JP3403873B2 - Rear wheel suspension for motorcycles - 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 wheel suspension system for a motorcycle.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open No. 62-25290 (hereinafter referred to as the first
A known example) shows a structure in which a front end portion of a rear fork having a pair of fork arms extending in the front-rear direction is axially attached to a center frame side extending in the up-down direction.

In this structure, one fork arm is
The pivot plate mounted on the side of the center frame is superposed on the inner side of the pivot plate, and the other fork arm is also superposed on the inner side of the pivot plate which also serves as a joint between the center frame and the lower frame.

Japanese Utility Model Publication No. 4-132232 (hereinafter, referred to as a second known example) shows an exhaust pipe that penetrates a pipe frame in the front-rear direction.

[0005]

The structure using the pivot plate as in the first known example has an advantage that the width of the vehicle body can be made as narrow as possible. But,
Since the fork arm overlaps the inside of the pivot plate, although the pivot plate is thin, the width of the vehicle body is widened by the thickness of the pivot plate.

Moreover, since the pivot plate is a relatively thin plate-shaped material, it is difficult to make the rigidity sufficiently high and yet thin. The main purpose of the present application is to solve such problems.

[0007]

[Means for Solving the Problems]

A rear wheel suspension system for a motorcycle according to the present application comprises a pair of left and right center frames extending vertically to form a part of a vehicle body frame, and a front end of which is pivotally attached to the center frames. A rear fork that supports
A motorcycle unit having a pair of left and right fork arms that extend in the front-rear direction and that includes a cushion unit that extends vertically through the rear fork and connects the upper end to the vehicle body side and the lower end to the rear fork side. In the rear wheel suspension system, one side of the pair of left and right center frames
Is opened toward the rear, and the space inside this opening is
Of the bearing portion of one side of the fork arm which is placed into the right and left
It is swingably supported by a pivot shaft supported between the side walls.
Provided because of the pivot box, before the fork arm
The serial one, the pivot at one of the center frame
Along with the axis on the side where the box is provided ,
It is characterized in that the cushion unit is displaced toward the one of the fork arms and is arranged in proximity.

Also, the pair of left and right fork arms are
The side opposite to the side provided with the pivot box and the
The intake passage may be arranged substantially linearly in the front-rear direction in a space formed between the cushion unit and the cushion unit .

Further, the exhaust pipe may be arranged on the axis of the one center frame.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment will be described below with reference to the drawings. FIG. 2 shows a side view of a motorcycle to which the invention of the present application is applied, in which a front wheel 1 is supported by a front fork 2 and a rear wheel 3 is supported by a vehicle body frame 5 via a rear fork 4.

The body frame 5 is of a cradle type, and has a pair of left and right main frames 7L extending in the front-rear direction from an upper portion of a head pipe 6 connecting the upper ends of the front forks 2.
(R), a down pipe 8 extending obliquely downward from the lower portion of the head pipe 6, and a pair of lower frames 9L (R) extending leftward and rightward from the lower end portion thereof and extending rearward.

Further, the rear portion of the vehicle body frame 5 forms a center frame 10L (R) which is bent from each rear end portion of the main frame 7L (R) and extends in the vertical direction, and each lower end portion thereof has a lower frame 9L (R). Are connected to the respective rear end portions thereof as described later.

The center frame 10L (R) may be separate from the main frame 7L (R), and the main frames may be a single member instead of the left and right pair.

The rear fork 4 has its front end portion directly or indirectly with respect to the center frame 10L (R).
A rear wheel 3 is rotatably supported at its rear end portion while being rotatably connected at 0a and extending rearward.

A lower end portion 13 of a cushion unit 12 is connected to a cushion link 11 connected to the rear fork 4 and the vehicle body frame 5 side. The cushion unit 12 penetrates the front portion of the rear fork 4 in the vertical direction, and the upper end portion 14 thereof is connected to an upper stay 15L (R) provided in the middle portion of the main frame 7. The rear fork 4 and the cushion unit 12 constitute a rear wheel suspension device.

An upper stay 15L (R) is projected upward from an intermediate portion of the left and right main frames 7L (R), and a rear stay 16L is provided from a lower portion of the main frame 7L (R).
(R) extends obliquely upward, and a seat rail 17 extending in the front-rear direction is connected between the upper stay 15L (R) and the upper stay 15L (R).

