JPH0237678Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a bicycle front derailleur that is configured to change gears by changing the chain to one of the selected sprockets of the front gear, which is composed of multiple sprockets with different numbers of teeth arranged side by side. Specifically, for a front gear with three or more sprockets, both when changing the chain from the smallest diameter sprocket to a larger diameter sprocket, and when changing the chain from an intermediate sprocket to the largest diameter sprocket. This invention relates to an improved gear shifting performance.

[Conventional technology]

A front derailleur for a bicycle has conventionally had a basic configuration shown in FIGS. 5 and 6 of the present application.
First, the structure of this conventional bicycle front derailleur will be explained based on FIGS. 5 and 6. Near the hangarug at the bottom of seat pipe 1,
A base member 3 is fixed by a clamp band 2, and a movable member 5 is attached to the base member 3 via a control mechanism constituted by a parallelogram pantograph link mechanism 4 or the like. The parallelogram pantograph link mechanism 4 swingably connects the upper ends of the outer link member 6 and the inner link member 7 to the base member 3 by pin connection, and the lower ends of these inner and outer link members 6 and 7. The movable member 5 is connected to the movable member 5 by pin connection. The pins for connecting the upper ends of the inner and outer link members 6 and 7 to the base member 3 and the pins for connecting the lower ends of the inner and outer link members 6 and 7 to the movable member 5 are each of a parallelogram. Therefore, when the inner and outer link members 6 and 7 are swung relative to the base member 3, the movable member 5 maintains its directionality constant. Translate in the medial and medial direction. Normally, the pantograph link mechanism 4 includes the inner link member 7.
By inserting the torsion spring 8 into the pin that connects the movable member 5 and the torsion spring 8, and hooking both ends of the spring 8 to the fixed member on the base member 3 side and the movable member 5, the tendency to deform in one direction is reduced. The inner and outer link members 6, 7 are deformed by swinging the inner and outer link members 6, 7 against the torsion spring 8 using the operating cable W. Mounted on the movable member 5 are an inner guide plate 9 and an outer guide plate 10, which are located substantially parallel to the sprocket S and have arcuate lower edges 9a, 10a corresponding to the outer periphery of the sprocket S.
These inner guide plate 9 and outer guide plate 1
0 is arranged so as to sandwich the chain C before it hangs on the sprocket S of the front gear from the inside out. Therefore, when the movable member 5 moves inward, the inner surface of the outer guide plate 10 moves the chain C between the inside and outside. The chain C is pushed inward to separate from the large diameter sprocket s3, and conversely, when the movable member 5 moves outward, the inner surface of the inner guide plate 9 pushes the chain C outward, removing the chain C that was hanging on the small diameter sprocket s1. hook onto the large diameter sprockets s2 and s3.
The chain C, which has been removed from the large diameter sprocket s3 by the outer guide plate 10, is dropped into the small diameter inner sprockets s2 and s1 by the tension applied by the rear derailleur (not shown), and is hooked thereon. Can be replaced. On the other hand, the chain C, which is hooked to the outer large-diameter sprocket s3 by the inner guide plate 9, is attached to the large-diameter sprocket s3 as the large-diameter sprocket s3 rotates.
Can be replaced with 3 teeth.

[Problem that the invention attempts to solve]

