JP2008201364A - Rear wheel suspension device for bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear wheel suspension device for a bicycle, capable of changing shock absorbance characteristics to various types, setting a gravity center position at a lower position, and providing size and weight reduction. <P>SOLUTION: This suspension device includes a head pipe 3, a vehicle body frame 1 having a vertical pipe 7 and a down tube 8, a swing arm 18 which is oscillatably supported by the vehicle body frame 1 and supports a rear wheel 20, and a shock absorber 21 supported by the down tube 8. A link 24 is jointed between the top end portion of a working rod 21a of the shock absorber 21 and the swing arm 18 so as to relatively oscillate through a first furculum 27 and a second furculum 28. A rod 30 is jointed between the link 24 and the vehicle body frame 1 so as to relatively oscillate around a third furculum 31 and a fourth furculum 32, and the third furculum 31 is positioned between the first furculum 27 and the second furculum 28. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a bicycle rear wheel suspension system that effectively absorbs an impact from a road surface received by a rear wheel to obtain good riding comfort and running stability.

Conventionally, there is a shock absorbing mechanism for a rear wheel of a bicycle as shown in FIG. In the figure, a vehicle body frame 50 is connected to each other in an arrangement in which a standing pipe 51, a down tube 52, and an upper pipe 53 are substantially triangular. The swing arm 54 that supports the rear wheel 55 is a first arm.
The third three arm pieces 54 a to 54 c are connected in a substantially triangular arrangement, and are supported on the vehicle body frame 50 via a pivot shaft 56 so as to be swingable. At the lower end portion of the link 60 that is swingably suspended from the upper pipe 53 via the support shaft 59, the tip of the operating rod 57 a of the shock absorber 57 supported by the down tube 52 and the swing arm 54 are provided.
Are connected to each other through support shafts 61 and 62 so as to be swingable.

In the bicycle, when the rear wheel 55 receives an upward impact force due to road surface unevenness during traveling, the swing arm 54 swings upward with the pivot shaft 56 as a fulcrum. As a result, when the operating rod 57a of the shock absorber 57 is pressed through the link 60, the shock absorbing mechanism built in the shock absorber 57 is operated to absorb the impact from the rear wheel 55.

Further, as a bicycle equipped with another shock absorbing mechanism, it has a body frame configured in a triangular shape similar to FIG. 8 and a V-shaped swing arm, and a support shaft is provided at the upper end of the standing pipe of the body frame. The link member mounted so as to be able to swing is relatively swung between the operating rod of the shock absorber mounted on the lower surface side of the upper pipe of the vehicle body frame and the free end of the back fork member via respective support shafts. Also known is a structure having a freely connected structure (see Patent Document 1).
Japanese Patent No. 3122610

However, in the shock absorbing mechanism of the bicycle shown in FIG.
Since the support shaft 61 that is the point of action for the link 7a is simply moved along a circular arc centered on the support shaft 59 of the link 60, the swing arm 54 accompanying the vertical movement of the rear wheel 55 is used. The swinging motion with the pivot shaft 56 as a fulcrum is the operating rod 5 of the shock absorber 57.
It only works with simple and unambiguous characteristics for 7a. That is, the relationship between the swing angle of the swing arm and the rear cushion stroke of the shock absorber 57 is fixed to a certain characteristic that changes linearly.

On the other hand, the shock absorbing mechanism described in Patent Document 1 is one selected from a plurality of shaft holes provided in a triangular link supported at the upper end of the V-shaped swing arm so as to be swingable on the standing pipe. Because it is designed to be attached, the stroke range (rear wheel movement amount) for absorbing the shock of the swing arm can be selected according to the condition of the road surface, but the point of action on the operating rod of the shock absorber is Since it is the same as the structure of FIG. 8 in that it can only be moved along a circular arc accompanying the swing of the triangular link, the characteristics of the shock absorber with respect to the swing angle of the swing arm are still the same. It will be fixed.

Further, in the bicycle of FIG. 8, the shock absorber 57 and the link 60 are disposed at a relatively upper portion of the vehicle body frame 50, so that the position of the center of gravity of the vehicle body becomes high. This also applies to the bicycle described in Patent Document 1.