A fuel tank 1 is provided on the main frame 7L (R).
8 is supported, and a seat 19 is supported on the seat rail 17. In addition, the seat rail 17 and the rear stay 1
An air cleaner 20 is arranged in the space between 6L (R), and a muffler 21 is supported by the rear stay 16.

An engine 22 is supported on the vehicle body frame 5, and its intake side is connected to an air cleaner 20 via a carburetor 23.
The exhaust side once extends to the front of the engine 22 and then extends rearward to be connected to the muffler 21 via the exhaust pipe 24.

FIG. 1 is a view showing the rear portion of the vehicle body frame 5 from the rear, FIG. 3 is a plan view of the vehicle body frame 5, and FIG. 4 is an enlarged side view of the rear portion of the vehicle body frame 5. In these drawings, the left and right upper stays 15L (R) are approximately V, respectively.
It extends inward from the main frame 7L (R) in a character shape,
A cushion mounting boss 25L (R) is mounted on the top portion thereof.

In particular, the mounting boss 25L on the left side extends to the right side of the vehicle body center line C, as is apparent from FIGS. Reference numeral 26 is a boss for attaching the seat rail 17.

As is apparent from FIG. 4, a pivot plate 27 which doubles as a joint member for connecting both members is provided between the lower end of the left center frame 10L and the lower frame 9L, and a pivot shaft hole 28 is provided. Has been.
Reference numeral 29 is a mounting protrusion of the rear stay 16.

On the other hand, between the right center frame 10R and the right lower frame 9 (in the figure, overlapping with the lower frame 9L and not visible), a pivot box 30 which also serves as a joint member for connecting both members is formed. There is.

Upper stay 15 of the center frame 10R
A joint pipe 31, which is a part of an exhaust pipe, is attached to an intermediate portion of the pivot box 30. Code 3
2 is a mounting protrusion of the rear stay 16R.

As is apparent from FIG. 1, the pivot plate 27 and the pivot box 30 are connected to each other by a pivot shaft 10a extending in the left-right direction so as to pivotally support the front end of the rear fork 4 (not shown). There is.

The lower ends of the pivot plate 27 and the pivot box 30 are connected by a cross pipe 33,
Brackets 34 and 3 provided at the middle and right ends thereof
The front end of the cushion link 11 (FIG. 2), not shown in FIG. 5, is supported.

The cushion unit 12 is arranged on the right side of the vehicle body with a large offset, and its centerline C1 is offset to the right by a dimension S1 from the vehicle body centerline C. Further, the pivot box 30 overlaps with the center line C2 of the center frame 10R in the rear view (state of FIG. 1).

FIG. 5 is a plan view of the rear fork 4. The rear fork 4 is provided with a pair of left and right fork arms 40 extending in the front-rear direction, and their front ends are connected and integrated with each other by a cross member 41.

The front side of the cross member 41 is formed as a curved concave portion 42, in which the cushion unit 12 is displaced to the right side of the vehicle body and penetrates in the vertical direction, and the front end portions left and right extend in the axial direction of the fork arms 40R, 40L. The protrusions are formed so as to project into, and the bearing portions 43 and 44 are provided at the respective tip portions.

The fork arm 40R has a substantially straight line shape which is substantially parallel to the center line of the vehicle body. On the other hand, the fork arm 40L is bent at the middle portion and the front half side is bent inwardly of the vehicle body, and the bearing portion 44 at the front end is more than the bearing portion 43. Is approaching the body center line C.

FIG. 6 shows a connecting structure of the bearing portions 43, 44 with the pivot plate 27 and the pivot box 30. The bearing portion 43 has a tubular shape, and the bearing 45 is fitted inside the tubular hole portion. A bearing hole 46 is formed inside thereof.

The bearing portion 44 is similar to the bearing portion 43. A bearing 47 is fitted inside the cylindrical hole portion, and a bearing hole 48 is formed inside the bearing 47.
A pivot shaft 10a having a bolt shape is inserted into the shafts 46 and 46.

The pivot box 30 is a member wider than the center frame 10R formed by casting or the like, and is provided with a swing space 50 opened rearward (FIG. 1). The size of this space is the bearing portion. It can accommodate 43.

Further, the swing space 50 is opened rearward, and the vertical width of the opening is such that the front end portion of the fork arm 40R is integrated with the bearing portion 43 in the vertical direction around the pivot shaft 10a. It is to the extent that it can be rocked.

Bolt through holes 53 and 54 are formed in side walls 51 and 52 that surround the swinging space 50 of the pivot box 30 and extend in the vertical direction in parallel with the left and right, and the outer side wall 53 has a bolt of the pivot shaft 10a. A recess 55 that accommodates the head portion 10b is formed around the bolt through hole 54.

The pivot plate 27 has a recess 57 for accommodating the nut 56 and a pivot shaft hole 28. In addition, the code | symbol C3 in a figure shows the centerline of 10 L of center frames.

The rear fork 4 has a pivot box 30.
Pivot shaft 10a penetrating each bearing portion 43, 44 from the side
The male screw portion 10c at the end is passed through the pivot shaft hole 28, and the nut 56 is tightened in the recess 57 to connect the same to the vehicle body side.

FIG. 7 is a view showing the joint pipe 31 in the axial direction judging surface. As is apparent from this figure, from the main body portion 60 penetrating the center frame 10R and the fitting portions 61 fitted and attached to both ends thereof. Become. The main body 60 has a double pipe structure, and a heat insulating material 64 is provided between the outer cylinder 62 and the inner cylinder 63.
Is intervening.

Due to this heat insulating material 64, despite the main body 60 penetrating the center frame 10R,
It is possible to prevent the exhaust heat due to the exhaust gas from being transferred to the center frame 10R side.

Base parts 61 provided on both sides of the main body part 60
Are the same, and an annular groove 65 is formed on the inner peripheral surface thereof, and a seal member 66 is fitted therein.

An exhaust pipe 67 on the exhaust chamber side, which forms a part of the exhaust pipe 24, is fitted and connected to the base portion 61 on the front side.
A muffler side exhaust pipe 68 connected to the muffler 21 is fitted and connected to the rear side cap portion 61.

The main body 60 and the center frame 10
When the diameter of the main body portion 60 is larger than the diameter (or width) of the center frame 10R, an appropriate patch member is welded and connected by an appropriate means such as welding.
Further, as for the attachment of the main body portion 60 and the base portion 61, an appropriate means such as welding press fitting is adopted.

FIGS. 8 and 9 show an alternative plan of the joint pipe 31, and in this example, flanges 70 and 71 are formed at the respective connection ends of the exhaust pipe 67 and the exhaust pipe 68, while penetrating the center frame 10R. The main body 72 is also formed with flanges 73 and 74 at both ends.

These flanges sandwich a mounting leg 76 integrally projected to the inner peripheral surface side of a pair of semi-cylindrical brackets 75 with a heat insulating material 77 interposed therebetween, and are connected by a bolt 78 and a nut 79.

Even in this case, the heat dissipation effect of the bracket 75 can be expected to have a heat insulating effect on the center frame 10R side, and the connecting structure can be simplified.

FIG. 10 is a plane cross-sectional view showing the disposition structure of the connecting tube 80 forming the intake passage.
0 has one end 81 connected to the air cleaner 20 and the other end 82
Is connected to a vaporizer 23 (not shown) (see FIG. 2).

Since the cushion unit 12 is deviated to the right side of the vehicle body, the connecting tube 80 is arranged closer to the vehicle body center line C, and is much more linear than the conventional one shown by the phantom line. It forms an intake passage, which contributes to the improvement of output.

Next, the operation of this embodiment will be described. As is apparent from FIGS. 1 and 6, the pivot box 30 is provided in the center frame 10R, and the pivot space 5 is provided.
Since the bearing portion 43 of the rear fork 4R is inserted into the 0,
The bearing portion 43 can be located on the axis C2 of the center frame 10R.

As a result, it becomes easy to increase the rigidity of the pivot box 30, although the width of the vehicle body can be reduced.

Further, since the center C1 of the cushion unit 12 can be displaced to the right side of the vehicle body by the dimension S1 from the center line C of the vehicle body, a relatively large amount is provided between the left side of the displaced cushion unit 12 and the center frame 10L. A space is formed.

