JPH06107264A - Rear wheel suspension for bicycle - Google Patents

Abstract

PURPOSE:To provide such a rear wheel suspension device that lowers a gravity center, allows a long cushion stroke, and does not damage rigidity of a front part frame. CONSTITUTION:A rear cushion unit 23 is arranged along a seat tube 5 and its upper end part is connected to a rear part frame 8 via a link member 22. The lower end part is connected to a vicinity of a hanger bracket 13. Thereby the direction of force from a road surface is shifted to approximately downward by the link member 22 so as to be buffered by the rear cushion unit 23. Therefore the rear cushion unit 23 can be arranged in a wide space of a front frame 6 so as to get a large stroke and be arranged in a low position adjacent to the seat tube so as to have a low gravity center. Or tube connection of the front frame 6 is never intermittent so as to have high rigidity.

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 device for a bicycle, which supports the rear wheel of the bicycle in a vertically swingable manner.

[0002]

2. Description of the Related Art Conventionally, some bicycles are equipped with a rear wheel suspension device for facilitating traveling on a rough road. As a rear wheel suspension system of this type of bicycle, a rear frame consisting of a chain stay and a seat stay that rotatably supports the rear wheel can be swung up and down on a front frame consisting of a top tube, down tube, seat tube, etc. In many cases, a cushion unit is interposed between the rear frame and the front frame.

The cushion unit mounting structure is mainly of the following three types. That is, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 54-156352, the seat stay is extended to the front side of the seat tube of the front frame, and the rear end of the cushion unit is connected to the extended end of the seat stay and is coupled to the seat tube. The structure of connecting the front part of the cushion unit to the front part of the above-mentioned top tube, and connecting the front part of the cushion unit to the seat tube and the rear part to the chain stay as disclosed in Japanese Utility Model Laid-Open No. 51-48257. A structure that connects and positions between so-called front frame and rear frame,
The front frame is provided with a tubular cushion unit accommodating portion, the cushion unit is inserted into the cushion unit accommodating portion, and the rear portion is connected to the rear frame.

An example of using the cushion unit accommodating portion is disclosed in JP-A-54-108325. This is a cushion unit in which a U-shaped front frame without a top tube, which is often used in women's bicycles, is divided at the bottom and the rear part of the front pipe is formed to be substantially horizontal. It is used as a housing part. Then, the entire cushion unit is inserted into the front pipe to connect the rear portion of the cushion unit to the rear frame. The rear pipe was welded to the rear end of the front pipe.

When the cushion unit is positioned between the front frame and the rear frame as shown in Japanese Utility Model Laid-Open No. 51-48257, the front portion of the cushion unit is connected to the top tube and the seat tube. There is also a structure in which the rear part is connected to the front part of the seat stay.

[0006]

However, in the conventional bicycle rear wheel suspension system, the cushion unit mounting structure has been a problem. In other words, the actual exploitation 54-156352
If the front part of the cushion unit is connected to the front part of the top tube as shown in Japanese Patent Publication, the impact from the rear wheel is easily transmitted to the head tube, and the cushion unit, which is a heavy load, follows the top tube. As a result, the position of the center of gravity becomes high.

When the cushion unit is positioned between the front frame and the rear frame as disclosed in Japanese Utility Model Laid-Open No. 51-48257, a large cushion stroke is required because the space for arranging the cushion unit is small. Will not be possible. In order to increase the space for arranging the cushion unit, the rear wheels have to be shifted to the rear side, which increases the total length of the rear frame. Moreover, the muddy water splashed up by the rear wheels easily gets on the cushion unit.

Further, if the cushion unit accommodating portion is provided in the front frame, the rigidity of the front frame is lowered. This is because the front frame is often formed into a generally inverted triangular shape in a side view by connecting pipe bodies such as a top tube, a down tube, and a seat tube. Because it will be interrupted. In addition, JP-A-54-108325
Even if the cushion unit is inserted into the pipe of the front frame as shown in Japanese Patent Publication, the front frame cannot be formed of a single pipe to provide the cushion unit accommodating portion, and the rigidity is still high. Will decrease.

The present invention has been made in order to solve the above-mentioned problems, and the rear wheel suspension of a bicycle has a low center of gravity and a long cushion stroke, and does not impair the rigidity of the front frame. The purpose is to obtain the device.

[0010]

In the rear wheel suspension system for a bicycle according to the present invention, a rear cushion unit is arranged near the front side of a seat tube with its axis oriented substantially vertically, and its upper end is connected via a link. It is connected to the rear arm and the lower end is connected to the vicinity of a hanger bracket that supports the crankshaft of the front frame.

