Endless belt power transmission systems or components – Control for variable input to output speed-ratio – Condition responsive
Reexamination Certificate
2000-11-21
2003-09-23
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Control for variable input to output speed-ratio
Condition responsive
C474S080000, C474S082000
Reexamination Certificate
active
06623389
ABSTRACT:
BACKGROUND OF THE INVENTION
(A) Field of the Invention
The present invention refers to a gear shift device for bicycles, of the type comprising:
at least one derailleur, having a first body destined to be attached to a bicycle frame and a second body that can be displaced with respect to the first body to cause the selective engagement of a bicycle chain on a number of sprockets, to achieve the various gears of the device,
an electric actuator to drive the displacement of the second body of the derailleur,
electronic control means for controlling said electric actuator,
manually-operated activating means, connected to said electronic control means, to cause activation of said electric actuator in order to select the required gear,
means for detecting the position of said second body of the derailleur and for indicating said position to said control means, so as to permit the automatic disabling of the electric actuator once the required position has been reached,
in which said electric actuator is directly associated with said derailleur.
A gear shift device of the kind outlined above is described and illustrated in U.S. Pat. No. 5,480,356, a patent held by the same applicant.
(B) Description of the Related Art
FIG. 1
of the attached drawings illustrates a racing bicycle, indicated as a whole by reference number
1
, comprising a frame
2
constructed, in a well-known manner, of tubular elements comprising stays
3
for supporting the rear wheel
4
. Reference number
5
indicates a fork for supporting a front wheel
6
, associated with a handlebar
70
, which is also made with a tubular structure.
In its lower part, the frame
2
carries a crankset
7
of substantially conventional type for driving the rear wheel
4
by means of a gear shift device made according to the present invention, indicated globally by the number
8
.
The gear shift device
8
essentially includes a rear assembly
9
and a front assembly
10
comprised, in a well-known manner, of a number of sprockets
11
of various diameters, co-axial with the axle A of the rear wheel
4
, and a number of crown wheels
12
, also of various diameters, co-axial with the axle B of the bicycle's crankset
7
.
The sprockets
11
and the crown wheels
12
can be engaged selectively by a chain transmission forming a closed ring
13
to achieve the different gear ratios available by means of the gear shift device
8
, by activating a rear derailleur
14
forming part of the rear assembly
9
and a front derailleur
15
belonging to the front assembly
10
.
FIG. 2
in the enclosed drawings illustrates the rear derailleur
14
made according to the solution proposed in U.S. Pat. No. 5,480,356. The rear derailleur
14
includes a first body
16
that is designed to be attached to the bicycle frame and a second body
17
connected to the first body
16
by means of a parallelogram linkage comprising two arms
18
and
19
, the ends of which are articulated at
20
,
21
and
22
,
23
to the two bodies
16
and
17
. The second body
17
includes, in a well-known manner, a rocker arm
24
that carries-the chain transmission wheels
25
and
26
.
Reference number
27
indicates an electric actuator, in the form of an electric motor combined with a reduction gear, that is directly incorporated in the derailleur
14
to drive the displacement of the second body
17
, and consequently also of the rocker arm
24
, through the various engagement positions of the chain
3
with the sprockets
11
.
FIG. 3
in the enclosed drawings illustrates the motor and reduction gear assembly
27
forming the object of the device described in U.S. Pat. No. 5,480,356. In said Figure, the body of the motor and reduction gear assembly
27
, indicated as
28
, is shown on a larger scale and in cross-section. The body
28
contains not only the motor
35
, but also an epicycloid reduction gear
29
connected to the shaft coming from the electric motor
35
. The epicycloid reduction gear
29
drives the rotation of a screw
30
. As shown in
FIG. 2
, the body
28
of the motor and reduction gear assembly is attached with an articulated coupling to the body
16
of the derailleur around an axis
22
, while the screw
30
engages a nut screw
31
, the body of which is mounted in an articulated manner around an axis
21
on the body
17
of the derailleur. As a result, the motor and gear reduction assembly lies along a diagonal of the parallelogram linkage and the turning of the motor causes a corresponding rotation of the screw
30
by the epicycloid gearing
29
, so that the nut screw
31
moves along the screw, leading to an elongation or shortening of the distance between the axes
21
and
22
of the parallelogram linkage.
As illustrated in
FIG. 3
, the body
28
of the motor and reduction gear assembly also contains a device
32
comprising an encoder, including an optical or magnetic sensor that co-operates in a well-known manner with a disc
34
carried by the screw
30
.
The electric power to the motor and reduction gear assembly
27
is provided by means of a battery
37
(
FIG. 1
) conveniently housed in one of the tubes of the bicycle frame
2
or, alternatively, in one side of the handlebar
70
, or inside the container of a microprocessor control unit
40
(only partially visible in
FIG. 1
) that may be attached, for instance, to the bicycle frame in the area of the crankset and is used to control the electric motor
35
on the basis of signals originating from two manually-operated control levers
43
and
44
(which could also be replaced by two buttons) associated, in a well-known manner, with a brake lever
41
(FIG.
1
). The microprocessor unit
40
is also connected to the encoder
32
, which detects the angular position of the screw
30
, and consequently of the rear derailleur, so as to stop the electric motor when a required transmission gear has been reached, said gear being selected by manually operating the levers
43
and
44
(which are operated to shift the chain into higher or lower gears, respectively). The connections between the aforementioned electric components are made, in the case of the above-mentioned well-known solution, by means of wires (not shown in the drawings) conveniently positioned inside the tubes of the bicycle frame
2
.
The above-mentioned earlier document describes the opportunity to use an encoder of any kind to provide the means for detecting the position of the second body of the derailleur. In the course of experience gained in the past by the applicant, an incremental encoder was used. With this type of transducer, however, any interruption in the electric power supply to the encoder made it necessary to provide for a procedure for re-calibrating the encoder by making the derailleur move to the position taken as the zero reference by the encoder. It is also important to bear in mind that there is an increasingly-felt need to increase the autonomy of the bicycle with battery-powered systems and therefore to reduce the consumption of electrical energy. For this purpose, control systems can be used that enable energy to be delivered only for the amount of time it takes to satisfy the requirement, after which the system returns to a low-consumption regime.
SUMMARY OF THE INVENTION
It is also true that, even using an incremental transducer, strategies can be adopted to keep the position value detected memorized at logic level in the control unit. However, this solution may not be sufficient to guarantee the reliability of the transducer, because while it is not being powered the position of the second body of the derailleur may undergo small variations due to the vibrations to which the bicycle is liable while in motion.
The purpose of the present invention is to achieve a gear shift device of the type outlined at the beginning of this description, in which the means for detecting the position of the movable body of the gear always guarantee a reliable and accurate indication of said position, even in the event of an interruption in the power supply, for instance.
With a view to achieving said p
Charles Marcus
Volpe and Koenig P.C.
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