JPH0236796Y2 - - Google Patents

Description

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

This invention relates to a rear derailleur for a bicycle that is configured to change gears by changing a chain to a selected sprocket of a multi-stage freewheel attached to the rear wheel of the bicycle.

[Conventional technology]

For example, bicycle rear derailleurs are manufactured by Tokko Akira.
As shown in Publication No. 42-23485, a tensioner is provided with a guide pulley at the top and a tension pulley at the bottom rotatably supported, and the tensioner is moved in parallel in the hub axis direction by a control mechanism such as a pantograph link mechanism. I'm getting used to it.
The tensioner is swingable about its upper portion with respect to the movable member of the control mechanism, and is elastically biased so that its lower portion rotates rearward. The chain is engaged with the tension pulley of the tensioner and the guide pulley in that order, and after leaving the guide pulley, the chain runs so as to be engaged with one sprocket of the freewheel. When the tensioner moves in the direction of the hub axis, the guide pulley swings the chain sideways before it hooks on the freewheel, and as a result, the chain is transferred to the sprocket next to the sprocket it was previously hooked on. If the chain is replaced with a sprocket of a different diameter, the required effective length of the chain will change, but this is because the tensioner itself is designed to elastically rotate as the lower part of the chain moves toward the rear. , automatically adjusted. In other words, the tension pulley that initially supports the chain introduced into the tensioner moves back and forth as the tensioner rotates, thereby removing slack in the chain and always applying appropriate tension to the chain. .

[Problem to be solved by the invention] By the way, in order to improve the shifting performance of the bicycle rear derailleur mentioned above, it is necessary to move the chain before it connects to the freewheel in the direction of the hub axis and change the chain directly. It is necessary that the peripheral edge of the guide pulley that performs this function and the tips of the teeth of each sprocket of the freewheel be as close as possible. If they are too far apart, an excessive amount of overshift is required, and
It is clear that the shift response becomes poor. In view of the above-mentioned circumstances, the derailleur disclosed in the above publication has a tensioner that is not parallel to the hub axis, but connects the tips of the teeth of each sprocket so that the distance of the guide pulley to each sprocket of the freewheel is constant. Although it was designed to move along a trajectory that is almost parallel to the line, even with this, there may still be dissatisfaction with the shifting performance. This occurs because even if the derailleur is the same, the mounting position of the derailleur and the number of teeth on the freewheel sprocket vary depending on the bicycle to which the derailleur is attached. That is,
Even if the freewheel type is the same, if the vertical mounting position of the derailleur itself is different,
The distance between the tip of the sprocket tooth and the circumferential edge of the guide pulley changes, and the number of teeth on the sprocket for the corresponding gear speed differs between the two types of freewheels, resulting in a change in the diameter of the tip circle of the sprocket. Even if you do so, the distance between the sprocket tooth tip and the guide pulley periphery will change in the same way as above. The distance between the guide pulley and the sprocket can be adjusted by adjusting the angle at which the derailleur itself is attached to the rear end plate of the bicycle frame, as is the case with the derailleur shown in the above publication. However, in doing so, the movement locus of the tensioner, which basically draws an arc with respect to the mounting base member, changes, so if the tensioner is located on the largest sprocket side or on the smallest sprocket side, The amount of adjustment is not constant for
On the contrary, it is difficult to find a suitable mounting angle. Therefore, the problem to be solved by the present invention is that even if the movement locus of the tensioner by a control mechanism such as a pantograph link mechanism remains fixed,
To enable the derailleur itself to completely adjust the distance between the periphery of a guide pulley of a tensioner and the tip of a tooth of a freewheel sprocket without introducing anything else.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. In other words, the present invention has a guide pulley on the top,
In a bicycle rear derailleur, the bicycle rear derailleur is equipped with a tensioner that rotatably supports tension pulleys at the bottom, and is configured such that the tensioner can be moved in parallel in the axial direction of a multi-stage freewheel by a control mechanism, which is attached to the upper part of the tensioner. The guide pulley and the tension pulley attached to the lower part have different diameters, and the support structure of the guide pulley and the tension pulley in the tensioner are such that the tension pulley is the guide pulley and the guide pulley is the guide pulley. By having the same support structure that can be replaced and attached to the tension pulley, the distance between the pulley attached to the top of the tensioner and the above multi-stage freewheel can be adjusted by replacing the guide pulley and tension pulley as appropriate. It is characterized by being configured so that it can be used.

[Functions and effects of the idea]

As mentioned above, in the present invention, the guide pulley and tension pulley have different diameters, in other words, the number of teeth, and are replaceable, so that they can be used as guide pulleys. If you use the pulley that was used as the tension pulley as the tension pulley, and the pulley that was used as the tension pulley as the guide pulley,
It is possible to increase or decrease the difference in the radius of the pulleys and the distance between the periphery of the guide pulley and the tip of the freewheel sprocket. For example, if you initially use a guide pulley with 10 teeth and a tension pulley with 12 teeth, then
If the number of teeth is 10, the outer diameter is approximately 38 mm, and if the number of teeth is 12, the outer diameter is approximately 46 mm. Therefore, by replacing the two pulleys as described above, the distance between the tip of the sprocket teeth and the periphery of the guide pulley will be approximately 46 mm. It can be increased or decreased by 4mm. Therefore, if the movement trajectory of the tensioner is relatively far from the line connecting the tips of the freewheel sprocket teeth, use a pulley with a large number of teeth as the guide pulley and a pulley with a small number of teeth as the tension pulley. If a pulley is used, and conversely, the movement trajectory of the tensioner is close to the line connecting the tips of the sprocket teeth, use a pulley with a small number of teeth as the guide pulley and a pulley with a large number of teeth as the tension pulley. You can use . Moreover, with the present invention, the distance between the periphery of the guide pulley and the tip of the sprocket can be adjusted without changing the movement trajectory of the tensioner, so even when the tensioner is located on the large-diameter sprocket side of the freewheel. Even if the guide pulley and the sprocket are located on the side of the small diameter sprocket, the amount of adjustment of the distance between the guide pulley and the sprocket is constant, and the effect of the adjustment is equally applied to each gear. From the above, in the bicycle rear derailleur of the present invention, even if the mounting position of the derailleur and the type of freewheel are different, the guide pulley of the tensioner can be adjusted to each sprocket completely without introducing any other parts. The distance can be adjusted by a certain amount, and the shift responsiveness can be improved in all ranges from low speed ranges to high speed ranges.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. A hub axle 2 that rotatably supports a multi-stage freewheel 1 and a hub or wheel (not shown) is attached to a rear end plate 4 of a bicycle frame 3, and is opened in a lower extending piece 5 of the rear end plate 4. The rear derailleur 6 is attached by fixing its base member 7 with bolts 8 using the screw holes. In the base member 7, the bases of a pair of inner and outer link members 9 and 10 extending parallel to the front are supported so as to be rotatable in the lateral direction.
A movable member 11 is rotatably attached to the tips of the link members 9 and 10, thereby forming a so-called parallelogram pantograph link mechanism 12. In the case of the illustrated example, as shown in FIG. 2, the rotation axes of the link members 9 and 10 are tilted with respect to the vertical,
When the pantograph link mechanism 12 is deformed, the movable member 11 moves within a plane inclined approximately corresponding to a line connecting the tooth tips of the sprockets s1, s2, . . . of the freewheel 1. This modification operation of the pantograph link mechanism 12 is performed by a known operating mechanism in which a speed change operating lever and the pantograph link mechanism 12 are connected by an operating cable. The movable member 11 has an upper part of a tensioner 14 rotatably supported with respect to a support shaft 13 parallel to the hub shaft 2, and a spring box 15.
A spring 16 loaded therein urges the lower part to rotate elastically rearward. The tensioner 14 spans between an outer guard plate 17 supported by the movable member 11, an inner guard plate 18 disposed inside at a certain distance from the outer guard plate 17, and the inner and outer guard plates 17 and 18 above and below. It has two upper and lower pulleys 21 and 22 rotatably supported on support shafts 19 and 20, respectively. Of these two upper and lower pulleys 21 and 22, the upper pulley 21 functions as a guide pulley and the lower pulley 22 functions as a tension pulley. The number (outer diameter) is different. In the illustrated example, the large diameter pulley 21 has 12 teeth, the small diameter pulley 22 has 10 teeth, and the difference in radius between these pulleys is approximately 4 mm. Specifically, each pulley 21, 22 is a third pulley.
As shown in the figure, threaded end portions 19b and 20b of bolts 19a and 20a as support shafts 19 and 20 passed through from the outer guard plate 17 side are screwed into female threads 23 and 23 provided at predetermined portions of the inner guard plate 18. At the same time, these bolts 19a, 20a are supported by intermediate shaft portions via bushes 24, 24. Note that an annular groove 2 is formed on the side surface of each pulley 21, 22.
5, 25 are formed, and the grooves 25, 2 are formed between these pulleys 21, 22 and the inner and outer guard plates 17, 18.
A dish-shaped dust cover 26, 2 whose periphery extends into 5
6 is interposed. Note that the bolt 19a and bush 24 that should support the guide pulley 21 are as follows:
Bolt 20a that should support tension pulley 22
In addition, the same bushing 24 is used, and by making the structure to be supported by the guide pulley 21 and the tension pulley 22 the same, as will be described later, the guide pulley 21 and the tension pulley 22 can be installed interchangeably. As is clear from the above, tensioner 14
can be disassembled by removing the upper and lower bolts 19b, 20b connecting the inner and outer guard plates 17, 18, and therefore the upper and lower pulleys 21, 22
can be replaced as shown in FIGS. 5 and 6. As shown in FIGS. 5 and 6, by replacing the upper and lower pulleys 21 and 22, the distance between the periphery of the upper pulley, that is, the pulley that functions as a guard pulley, and the sprockets s1, s2, etc. of the freewheel 1 can be increased. L can be changed by the difference in radius between the large diameter pulley and the small diameter pulley. As a result, the distance between the guide pulley 21 of the tensioner and the freewheel sprockets s1, s2, etc. is adjusted so that the shift response is optimized while keeping the movement trajectory of the tensioner 14 constant due to the deformation of the pantograph link mechanism 12. can be adjusted to Of course, the scope of the present invention is not limited to the embodiments described above. For example, in the illustrated example, the large diameter pulley has 12 teeth, the small diameter pulley has 10 teeth, and the difference in the number of teeth is 2. , the difference in the number of teeth can also be set to 1 or 3 or more. In addition, in the illustrated example, a so-called slant pantograph link mechanism is employed, in which the tensioner is configured to move along a line connecting the tips of the teeth of each freewheel sprocket, which is slightly inclined with respect to the hub axis. It goes without saying that the present invention can be similarly applied to a case where the pantograph link mechanism is configured such that the tensioner moves parallel to the hub axis. Even in this case, by replacing the upper and lower pulleys with different diameters, the distance between the guide pulley and the sprocket can be changed by a predetermined amount whether the tensioner is located on the high speed side or the low speed side. Can be done.