[0011]

The cushion unit is arranged along the seat tube and positioned at a relatively low position. Further, the force received from the road surface when the rear wheel moves over the unevenness of the road surface and the rear arm swings is transmitted to the link, and the direction thereof is changed substantially downward.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 is a side view of a bicycle equipped with a rear wheel suspension device according to the present invention, FIG. 2 is an enlarged side view of the rear wheel suspension device according to the present invention, and FIG. 3 is a main part III-III in FIG. 2 is a sectional view taken along line IV-IV of FIG.
IV line sectional view, FIG. 5 is a VV line sectional view in FIG. 2, FIG. 6 is a VI-VI line sectional view of a main part in FIG. 2, and FIG. 7 is an exploded perspective view of a rear wheel suspension device according to the present invention. is there.

In these figures, 1 is an off-road bicycle. The frame of the bicycle 1 includes a front frame 6 having a head tube 2, a top tube 3, a down tube 4, and a seat tube 5 and having a substantially inverted triangular shape in a side view, and a front frame 6 which is vertically swingably connected to the rear frame 6. It is configured by a rear frame 8 having a substantially triangular shape in a side view, which rotatably supports the wheel 7. In this embodiment, the rear frame 8 constitutes a rear arm.

Reference numeral 9 is a front wheel, and 10 is a front fork for rotatably supporting the front wheel 9. The front fork 10 is a fork body located on the left and right of the front wheel 9 and a steering shaft (not shown) located at the center in the vehicle width direction. ) And a steering shaft is rotatably supported by the head tube 2. A handle 11 is fixed to the upper portion of the steering shaft. Further, the left and right fork bodies of the front fork 10 constitute a telescopic type shock absorber with an attenuator having an outer cylinder 10a and an inner cylinder 10b.

Seat tube 5 of the front frame 6
The sheet pillar 12a to which the seat 12 is attached is fitted and supported at the upper end portion, and the rear end portion of the down tube 4 is welded to the lower end portion via the hanger bracket 13. The hanger bracket 13 is provided with its axis oriented in the vehicle width direction, and the crankshaft 14 is rotatably supported therein.

A crank 14a and a pedal 14b are mounted on the crankshaft 14, and a conventionally known chain type power transmission device 15 is mounted on the right side portion of the vehicle body. 16 is the chain type power transmission device 15
Is a front transmission, and 17 is also a rear transmission. These front and rear transmissions 16 and 17 are conventionally known ones that change the winding diameter of the chain 18 to change gears.
6 is attached to the seat tube 5, and the rear transmission 17 is an end bracket 8 on the right side of the vehicle body in the rear frame 8.
It is attached to a.

The rear frame 8 is supported by the two plate-shaped brackets 13a, 13a of the hanger bracket 13 and extends toward the rear from the hanger bracket 13. A chain stay 19 is provided at the rear end of the chain stay 19. The seat stay 20 connected via the bracket 8a and a connecting pipe 21 for connecting the front end of the chain stay 19 and the front end of the seat stay 20 are formed into a substantially triangular shape in a side view. 8
The axle 7a of the rear wheel 7 is attached to a. In the rear frame 8, the front end of the seat stay 20 has a link member 22 and a rear cushion unit 23, which will be described later.
Is connected to the front frame 6 via. The rear wheel suspension device according to the present invention includes the rear frame 8, the link member 22, the rear cushion unit 23, and the like.

The chain stays 19, the seat stays 20, and the connecting pipes 21 forming the rear frame 8 are each formed of a pipe material, and as shown in FIG. 4, FIG. 6 and FIG. ing. A cross member 19a is interposed between the left and right chain stays 19 and a cross member 20a is interposed between the left and right seat stays 20.

As shown in FIGS. 6 and 7, the structure of the front end pivotally supporting portion of the chain stay 19 is such that a bearing pipe 24 is welded to the front ends of the left and right chain stays 19, and the bearing pipe 24 is connected to the pair of plate-shaped brackets. It is structured such that it is interposed between 13a and 13a and is connected via a support shaft 25. Reference numeral 25a is a bearing bush fitted in the bearing pipe 24, and 25b is a collar slidably fitted in the bearing bush 25a.
Has been inserted. Also, 25c is an oil seal, 25
d is a washer.

The link member 22 has a seat stay 20.
A first link 27 made of an elongated plate material connected to a front end of the seat via a support shaft 26, and a side surface connected to an end of the first link 27 opposite to the seat stay 20 via a support shaft 28. The second link 29 has a substantially triangular shape when viewed. The second link 29 has one triangular top portion connected to the first link 27, the other top portion pivotally supported by the seat tube 5 via the support shaft 30, and the rear cushion unit 23 via the support shaft 31. Is connected to the upper end of.

