JPH0310145Y2 - - Google Patents

Description

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

This invention relates to a rear derailleur for bicycles.
In detail, even if the chain is run in the opposite direction while the replacement frame with the guide pulley and tension pulley is pushed towards the large gear side of the multi-stage freewheel,
To prevent a chain from inadvertently climbing over the upper edge of an outer frame of a replacement frame and coming off.

[Conventional technology]

For example, the rear derailleur for bicycles is manufactured by Jikaisho.
As shown in Publication No. 60-28592, a base member attached to a bicycle frame, a pair of inner and outer link members whose base ends are swingably connected to the base member, and tips of these link members. A deformable pantograph link mechanism is formed by a movable member connected to the link member so as to be able to swing relative to these link members, and a guide pulley and a tension pulley are respectively rotatable in the movable member of the pantograph link mechanism. It is constructed by rotatably supporting a replacement frame supported in one direction while elastically biasing it in one direction. The above-mentioned replacement frame has a tension pulley at the bottom and a guide pulley at the top.
The chain leaving the front gear and traveling towards the rear,
First, the chain is hooked from below to the back of the tension pulley, and then to the front of the guide pulley. go. In other words, the guide pulley is located on the entrance side of the chain to the multi-stage freewheel, and when the pantograph link mechanism is deformed and the guide pulley is moved laterally,
Accordingly, the chain is swung laterally and transferred to the gear directly above the guide pulley. Normally, with this type of derailleur, when the multi-stage freewheel and chain are stopped, the chain that meshes with the freewheel will prevent the changeover frame from moving, so even if the derailleur control lever is operated, the changeover frame will not move. It is not possible to change the chain by moving the . By the way, with recent rear derailleurs, such as the one shown in Japanese Utility Model Application No. 57-170391, even when the chain is stopped and the freewheel rotation is stopped, the derailleur operation lever cannot be operated. A device that can be rotated has been proposed. In this system, the traction force applied to the operating cable by the operating lever is stored in the energy storing means in the derailleur, and when the bicycle starts running, the freewheel rotates, and the chain starts running, the changing frame is replaced. This is achieved by releasing the stored force stored in the storage means when the external force that prevents the movement of is released, and using this force to move the replacement frame. Mechanisms for achieving such functionality are commonly referred to as saver mechanisms.

[Problem that the invention attempts to solve]

By the way, it has been pointed out that the following problem arises in the bicycle rear derailleur including the above-mentioned saver mechanism. In other words, when the bicycle is stopped, elasticity is stored in the energy storage means in the derailleur by operating the lever,
In other words, if the chain is run in the opposite direction while the reversing frame is given elasticity to move toward the large gear, the chain will tilt laterally from the freewheel to the guide pulley and the chain will be reassembled. There is a possibility that it may climb over the upper edge of the outer frame of the frame and come off the replacement frame. This type of chain reversal occurs when the pedals of a parked bicycle are rotated in the opposite direction to a convenient position for placing one's feet on the bicycle. This is because the chain is attached to a freewheel that only allows reverse rotation relative to the hub, so the pedals can be freely reversed. As mentioned above, the chain that has come off the top of the replacement frame to the outside may become caught between the replacement frame and the pantograph link mechanism and become locked. In this case, when the pedal is depressed, the pedal force acts to bend the derailleur backwards, resulting in damage to the derailleur mounting portion or the derailleur itself. The simplest way to prevent the chain from coming off from the chain tensioning frame is to strengthen the elasticity imparted to the chain tensioning frame in the chain tension removal direction at the attachment point of the chain to the pantograph link mechanism. It is possible to increase the chain tension under normal conditions, but if the chain tension is increased too much, the derailleur's shifting performance, especially the performance of changing from a small gear to a large gear, will be extremely deteriorated. Furthermore, in the above-mentioned Japanese Utility Model Application Publication No. 60-28592, a suppressing part for suppressing the separation of the chain from the outer frame is provided in the outlet passage of the chain from the guide pulley in the outer frame of the replacement frame. Accordingly, a device has been proposed that solves the above problem.
Specifically, the suppressing part is provided with an L-shaped notch in the outlet passage portion, and when the chain tries to come off from the outer frame, the chain is caught in this notch, and the chain climbs over the outer frame. I'm trying not to be able to do that. However, providing the L-shaped notch at the position described above has the disadvantage that the speed change efficiency of the derailleur deteriorates. That is, the exit portion of the chain from the guide pulley is precisely the portion that presses the chain inward when the replacement frame moves to the large gear side of the freewheel. The pressure acting part that pushes the chain when the transfer frame moves to the large gear side should be installed as close to the freewheel as possible, that is, at a high position from the support center of the guide pulley. This is preferable in terms of improving responsiveness. Furthermore, the outlet passage portion of the chain in which the notch should be provided is integral with the movable member of the pantograph link mechanism as an outer frame, and is separate from the swinging inner frame, as shown in the above-mentioned publication. If not used, it cannot be unambiguously specified, and the outer frame and inner frame swing together relative to the movable member of the pantograph link mechanism, and the exit passage portion changes depending on the swing angle of the replacement frame. It cannot be practically applied to a general rear derailleur. This idea was devised under the above circumstances, and is a general-purpose replacement frame that has an outer frame and an inner frame that swing together relative to the movable member of the pantograph link mechanism. It can be applied to a derailleur and does not deteriorate the shifting performance of the derailleur, and also prevents the chain from locking when the chain runs in reverse, and prevents the shifting force from acting on the replacement frame towards the large gear side. To provide a rear derailleur for a bicycle which prevents a chain from completely coming off an outer frame of a replacement frame even if the chain is run in the opposite direction while the bicycle is in use.

[Means to solve the problem]

In order to solve the above problem, this invention takes the following technical measures. That is, in a bicycle rear derailleur configured to move a replacement frame having a guide pulley and a tension pulley by a control mechanism such as a pantograph link mechanism, the arcuate upper edge of the outer frame of the replacement frame is , a guide part that bulges in a step-up shape in side view is provided in front of the chain pressing part that presses the vicinity of the outlet of the chain applied to the guide pulley to the multi-stage freewheel, and this guide part causes the arcuate upper edge to It is characterized by a structure in which the chain that rides on the part and runs in the opposite direction is dropped inside.

[Effect]

When the derailleur operation lever is operated or the saver mechanism is activated and the transfer frame is about to move toward the freewheel's large gear, the chain is pulled diagonally upward and outward when viewed from the transfer frame. Become. More specifically, the chain between the guide pulley and the freewheel is inclined so as to extend beyond the outer frame of the replacement frame when viewed from the guide pulley. When the chain runs in the opposite direction in this state, the chain runs onto the upper edge of the outer frame from the side closest to the freewheel. In a normal derailleur, when the chain is further run in the reverse direction, the chain slides forward while riding on the upper edge of the outer frame as described above, and eventually comes off the upper edge of the outer frame completely. However, in the present invention, as described above, the chain pushing action part that actually pushes the chain on the upper edge of the outer frame on which the reverse running chain rides, that is, the chain pushing action that pushes the vicinity of the outlet of the chain hanging on the guide pulley to the multistage freewheel. Since a guide part is formed in front of the part that bulges out in a stepped manner when viewed from the side, the chain that slides on the upper edge of the outer frame as described above is located at this raised part. It is guided to slide inward and then engages the guide pulley.

【effect】

As mentioned above, in the present invention, the reverse-running chain slides on the arcuate upper edge of the outer frame, and as it slides forward, the stepped guide section causes the chain to fall inside where the guide pulley is located. As a result, the chain running in the opposite direction will not be locked, as would be the case when the chain running in the opposite direction is hooked to the notch to forcibly prevent it from coming off to the outside, and the pantograph link mechanism No excessive force is applied to the derailleur body. In addition, the present invention is based on the premise that the chain running in reverse is to be slid on the upper edge of the outer frame, and the stepped guide portion is formed forward of the chain pressing portion. However, it does not reduce the chain pressing function of the outer frame of the replacement frame when moving to the large diameter gear side.
There is no negative effect on the shifting performance of the rear derailleur. Moreover, it can be applied very easily to a general type of replacement frame in which the outer frame swings together with the inner frame.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is an overall side view of an embodiment of a bicycle rear derailleur 1 of the present invention. This rear derailleur 1 has one end attached to the bicycle frame.
a pantograph link mechanism 2 as a control mechanism;
The pantograph link mechanism 2 includes a replacement frame 4 attached to the movable member 3 of the pantograph link mechanism 2. The pantograph link mechanism 2 includes a base member 5 attached to a bicycle frame, a pair of parallel link members 6 and 7 whose base ends are rotatably supported by the base member 5, and these link members 6,
The movable member 3 is connected to the link members 6 and 7 so as to be relatively rotatable at the distal end of the link member 7 . Pins 8, 9, 10, 11 for connecting both ends of these link members 6, 7 and the base member 5 and movable member 3 so as to be relatively rotatable form the vertices of a parallelogram, and therefore When the pantograph link mechanism 2 is deformed so as to rotate each link member 6, 7 with respect to the base member 5, the movable member 3 is moved substantially parallel to the hub axis direction. In the illustrated example, each of the pins 8, 9, 10, and 11 is tilted vertically so that the upper part thereof is tilted toward the bicycle, and the movable member 3 is moved in parallel within a plane that is tilted by a predetermined amount with respect to the hub axis. I have to. This is to allow the guide pulley 12 of the replacement frame 4 to move while maintaining a substantially constant distance from each gear G1, G2, . . . of the multi-stage freewheel F. In addition,
A return spring (not shown) is incorporated inside the pantograph link mechanism 2, and this urges the pantograph link mechanism 2 so that the movable member 3 always moves in one direction, that is, toward the top side.
Furthermore, an actuating arm 13 is attached within the pantograph link mechanism 2 and is always biased in one direction by a storage spring. The other end of the operating cable W, which consists of an outer cable w1 and an inner cable w2, one end of which is connected to the derailleur operating lever, connects the outer cable w1 to an outer receiver 14 formed in an appropriate portion of the base member 5, and connects the inner cable w2 to the outer cable w1. They are connected to the pantograph link mechanism 2 by being fixed to the actuating arms 13, respectively. When the inner cable w2 is normally pulled, the pantograph link mechanism 2 deforms against the return spring, and the movable member 3 moves to the low side, that is, to the large diameter gear side of the freewheel. On the other hand, when the inner cable w2 is pulled when the bicycle is stopped, the pantograph link mechanism 2 itself cannot be deformed, but the operating arm 13 rotates while accumulating the energy storage spring. Then, when the bicycle starts moving and the pantograph link mechanism 2 becomes deformable, the pantograph link mechanism 2 is deformed by the force of the energy storage spring, and the movable member 3 moves to the large diameter side of the freewheel. The replacement frame 4 has an outer frame 15 and an inner frame 1.
6, and a guide pulley 12 and a tension pulley 17 rotatably supported between the inner and outer frames 15 and 16. And this replacement frame 4 is
A support shaft protruding from the outside of the outer frame 15 (not shown)
is rotatably housed and held in the movable member 3, making it rotatable. A spring (not shown) housed in a spring box 18 formed in the movable member 3 always elastically biases the movable member 3 in the clockwise direction in FIG. 1 about the support shaft. The upper part of the outer frame 15, that is, the front part of the upper edge part 19 of the guide pulley support part has a smooth, almost arcuate curved shape, and its inner surface is such that the replacement frame 4 can be used as a freewheel. It functions as a pressing part that presses the side surface of the chain CH when moving from the small diameter gear side to the large diameter gear side. This pressing area is a predetermined range in the front-rear direction on the upper edge 19, and this range includes the amount of slack removed from the chain CH by the rotation of the replacement frame 4 about its rotation axis, and It changes depending on the position of the freewheel of the replacement frame 4 in the width direction. That is, when the chain CH is engaged with the smallest diameter gear of both the front gear and the freewheel, the replacement frame 4 rotates largely clockwise around the support shaft in FIG. 1 to take up the slack in the chain. Conversely, when the chain is engaged with the largest diameter gear of both the front gear and the freewheel, the exchange frame 4 is supported as shown in FIG. 1 by the tension pulley 17 being pulled forward. Rotates significantly counterclockwise around the axis. Therefore, depending on how the replacement frame 4 rotates around the support shaft, the outer frame 1
The part that substantially presses the chain in 5 changes back and forth. In the present invention, the arc-shaped upper edge of the outer frame 15 bulges further forward from the above-mentioned substantial pressing operation part in a step-up shape in side view as shown in FIGS. 1 and 3. A guide portion 20 is formed.
If a relatively large chamfer 21 is formed on the inner surface of the stepped portion 20' of the guide portion 20, as shown in FIG. 4, the dropping effect of the chain CH will become more pronounced. In addition, this guide section 2
In order to enhance the effect of dropping the chain CH of 0, as shown in FIG.
It is best to bend 0' outward. Next, the operation of the present invention will be specifically explained based on FIGS. 2, 3, and 4. It is now assumed that the replacement frame 4 is about to move to the large-diameter gear side of the freewheel F (toward the rear in FIGS. 1 and 3, and to the right in FIG. 2). At this time, the chain between the guide pulley 12 and the freewheel
CH is the outer frame 15 as shown by the imaginary line in FIG.
It is sloped to go beyond. In this state, if you reverse the pedal and run the chain CH in the opposite direction,
As shown in FIG. 3, the chain CH rides on the rear part of the upper edge of the outer frame 15, and then slides forward on the upper edge 19. However, in the present invention, the stepped guide part 20 is formed in the front part of the upper edge part 19, so the chain CH sliding on the upper edge part 19 as described above can further climb over the guide part 20. Therefore, it is impossible for the guide member 20 to completely come off the outside of the outer frame 15, but to be dropped into the inside of the outer frame 15 by the guide portion 20. Of course, the scope of the present invention is not limited to the embodiments described above. The pantograph link mechanism as a control mechanism is not limited to the one shown in the drawings, but may be any mechanism that currently exists or will be realized in the future for moving the reversible frame laterally. Moreover, the format and overall shape of the outer frame and inner frame of the replacement frame 4 are not limited. That is, in the illustrated example, the outer frame is of a type in which a portion covering the guide pulley and a portion covering the tension pulley are integrally formed, and the outer frame as a whole swings relative to the movable member 3 of the pantograph link mechanism 2. However, as shown in the previously introduced Utility Model Application No. 60-28592, an outer frame that is integral with a movable member and is formed so as not to swing relative to the movable member has exactly the same effect. The present invention can be applied. Furthermore, the present invention does not ask whether or not a saver mechanism is incorporated in the pantograph link mechanism.

[Brief explanation of the drawing]

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 side view illustrating the operation, and Fig. 4 is a - of Fig. 3. FIG. 5 is an enlarged cross-sectional view taken along the line, and is a view corresponding to the V direction arrow view of FIG. 3 of another embodiment of the main part of the present invention. 1... Bicycle rear derailleur, 2... Control mechanism (pantograph link mechanism), 4... Interchangeable frame, 12... Guide pulley, 15... Outer frame, 1
7...Tension pulley, 19...(outer frame)
Upper edge part, 20...guiding part, 20'... raised part.

Claims (1)

[Scope of Claim for Utility Model Registration] In a bicycle rear derailleur configured to move an interchangeable frame having a guide pulley and a tension pulley by a control mechanism such as a pantograph link mechanism, A guide part that bulges out in a step-up manner when viewed from the side is provided in front of the chain pressing action part that presses the vicinity of the outlet of the chain applied to the guide pulley to the multi-stage freewheel at the arcuate upper edge. A rear derailleur for a bicycle, characterized in that the chain that rides on the arcuate upper edge and runs in the opposite direction is dropped inside.