[Brief explanation of drawings]

Fig. 1 is an overall side view of an embodiment of the bicycle rear derailleur of the present invention, Fig. 2 is a view taken in the direction of Fig. 1, Fig. 3 is a longitudinal sectional view of the tensioner, and Figs. 4 and 5 are FIG. 3 is an explanatory diagram of the operation of the embodiment. 1... Multi-stage freewheel, 12... Control mechanism (pantograph link mechanism), 14... Tensioner, 21... Guide pulley, 22... Tension pulley.

Claims (1)

[Claims for Utility Model Registration] A tensioner is provided with a guide pulley rotatably supported at the upper part and a tension pulley at the lower part, and the tensioner is configured to be moved in parallel in the axial direction of the multi-stage freewheel by a control mechanism. In this bicycle rear derailleur, the guide pulley attached to the upper part of the tensioner and the tension pulley attached to the lower part have different diameters, and a support structure for the guide pulley in the tensioner and a support structure for the tension pulley are provided. By making the structure the same support structure that can be installed by replacing the tension pulley with a guide pulley and the guide pulley with a tension pulley, the guide pulley and tension pulley can be replaced as appropriate and installed on the top of the tensioner. 1. A rear derailleur for a bicycle, characterized in that the distance between the pulley and the multi-stage freewheel can be adjusted.