Further, in the bicycle shown in FIG. 8, the swing arm 5 that constitutes a link mechanism together with the link 60.
4 includes a plurality of members, ie, first to third arm pieces 54 a to 54 c, and each of the arm pieces 54 a to 54 as the link 60 is supported by the upper pipe 53.
Since the shape of c increases, the weight of the swing arm 54 increases, and the weight of the bicycle is hindered. This also applies to the bicycle described in Patent Document 1.

The present invention has been made in view of the above-described conventional problems, and it is possible to appropriately set the characteristics of the shock absorber of the rear wheel, and to set the position of the center of gravity low, and to realize a reduction in size and weight. The object is to provide a rear wheel suspension.

In order to achieve the object, a bicycle rear wheel suspension according to the present invention includes a head pipe that supports a steering shaft, a vertical pipe that supports a seat, and a down-tilt that is inclined downward and connects the pipes. A body frame having a tube, a swing arm supported swingably on the body frame and supporting a rear wheel, a shock absorber supported by the down tube, a tip end portion of an operating rod of the shock absorber, and the swing arm A link connected to each other through a first fulcrum and a second fulcrum, respectively,
A rod connected between the link and the vehicle body frame via a third fulcrum and a fourth fulcrum, respectively, so as to be relatively swingable, and the third fulcrum is between the first fulcrum and the second fulcrum. positioned.

According to this configuration, when the rear wheel is flipped up by the unevenness of the traveling road surface and the swing arm swings upward during traveling, the link connected to the swing arm via the second fulcrum moves forward, and shock is applied. By pushing the operating rod of the absorber, the shock received by the rear wheel is absorbed by the shock absorber. At this time, the rod connected to the link via the third fulcrum swings around the fourth fulcrum on the body frame when the link moves forward to guide the link.

Therefore, the link includes a swing of the second fulcrum that is displaced along the arc whose center is the swing arm connecting portion to the vehicle body, and a second that is displaced along the arc that is centered on the fourth fulcrum. Since the three fulcrum swings act together, the first fulcrum, which is the point of action for the shock absorber's operating rod, was a simple movement along the arc in the conventional bicycle, whereas the front lifted Perform complex movements that move forward while receiving power. Therefore, the relationship between the swing angle of the swing arm and the rear shock stroke of the shock absorber is fixed to a unique one that changes in a straight line in a conventional bicycle, whereas the shock absorption characteristic that changes in a curve In addition, the shock absorption characteristics can be variably set, for example, by changing the length of the rod. Thereby, since it can change suitably and set so that it may have the shock absorption capability which can adapt to each with respect to the wide use of a bicycle, it can respond to a user's various needs. Further, since the shock absorber, the link and the rod are provided below, the center of gravity of the bicycle is lowered, and the maneuverability and running stability are improved.

In the present invention, the fourth fulcrum can be alternatively arranged on either the down tube or the standing pipe. When the fourth fulcrum is provided on the down tube, the effect of absorbing the shock is good at the initial stage when the swing arm starts to swing, and the effect of absorbing the shock becomes dull as the swing angle of the swing arm increases. In addition, since it increases linearly, it is possible to obtain direct maneuvering performance rich in agility and improve riding comfort by applying it to a comparatively gentle road surface with many small irregularities. On the other hand, when the fourth fulcrum is arranged on the vertical pipe, the impact absorbing effect at the initial stage when the swing arm begins to swing is slow, and the impact absorbing effect is increased as the swing arm swing angle increases. Since it increases substantially linearly and this shock absorption effect continues until the swing arm swing angle is maximized, by applying it to a road surface with relatively large irregularities, It effectively absorbs the impact received by the rear wheels to easily overcome obstacles, and improves the durability and running performance of the body frame.

In the present invention, preferably, the swing arm has an L-shaped side shape with a front portion bent downward, a front end portion is swingably supported by a vehicle body frame, and the L-shaped corner portion A second fulcrum is arranged. According to this configuration, by appropriately increasing the distance from the front end portion serving as the swing center of the swing arm to the corner portion, the second corner portion due to swing of the swing arm is obtained.
The effect of the shock absorber can be set appropriately by increasing the movement amount of the fulcrum, that is, the movement amount of the link. Moreover, since the 2nd fulcrum is arrange | positioned at the L-shaped corner | angular part of a swing arm,
Since the position of the link is lowered, the shock absorber connected to the link via the first fulcrum can be arranged at the lower position of the down tube. As a result, the position of the center of gravity of the vehicle body is lowered, and the steering performance and the running stability are reduced. Will improve. Furthermore, since the swing arm can be composed of an arm member having an L-shaped side surface shape, the structure is simplified and miniaturized compared to a swing arm that combines three large arm pieces like a conventional bicycle. Since the weight is reduced accordingly, the weight of the entire bicycle can be reduced and the manufacturing cost can be reduced.

In the present invention, preferably, the position of the third fulcrum on the link is variably set. According to this configuration, when the position of the third fulcrum is set closer to the front side of the link, the effect of absorbing the shock is slow at the initial stage when the swing arm starts to swing, and the swing angle of the swing arm increases. As a result, a characteristic that the effect of shock absorption increases almost linearly is obtained. On the other hand, when the position of the third fulcrum is set closer to the rear of the link, the effect of absorbing shock is relatively good from the beginning when the swing arm starts to swing, and as the swing angle of the swing arm increases. The characteristic that the effect of shock absorption increases almost linearly is obtained. Therefore, good shock absorbing performance can be obtained by appropriately selecting and setting the position of the third fulcrum according to the application.

In the present invention, preferably, the position of the second fulcrum on the swing arm is variably set so as to change the distance from the swing center of the swing arm. According to this configuration, by changing the distance from the swing arm swing center to the second fulcrum with respect to the swing angle of the swing arm, the amount of movement of the link due to swing of the swing arm is changed, and the shock absorber Effectiveness can be adjusted.

According to the bicycle rear wheel suspension device of the present invention, the link that connects the shock absorber and the swing arm is swinging at the second fulcrum where the link is displaced along an arc whose center is the connecting portion of the swing arm to the vehicle body. In addition to the swing of the third fulcrum that is displaced along the arc with the fourth fulcrum as the swing center, it moves along a complicated system path that is obliquely forward and upward. The relationship between the shock absorber and the rear shock stroke becomes a shock absorbing characteristic that changes in a curved line, and the shock absorbing characteristic can be variably set. Thereby, it can change suitably and set so that it may have the impact absorption capability which can adapt to the wide range use of a bicycle, and it can respond to a user's various needs.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic right side view showing a bicycle provided with a rear wheel suspension device according to a first embodiment of the present invention. This bicycle has a head pipe 3 that supports a steering shaft 2 by being inserted in a swingable manner.
A standing pipe 7 that supports the seat 4 at the upper end, a down tube 8 that is inclined downward and connects the head pipe 3 and the lower part of the standing pipe 7, and the head pipe 3 and the upper part of the standing pipe 7. A substantially triangular body frame 1 is constituted by the upper pipe 9 connecting the two. A front fork 12 is connected to the lower portion of the steering shaft 2, and a front wheel 13 is supported at the lower end of the front fork 12. Handle 1 on top of steering shaft 2
4 is attached.

A swing arm bracket 17 is provided at a connection portion between the down tube 8 and the standing pipe 7 of the vehicle body frame 1, and the swing arm bracket 17 has a swing arm 18 having an L-shaped side shape whose front portion is bent downward. A front end portion is swingably supported via a pivot shaft 19. A rear wheel 20 is supported at the rear end of the swing arm 18. A pair of left and right connecting pieces 23 are fixed to a bent portion 18 a that is a substantially L-shaped corner of the swing arm 18.

A shock absorber 21 is swingably attached to the down tube 8 via an attachment shaft 22. The tip of the operating rod 21a of the shock absorber 21 and the connecting piece 23 at the corner of the swing arm 18 are connected by a pair of left and right links 24 with the vertical pipe 7 interposed therebetween.
The first support shaft 27 and the second support shaft 28 are connected to each other so as to be able to swing relative to each other. The link 24 has a side shape that is slightly bent downward at the center in the longitudinal direction. The link 24 may be linear.

A first attachment piece 29 is fixed to a position below the link 24 in the down tube 8, and the bent portion (intermediate portion) of the link 24 and the first attachment piece 29 are connected by a rod 30.
The third and fourth support shafts 31 and 32 are connected to each other so as to be relatively rotatable. That is, the rod 30 connects the link 24 and the down tube 8 through the first mounting piece 29 so as to be relatively swingable, and the third support shaft 31 of the link 24 is the first support shaft 27 and the second support shaft. 28. These links 24 and rods 30 constitute a link mechanism. Thus, the link 24, the operating rod 21a, and the swing arm 18 are respectively connected to the first support shaft 2.
7 and the second fulcrum 28 and the first and second fulcrums are set so as to be relatively swingable, and the rod 30, the link 24, and the down tube 8 are respectively connected to the third fulcrum 31 and the fourth fulcrum. It is set so as to be able to swing relative to each other via third and fourth fulcrums that are the axes of the support shafts 32. Further, a second mounting piece 33 capable of connecting the rod 30 in place of the first mounting piece 29 is fixed to the standing pipe 7.

In FIG. 2, which shows a plan view of the main part of the bicycle, the swing arm 18 has a bent portion 18a.
On the other hand, the rear side is formed in a bifurcated shape extending on both the left and right sides of the rear wheel 20, and the front side is formed in a bifurcated shape extending on the left and right sides of the swing arm bracket 17 (FIG. 1). The pair of links 24 positioned on both the left and right sides of the vertical pipe 7 are connected at their front end portions to the operating rod 21a of the shock absorber 21 via the first support shaft 27, and each rear end portion is a swing arm. The two connecting shafts 23 are connected to the 18 connecting pieces 23. The rear end of the rod 30 is swingably connected to the pair of left and right links 24 via the third support shaft 31, and the front end of the rod 30 is connected to the pair of left and right first mounting pieces 29 via the fourth support shaft 32. It is swingably connected.

Next, the action of absorbing an impact by the rear wheel suspension device will be described. Rear wheel 2 in FIG.
When 0 is flipped up by the unevenness of the traveling road surface, the swing arm 18 that supports the rear wheel 20 swings upward with the pivot shaft 19 as a fulcrum. The link 24 connected to the connecting piece 23 of the bent portion 18a of the swing arm 18 is pushed forward by a distance corresponding to the swing angle of the swing arm 18 and moved to the middle portion of the link 24 at the third support shaft. As the link 24 moves forward, the rod 30 slidably connected via 31 swings forward with the fourth support shaft 32 as a fulcrum. Accordingly, the link 24 is guided to swing around the fourth support shaft 32 by the swinging rod 30. That is, the link 24 is moved forward while swinging in a state where the front side is lifted with the second support shaft 28 as a fulcrum, so that the shock absorber 21 is supported via the first support shaft 27 and the support shaft 22 is supported as a fulcrum. The operating rod 21a is pushed into the inside while swinging so as to lift up.

When the link mechanism including the link 24 and the rod 30 performs the above-described operation, the impact received by the rear wheel 20 is absorbed by a shock absorbing mechanism (not shown) such as a hydraulic cylinder and a coil spring included in the shock absorber 21. The After that, swing arm 1
In response to the restoring force of the operating rod 21a constantly biased in the direction protruding by the hydraulic cylinder and the coil spring of the shock absorber 21, 8 is quickly returned to its original position.

The link 24 includes a swing of the second support shaft 28 that is displaced along an arc centered on the pivot shaft 19 and a swing of the third support shaft 31 that is displaced along an arc centered on the fourth support shaft 32. Since the action is combined with the movement, the first support shaft 27, which is the action point for the operating rod 21a of the link mechanism,
Unlike a simple movement that moves along a circular arc in a conventional bicycle, a movement that moves forward and obliquely upward is performed. Therefore, as shown in FIG. 3, the relationship between the swing angle of the swing arm 18 and the rear shock stroke of the shock absorber 21 is fixed to a linearly changing characteristic in the conventional bicycle. Then, the characteristic changes in a curved line. The characteristic can be variably set by changing the length of the rod 30 or changing the position of the third support shaft 31 on the link 24.

