JP3125566B2 - Rear wheel suspension for small vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear suspension for a small vehicle, and more particularly to a structure of a spring upper bracket suitable for use in an off-road motorcycle having a single suspension (mono suspension). In addition, the present invention relates to a rear wheel suspension device for a small vehicle such as a three-wheeled vehicle or a four-wheeled vehicle having a suspension structure having a swing arm.

[0002]

2. Description of the Related Art Conventionally, in a small vehicle such as a motorcycle, a rear wheel suspension device is provided at a rear portion of a body frame b for suspending an engine a as shown in FIG. A swing arm d swingably and rearwardly extending from a pivot shaft c fixed to the rear end,
The lower end is connected to lever e1 and rod e by swing arm d.
2 and the upper end is an upper bracket b
1 and a suspension unit f fixed to the upper part of the body frame b. In FIG. 5, reference symbol g denotes an air cleaner, and h denotes a carburetor.

The suspension unit f has a spring f1 and a shock absorber (buffer) f2 formed coaxially and integrally. The lever e1
Has one end rotatably connected to the lower part of the pivot shaft c of the body frame b, and the other end connected to the lower end of the suspension unit f. The rod e2 has a lower end substantially at the center of the lever e1. The upper end is connected rotatably to the swing arm d.

[0004] With the above configuration, the rear wheel suspension device is
When the swing motion of the swing arm d is transmitted to the suspension unit f by the arm e1 and the rod e2, the lever ratio changes due to the link operation of the arm e1 and the rod e2, so that the suspension unit f is progressive with respect to the swing arm d. Characteristic (the characteristic that the operation of the suspension unit is accelerated as the sinking of the wheel becomes deeper). The above operation of the suspension unit f can make the behavior of the rear wheels appropriate.

[0005]

However, the conventional structure in which the suspension unit is supported by the bracket welded to the frame, the strength of the body frame to support the load from the suspension unit (including the spring). The weight,
Space is increasing. In addition, the power point and the point of action of the suspension unit are located on separate parts from the swing arm and the frame, respectively, and the dimensional deviation tends to be large because of the separate parts, which tends to cause an accuracy problem. Therefore, components (bush,
Pillow balls), which increases the number of parts and causes an increase in cost. In addition, the coaxiality (parallelism) of the rod serving as the rotation axis at the point of force and the point of action becomes a problem. If the coaxiality is poor, a prying force acts on the rod and the operability of the suspension unit deteriorates.

[0006] When a suspension having a long stroke is set, the position of the upper bracket is increased, and consequently, the vehicle height is increased and the position of the center of gravity is increased. Further, when the lever ratio is changed, the spring mounting position must be changed. However, since the spring is mounted on the welded bracket, it is difficult to change the mounting position. Further, in a suspension having a long stroke, the spring is located at a position for blocking between the carburetor and the air cleaner, so that the intake passage (outlet tube) is largely bypassed, which hinders downsizing of the vehicle.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has been made to reduce the weight and space of a vehicle body, improve the operability of a suspension unit, lower the vehicle height and the position of the center of gravity, and reduce the lever height. It is an object of the present invention to provide a rear wheel suspension system for a small vehicle that can easily change the ratio and reduce the size of the vehicle.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 has a rear end supporting a rear wheel and a front end connected to a vehicle body frame by a pivot shaft. In a rear suspension system for a small vehicle having a rear swing arm swinging vertically in the center and a suspension unit including a spring member and a shock absorber for braking the swing of the swing arm, the rear wheel suspension device is substantially separate from the shock absorber. A spring member extending along the front-rear direction of the vehicle and having a front end located above the pivot shaft and a rear end connected to the swing arm; and a rotary type member located below the pivot shaft and connected to the swing arm. A shock absorber that extends vertically and has a lower end inserted through the pivot shaft and an upper end supporting the front end of the spring member and a bracket separate from the vehicle body frame. Tsu has a preparative member, the configuration of the rear-wheel suspension system for small vehicles, characterized in that a fixing member which is interposed between the bracket member and the engine to secure the bracket member to the engine.

[0009]

According to the first aspect of the invention, when the swing arm swings and the rear wheel swings up and down, the pushing force and the pulling force of the swing arm act on the rear end of the spring member, and the spring is moved. The member tries to go forward or backward. The force of this spring member going forward and backward is received and retained by the bracket member at its front end. Since the lower end of the bracket member is inserted into the pivot shaft and fixed to the engine by the fixing member, the bracket member does not rotate around the pivot shaft (is not stopped) and rigidly supports the spring member. That is, the engine (via the fixing member) and the frame (via the pivot shaft) can be regarded as supporting the spring member as a rigid body. Therefore, the spring member is compressed and extended by the swing arm and the bracket in order to prevent the spring member from moving forward and backward. In addition, since the spring is provided extending substantially along the vehicle front-rear direction,
As described above, the stroke in which the spring member is compressed / extended is in the front-rear direction.

[0010] Further, since the bracket member is rigidly supported by the pivot shaft and the engine without welding, the coaxiality can be accurately and easily obtained as compared with a bracket fixed by conventional welding. Therefore, since the force to pry when swinging the swing arm does not act on the rod of the spring member and the operability of the suspension unit is good, the stroke of the rear wheel is completely converted to the stroke of the suspension unit, and there is no useless behavior. Absent. Further, since the spring member extends rearward from slightly above the pivot shaft and the rotary tamper is located below the pivot shaft, the overall position of the suspension unit is lowered. Therefore, the position of the center of gravity of the vehicle is lowered, and the running stability and the turning performance of the vehicle are improved. Also,
Since the overall position of the suspension unit is lowered, an empty space between the swing arm and the seat increases. Further, the bracket member is much easier to replace than the upper bracket fixed by welding.
Therefore, it is easy to change the specifications such as the lever ratio. Further, since the spring member is not limited in its stroke by the stroke of the shock absorber, the overall length of the spring is shortened while the stroke is increased. When the swing arm swings, the shock absorber buffers the swing motion. Since the shock absorber is a rotary type, it takes up little space and does not get in the way.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are explanatory views of a rear wheel suspension device for a motorcycle according to an embodiment of the present invention. FIG. 1 shows a state in which a spring member is in a maximum extension state, FIG. 2 shows a state in which the spring member is in a maximum contraction state, FIG. 3 is a detailed cross-sectional view around the pivot shaft of the rear wheel suspension, and FIGS. 4A, 4B, and 4C are a plan view, a front view, and a side view of the bracket member. Note that the small vehicle of the present invention is not limited to motorcycles, but can be applied to three-wheeled and four-wheeled vehicles.

As shown in FIGS. 1 to 4, the rear wheel suspension of the embodiment is disposed rearward from a pivot shaft 10 which is located substantially at a rear end 8 a of an engine case 8.
A rear swing arm 14 having a rear end supporting a rear wheel (not shown) and a front end connected to a vehicle body frame 12 by a pivot shaft 10 and swinging vertically about the pivot shaft 10; Spring member 16 for damping swing of arm 14 and rotary damper (buffer)
And a bracket unit 20 for supporting the front end 16a of the spring member 16.

As shown in detail in FIG. 3, the pivot shaft 10 is provided at the rear end portion 12a of each of the two body frames 12 arranged side by side in the vehicle body width direction and at the rear of the engine case 8 at the rear of the engine case 8. End 8a and bracket member 20
And are fastened to them. A rear swing arm 14 is rotatably supported on the pivot shaft 10 via a bearing 10a.

