JPH0438631B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention transmits the movement of the rear arm to the shock absorber via two links, increases the spring constant near the full bend of the shock absorber, and achieves progressive The present invention relates to a rear wheel suspension system for a motorcycle, which provides excellent cushioning characteristics.

[Prior Art] In a conventional rear wheel suspension system for a motorcycle, the shock absorber is directly attached to the rear arm, so the movement of the rear wheel and the movement of the shock absorber are in a fixed relationship.

For this reason, setting the shock absorbing characteristics to soft improves the ride comfort, but it also makes it easier to bottom out, and conversely, setting the shock absorbing characteristics to hard may worsen the ride comfort and reduce the rear wheels' ability to follow the road surface. There was a problem.

Therefore, as a countermeasure to this problem, one shock absorber is placed near the front end pivot point of the rear arm, and this shock absorber and the vehicle body are connected via a first link, and this first link and the rear arm are connected. A rear wheel suspension system has been developed that is connected via a second link and the movement of the rear arm is transmitted to the shock absorber via the two links.

According to this rear wheel suspension system, the movement of the rear arm is gradually amplified and transmitted to the shock absorber, so the larger the swing stroke of the rear arm, the more the compression amount of the shock absorber increases in a quadratic manner. This has the advantage that the rear wheels have good road following characteristics.

[Problems to be Solved by the Invention] By the way, while the motorcycle is running, a large impact is directly applied to the first link and the second link through the rear arm. The pivot portion of the frame of the link is required to have great rigidity and mechanical strength to withstand the above impact.

For this reason, there are problems in that the configuration of the attachment portion of the frame of the first link becomes complicated and the attachment portion becomes larger.

The present invention was made based on the above circumstances, and is capable of widely dispersing the impact transmitted to the frame via the first link to each part of the frame, and has a special structure for supporting the first link. The support strength of the first link can be increased without using special members, and the first link and the second link can be made as compact as possible, reducing the unsprung load of the shock absorber. An object of the present invention is to provide a rear wheel suspension system for a motorcycle that can improve the road surface followability of a rear arm.

[Means for Solving the Problems] Therefore, in the present invention, the head pipe is extended rearward from the head pipe, and at least its rear half is located below the head pipe, and the rear half is spaced apart from each other in the left-right direction. a main frame member configured with a pair of seat pillar tubes, and left and right back stays connected to the seat pillar tubes of the main frame member and extending rearward and upward from the seat pillar tubes; The front ends of a pair of left and right arm members constituting the rear arm are pivoted to the lower part of the seat pillar tube of this frame so as to be able to swing in the vertical direction, and near the front end pivot point of this rear arm,
A shock absorber having one end supported on the upper part of the frame is disposed, and a first shock absorber pivotally supported by the frame is arranged between the other end of the shock absorber and the rear arm.
In a rear wheel suspension system for a motorcycle connected via a link and a second link pivotally supported on a rear arm, a link between the seat pillar tube and the back stay is provided at the joint between the seat pillar tube and the back stay. Join the left and right gussets,
One end of the first link is interposed between these gussets, and the first link is rotatably connected via a pivot shaft, and the second link is connected to a cross member that connects the front parts of the left and right arm members to each other. The present invention is characterized in that the links are rotatably connected, and the first link and the second link are arranged within the width of the frame and the rear arm.

[Function] According to this configuration, when the rear arm is swung, the impact applied to the pivot joint of the first link is transmitted to both the main frame member and the back stay via the gusset, so this impact is absorbed by the frame. can be dispersed over a wide range.

Furthermore, since the gusset serves to reinforce the joint between the main frame member and the backstay, it is inherently highly rigid, and there is no need to provide special brackets to pivotally connect the first link to the frame. do not have.

From this, it is possible to simplify the configuration of the pivot portion of the first link while ensuring sufficient support strength for the first link.

Further, the first link fits between the gussets of the frame, and the second link also fits inside the left and right arm members of the rear arm, so that the left-right width of the second link can be kept particularly narrow. For this reason, the two links can be made as compact as possible to reduce weight.
The unsprung load of the shock absorber can be reduced.

[Embodiment] The present invention will be described below based on a first embodiment shown in FIGS. 1 to 3.

Reference numeral 7 in the figure is a frame constituting the body of the motorcycle, and a main frame member 2 extending obliquely downward to the rear and a down tube 3 extending downward are welded to a head pipe 1 located at the front end of the frame. The main frame member 2 includes a single large-diameter main pipe 2a, as shown in FIG. The rear half of the main pipe 2a is branched left and right, and these branched portions constitute a pair of left and right seat pillar tubes 4, 4 that extend downward.

Further, the down tube 3 extends rearward by branching left and right from the middle, and the rear ends of these branch portions are connected to the lower ends of the seat pillar tubes 4, 4.

The front ends of a pair of left and right seat rails 5, 5 are welded to the middle of the main pipe 2a. Left and right back stays 6, 6 are installed between the intermediate lower surfaces of these seat rails 5, 5 and the lower rear surfaces of the seat pillar tubes 4, 4. It extends rearward and diagonally upward from the lower rear surface. Therefore, the frame 7 of this embodiment has a semi-double cradle type structure.

At the lower front of the seat pillar tubes 4, 4,
Rear arm brackets 8, 8 are welded,
A front end portion of a rear arm 10 is pivotally connected between the rear arm brackets 8, 8 via a pivot shaft 9. The rear arm 10 includes a pair of left and right arm members 11, 11 each having a rectangular cross section, and a cross member 12 that connects the front ends of these arm members 11, 11 to the left and right, when viewed from above.
The rear wheel 13 is pivotally supported between the rear end portions of the arm members 11, 11.

The rear arm 10 having such a configuration is suspended by one shock absorber 14. That is, although the shock absorber 14 is not shown in detail, it consists of a shock absorber and a coil spring that biases the shock absorber in the direction of extension.
is connected to the main pipe 2a via the pivot shaft 16.
It is connected to a bracket 17 welded to the top surface of the holder. The rear end pivot portion 18 of the shock absorber 14 projects rearward from the backstays 6, 6 and is located above the front end pivot portion of the rear arm 10. It is indirectly connected to via a link mechanism 19. Therefore, this buffer 14
is in a nearly horizontal forward oblique position along the main pipe 2a.

By the way, the link mechanism 19 is provided to non-linearly change the expansion and contraction stroke of the shock absorber 14 in accordance with the swing stroke of the rear arm 10, and this structure will be explained below. That is, a pair of support protrusions 20, 20 are provided on the upper surface of the cross member 12 constituting the rear arm 10, spaced apart in the left-right direction, and a second link is provided between the support protrusions 20, 20. A lower end portion of a connecting rod 21 extending upward is interposed therebetween. The connecting rod 21 is pivotally supported by a pivot pin 23 passing through support projections 20, 20 through collars 22, 22. Pivot pin 23
passes through a pivot hole 24 formed at one end of the cooking stove 21, and a vibration-proof rubber structure 25 is press-fitted into the pivot hole 24. The anti-vibration rubber structure 25 has a rubber anti-vibration 27 baked and fixed on the outer circumferential surface of a collar 26, and a sleeve 28 is also baked and fixed on the outer circumferential surface of the rubber anti-vibration 27. Therefore, the connecting rod 21 is The vibration isolating rubber structure 25 press-fitted into the pivot hole 24 is positioned between the support protrusions 20, 20, the pivot pin 23 is inserted into the collar 26, and the cotter pin 29 is attached to the insertion tip of the pivot pin 23. It is adapted to be pivotally supported on the support projections 20, 20 by.

On the other hand, gussets 30, 30 for reinforcing this joint are welded to the upper surface of the joint between the seat pillar tubes 4, 4 and the back stays 6, 6. A pivot shaft 31 is spanned between these gussets 30, 30, and is tightened with a nut 32. A collar 33 and bearing sleeves 34, 34 are provided on the outer peripheral surface of this pivot shaft 31.
A pivot tube body 35 is rotatably attached thereto. On the rear surface of this pivot tube body 35, a pair of left and right links 36, 3 having a substantially L-shape are provided as first links.
The front ends of 6 are welded, and these links 36,
The rear end of the shock absorber 36 extends upward and is located on either side of the rear end pivot portion 18 of the shock absorber 14. A pivot pin 38 is installed between the extending upper ends of these links 36, 36 via collars 37, 37, and is held by a split pin 39 to prevent it from coming off. Therefore, the pivot pin 38
It rotatably passes through the rear end pivot part 18 of 4, and this rear end pivot part 18 is connected to the links 36, 36.
is connected to. Further, a pivot shaft 41 is installed between the intermediate portions of the links 36, 36 located between the pivot points at both ends thereof, via collars 40, 40.
It is tightened by a nut 42. This pivot shaft 41 rotatably passes through a pivot hole 43 formed at the upper end of the conrod 21 via a collar 44 and a bearing sleeve 45.
and links 36, 36 are rotatably connected. For this reason, the connecting rod 21 and the links 36, 3
6 is arranged on the upper surface side of the front end pivot portion of the rear arm 10.

Note that the distance _L1 from the pivot point A of the rear arm 10 to the lower end pivot point B of the connecting rod 21 on this rear arm 10 is from the pivot point C at one end of the links 36, 36 to the other end of the connecting rod 21 on the links 36, 36. It is set longer than the distance _L2 to the pivot point D.

Next, the operation of the above configuration will be explained.

When an impact force F is applied to the rear wheel 13, the rear arm 1
0 is counterclockwise around pivot point A (direction of arrow E)
Rotate to. Then, the pivot point B at one end of the connecting rod 21 located on the rear arm 10 also moves in the same direction. In this case, the pivot point A of the rear arm 10
Since the distance from pivot point B to pivot point B is shorter than the distance from pivot point B to pivot point O of the rear wheel 13, the rotation stroke of pivot point B is AB/AO contraction with respect to the rotation stroke of rear arm 10. It will be less. Due to this movement of the pivot point B, the links 36, 36 connected by the connecting rod 21 also try to rotate in the above direction about the pivot point C at one end. Since the distance L ₂ between the pivot points is shorter than the distance L ₁ on the rear arm 10, it becomes larger than the rotation angle of the rear arm 10. Therefore, the rotation angle of the rear arm 10 is amplified by the connecting rod 21 and the links 36, 36 and transmitted to the shock absorber 14, and the larger the rotation angle of the rear arm 10, the more the shock absorber A so-called progressive characteristic in which the buffer characteristic of No. 14 gradually becomes harder is obtained. As a result, when the stroke of the rear arm 10 is small, the shock absorber 14 gently absorbs the impact, and when the stroke is large, the shock absorber 14 becomes stiffer accordingly to prevent bottoming out.

According to the suspension system having such a configuration, the movement of the rear arm 10 is controlled by the link 3 via the connecting rod 21.
6 and 36, and the shock absorber 14 is actuated by these links 36, 36. Therefore, the link portions 36, 36 are pivoted to the frame 7.
A large impact will be applied through the rear arm 10.

However, since these links 36, 36 are pivotally supported by gussets 30, 30 welded to the joints between the seat pillar tubes 4, 4 and the backstays 6, 6, the impact applied to the pivoting parts of the links 36, 36 is is transmitted to both the seat pillar tubes 4, 4 and the backstays 6, 6 through the gussets 30, 30, and this impact can be dispersed over a wide range of the frame 7.

Moreover, the gussets 30, 30, which are inherently highly rigid, for reinforcing the joints between the seat pillar tubes 4, 4 and the backstays 6, 6, are replaced with the link 3.
6 and 36 are also used as members for pivotally connecting the frame 7, even though the link mechanism 19 is interposed between the shock absorber 14 and the rear arm 10.
There is no need to provide special brackets for pivotally connecting the links 36, 36 to the two.

Therefore, while ensuring sufficient support strength for the links 36, 36, the structure of the pivoting portions of the links 36, 36 can be simplified, and the number of parts can also be reduced.

Further, the links 36, 36 are connected to the gussets 30, 3
0 and the backstays 6, 6, and the connecting rod 21 is also inserted between the cross member 12.
Since it is pivotally supported on the upper surface and goes inside the left and right arm members 11, 11 of the rear arm 10, the connecting rod 21 and the links 36, 36 can be accommodated within the width of the frame 7 and the rear arm 10.

In particular, the conrod 2 pivoted to the rear arm 10
1 does not need to straddle the left and right arm members 11, 11, the left and right width of the connecting rod 21 can be kept narrow. From this, the stove 2
1 and the links 36, 36 can be made as compact as possible to reduce their weight.
4 can reduce the unsprung load of the rear wheel 13.
It is possible to improve the road followability of the vehicle.

Note that the present invention is not limited to the first embodiment described above, and the second embodiment of the present invention is shown in FIGS. 4 to 6.
An example is shown. However, in this second embodiment, the same components as those in the above-described first embodiment are given the same numbers and the explanation thereof will be omitted.

That is, a solid cross member 51 is interposed in the front end sides of the arm members 11, 11 that are opposed to each other. Support members 53, 5 each having a cylindrical shape with a bottom are provided in the mounting holes 52, 52.
3 is inserted into the cross member 51, and bolts 54, 54 are passed through the bottom surface of the cross member 51, and the common ends thereof are screwed into both end surfaces of the cross member 51, thereby fixing the arm members 11, 11 between the arm members 11, 11. A pair of mounting holes 55, 55 are provided on the cross member 51, spaced apart in the left-right direction, and the bolts 54, 54 are passed through the mounting holes 55, 55. Further, lower end portions of cushion rods 56, 56 along the vertical direction are fitted into the mounting holes 55, 55 as second links. Cushion rods 56, 56 have connecting arms 58, 5 on both end surfaces of a rod-shaped rod body 57.
8 are screwed together, and these connecting arms 5
8 and 58 are arranged so that the amount of protrusion in the axial direction can be changed by loosening a nut 59. As a result, the entire length of the cushion rods 56, 56 is freely variable.

And, at the sacral end of the connecting arms 58, 58,
A ball joint 60 is rotatably provided, and the bolts 54, 54 pass through the ball joints 60, 60. Therefore,
The bolts 54, 54 not only connect the arm members 11, 11 and the cross member 51, but also connect the lower ends of the cushion rods 56, 56 to the cross member 51.

On the other hand, gussets 61, 61 for reinforcing this joint are welded to the rear surface of the joint between the seat pillar tubes 4, 4 and the backstays 6, 6. The pivot shaft 31 installed between the gussets 61, 61 rotatably passes through a pivot hole 63 formed at one end of the swing block 62 via the collar 33 and the bearing sleeves 34, 34. This swing block 62 constitutes a first link, and is provided with a pair of left and right support protrusions 64, 64 on the other end side. A device recess 65 provided on the rear end surface of these support protrusions 64, 64,
Ball joints 60, 60 at the upper ends of the cushion rods 56, 56 are interposed within the shaft 65, and are rotatably connected by bolts 66, 66. Further, pivot parts 67, 67 are integrally provided on the upper surfaces of the support protrusions 64, 64, and these pivot parts 67, 67 are connected to the rear end pivot part 1 of the shock absorber 14.
It is located on both sides of 8. And the cardinal branch 6
A pivot pin 69 is installed between 7 and 67 via collars 68 and 68, and is held by a split pin 70 to prevent it from coming off. Therefore, this pivot pin 69 rotatably passes through the rear end pivot portion 18 of the shock absorber 14.
is connected to the swing block 62.

Also in the second embodiment with such a configuration, the swing block 62 is connected to the seat pillar tubes 4, 4.
Cushion rods 56, 56, which are pivotally connected to the left and right gussets 61, 61 spanning the back stays 6, 6, and which transmit the movement of the rear arm 10 to the swing block 62, also connect to the cross member 51 at the front end of the rear arm 10. Because it is pivoted to
The same effects as in the first embodiment can be obtained.

[Effects of the Invention] According to the present invention described in detail above, the impact applied to the pivot portion of the first link is transmitted to both the seat pillar tube and the backstay through the gusset, and this impact is spread over a wide area of the frame. can be dispersed throughout.

Moreover, since the inherently rigid gusset for reinforcing the joint between the seat pillar tube and the backstay is used as the pivot member for the first link, the first link can be pivoted to the frame. There is no need to provide special brackets for this purpose.

Therefore, the structure of the pivoting portion of the first link can be simplified while ensuring sufficient support strength for the first link.

In addition, the first link is inserted between the gussets, and the second link is also inserted inside the left and right arm members of the rear arm, so it is difficult to fit these two links within the width of the frame and rear arm. You can fit it without any problems. Therefore, it is possible to make the two links as compact as possible to reduce their weight, which has the advantage of reducing the unsprung load of the shock absorber.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a side view of the frame, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. −
4 to 6 show a second embodiment of the present invention, FIG. 4 is a side view of the frame, and FIG. 5 is a sectional view taken along the line in FIG. The figure is a sectional view taken along the line - in FIG. 4. 1...Head pipe, 2...Main frame member,
4... Seat pillar tube, 6... Back stay,
7...Vehicle body (frame), 10...Rear arm, 11
...Arm member, 12, 51...Cross member, 14
...Buffer, 21, 56...Second link (conrod, cushion rod), 30,61...Gusset,
31... Pivot axis, 36, 62... First link (link, swing block).

Claims (1)

[Scope of Claims] 1. A pair of seat pillar tubes extending rearward from the head pipe, at least the rear half of which is located below the head pipe, and the rear half of which is spaced apart from each other in the left-right direction. a main frame member, and left and right backstays connected to the seat pillar tube of the main frame member and extending rearward and upward from the seat pillar tube, the lower part of the seat pillar tube of the frame. The front ends of a pair of left and right arm members constituting the rear arm are pivotally connected to be able to swing in the vertical direction, and a shock absorber, one end of which is supported by the upper part of the frame, is arranged near the front end pivot point of the rear arm. Also, between the other end of this shock absorber and the above rear arm,
In a rear wheel suspension system for a motorcycle connected via a first link pivotally supported on the frame and a second link pivotally supported on the rear arm, these seats are connected at the joint between the seat pillar tube and the backstay. The left and right gussets spanning between the pillar tube and the backstay are joined, one end of the first link is interposed between these gussets, and the first link is rotatably connected via the pivot shaft; The second link is rotatably connected to a cross member that connects the front parts of the left and right arm members to each other, and the first link and the second link are arranged within the width of the frame and the rear arm on the left and right sides. A rear wheel suspension system for a motorcycle, characterized in that: