JPH05213257A - Rear wheel suspension device of motorcycle - Google Patents

Abstract

PURPOSE:To improve space efficiency, to perform the effective use of the spring constant of a leaf spring, and to ensure durability of the leaf spring by a method wherein the second coupling point of an intermediate link is caused to approach a straight line for interconnecting the front end pivotal support point of the leaf spring and the pivotal support point of the intermediate link to a rear arm along with raising of the rear arm. CONSTITUTION:A rear wheel suspension device for a motorcycle comprises a tie plate- form leaf spring 31 of a cushioning spring, a link mechanism 56 for coupling the rear end part 31a thereof to a rear arm 21, an intermediate link 38 pivotally supported on the rear arm 21, a lever 37 having a rotary fulcrum 34 in a position, located eccentrically from the rear arm pivot 27 of a car body fixing part, and coupled to the first coupling point 38d of the intermediate link 38 and giving rotation characteristics to the intermediate link 38, and a spring 39 for intercoupling the rear end part 31a of the leaf sprung 31 to the second coupling point 38h of the intermediate 38. The second coupling point 38h is caused to approach a straight line A for interconnecting the front end pivotal support point 59 of the leaf spring 31 to the pivotal support point 38c of the intermediate link 38 to the rear arm 21 along with raising of the rear arm 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel suspension system for a motorcycle, and more particularly to a spring constant in the bending direction of a leaf spring when the leaf spring is used as a buffer spring. To the improvement of the link mechanism for connecting the rear end of the leaf spring to the rear arm.

[0002]

2. Description of the Related Art Conventionally, a rear wheel suspension system for a motorcycle has a structure in which a shock absorber composed of a coil spring and a telescopic tubular damper is interposed between a rear arm and a vehicle body frame. And recently, with one shock absorber,
Between the pivot arm of the rear arm and the fuel tank lower part of the body frame, or the seat lower part,
It is common to employ a structure that is arranged directly or via a link mechanism (for example, JP-A-59-12058).
(See Japanese Patent Publication No. 5).

However, in the above-mentioned conventional apparatus, the shock absorber occupies the space for arranging the parts located in the center of the vehicle, so that it is difficult to secure the space for arranging the other on-vehicle parts such as the air cleaner and the battery, and the intake system. Cannot be arranged in a straight line, and there is a problem that the space efficiency in arranging components is poor.

[0004]

On the other hand, the present inventors are currently studying to employ a leaf spring instead of the coil spring. In the case of this structure, the rear end of the leaf spring is connected to the rear arm. Depending on the connection structure, although the above space efficiency can be improved,
As the rear arm moves up and down, a bending force in an undesired direction acts on the leaf spring, which may make it impossible to effectively use the spring constant of the leaf spring in the bending direction or reduce the durability of the leaf spring.

The present invention has been made in view of the above-mentioned conventional problems and problems when a leaf spring is adopted, and it is possible to improve the space efficiency and effectively use the spring constant of the leaf spring. It is an object of the present invention to provide a rear wheel suspension device for a motorcycle that can ensure the durability of a leaf spring.

[0006]

SUMMARY OF THE INVENTION The present invention provides a rear wheel suspension system for a motorcycle including a shock absorbing spring for cushioning a shock applied to a rear wheel from a road surface and a damper for suppressing irregular vertical vibration of the rear wheel. As shown in FIG. 8, the buffer spring is a strip plate-shaped leaf spring 31, and a rear end portion 31 of the leaf spring 31 is provided.
The link mechanism 56 connecting a to the rear arm 21 has an intermediate link 38 pivotally supported by the rear arm 21, and a rotation fulcrum 34 at a position eccentric from the rear arm pivot 27 of the vehicle body fixing portion. First connection point 38
a lever 37 connected to the intermediate link 38 for imparting rotational characteristics to the intermediate link 38; and a spring link 39 connecting the rear end 31a of the leaf spring 31 and the second connecting point 38h of the intermediate link 38. Also, the second connection point 38h is the front end pivot fulcrum 59 of the leaf spring 31 as the rear arm 21 rises.
It is characterized in that it is configured so as to approach a straight line A that connects the center link 38 and the pivot 38c of the intermediate link 38 to the rear arm 21. In this case, as shown in FIG.
Most preferably, the connecting point 38h is located on the straight line A when the rear arm 21 is raised to the highest position.

[0007]

According to the rear wheel suspension device of the present invention, when the rear wheel rides on the convex portion of the road surface, the rear arm 21 rises, and as the rear arm 21 rises, the rear end portion 31a of the leaf spring 31.
Is pulled up, and the shock is absorbed and relaxed by the spring constant of the leaf spring 31 in the bending direction.

In this case, in order to effectively use the spring constant of the leaf spring 31 in the bending direction, the force a acting on the rear end portion 31a of the leaf spring 31 always acts in the direction of the center of curvature of the leaf spring 31. It is desirable to configure it (see FIG. 8A).
In the present invention, in the link mechanism 56, the intermediate link 38 rotates around the pivotal support point 38c as the rear arm 21 rises, whereby the second connection point 38h between the spring link 39 and the intermediate link 38 is moved forward. Since it is configured to be close to the straight line A connecting the fulcrum 59 and the rear arm pivot fulcrum 38c,
As the rear arm 21 rises, the second connection point 38h moves to the front end pivotal fulcrum 59 side, and the direction of pulling the leaf spring 31 of the spring link 39 comes closer to the above-mentioned curvature center direction, so that the bending constant of the leaf spring 31 is changed. Can be used more efficiently,
As a result, an unreasonable load does not act on the leaf spring, so that the durability can be improved.

Further, since the buffer spring is changed from the conventional coil spring to a strip-shaped plate spring, it is easy to dispose the plate spring in the front-rear direction below the engine, and the conventional coil spring is arranged. In addition, a space is created in the center of the vehicle, and it is possible to dispose on-vehicle components such as an air cleaner and a battery or to dispose the intake system in a straight line by using this space, and the space efficiency is improved accordingly.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 are views for explaining a rear wheel suspension system of a motorcycle according to an embodiment of the present invention. FIG. 1 is a side view, FIG. 2 is a plan view, and FIGS. III-III line sectional view, IV-IV line sectional view, FIGS. 5 and 6 are side views and sectional front views of an initial load adjusting mechanism of a leaf spring, and FIG. 7 is a left side surface of a motorcycle equipped with the embodiment apparatus. 8 and 9 are schematic views showing the operation of the apparatus of this embodiment.

In the figure, reference numeral 1 is a motorcycle in which the suspension system of the embodiment is adopted. The vehicle body frame 2 of the motorcycle 1 is of a so-called semi-double cradle type and has the following structure. The front end of the front half 4a of the tank rail 4 is connected to the head pipe 3, the rear arm brackets 5, 5 are connected to the rear ends of the rear half 4b, and the lower ends of the rear arm brackets 5 are connected to the left side of the down tube 6,
The rear end of the right branch portion 6a is connected, and the front end of a front half portion 6b formed of one square pipe of the down tube 6 is connected to the head pipe 3. Further, a reinforcing tension pipe 7 consisting of one round pipe is provided near the branch point of the tank rail 4 and the front half portion 6b of the down tube 6.
The structure is connected with. The tank rail 4 is formed by stacking the front half portions 4a of two rectangular pipes in the vehicle width direction and joining them together as one, and the rear half portion 4b is expanded and separated in the vehicle width direction. The left and right rear arm brackets 5, 5 are connected by an upper cross pipe 5b and a lower cross pipe 5c. Reference numeral 8 is a seat rail, and 9 is a back stay that supports a rear end portion of the seat rail 8.

A fuel tank 10 is provided on the tank rail 4 of the vehicle body frame 2, and a seat 11 is provided on the seat rail 8.
However, an engine 12 is mounted in each cradle composed of the tank rail 4, the rear arm bracket 5, and the down tube 6.

The engine 12 is of a water-cooled two-cycle single-cylinder type, and a cylinder block 14 and a cylinder head 15 are laminated and fastened to the front portion of a crankcase 13 integrated with a transmission case in a forwardly inclined state. It has a structure. The engine 12 is mounted on the vehicle body frame 2 with the following structure. The front and bottom bosses 13a and 13b of the crankcase 13 are bolted to the support bracket 61 that is bolted to the rising portions of the left and right branch portions 6a of the down tube 6 and the bracket 6c that is welded and fixed to the bottom. Fix it. The rear boss portion 13c of the crankcase 13 is supported by a pivot shaft 27 described later. Further, the suspension boss portion 15a of the cylinder head 15 is bolted and fixed to the tank rail 4 via the suspension bracket 15b.

The support bracket 61 is shown in FIG.
As shown in FIG. 6, left and right flange portions 61a having a substantially triangular shape in a side view are integrally connected to each other by upper and lower connecting portions 61b and 61c.
On the left side of the down tube 6 with a pair of upper and lower bolts 61d,
It is fixed to the right branch portion 6a.

A rear arm 21 is pivotally supported by the rear arm bracket 5 so as to be vertically swingable. The rear arm 21 has a pair of left and right arm bodies 22a and 22b in the shape of a rectangular tube, and a pivot portion 23 formed at the front end of the arm body 22a and 22b. A member 24 is connected and fixed, and a rear wheel 26 is pivotally supported by an axle 25 that is inserted and fixed between the rear ends of the left and right arm bodies 22a and 22b. The pivot portion 23 is axially supported by a pivot shaft 27 inserted through the bearing through a bearing, and the pivot shaft 27 is fixed to the left and right rear arm brackets 5 with a nut 27a. The rear boss portion 13c of the crankcase 13 is located between the left and right pivot portions 23, 23.

A rear wheel suspension device 29 is arranged from the front part of the rear arm 21 to the lower part of the engine 12. The rear wheel suspension device 29 is disposed between the rear arm 21 and the rear arm bracket 5, and is provided with a rotary damper 30 for suppressing irregular vertical vibration of the rear wheel 26, the rear arm 21 and the body frame 2. A leaf spring 31 that is arranged between the Dunun tube 6 and reduces the shock applied to the rear wheel 26 from the road surface, and a link mechanism 56 that connects the leaf spring 31, the damper 30 and the rear arm 21.
It consists of and.

The rotary damper 30 includes a case body 32.
A substantially plate-shaped wing-shaped piston 33 that defines two chambers in the case is housed and arranged in a damper case 32 that is substantially fan-shaped in a side view and is composed of a and a lid 32b.
The rotary shaft 34 is inserted into the shaft a and is spline-fitted, and the rotary shaft 34 is rotatably supported by the damper case 32. Although not shown, the lid 32b is formed with a plurality of oil passages that communicate the two chambers defined by the piston 33, and a throttle mechanism is arranged in the passages. .. When the piston 33 is rotated around the rotary shaft 34, the hydraulic oil moves from one chamber through the throttle mechanism to the other chamber, and this damper 30 generates a damping force.

The damper case 32 includes upper and lower boss portions 3
2d and 32e are integrally formed, and both boss portions 32 are formed.
d and 32e are fixed to the support brackets 36a and 36b with fixing bolts 35a and 35b. The support brackets 36a and 36b are respectively attached to the upper cross pipe 5
b, fixed to the lower cross pipe 5c by welding.

The rear end portion 31a of the leaf spring 31 is supported by the rear arm 21 via the link mechanism 56 described later, and the front end portion 31b is a front spring bracket 47a.
It is supported by the vehicle body frame 2 via a pivotal support mechanism 47 composed of a support bolt 59 and an initial load adjusting mechanism 57. The front end portion 31b is the front spring bracket 47a.
To the support plate 47 with a rubber sheet 47e interposed.
b, it is fastened and fixed with a fixing bolt 47c. The rubber sheet 47e is for relieving the stress when the resin plate spring is sandwiched between the metal brackets.

The initial load adjusting mechanism 57 has the following structure. Left and right branch portions 6a of the down tube 6
The left and right guide brackets 58 are fixed to each other, the supporting bolts 59 are bridged and inserted between the vertically extending elongated holes 58a of the brackets 58, and fixed by nuts 59a. A connecting hole 60a formed at the lower end of the adjusting bolt 60 is fitted and connected to the central portion of the support bolt 59, and the adjusting bolt 60 is
The threaded portion 60b of the support bracket 61 is inserted into the lower connection portion 61c of the support bracket 61, and the threaded portion 60b is fitted with the adjusting nut 60c.
It has a screwed structure.

Further, the support bolt 59 has a connecting portion 47d of the front spring bracket 47a, and the adjusting bolt 6 has the connecting portion 47d.
Collar 59b for restricting lateral movement of 0, and bearing 59
It is rotatably connected via c. As a result, the front spring bracket 47a and thus the front end 31b of the leaf spring 31 are pivotally supported in the front-rear direction with respect to the vehicle body frame 2 and their vertical positions can be adjusted.

The leaf spring 31 is located above the center of the leaf spring 31 in the longitudinal direction, and the leaf spring 31 is caused by the vertical movement of the rear arm 21.
Front and rear pillows 62 and 63, which serve as fulcrums for the deformation, are arranged so that their longitudinal positions can be adjusted.

The front pillow 62 connects a pair of left and right side plates 62a having a plurality of mounting screw holes 62c arranged in a row in the front-rear direction with a base plate 62b, and at the same time, the lower surface of the base plate 62b. A block 62d made of an elastic material such as relatively hard rubber or urethane foam is attached to the. The side plate 62a is fixed by fixing bolts 62e in the vicinity of the connecting portion of the left and right branch portions 6a with the rear arm bracket 5 by selecting the front-rear direction position. As shown in FIG. 1, the block 62d of the front pillow 62 is dimensioned and mounted so as to contact the upper surface of the leaf spring 31 even at the most lowered position of the rear arm 20.

The rear pillow 63 has a block 6 made of the same material as the front block 62d on the lower surface of the base plate 63a.
3b is attached. And the base plate 6
3a is fixed by screwing the fixing bolt 63c into one of the mounting screw holes 63e of the mounting plate 63d fixed to the connection point between the branch portion 6a and the lower cross pipe 5c, by selecting its longitudinal position. ing. This rear pillow 6
3, the respective dimensions and mounting positions are set so that the leaf spring 31 contacts the rubber block 63b from the time when the rear arm 21 is lifted by a predetermined amount.

The link mechanism 56 includes the rear arm 2
A pair of left and right intermediate links 38, 38 pivotally supported by 1;
A pair of left and right levers 37, 37 connected to the intermediate link 38 and rotating the piston 33 of the damper 30;
It is composed of a pair of left and right spring links 39, 39 connecting the respective intermediate links 38 and the leaf spring 31.

The left and right intermediate links 38, 38 are plate-shaped members having a substantially triangular shape in a side view, and connecting collars 38f, 38g are interposed between the links, and the connecting holes 38 are formed.
Connection bolts 38c and 38d are inserted into a and 38b, and nuts 38e and 38e are screwed together to be integrally connected.

A support bracket 24a fixed to the lower surface of the cross member 24 is connected to a connecting collar 38f fitted to the connecting bolt 38c via a bearing 24b, whereby the intermediate link 38 is connected to the rear arm 2.
It is pivotally supported at 1. Hereinafter, the connecting bolt 38c will be referred to as a pivot point of the intermediate link 38.

The lower ends 37a of the pair of left and right levers 37 are rotatably connected to the connecting collar 38g fitted on the connecting bolt 38d via bearings. As a result, the lever 37 is rotatably connected to the intermediate link 38, and hereinafter, the connecting bolt 38d is referred to as a first connecting point. Note that 37b and 37c are the left and right levers 37 described above.
These are bolts and nuts that fasten and unify each other. The upper end 37d of the lever 37 is spline-fitted to the outward protruding end of the rotary shaft 34 of the damper 30, and is fixed by tightening the nut. As a result, as the rear arm 21 swings, the lever 37 rotates via the intermediate link 38, and the lever 37 rotates the piston 33 of the damper 30.

Further, connecting pins 38h are provided on the outer surface of the intermediate link 38, and the upper ends 39a of the left and right spring links 39 are connected to the connecting pins 38h via bearings. Thus, the spring link 39 is rotatably connected to the intermediate link 38, and the connecting pin 38h is hereinafter referred to as a second connecting point. The left and right support pins 43a of the rear spring bracket 43 are inserted into the lower ends 39b of the left and right spring links 39 via bearings, and the rear end of the leaf spring 31 is attached to the support portion 43b of the rear spring bracket 43. The portion 31a is bolted and fixed.

Next, the function and effect of this embodiment will be described. In the device of this embodiment, when the rear wheel 26 rides on, for example, a convex portion of the road surface, the rear arm 21 is lifted by the impact force, and the rear end portion 31a of the leaf spring 31 is accordingly moved to the intermediate link 38,
The leaf spring 31 is pulled up via the spring link 39, and the leaf spring 31 bends around the front pillow 62 as a fulcrum, and the impact force is alleviated according to the spring constant of the leaf spring 31 in the bending direction. Further, when the rear arm 20 further rises, the leaf spring 31 is further bent around the rear pillow 63 as a fulcrum (see the chain double-dashed line in FIG. 1), which increases the spring constant and raises the spring characteristic, so that a so-called progressive effect is obtained.

As the rear arm 21 moves up and down, the lever 37 rotates via the intermediate link 38, and the lever 37 rotates the piston 33 in the damper 30.
As a result, a damping force is generated when the hydraulic oil in one chamber of the damper 30 flows into the other chamber through the throttle mechanism of the oil passage, and irregular vertical vibration of the rear wheel 26 is suppressed.

The operation of the link mechanism 56 and the leaf spring 31 will now be described in detail with reference to FIG. 8. At the first connecting point 38d of the intermediate link 38, the pivot point 34 is provided at the rear position of the pivot shaft 27. Since the lever 37 included therein is connected, the intermediate link 38 rotates counterclockwise about the pivot point 38c for the rear arm 21 as the rear arm 21 rises. As a result, the second connecting point 38h of the spring link 39 to the intermediate link 38 is moved to the front end pivotal fulcrum 59 of the leaf spring 31 and the pivotal fulcrum 38 as the rear arm 21 is raised.
It will move so as to approach the straight line A connecting with c. Therefore, as compared with the case where the spring link 39 is directly connected to the rear arm 21 without the intermediate link 38, the connection point 38h of the spring link 39 moves downward in the drawing. As a result, as shown in FIG. 8A, the direction of the pulling force acting on the rear end portion 31a of the leaf spring 31 becomes closer to the direction of the center of curvature of the leaf spring (see arrows a and a '), and as a result, the leaf spring The spring constant in the bending direction of the spring 31 can be used more effectively.

Further, in the present embodiment, the leaf spring 31 is arranged below the engine in the front-rear direction, and the damper 30 is attached to the rear arm 21.
Cylinder block 1 because it is placed near the pivot part of
A relatively large space is formed at the rear of the space 4, the carburetor 14a and the air cleaner 14b can be arranged by utilizing the space, the intake system can be linearly configured, and the space efficiency can be improved.

In the above embodiment, the link mechanism 56 is used.
Is the second connection point 3 of the spring link 39 to the intermediate link 38.
Although 8h is configured to approach the straight line A from the upper side as the rear arm 21 rises, it may be configured to approach the straight line A from the lower side conversely.

In the above embodiment, the lever 37 for imparting the rotation characteristic to the intermediate link 38 is the piston 3 of the damper 30.
Although the case where the arm that drives 3 is also used has been described,
The lever of the present invention may be pivotally supported on a vehicle body fixing portion such as a vehicle body frame or a crankcase.

[0036]

As described above, according to the rear wheel suspension system for a motorcycle according to the present invention, the link mechanism for connecting the leaf spring to the rear arm is provided with the intermediate link pivotally supported by the rear arm.
The intermediate link includes a lever that imparts a turning characteristic and a spring link that connects the intermediate link and the leaf spring, and a connection point between the spring link and the intermediate link is a front end of the leaf spring as the rear arm is raised. Since it is configured to approach the straight line connecting the pivot point and the rear arm pivot point of the intermediate link, the direction of the force acting on the rear end portion of the leaf spring can be made closer to the direction of the center of curvature of the leaf spring. There is an effect that the spring constant of the leaf spring in the bending direction can be effectively used, and an effect that an unreasonable load acts on the leaf spring to improve the durability.

[Brief description of drawings]

FIG. 1 is a side view of a rear wheel suspension system for a motorcycle according to an embodiment of the present invention.

FIG. 2 is a plan view of the apparatus of the above embodiment.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a side view of an initial load adjusting mechanism portion of the above embodiment.

FIG. 6 is a sectional front view of the initial load adjusting mechanism portion.

FIG. 7 is a left side view of a motorcycle equipped with the device of the embodiment.

FIG. 8 is a schematic diagram for explaining the operation of the apparatus according to the embodiment.

[Explanation of symbols]

 1 Motorcycle 21 Rear Arm 26 Rear Wheel 27 Rear Arm Pivot 29 Rear Wheel Suspension Device 30 Damper 31 Leaf Spring 31a Rear End 34 Rotating Shaft (Rotation Support Point) 37 Lever 38 Intermediate Link 38c Pivot 38d First Connection Point 38h Second Connection Point 39 Spring link 56 Link mechanism 59 Pivot bolt (front end pivot point) A Straight line

Claims (1)

[Claims] 1. A rear wheel suspension system for a motorcycle, comprising: a buffer spring for reducing a shock applied to a rear wheel from a road surface; and a damper for suppressing an irregular vertical vibration of the rear wheel. And a link mechanism for connecting the rear end of the leaf spring to the rear arm is eccentric from the intermediate link pivotally supported by the rear arm and the rear arm pivot of the vehicle body frame or engine (hereinafter referred to as the vehicle body fixing portion). A lever that has a rotation fulcrum at a predetermined position and is connected to a first connection point of the intermediate link to impart a rotation characteristic to the intermediate link; a second connection between the rear end of the leaf spring and the intermediate link. And a spring link for connecting the point and the second connecting point so that the second connecting point approaches a straight line connecting the front end pivot of the leaf spring and the pivot of the intermediate link to the rear arm as the rear arm rises. Shi A rear-wheel suspension system for a motorcycle, characterized in that