The spring member 16 is provided separately from the rotary damper 18 when viewed from the side of the vehicle body so as to extend substantially horizontally so that the front end 16a is slightly upward in the vehicle longitudinal direction. Also, the spring member 16
The front end 16a is located above the pivot shaft 10 and the rear end 16b is connected to the swing arm 14 via the rod 22 and the lever 24. The spring member 16 includes a coil spring 16c having a substantially cylindrical shape, holding members 16d and 16d sandwiching the coil spring 16c from a front end 16a and a rear end 16b, and holding members 16d and 16c.
a rod 16e1 and a cylindrical body 16e2 extending from the center of d along the central axis of the spring 16c.
1 has a guide rod 16e which is inserted into the cylindrical body 16e2 and slides with each other to make the spring 16c extend and contract in a straight line. The front end 16a and the rear end 16b of the spring member 16 are respectively
The upper end 20b of the bracket member 20 and the lever 2
4 are respectively pin-coupled to the rear upper end 24b and are rotatably connected.

The rotary damper 18 is connected to the swing arm 14 via a lever 24. The rotary damper 18 is disposed below the pivot shaft 10 and behind the lower end of the vehicle body frame 12 when viewed from the side of the vehicle body, and its rotation center axis is parallel to the pivot shaft 10.

The bracket member 20 extends vertically and has a lower end portion 20a inserted through the pivot shaft 10 and an upper end portion 2a.
Ob supports the front end 16 a of the spring member 16 and is provided separately from the body frame 12. In the embodiment, as shown in FIGS. 1 to 4, the bracket member 20 is formed by connecting two pieces each having a substantially S-shape in a side view from the left and right, and is generally downwardly spread in a front view. Has a gate-like shape connected at the top. The lower end portion 20a of the bracket member 20 has an insertion hole 20a for the pivot shaft 10.
1 and a fitting hole (pin fitting hole) 2 for a knock pin 26 to be described later
0a2, and a fitting hole 20b for a pin for coupling with the front end 16a of the spring member 16 is formed in the upper end 20b.
1 is drilled. The left and right pieces are connected to the upper end 20b of the bracket member 20 by a reinforcing plate 20c.

In the vicinity of the pivot shaft 10, as shown in FIG. 3, the bracket member 20 is fixed to the engine case 8a by being interposed between the lower end portion 20a of the bracket member 20 and the rear end portion 8a of the engine case 8. Knock pin 2
6 (corresponding to a fixing member). That is, a pin fitting hole 26a is formed near the opening of the pivot shaft 10 through hole 8a1 at the rear end 8a of the engine case, and the pivot shaft 10 insertion hole 2 at the lower end 20a of the bracket member 20 is formed.
A pin fitting hole 20a2 is formed near 0a1.
These pin insertion holes 26a and 20a2 are formed correspondingly, and when the pivot shaft 10 is inserted through the vehicle body frame 12, the bracket member 20 and the engine case 8, when the bracket member 20 is in a predetermined position. Oppose. One knock pin 26 is fitted into these opposed pin fitting holes 26a and 20a2. This knock pin 2
6, the bracket member 20 is prevented from rotating with respect to the pivot shaft 10, and becomes a rigid body integral with the engine case 8 and the like.

The lever 24 has a substantially L-shape that is long in the front-rear direction of the vehicle body when viewed from the side, and has a front end 24 a pivotally supported by the rotary tamper 18.
It swings up and down around the axis of. The rear upper end 24 b of the lever 24 is pin-connected to the rear end 16 b of the spring member 16. The lower rear end 24c of the lever 24 is connected to an appropriate position at the front of the swing arm 14 via the rod 22. Rod 2
A pair 2 is provided on the left and right sides of the lever corresponding to the left and right swing arms 14.

In addition, above the rear part of the engine case 8,
A carburetor 28 is provided, and an air cleaner 30 is connected to the carburetor 28 via an outlet tube 32. Air cleaner 30
Is located above the pivot shaft 10 and the spring member 16.

Next, the operation of the embodiment will be described. When the swing arm 14 swings in the direction in which the rear wheel rises and falls when swinging (FIG. 2 shows a state where the spring member 16 is in the most contracted state, and FIG. 1 shows a state where the spring member 16 is in the most extended state). The swing motion of the arm 14 is controlled by the rod 22 and the lever 24.
To the rear end 16b of the spring member 16 via
The rear end 16b has a pressing force of the swing arm 14
The pulling force acts to cause the spring member 16 to move forward and backward. The force of the spring member 16 going forward and backward is received and retained by the upper end of the bracket member 20 connected to the front end 16a. Since the lower end portion 20b of the bracket member 20 is inserted into the pivot shaft 10 and is fixed to the engine case 8 by the knock pin 26, the bracket member 20 is prevented from rotating around the pivot shaft 10 without being rotated, and is thus prevented from rotating.
Is rigidly supported. That is, the engine case 8 (via the knock pin 26) and the vehicle body frame 12 (via the pivot shaft 10) can be regarded as supporting the spring member 16 as a rigid body.

Accordingly, since the bracket member 20 suppresses the spring member 16 from moving forward and backward, the spring member 16 is compressed and extended by the swing arm 14 and the bracket member 20. Further, since the spring member 16 is disposed so as to extend substantially in the vehicle front-rear direction, the stroke in which the spring member 16 is compressed / extended is performed in the front-rear direction.

In the embodiment, the use of the bracket member 20 eliminates the conventional upper bracket fixed by welding, so that the frame height can be reduced by the amount of the upper bracket. Further, since the strength for welding and supporting the upper bracket is not required, the strength of the frame can be reduced, so that the weight can be reduced. Also, the bracket member 20
Is rigidly supported by the pivot shaft 10 and the engine case 8 without welding, so that the coaxiality can be accurately and easily obtained as compared with a bracket fixed by conventional welding. Therefore, since the force to squeeze when swinging the swing arm 14 does not act on the connecting rod of the spring member 16 and the operability of the suspension unit is good, the stroke of the rear wheel is completely converted to the stroke of the suspension unit, resulting in useless behavior. Will not occur.

Further, since the stroke of the spring member 16 is not restricted by the stroke of the rotary tamper 18, the overall length of the spring is shortened while the stroke is increased. When the swing arm 14 swings, the rotary tamper 18 buffers the swinging motion. Since the rotary tamper 18 is a rotary type, it does not require much space for installation and does not get in the way.

The spring member 16 is connected to the pivot shaft 10.
It extends rearward from slightly above and has a rotary tamper 18
Is located at the lower part of the vehicle body, so that the overall position of the suspension unit is lowered. Therefore, the position of the center of gravity of the vehicle is lowered, and the running stability and the turning performance of the vehicle are improved. Further, since the overall position of the suspension unit is lowered, an empty space between the swing arm and the seat increases. Therefore, upstream of the carburetor 28 (the outlet tube 32 and the air cleaner 30)
Since there is no obstacle to it, it can be straightened, reducing intake loss and improving power and response. Further, since the space 36 upstream of the carburetor 28 is increased, the layout of additional devices such as an intake device, an exhaust device, and an antilock brake is easy.

Further, since the bracket member 20 is fixed to the pivot shaft 10 and the engine case 8 without welding, it is easy to obtain the parallelism of each shaft for connection with a spring member or the like. The displacement of the spring in the left-right direction is greatly reduced as compared to. Therefore, the quality can be made uniform. Further, since it is easy to obtain the parallelism of each shaft for connection with the spring member or the like, it is possible to eliminate the conventional parts (rubber bush, pillow ball, etc.) for absorbing the tolerance. Therefore, cost reduction and long-term stabilization of performance can be achieved.

Since the bracket member 20 is much easier to replace than the upper bracket fixed by welding, it is easy to change the specifications of the suspension such as the lever ratio.

In the above embodiment, the bracket member is fixed to the engine case. However, the engine of the present invention is not limited to the engine case, and can be fixed at an appropriate position of the engine unit. Further, the small vehicle is not limited to a motorcycle.

[0028]

As described above, according to the present invention, the use of the bracket member eliminates the conventional upper bracket fixed by welding, so that the frame height can be reduced by the amount of the upper bracket. Also, because it does not need the strength to weld and support the upper bracket,
Since the strength of the frame can be reduced, the weight can be reduced. Also,
Since the bracket member is rigidly supported by the pivot shaft and the engine case without welding, the coaxiality can be accurately and easily obtained as compared with a bracket fixed by conventional welding. Therefore, since the force to pry when the swing arm swings does not act on the connecting rod of the spring member and the operability of the suspension unit is good, the stroke of the rear wheel is completely converted to the stroke of the suspension unit, causing useless behavior. Never.

Also, since the stroke of the spring member is not restricted by the stroke of the rotary shock absorber, the overall length of the spring is shortened while the stroke is increased. Also, since the shock absorber is a rotary type, it does not take up much space for installation. The spring member extends rearward from slightly above the pivot shaft and the rotary tamper is located below the pivot shaft, so that the overall position of the suspension unit is lowered. Therefore, the position of the center of gravity of the vehicle is lowered, and the running stability and the turning performance of the vehicle are improved. Further, since the overall position of the suspension unit is lowered, an empty space between the swing arm and the seat increases. Therefore, since there is no obstacle to the upstream of the carburetor (outlet tube, air cleaner), the carburetor can be straightened, so that the intake loss is reduced, and the power and response can be improved. Further, since the space upstream of the carburetor is increased, the layout of additional devices such as an intake device, an exhaust device, and an antilock brake is easy.

Further, since the bracket member is fixed to the pivot shaft and the engine case without welding, it is easy to obtain the parallelism of each shaft for connection with the spring member and the like, and the bracket member is compared with the prior art. The displacement of the spring in the left and right direction is greatly reduced. Therefore, the quality can be made uniform. Further, since it is easy to obtain the parallelism of each shaft for connection with the spring member or the like, it is possible to eliminate the conventional parts (rubber bush, pillow ball, etc.) for absorbing the tolerance. Therefore, cost reduction and long-term stabilization of performance can be achieved. Since the bracket member is much easier to replace than the upper bracket fixed by welding, it is easy to change the specifications of the suspension such as the lever ratio.

[Brief description of the drawings]

FIG. 1 is a detailed side view of a rear wheel suspension device for a motorcycle according to an embodiment of the present invention, which is in a fully extended state.

FIG. 2 is a detailed side view of the rear wheel suspension device at the time of the most contraction.

FIG. 3 is a detailed cross-sectional view around a pivot shaft of the rear wheel suspension device.

FIGS. 4A, 4B, and 4C are a plan view, a front view, and a side view of the bracket member of the embodiment.

FIG. 5 is a configuration explanatory view of a conventional rear wheel suspension device.

[Explanation of symbols]

 Reference Signs List 8 engine case 10 pivot shaft 12 body frame 14 swing arm 16 spring member 16a, 16b front end and rear end of spring member 18 rotary tamper 20 bracket member 20a, 20b lower end and upper end of bracket member 20a2 Knock pin of bracket member Fitting hole 22 Rod 24 Lever 26 Dowel pin 26a Fitting hole for dowel pin at rear end of engine case

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B62K 25 / 20,25 / 26

Claims (1)

(57) [Claims] A rear swing arm having a rear end supporting a rear wheel and a front end connected to a vehicle body frame by a pivot shaft, the rear swing arm swinging up and down about the pivot shaft; A rear wheel suspension device for a small vehicle having a spring member for braking the movement and a suspension unit comprising a shock absorber, which is disposed separately from the shock absorber and extends substantially along the vehicle front-rear direction, and has a front end above the pivot shaft. A spring member whose rear end is connected to the swing arm and a rotary type shock absorber located below the pivot shaft and connected to the swing arm, and a vertically extending lower end is inserted through the pivot shaft. The upper end supports the front end of the spring member, and is interposed between the bracket member and the engine separately from the vehicle body frame and the bracket member. A rear suspension system for a small vehicle, comprising: a fixing member for fixing the bracket member to the engine.