The first link 27 and the second link 2 are also provided.
9 are provided on both left and right sides of the seat tube 5,
The left and right parts are connected by support shafts 26, 28, 30, 31. In addition, each of the support shafts 26, 28, 3
The structure of the part to which 0 and 31 are attached is substantially the same as the structure of the front end pivotal support part of the chain stay 19, and as described above, the bearing bush and the collar are interposed between the support shaft and the connected member. Has been done. That is, as shown in FIGS. 4 and 7, the portion to which the support shaft 26 is attached is the seat stay 20.
The bearing bush 26 to the bearing pipe 32 welded to the front end of the
A and the collar 26b are fitted, the first links 27 are arranged on both sides of the bearing pipe 32, and the support shaft 26 penetrates them.

As shown in FIGS. 3 and 7, at the portion where the support shaft 28 is mounted, the bearing bush 28a and the collar 28b are fitted into the boss portion 29a formed integrally with the second link 29, and the second link is formed. The first links 27 are positioned on both sides of the support shaft 29, and the support shaft 28 penetrates them.

As shown in FIG. 5 and FIG. 7, in the portion where the support shaft 30 is mounted, the bearing bush 30a and the collar 30b are fitted into the bearing pipe 33 which is fixedly penetrated through the seat tube 5, and the bearing pipe 33 is fitted. Second link 29 on both sides
Are positioned and the support shaft 30 penetrates them.

The portion to which the support shaft 31 is attached is shown in FIGS.
And as shown in FIG. 7, the rear cushion unit 23
The bearing bush 31a and the collar 31b are fitted into the upper end portion 23a of the above, the second links 29 are positioned on both sides of the upper end portion 23a, and the support shaft 31 penetrates them.

The rear cushion unit 23 has a structure including a compression coil spring 23b and an attenuator 23c. The rear cushion unit 23 has an upper end 23a connected to the second link 29 and a lower end 23d connected to the two plate brackets 4a, 4a of the down tube 4 via a support shaft 34. It is supported by the front frame 6 with its axis oriented substantially vertically.

The plate-shaped brackets 4a, 4a are the rear end of the down tube 4 and are the hanger bracket 1.
It is arranged in the vicinity of 3. As shown in FIG. 3, the connecting structure of the plate-shaped bracket 4a and the rear cushion unit 23 is such that the lower end portion 23d of the rear cushion unit 23 is faced between the plate-shaped brackets 4a and the spindle 3 is attached to them.
It has a structure in which 4 is penetrated. A collar 3 is provided between the support shaft 34 and the lower end of the rear cushion unit 23.
4a is interposed.

In the rear wheel suspension system constructed as described above, when an upward force is applied to the rear wheel 7 by the rear wheel 7 riding over unevenness on the road surface, the rear frame 8 causes the front end pivot of the chain stay 19 to rotate. It swings counterclockwise in FIGS. 1 and 2 around the support (support shaft 25). At this time, the front end portion of the seat stay 20 moves to the left in the figure to push the first link 27 to the left, and the second link 2
9 rotates counterclockwise around the support shaft 30 to contract the rear cushion unit 23.

Therefore, the force received from the road surface when the rear wheel 7 rides over the unevenness of the road surface and the rear frame 8 swings is changed by the link member 22 from the seat stay 20 to a substantially downward direction, and the rear cushion unit. Two
It is transmitted to 3 and buffered. Therefore, the rear cushion unit 23 can be arranged in a wide space of the front frame 6 apart from the rear frame 8, and a large cushion stroke can be obtained.

Further, the impact from the road surface can be received by the relatively rigid portion near the hanger bracket 13. Further, the rear cushion unit 23, which is a heavy load, is arranged along the seat tube 5, and is positioned relatively low.

Furthermore, the rear cushion unit 23
Is disposed in the space of the front frame 6 that is substantially in the shape of an inverted triangle when viewed from the side, so that the pipe members that form the front frame 6 do not break in the middle.

In addition, since the link member 22 is interposed between the upper end of the rear cushion unit 23 and the rear frame 8, the stroke amount of the rear cushion unit 23 can be changed according to the swing amount of the rear frame 8. Can be That is, the stroke amount in the rear cushion unit 23 can be shortened when the swing amount of the rear frame 8 is relatively small, and the stroke amount can be increased when the swing amount becomes large, so that the shock absorbing property is enhanced. be able to.

The bicycle rear wheel suspension device according to the present invention may be constructed as shown in FIGS. 8 is a side view showing another embodiment of the rear wheel suspension system in which the pivot position of the chain stay is changed, FIG. 9 is a sectional view taken along the line IX-IX of the main part in FIG. 8, and FIG. It is an X-ray sectional view. 1 to 7 in these figures.
The same or equivalent members as those described in 1 are assigned the same reference numerals and detailed description thereof will be omitted.

The rear wheel suspension system shown in FIGS. 8 to 10 has a pivotal support position of the chain stay 19 of the rear frame 8 and a second position.
The structure is the same as the rear wheel suspension system shown in FIGS. 1 to 7 except that the structure for attaching the link 29 to the seat tube 5 is different.

The front end pivotal support portion of the chain stay 19 is located above the front transmission 16, and as shown in FIG. 9, the bearing pipe 4 fixedly penetrated through the seat tube 5.
The bearing bush 41a and the collar 41b are fitted into the bearing pipe 41, the front ends of the chain stays 19 are positioned on both sides of the bearing pipe 41, and the support shaft 25 is passed through them. In addition, 42 is a seal member.

Further, the second link 29 is connected to the seat tube 5
The bearing member 43 is welded and fixed to the seat tube 5 as shown in FIG. 10, the bearing bush 43a and the collar 43b are fitted into the bearing member 43, and the second link 29 is provided on both sides of the bearing member 43. Is positioned so that the support shaft 30 penetrates through them.

When the pivotal position of the chain stay 19 is set to the upper side in this manner, most of the chain stay 19 is positioned above the chain 18. That is, the chain 18 is less likely to hit the chain stay 19 even if the vehicle body moves up and down greatly.

In each of the above-mentioned embodiments, the rear arm is composed of the rear frame 8 having a substantially triangular shape in a side view, but the rear arm may be formed only by the chain stay portion in the embodiment. When doing so, the first link 27 of the link member 22 is extended to the rear of the vehicle body, and the rear end portion of the first link 27 is attached to the end bracket 8a.
Rotatably connected to. Even in this case, the same effect as the present embodiment can be obtained.

[0038]

As described above, in the rear wheel suspension system for a bicycle according to the present invention, the rear cushion unit is arranged in the vicinity of the front side of the seat tube with its axis oriented substantially vertically, and the upper end portion is provided with a link. The rear end is connected to the hanger bracket that supports the crankshaft in the front frame, and the force received from the road surface when the rear wheel swings over the unevenness of the road surface due to the link is connected to the rear arm. The direction is changed to a substantially downward direction and is transmitted to the rear cushion unit to be buffered.

Therefore, since the rear cushion unit can be arranged in the wide space of the front frame away from the rear arm, the cushion stroke can be increased and the rear cushion unit having sufficient shock absorption can be used. Like

Further, since the impact from the road surface can be received by the relatively rigid portion near the hanger bracket, it is difficult to be transmitted to the head tube side. Further, since the rear cushion unit, which is a heavy load, is arranged along the seat tube and is positioned at a relatively low position, the center of gravity becomes low.

In addition, since the pipe members forming the front frame are not interrupted on the way, the rigidity of the front frame is not impaired by the rear wheel suspension device.

[Brief description of drawings]

FIG. 1 is a side view of a bicycle equipped with a rear wheel suspension device according to the present invention.

FIG. 2 is an enlarged side view showing a rear wheel suspension device according to the present invention.

FIG. 3 is a sectional view taken along line III-III of the main part in FIG.

FIG. 4 is a sectional view taken along the line IV-IV of a main part in FIG.

5 is a sectional view taken along line VV in FIG.

FIG. 6 is a sectional view taken along line VI-VI of a main part in FIG.

FIG. 7 is an exploded perspective view of a rear wheel suspension device according to the present invention.

FIG. 8 is a side view showing another embodiment of the rear wheel suspension device in which the pivot position of the chain stay is changed.

9 is a sectional view taken along line IX-IX of the main part in FIG.

10 is a sectional view taken along line XX in FIG.

[Explanation of symbols]

 2 head tube 3 top tube 4 down tube 5 seat tube 6 front frame 7 rear wheel 8 rear frame 13 hanger bracket 19 chain stay 20 seat stay 22 link member 23 rear cushion unit

Claims (1)

[Claims] 1. A front frame comprising a head tube, a top tube, a down tube, and a seat tube, which has a substantially inverted triangular shape in a side view, and a rear arm for rotatably supporting a rear wheel, the front end of the rear arm being a front portion. In a rear wheel suspension device of a bicycle, which is pivotally supported in a vertical direction on a rear frame and is connected to a front frame via a rear cushion unit, the rear cushion unit is provided with an axis line near the front side of the seat tube. Arranged in a substantially vertical direction, the upper end portion is connected to the rear arm via a link, and the lower end portion is connected in the vicinity of a hanger bracket that supports the crankshaft by connecting the down tube and the seat tube. A rear wheel suspension device for a bicycle characterized by: