Endless belt power transmission systems or components – Control for variable input to output speed-ratio – Including belt shiftable axially from one to another surface...
Reexamination Certificate
2000-06-07
2002-10-29
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Control for variable input to output speed-ratio
Including belt shiftable axially from one to another surface...
Reexamination Certificate
active
06471610
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a front derailleur for a bicycle, and more specifically to a front derailleur with a wire guide for changing the direction of a wire, which is employed to drive an actuating mechanism of a bicycle, therefore, reducing the friction between the wire and stopper, as well as allowing to elongate the stroke of wire.
BACKGROUND OF THE INVENTION
A bicycle is commonly used as a transportation vehicle and widely employed as a sport machine. Basically, the bicycle includes several parts, such as transmission system, brake system, frame, and so on, although these parts vary from different types of bicycles. The frame constructs the main body of a bicycle and allows other systems, such as derailleur system, transmission system and brake, to be attached thereon. The transmission system, a mechanism in combination of chain, chainwheel, freewheel, pedal, and so on, plays a role to transmit a force generated from cyclist to drive the bicycle. In the derailleur system, which includes a chain, front derailleur, rear derailleur, wire, and shift lever, the chain can be shift among sprockets of the chainwheel and freewheel by the front derailleur and rear derailleur in response to forces generated by cyclist or return spring of derailleur system. Since the sprockets of the chainwheel and freewheel have different teeth, the cyclist may adjust the chain through the front derailleur and rear derailleur to obtain a gear ratio between the sprockets of the chainwheel and freewheel, so as to ride the bicycle in a time-saving or labor-saving mode. Therefore, the derailleur system is a vital factor for the performance of bicycle.
Referring to
FIG. 1
, a front view of front derailleur is shown. The front derailleur includes a link
37
, actuating arm
36
, wire
32
, and chain guide
38
. The chain guide
38
is connected with the link
37
and actuating arm
36
, which are fixed on a seat tube
34
by a clamp
35
. The link
37
and actuating arm
36
constitute a simple four-bar linkage mechanism, in which the actuating arm
36
is driven by a tension transmitting through the wire
32
. When the cyclist push a shift lever (not shown in this figure), a tension transmitting through the wire
32
would drive the actuating arm
36
to push the chain guide
38
outwardly among the chainweel sprockets
42
,
44
and
46
, therefore, shifting the chain
40
thereon. However, because the wire
32
could only transmit a tension, the front derailleur must implant a return spring
39
to provide a return force for pulling the chain guide
38
inwardly, while the tension released.
Accordingly, the return spring
39
has to provide an strong enough return force to push the chain guide
38
inwardly back in order to overcome a great amount of tension of the chain
40
while the cyclist ride the bicycle uphill. If the return spring
39
can not effectively push the chain
40
inwardly after the tension of the wire
32
is released, it would be dangerous for the cyclist while riding a bicycle uphill. Nonetheless, the grater return force of return spring
39
brings the heavier load the cyclist needs to turn the shift lever for shifting the chain guide
38
. Besides that, the friction between the wire
32
and stopper
30
, through which the wire extending out of a flexible tube
31
that is employed to coat the wire, also contributes an extra amount to the load the cyclist needs to turn the shift lever. Therefore, how to reduce the load for pushing the shift lever as well as providing a strong enough return force of return spring turns to be an important issue for upgrading the performance of bicycle.
In addition, as for some specifications of conventional shift levers, the stroke of the wire
32
is strictly limited in a specific range. For compatible to some conventional shift levers, the stopper
30
needs to be modified along the seat tube in order to obtain a longer stroke of wire. The closer distance from the stopper
30
to the actuating arm
36
, the longer stroke of the wire
32
. Thus, the stopper
30
is suggested to be positioned as close as to the actuating arm
36
for fitting some conventional shift levers. However, changing the position of stopper
30
would affect the effective force lever of pulling the actuating arm
36
, increase the friction between the wire and stopper, and degrade the compatibility of front derailleur for conventional shift levers, therefore, preventing the front derailleur from being operated in an efficient way. In brief then, the position of stopper
30
is rigid according to conventional designs, thereby limiting the cooperation between some shift levers and front derailleurs.
SUMMARY OF THE INVENTION
An object of this invention is to provide a wire guide for straightening a wire thereby reducing the friction between the wire and stopper, which is at the end of a flexible tube for coating the wire.
Another object of this invention is to modify the stroke of wire for making sure that the front derailleur would be operated in an effective range, and suited for some conventional shift levers.
This invention discloses a novel front derailleur with a wire guide to straighten the wire relative to a stopper, which is at the end of a flexible tube for coating the wire. Since the angle between the wire and the stopper has been straightened, the friction between them would be further decreased. Therefore, the performance of bicycle is improved, due to the reduction of friction within the front derailleur system.
In addition, the position of wire guide, or stopper according to conventional designs, would affect the efficiency of front derailleur and the stroke of the wire, which contributes to the compatibility for some conventional shift levers. Since the present wire guide can be placed closer to the actuating arm than the conventional stopper does, the present front derailleur is capable to provide a longer stroke for fitting various conventional shift levers.
REFERENCES:
patent: 4452593 (1984-06-01), Coue
patent: 5649877 (1997-07-01), Patterson
patent: 5857932 (1999-01-01), Sugimoto
Chien Yu-Jen
Tseng Ching-Huan
Bucci David A.
Johnson Vicky A.
Powell Goldstein Frazer & Murphy LLP
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