By the way, as shown in Fig. 5, recent front gears have, for example, three sprockets, and the innermost minimum diameter sprocket s
The outer diameter of sprocket 1 is made considerably smaller than that of the outermost maximum diameter sprocket s3 to improve climbing performance. In the front derailleur of a bicycle equipped with such a multi-stage front gear, the sprocket s1 is particularly connected from the smallest diameter sprocket s1 to the adjacent intermediate sprocket s.
In order to effectively change the chain C to 2, as shown in FIG.
Measures are taken to make the height difference with respect to the lower edge 10a of the front derailleur larger than that of a normal front derailleur, and to bring the lower edge 9a, which substantially pushes the chain C, as close to the outer periphery of the minimum diameter sprocket s1 as possible. In this way, it is possible to push outward the part of the chain C that is close to the smallest sprocket s1 that is about to engage the smallest diameter sprocket s1, so that the response can be improved with a small amount of movement of the movable member 5 or the inner guide plate 9. Chain C can be efficiently hooked onto intermediate sprocket s2 and replaced. However, setting the vertical height low while keeping the lower edge 9a of the inner guide plate 9 in an arc shape concentric with the sprocket as described above means that the chain C will not be able to hang from the minimum diameter sprocket s1 to the intermediate sprocket s2. Although it can improve the replacement performance, it is possible to improve the replacement performance from the intermediate sprocket S2 to the maximum diameter sprocket S3.
When replacing the chain C with the chain C, the following inconvenience occurs. As shown in FIG. 5, since the lower edge 9a of the inner guide plate 9 is lower than that of a general front derailleur, the maximum diameter sprocket s3 of the lower edge 9a of the inner guide plate 9 The amount of overlap to the inside of
Even if you try to push it to the 3rd side and hook it on this, the 6th
As shown by the imaginary line in the figure, the chain C is squeezed between the inner wall of the inner guide plate 9 and the largest diameter sprocket s3. In other words, in the conventional triple sprocket compatible front derailleur shown in FIGS. 5 and 6, the lower edge 9 of the guide plate 9
As a result of lowering a, even though the shifting performance from the smallest diameter sprocket s1 to the intermediate sprocket s2 can be improved,
From intermediate sprocket s2 to maximum diameter sprocket s
The shiftability to 3 was actually worse. As is clear from the above explanation, this is because the position of the lower edge 9a of the arc-shaped inner guide plate, which should actually push the chain C during gear shifting, has been lowered, resulting in a shift from the minimum diameter sprocket s1 to the intermediate sprocket s2. Chain C
When replacing the chain C, the part where the inner guide plate actually pushes the chain C approaches the smallest sprocket s1, but when replacing the chain C from the intermediate sprocket s2 to the largest diameter sprocket s3,
This is because the part where the inner guide plate actually pushes the chain C will be too close to the intermediate sprocket s2. The present invention was devised under the above circumstances, and is intended for bicycles equipped with three or more sprockets with a large difference in outer diameter between the largest diameter sprocket s3 and the smallest diameter sprocket s1. Not only is the shifting performance good when changing the chain C from sprocket s1 to a larger diameter sprocket, but also the intermediate diameter sprocket s2
To provide a front derailleur for a bicycle which can also improve shifting performance when replacing a chain C with a sprocket S3 having the largest diameter.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. That is, the present invention has a minimum diameter sprocket,
Used in combination with a multi-stage front gear comprising at least one intermediate sprocket with a larger diameter and a maximum diameter sprocket with a larger diameter,
The chain is provided with an inner guide plate and an outer guide plate which are each made of a single member and which face each other so as to sandwich the chain that is about to be hung on the sprocket. In the bicycle front derailleur configured as shown in FIG. With respect to the part B that is pressed when replacing the sprocket, the vertical position of the part A that is pressed when replacing the chain hanging on the intermediate sprocket with a larger diameter sprocket at the middle or front part of the inner guide plate. , it is characterized in that it is clearly deviated upwards from the extension line of the circular arc forming the part B. Part A to press when replacing chain C on intermediate sprocket s2 with large diameter sprocket s3
To position as above, for example,
Usually, the front part of the lower edge 9a of the inner guide plate 9, which is formed in an arc shape approximately corresponding to the outer circumference of the sprocket s, is recessed over a predetermined width in the transverse direction of the chain C of the inner guide plate 9. It is conceivable to make the lower edge 9a of the plate 9 step-shaped so that the front part thereof is farther from the sprocket than the rear part. Furthermore, a bulge is provided at a predetermined distance above the lower edge 9a on the inner surface of the front part of the inner guide plate 9, and this bulge is used to replace the chain C that hangs on the intermediate sprocket s2 with the large diameter sprocket s3. In some cases, the part A may be used to press the chain.

[Action and effect]

When replacing the chain C that hangs over the minimum diameter sprocket s1, which is formed by making the rear lower edge of the inner guide plate into an arc shape that substantially corresponds to the outer periphery of the front gear as described above, to the intermediate sprocket s2, With respect to the pushing part B, the vertical position of the pushing part A when replacing the chain hanging on the intermediate sprocket s2 with a sprocket s3 having a larger diameter at the middle or front part of the inner guide plate is determined by the pushing part B. As a result of being clearly deviated upwards from the extension line of the circular arc that forms the
When pushing the chain C hanging on the intermediate sprocket s2 toward the large-diameter sprocket s3, the inner guide plate 9 pushes a part farther from the intermediate sprocket s2 than in the past. This actually means that the amount of overlap between the part A that pushes the chain C on the intermediate sprocket s2 and the maximum diameter sprocket s3 is smaller than in the past, or does not exist. As seen in the front derailleur, when changing the chain C from the intermediate sprocket s2 to the large diameter sprocket s3, the part that pushes the chain overlaps the largest diameter sprocket s3, and as a result, the inner guide plate 9 and the largest diameter The problem of the chain C being caught between the sprocket s3 and the sprocket s3 is eliminated, and the chain C can be changed smoothly from the intermediate sprocket s2 to the largest diameter sprocket s3. On the other hand, when replacing the chain C hanging on the minimum diameter sprocket s1 with the intermediate sprocket s2, the part B where the inner guide plate 9 pushes the chain C is the position closest to the minimum diameter sprocket s1 as much as possible, as in the conventional case. The function of replacing the chain C on the smallest diameter sprocket s1 with the intermediate sprocket s2 is not diminished. As a result of the above, the bicycle front derailleur of the present invention has a considerably smaller outer diameter of the smallest sprocket s1, and when replacing the chain C with a selected sprocket of a front gear having three or more sprockets, Therefore, it is difficult to replace the chain from the smallest diameter sprocket s1 to the intermediate sprocket s2, and to replace the chain C from the intermediate sprocket s2 to the largest diameter sprocket s3, which was considered difficult with the general shape of the inner guide plate. Improved efficiency can be achieved.
Furthermore, in order to implement the present invention, it is only necessary to change the shape of the inner guide plate 9 without adding any specially manufactured parts, which is very advantageous in terms of cost.

[Explanation of Examples]

An example of the front derailleur of the present invention is shown in FIGS. 1 to 3. In addition, in these figures,
Components equivalent to those of the conventional example shown in FIGS. 5 and 6 are given the same reference numerals. In the front derailleur of the present invention, the structure other than the guide plate 9 can be the same as the structure of the conventional example shown in FIGS. 5 and 6. That is, a base member 3 is fixed to the seat pipe 2 via a clamp band 2, and a movable member 5 is supported on this base member 3 so as to be able to reciprocate in and out directions via a control mechanism such as a pantograph link mechanism 4. has been done. The movable member 5 includes
An inner guide plate 9 and an outer guide plate 10, which are substantially parallel to the sprockets, are installed so as to face each other on the inside and outside with the chain C that is about to engage the front gear sprockets s1, s2, and s3 interposed therebetween. As shown in FIG. 1, the outer guide plate 10 has an arc-shaped lower edge 10 that corresponds to the circumferential edge extending a predetermined angle rearward from the top of the approximately maximum diameter sprocket s3.
In addition to having a, it has a roughly crescent-shaped side view shape,
Its upper part is connected to a movable member 5. The vertical position of the outer guide plate 10 is set by adjusting the tightening position of the clamp band 2 with respect to the seat pipe so that the lower edge 10a does not interfere with the outer periphery of the maximum diameter sprocket s3. In addition, the rear end of the outer guide plate 10 corresponds to the outer diameter of the minimum diameter sprocket s1, and sufficiently intersects with the chain C (shown by a solid line in FIG. 1) that is about to engage the minimum diameter sprocket s1 when viewed from the front. It will be postponed until the end. On the other hand, the shape of the inner guide plate 9 in this example when viewed from the front is similar to that of the conventional example shown in FIG. That is, the lower edge 9a has an approximately crescent-shaped front view shape with an arcuate shape that is considerably lower than the position of the lower edge 10a of the outer guide plate 10,
Its upper part is connected to the movable member 5. Now, as shown in Figure 1, chain C
The running path of the sprocket differs depending on the outer diameter of the sprocket on which it hangs. That is, when the sprocket is attached to the smallest diameter sprocket s1 (indicated by a solid line in the figure), when it is attached to the intermediate sprocket s2 (indicated by a phantom line in the figure), and when it is attached to the largest diameter sprocket s3. (not shown), there will be a height difference in the running path of the part where the sprocket is about to catch. When looking at this using the guide plate as a reference, the portion that the chain C crosses in the front and back direction of the guide plate differs depending on which sprocket the chain C is attached to. In the present invention, when replacing the chain C hanging on the intermediate sprocket s2, that is, the chain C shown by the imaginary line in FIG. When the hanging chain, that is, the chain C shown by a solid line in FIG. 1, is replaced with the intermediate sprocket s2, the inner guide plate 9 is pushed through the part B, and is located outside the arc concentric with the sprocket. To this end, in this example, as shown in detail in FIGS. 2 and 3, a predetermined width on the lower edge 9a side of the inner guide plate 9 is achieved by recessing it from approximately the center in the front-rear direction to the front end. ing. As a result, in FIG. 2, the part A that actually pushes the chain C is moved to the rear in the traveling direction of the chain C from the part A' that is supposed to push the chain C if the above-mentioned recess is not provided. Therefore, when the inner guide plate 9 is moved toward the front in FIG. And it will be replaced. On the other hand, when replacing the chain C hanging on the minimum diameter sprocket s1 with the intermediate sprocket s2, the running path of the chain C shown by a solid line is located at the part indicated by the symbol B, that is, the rear part of the lower edge 9a of the guide plate 9. The intersecting portion pushes the chain C outward, and then the chain C is hooked onto the intermediate sprocket s2 and replaced. In Fig. 2, the inner guide plate 9 of the present invention is shown at a position A' where the inner guide plate 9 is supposed to push the chain C hanging on the intermediate sprocket s2 when the above-mentioned recess is not provided, and at the chain C in a similar state.
As is clear from comparing the position of the part A that presses in the chain running direction, the part indicated by the code A has a lower code.
The part indicated by A' is further away from the intermediate sprocket s2, and the largest diameter sprocket s3
Both do not overlap. Therefore, the bicycle front derailleur of the present invention solves the problem of the conventional front derailleur shown in FIG. The problem of the chain C being squeezed between the inner guide plate 9 and the largest diameter sprocket s3 is eliminated. FIG. 4 shows another embodiment of the inner guide plate 9 of the bicycle front derailleur of the present invention. In this example, the portions corresponding to the recessed portions in the embodiments of FIGS. 1 to 3 are deleted. Even in this case, the part A that presses the chain C on the intermediate sprocket s2 is shifted to the rear in the running direction of the chain from the part A' that is conventionally assumed to push the chain C.
The same effects and effects as the example shown in the figure can be expected. Of course, the scope of the present invention is not limited to the embodiments described above. Inner and outer guide plates 9,1
The overall shape of 0 can be changed in design. in short,
In the inner guide plate, if the vertical positional relationship in front view of the part B that substantially pushes the chain C hanging on the smallest sprocket and the part A that substantially pushes the chain C hanging on the intermediate sprocket is as described above. , the other parts may be formed in any manner. That is, the bicycle width direction (thickness direction of the guide plate) between the above part A and the above part B
The positional relationship between the two does not matter. Therefore, in the embodiment, in order to position the above-mentioned portion A on the outside in the radial direction of the sprocket with respect to the portion B, the front portion of the lower edge 9a of the inner guide plate 9 is recessed or the portion is deleted. Although the lower edge 9a is shaped like a step when viewed from the front, conversely, a predetermined portion of the inner surface of the front portion of the inner guide plate 9 that is away from the lower edge upward may be made to bulge out relative to other portions. , this bulging portion substantially functions as a portion A that presses the chain C when changing the chain C from the intermediate sprocket s2 to the large diameter sprocket s3, and this case is also naturally included in the scope of the present invention. Also, regarding the pantograph link mechanism as a control mechanism for moving the movable member 5, the illustrated example shows a so-called low normal type, but even if a top normal type is adopted,
Of course it's good.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the bicycle front derailleur of the present invention, with Figure 1 being an overall front view, and Figure 2 showing the relationship between the inner guide plate and each sprocket or chain, as well as their functions. Figure 3 is a sectional view taken along the line -- in Figure 2, Figure 4 is a front view showing another aspect of the inner guide plate, and Figure 5 is a conventional front derailleur on which the present invention is based. FIG. 6 is a front view of the entire structure, and FIG. 6 is a view taken in the direction of the arrow in FIG. 4...Control mechanism (pantograph link mechanism),
9...Inner guide plate, 10...Outer guide plate, S...Sprocket, s1...Minimum diameter sprocket, s2...Intermediate sprocket, s3...
Maximum diameter sprocket, C...Chain.

Claims (1)

[Claims for Utility Model Registration] Used in combination with a multistage front gear comprising a smallest diameter sprocket, at least one intermediate sprocket with a larger diameter, and a largest diameter sprocket with a larger diameter, The inner guide plate and the outer guide plate are each made of a single member and are opposed to each other so as to sandwich the chain to be hung on the inner and outer sides, and the inner guide plate and the outer guide plate are moved in parallel in the inner and outer directions by a control mechanism. In the bicycle front derailleur configured, the rear lower edge of the inner guide plate is formed into an arc shape that substantially corresponds to the outer periphery of the front gear, and the chain that hangs over the smallest diameter sprocket is connected to the intermediate sprocket. Part B to press when replacing
On the other hand, when replacing the chain hanging on the intermediate sprocket with a sprocket of a larger diameter at the middle or front part of the inner guide plate, the vertical position of the part A to be pressed is determined by the part B.
A front derailleur for a bicycle, characterized in that the bicycle front derailleur is provided so as to be clearly deviated upward from an extension line of an arc forming the front derailleur.