Therefore, since the connecting tube 80 can be arranged so that the intake passage is linear by utilizing this space, the output of the engine 22 can be improved accordingly.

Further, since the joint pipe 31 is passed through the center frame 10R, the vehicle body can be made compact by narrowing the vehicle body width without extending the exhaust pipe to the outside of the vehicle body. Moreover, the use of the heat insulating material 64 and the bracket 75 makes it difficult to transfer the exhaust heat to the center frame 10R side.

[0053]

According to the invention of claim 1, the bearing portion of one of the fork arms is provided on one of the center frames.
Insert it into the bot box from the rear facing opening, then left
Swivel supported by a pivot shaft supported between the right side walls
By doing so, the bearing part is arranged on the axis of one of the center frames and the cushion unit is pivoted.
The vehicle is deviated to one side of the vehicle body where the toe box is provided . For this reason, the rigidity of the pivot portion of the center frame can be increased even though the width of the vehicle body can be reduced.

According to the invention of claim 2, in addition to the invention of claim 1, the intake passage is linearly arranged in the space formed on the side opposite to the direction of deflection of the cushion unit. Therefore, it becomes easy to dispose the intake passage linearly due to the deviation of the cushion unit, and the output of the engine can be improved accordingly.

According to the invention of claim 3, in addition to the invention of claim 1, the exhaust pipe is arranged on the axis of one of the center frames. For this reason, the exhaust pipe does not have to be extended to the outside of the vehicle body, and the vehicle body width can be narrowed accordingly.

[Brief description of drawings]

FIG. 1 is a diagram showing a rear wheel suspension system from the rear of a vehicle body.

FIG. 2 is a side view of a motorcycle to which the present invention is applied.

FIG. 3 is a plan view of a body frame

FIG. 4 is a side view of a body frame showing a pivot part.

FIG. 5 is a plan view of the rear fork.

FIG. 6 is a sectional view showing a shaft mounting portion of a rear fork.

FIG. 7 is a sectional view of an exhaust pipe portion that penetrates the center frame.

FIG. 8 is a diagram showing the above exhaust pipe separate plan from the axial direction.

9 is a sectional view taken along line 9-9 of FIG.

FIG. 10 is a view showing the arrangement structure of an intake passage.

[Explanation of symbols]

3: Rear wheel, 4: Rear fork, 5: Body frame, 7:
Main frame, 10: Center frame, 10a: Pivot shaft, 12: Cushion unit, 30: Pivot box, 31: Joint pipe, 40: Fork arm, 43: Bearing part, 44: Bearing part, 50: Swing space, 8
0: Contube

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-205581 (JP, A) JP-A-61-205584 (JP, A) JP-A-1-226485 (JP, A) Jitsuhei 4- 13232 (JP, Y2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B62K 25/20

Claims (3)

(57) [Claims] 1. A pair of left and right center frames extending vertically to form a part of a vehicle body frame, a rear fork having a front end axially attached to the center frame and supporting a rear wheel at a rear end, and a rear fork penetrating the rear fork. And a cushion unit in which the upper end is connected to the vehicle body side and the lower end is connected to the rear fork side, and the rear fork has a pair of left and right fork arms extending in the front-rear direction. In the left and right pair of center frames
One side is opened backwards, and inside this opening
The bearing part on one side of the fork arm put into the side space
Pivot shaft supported between the left and right side walls allows it to swing freely
A pivot box for supporting provided, the one of the fork arms, the peak at one of the center frame
A rear-wheel suspension system for a motorcycle, wherein the rear-wheel suspension system is arranged on an axis on which a bot box is provided, and a cushion unit is eccentrically arranged on the one fork arm side. 2. The one of the pair of left and right fork arms
The side opposite to the side provided with the pivot box and the cushion
In the space formed between the Yon'yunitto, rear-wheel suspension system for a motorcycle according to claim 1, characterized in that it arranged substantially linearly the intake passage to the front-rear direction. 3. The automatic 2 according to claim 1, wherein the exhaust pipe is arranged on the axis of the one center frame.
Rear wheel suspension system for wheeled vehicles.