That is, in FIG. 3, A is a reference portion (first to third support shafts 27 and 37 shown in FIG. 1) of the link 24 at one end of a rod 30 having a reference length (for example, 35 mm).
-Characteristic curve when B is slidably connected via the third support shaft 31 to the distance between the second support shafts 31 and 28 (0.65 times), B is one end of the rod 30 which is 5 mm longer than the reference length A characteristic curve when the portion is pivotably connected to the reference portion of the link 24 via the third support shaft 31, C is the third end portion of the rod 30 that is 5 mm shorter than the reference length. A characteristic curve D when pivotally connected via the support shaft 31 is D. The third support shaft 31 is located at a position where one end portion of the rod 30 having a reference length is displaced 5 mm forward relative to the reference portion of the link 24. The characteristic curve E when pivotally connected via the third shaft 31 is located at a position where one end of the rod 30 of the reference length is displaced 5 mm toward the rear with respect to the reference portion of the link 24 via the third support shaft 31. Characteristic curves when swingably connected are shown.

When the characteristic curves of A and E are set to be obtained, the impact absorption is relatively good from the beginning when the swing arm starts to swing, and the impact increases as the swing angle of the swing arm increases. The effect of absorption is slightly dull and increases almost linearly. Further, when the characteristic curve B is set to be obtained, the effect of absorbing the shock is duller than the characteristic curves A and E at the beginning of the swing of the swing arm, and the swing angle of the swing arm is As it becomes larger, the effect of shock absorption increases almost linearly like the characteristic curves of A and E. on the other hand,
When the characteristic curves of C and D are set to be obtained, the impact absorbing effect is as good as the characteristic curves of A and E from the beginning when the swing arm starts to swing, and the swing angle of the swing arm As the force increases, the impact absorbing effect increases substantially linearly, and then the rod 30 becomes difficult to be pushed in from the time when the swing angle of the swing arm approaches the maximum, and the impact absorbing effect decreases.

In the bicycle, the size of the rear shock stroke of the shock absorber 21 with respect to the swing angle of the swing arm 18 can be changed by appropriately selecting and changing the length of the rod 30 or the connecting position of the rod 30 to the link 24 as shown in FIG. As shown in each characteristic curve of A to E, various characteristics can be variably set. Therefore, for a wide range of uses of the bicycle, it is possible to set so as to have an impact absorbing capacity that can be adapted to each of them. It can respond to various needs of users. Further, the shock absorber 21, the link 24, and the rod 3
Since 0 is provided below, the center of gravity of the bicycle is lowered, and maneuverability and running stability are improved.

The swing arm 18 has an L-shaped side surface with a front portion bent downward, a front end portion is supported on the body frame 1 so as to be swingable, and a second support shaft 28 is supported on the L-shaped corner portion 18a. Therefore, the distance from the front end portion that is the swing center of the swing arm 18 to the corner portion is appropriately increased, whereby the amount of movement of the second support shaft 28 of the corner portion 18a due to the swing of the swing arm 18 is increased. That is, the effect of the shock absorber 21 can be appropriately set by increasing the amount of movement of the link 24. Further, since the second support shaft 28 is arranged at the L-shaped corner of the swing arm 18, the position of the link 24 is lowered, so that the shock absorber connected to the link 24 via the first support shaft 27. As a result, the position of the center of gravity of the vehicle body is lowered, and the steering performance and running stability are improved.

Moreover, since the swing arm 18 can be comprised with the arm member which has an L-shaped side surface shape,
Compared to a swing arm that combines three large arm pieces like a conventional bicycle, the structure is simplified and downsized, so the entire bicycle is lighter and the manufacturing cost is reduced. be able to. In addition, since neither the shock absorber 21 nor the link mechanisms 24, 30 are supported by the upper pipe 9, the upper pipe 9 can be reduced. In such a case, further weight reduction and cost reduction can be achieved. .

4, the other end of the rod 30 is connected to the down tube 8 via the second attachment piece 33 of FIG. 4 instead of being connected to the down tube 8 via the first attachment piece 29 in FIG. A state in which the four support shafts 32 are swingably connected is shown. FIG. 5 shows a characteristic curve of the rear shock stroke of the shock absorber 21 with respect to the swing angle of the swing arm 18 in such a configuration. In FIG. 5F, one end of a rod 30 having a reference length (for example, 35 mm) is connected to the link 24.
4 is a characteristic curve when G is connected to the central reference portion (same as FIG. 1) shown in FIG. 4 via the third support shaft 31 and G is linked to one end of the rod 30 having a reference length. The characteristic curves are shown respectively when they are pivotably connected via a third support shaft 31 to a position displaced by 7 mm toward the rear with respect to 24 reference parts. A to C are the same characteristic curves as A to C in FIG.
And for comparison with the characteristic curve of G and G.

When the link mechanism is changed as shown in FIG. 4, as shown in the characteristic curves of F and G, the impact absorbing effect at the initial stage when the swing arm starts to swing is considerably duller than in the case of FIG. ,
As the swing angle of the swing arm increases, the effect of shock absorption increases substantially linearly, and this increase in the effect of shock absorption continues until the swing angle of the swing arm 18 reaches a maximum. Therefore, in applications where the road surface has relatively large irregularities, the impact received by the rear wheels 20 can be effectively absorbed, so that obstacles can be easily overcome and the durability and running performance of the body frame 1 are improved. Therefore, it becomes suitable. On the other hand, for the purpose of traveling on a comparatively gentle road surface with only small unevenness, if the rod 30 is connected to the down tube 8 via the first mounting piece 29 as shown in FIG. The characteristics shown in the curve are preferable because direct maneuvering performance rich in agility can be obtained and riding comfort is improved.

FIG. 6 is a schematic side view showing a main part of a bicycle provided with a rear wheel suspension device according to a second embodiment of the present invention. In this embodiment, the third support shaft 31 for connecting the rod 30 to the link 24.
A plurality (four in this embodiment) of connecting holes 24a to 24d are inserted in a row from the central portion toward the rear side. Further, a connecting piece 34 that extends from the bent portion 18 a toward the pivot shaft 19 that is the swing center of the swing arm 18 is fixed to the swing arm 18. The connecting piece 34 is fixed to the bent portion 18 a from the pivot shaft 19. A plurality (four in this embodiment) of connecting holes 34a to 34 through which the second support shaft 28 is inserted in a row in the direction toward
d is arranged.

In this embodiment, since the rod 30 can be connected by inserting the third support shaft 31 into one selected from the four connection holes 24a to 24d of the link 24, the connecting position of the rod 30 in the link 24 is easy. Can be changed. One end of the rod 30 is connected to the fourth support shaft 3.
Similarly, in the case where the rod 30 is connected to the second attachment piece 33 of the vertical pipe 7 via 2, the other end of the rod 30 is set to one selected from the four connection holes 24a to 24d as the third support shaft. Since the rod 30 can be connected to the link 24 by inserting 31, the connecting position of the rod 30 in the link 24 can be easily changed. In any case, the two front connecting holes 24
The rods 30 having different lengths are used when the rod 30 is connected to a and 24b and when the rod 30 is connected to the two rear connection holes 24c and 24d.

Furthermore, the connection position of the link 24 to the swing arm 18 can be easily changed by inserting the second support shaft 28 into one selected from the four connection holes 34 a to 34 d of the connection piece 34. Can do. In this case, the position of the second support shaft 28 that is the connecting portion between the swing arm 18 and the link 24 changes the distance from the pivot shaft 19 that is the swing center of the swing arm 18. The amount of movement of the second support shaft 28 with respect to the swing angle of the swing arm 18 as the center changes, and the distance from the pivot shaft is the largest when the connecting hole 34a having the longest distance from the pivot shaft 19 is used. It becomes the smallest when the shortest connecting hole 34d is used. Accordingly, the swing arm 18 and the link 2 are connected using the connecting hole 34a.
4 is connected to the shock absorber 21 and the shock absorbing effect is best.
When the swing arm 18 and the link 24 are connected using the connecting hole 34d, the shock absorbing effect by the shock absorber 21 is the slowest.

In the rear-wheel suspension device of this embodiment, the third support shaft 31 or the second support shaft 28 is inserted and fastened to desired connection holes 24a to 24d and 34a to 34d appropriately selected, or the fourth support shaft 3
Since various shock absorption characteristics can be easily obtained simply by performing a simple operation of attaching 2 to the first mounting piece 29 or the second mounting piece 33, the bicycle user should run the bicycle for the purpose of running the bicycle. It is possible to easily select a shock absorbing characteristic that is optimal for traveling conditions including the road surface and easily variably set it. The connection holes 24A to 24d for the third support shaft 31 and the second support shaft 28.
Any one of the connection holes 34a to 34d may be used.

FIGS. 7A and 7B are a schematic side view and a plan view showing a main part of a bicycle provided with a rear wheel suspension device according to a third embodiment of the present invention. In the second embodiment, the third support shaft 31 shown in FIG. 6 is inserted into the desired connection holes 24 a to 24 d and fastened, so that the rod 3 is placed at a desired position of the link 24.
In the embodiment shown in FIG. 7, the connecting position of the rod 30 in the link 24 can be changed more easily by a one-touch operation. That is, the rod 30
The third support shaft 31 is fixed to the tip of the connection side to the link 24 of the left and right links 24,
24, a rotary drum 37 is rotatably supported via a rotary spindle 38, and a third spindle 31 is
The rotary drum 37 is slidably fitted in a support hole 37a provided at a position deviated from the rotation center. The tip of the rod 30 is inserted into a notch 39 provided at the center in the axial direction of the rotary drum 37 and connected to the third support shaft 31. Therefore, when the rotating drum 37 is rotated in any direction using a rotating tool, the third support shaft 31 is linked to the link 24 along with the rotation.
On the other hand, the connecting position of the rod 30 in the link 24 is changed. This eccentric shaft structure can also be used for the second support shaft 28 that connects the swing arm 18 and the link 24.

1 is a schematic side view showing a bicycle provided with a rear wheel suspension device according to a first embodiment of the present invention. It is a top view which shows the principal part of a bicycle same as the above. It is a characteristic view which shows the relationship between the rocking | fluctuation angle of a swing arm and the rear shock stroke of a shock absorber when the connection position and rod length of the rod in the bicycle same as the above are changed. It is a side view which shows the principal part of the state which changed the connection position of the rod to the vehicle body frame in a bicycle same as the above. FIG. 5 is a characteristic diagram showing the relationship between the swing angle of the swing arm and the rear shock stroke of the shock absorber in the state of FIG. 4 and the state of FIG. 1. It is a schematic side view which shows the principal part of the bicycle provided with the rear-wheel suspension apparatus which concerns on 2nd Embodiment of this invention. (A), (b) is the schematic side view and top view which show the principal part of the bicycle provided with the rear-wheel suspension apparatus which concerns on 3rd Embodiment of this invention. It is a schematic side view which shows the bicycle provided with the conventional rear-wheel suspension apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body frame 2 Steering shaft 3 Head pipe 4 Seat 7 Standing pipe 8 Down tube 18 Swing arm 18a Bending part (corner part)
19 Pivot shaft (swing center of swing arm)
20 Rear wheel 21 Shock absorber 21a Actuating rod 24 Link 27 First support shaft (first fulcrum)
28 Second spindle (second fulcrum)
30 Rod 31 Third spindle (third fulcrum)
32 4th support shaft (4th support point)

Claims (6)

A vehicle body frame having a head pipe that supports the steering shaft, a vertical pipe that supports the seat, and a down tube that is inclined downward toward the rear and connects the pipes;
A swing arm that is swingably supported by the body frame and supports a rear wheel;
A shock absorber supported by the down tube;
A link connected between the tip of the operating rod of the shock absorber and the swing arm via a first fulcrum and a second fulcrum, respectively, so as to be relatively swingable;
A rod connected to the link and the vehicle body frame via a third fulcrum and a fourth fulcrum, respectively, so as to be relatively swingable;
The rear wheel suspension device for a bicycle, wherein the third fulcrum is located between the first fulcrum and the second fulcrum. The bicycle rear wheel suspension device according to claim 1, wherein the fourth fulcrum is disposed on the down tube. The bicycle rear wheel suspension device according to claim 1, wherein the fourth fulcrum is disposed on the standing pipe. 4. The swing arm according to claim 1, wherein the swing arm has an L-shaped side shape with a front portion bent downward, and a front end portion is swingably supported by the vehicle body frame. A bicycle rear-wheel suspension device in which the second fulcrum is disposed at a corner of the shape. The bicycle rear wheel suspension system according to any one of claims 1 to 4, wherein a position of a third fulcrum on the link is variably set. The position of the second fulcrum on the swing arm according to any one of claims 1 to 5,
A bicycle rear wheel suspension that is variably set to change the distance from the swing center of the swing arm.

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