttle valve 54 acts as a resistance of the flow path to increase the pressure in the chamber A and control the downward movement of the piston 51 to exert a dumping action.

That is, in the above-mentioned first and second dampers 40 and 42, the dumping function does not work when the compression force acts, and the dumping function works only when the tension force acts.

Further, the above-mentioned first and second dampers 4
Nos. 0 and 42 have only one check valve 53, and therefore when the tensile force acts, that is, when the piston 51 shown in FIG. 4 moves downward, the check valve 53 operates immediately. Since the dump function is activated, the delay of the generation of the damping force can be prevented as much as possible.

Therefore, according to the rear wheel suspension system 30 equipped with the above-mentioned first and second dampers 40 and 42,
As shown in the drawing, when the rear wheel 2 rotates counterclockwise about the swing arm pivot 4 as indicated by the arrow A, the first unit forming the cushion unit 31 via the bell crank 41.
In this case, the damper 40 has a compressive force that contracts both ends thereof, and the second damper 42 has a tensile force that pulls both ends thereof. Therefore, in this case, the first damper 40 does not have a dumping action. The piston 51 is moved to the B chamber side. Further, since the piston 51 of the second damper 42 moves to the A chamber side by the pulling force, a dumping action occurs.

Further, as shown in FIG. 6, when the rear wheel 2 rotates clockwise about the swing arm pivot 4 as indicated by arrow B, the first damper forming the cushion unit 31 via the bell crank 41. Since a tensile force pulling both ends of the piston 40 acts, and a compressing force of contracting both ends of the second damper 42 acts, the piston 51 of the first damper 40 moves toward the chamber A side by the tensile force in this case. Since the second damper 42 is moved, a compressing force is exerted on the second damper 42. Therefore, the piston 51 is moved to the B chamber side without the dumping action.

That is, in the above-mentioned rear wheel suspension system 30 shown in FIG. 1, when the rear wheel 2 rotates counterclockwise about the swing arm pivot 4 as shown by arrow A, the second damper 42 is rotated. When the rear wheel 2 rotates clockwise around the swing arm pivot 4 as shown by the arrow B, only the first damper 40 exerts the dumping action, and the damping effect on the coil spring 20 is exerted. Force will be applied.

Therefore, in the above-mentioned rear wheel suspension device 30,
When the rotation direction of the rear wheel 2 changes, that is, the first and second
Only one check valve 53 (FIG. 2) is provided in each of the first and second dampers 40, 42 even in the transitional period in which either one of the dampers 40, 42 exhibits a dumping action. Since the check valve 53 is not operated, the check valve 53 immediately operates to exert the dumping function, so that the delay in the generation of the damping force with respect to the coil spring 20 is prevented as much as possible.

[0031]

As described above, the rear wheel suspension system of the present invention has one check valve, and the check valve performs the dumping function only when the swing arm swings in one direction. Since the first damper and the second damper having the one check valve and having the check valve perform the dumping function only when the swing arm swings in the other direction,
Unlike the conventional damper, it is not necessary to simultaneously operate the two check valves in the transition period of the rear wheel swing, so that the risk of the operation timing being shifted can be reduced as much as possible. During the period, the damper exerts a smooth and stable damping characteristic to prevent swinging of the steering wheel in the motorcycle, deterioration of the wheel traction (grounding) performance, or hopping during engine braking as much as possible. The movement performance of the motorcycle can be remarkably improved.

Since only one check valve needs to be provided as the damper unit, the number of parts can be reduced and the damper can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a conceptual view of a main part of a motorcycle equipped with a rear wheel suspension device according to the present invention.

FIG. 2 is a fragmentary enlarged view of a damper of a rear wheel suspension system according to the present invention.

FIG. 3 is a fragmentary enlarged view showing the action of the damper of the rear wheel suspension system according to the present invention.

FIG. 4 is a fragmentary enlarged view showing the action of the damper of the rear wheel suspension system according to the present invention.

FIG. 5 is a conceptual diagram of a main part of the motorcycle showing the operation of the rear wheel suspension system according to the present invention.

FIG. 6 is a conceptual diagram of a main part of the motorcycle showing the operation of the rear wheel suspension system according to the present invention.

FIG. 7 is a conceptual diagram of a main part of a motorcycle equipped with a conventional rear wheel suspension device.

FIG. 8 is a fragmentary enlarged view of a damper used in a conventional rear wheel suspension system.

FIG. 9 is an enlarged fragmentary view showing the action of a damper used in a conventional rear wheel suspension system.

FIG. 10 is a fragmentary enlarged view showing the action of a damper used in a conventional rear wheel suspension system.

[Explanation of symbols]

 2 ... Rear wheel 5 ... Swing arm 30 ... Rear wheel suspension device 40 ... First damper 42 ... Second damper 53 ... Check valve

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[Procedure amendment]

[Submission date] June 17, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

[Claims] Claim: What is claimed is: 1. A rear wheel suspension system for a motorcycle, wherein a rear wheel is suspended, the rear wheel suspension system having one check valve, and only when the swing arm swings in one direction by the check valve. It has a first damper that performs a dumping function and a second damper that has one check valve and that performs a dumping function only when the swing arm swings in the other direction due to the check valve. Rear wheel suspension system for motorcycles.