U.S. patent application number 11/754343 was filed with the patent office on 2007-10-04 for method and apparatus for shifting a bicycle transmission.
This patent application is currently assigned to SHIMANO, INC.. Invention is credited to TADASHI ICHIDA.
Application Number | 20070232425 11/754343 |
Document ID | / |
Family ID | 21695452 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070232425 |
Kind Code |
A1 |
ICHIDA; TADASHI |
October 4, 2007 |
METHOD AND APPARATUS FOR SHIFTING A BICYCLE TRANSMISSION
Abstract
A control mechanism for controlling a bicycle transmission to
set a speed stage of a bicycle comprises a shift command
communication path for communicating electronic shift commands to
select a speed stage of the bicycle, a transmission command
communication path for communicating information for controlling
the operation of the bicycle transmission, and a transmission
control unit operatively coupled to the shift command communication
path and to the transmission command communication path for
receiving the shift commands and for generating the information for
controlling the operation of the bicycle transmission. When the
transmission control unit receives at least one shift command
requesting a shift through N speed stages to a destination speed
stage, where N is an integer greater than one, the transmission
control unit generates information for causing the bicycle
transmission to move to the destination speed stage.
Inventors: |
ICHIDA; TADASHI; (Sakai
City, JP) |
Correspondence
Address: |
DELAND LAW OFFICE
P.O. BOX 69
KLAMATH RIVER
CA
96050-0069
US
|
Assignee: |
SHIMANO, INC.
3-77 Oimatsu-cho
Osaka
JP
590-8577
|
Family ID: |
21695452 |
Appl. No.: |
11/754343 |
Filed: |
May 28, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10001324 |
Nov 23, 2001 |
|
|
|
11754343 |
May 28, 2007 |
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Current U.S.
Class: |
474/70 ;
474/69 |
Current CPC
Class: |
B62M 25/08 20130101;
B62M 25/045 20130101 |
Class at
Publication: |
474/070 ;
474/069 |
International
Class: |
F16H 61/00 20060101
F16H061/00; F16H 59/36 20060101 F16H059/36 |
Claims
1. An apparatus for controlling a bicycle transmission to set a
speed stage of a bicycle, comprising: a shift command communication
path for communicating electronic shift commands to select a speed
stage of the bicycle; a transmission command communication path for
communicating information for controlling the operation of the
bicycle transmission; a transmission control unit operatively
coupled to the shift command communication path and to the
transmission command communication path for receiving the shift
commands and for generating the information for controlling the
operation of the bicycle transmission; wherein, when the
transmission control unit receives at least one shift command
requesting a shift through N speed stages to a destination speed
stage, where N is an integer greater than one, the transmission
control unit generates information for causing the bicycle
transmission to move to the destination speed stage; and wherein
the shift command requesting a shift through N speed stages
comprises a command signal that occurs for a time interval greater
than a prescribed value.
2. The apparatus according to claim 1 further comprising a
manually-operated shift control unit operatively coupled to the
shift command communication path.
3. The apparatus according to claim 2 further comprising: a speed
sensor operatively coupled to a speed communication path; and an
automatic shift control unit operatively coupled to the speed
communication path and to the shift command communication path for
automatically generating shift commands based on information
received from the speed sensor.
4. The apparatus according to claim 2 further comprising: a cadence
sensor operatively coupled to a cadence communication path; and an
automatic shift control unit operatively coupled to the cadence
communication path and to the shift command communication path for
automatically generating shift commands based on information
received from the cadence sensor.
5. The apparatus according to claim 1 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
6. An apparatus for controlling a bicycle transmission to set a
speed stage of a bicycle, comprising: a shift command communication
path for communicating electronic shift commands to select a speed
stage of the bicycle; a transmission command communication path for
communicating information for controlling the operation of the
bicycle transmission; a transmission control unit operatively
coupled to the shift command communication path and to the
transmission command communication path for receiving the shift
commands and for generating the information for controlling the
operation of the bicycle transmission; wherein, when the
transmission control unit receives at least one shift command
requesting a shift through N speed stages to a destination speed
stage, where N is an integer greater than one, the transmission
control unit generates information for causing the bicycle
transmission to move to the destination speed stage; and wherein
the shift command requesting a shift through N speed stages
comprises a first command signal and a second command signal,
wherein the first command signal and the second command signal
occur simultaneously.
7. The apparatus according to claim 6 wherein the first command
signal occurs prior to the second command signal.
8. The apparatus according to claim 6 further comprising a
manually-operated shift control unit operatively coupled to the
shift command communication path.
9. The apparatus according to claim 8 further comprising: a speed
sensor operatively coupled to a speed communication path; and an
automatic shift control unit operatively coupled to the speed
communication path and to the shift command communication path for
automatically generating shift commands based on information
received from the speed sensor.
10. The apparatus according to claim 8 further comprising: a
cadence sensor operatively coupled to a cadence communication path;
and an automatic shift control unit operatively coupled to the
cadence communication path and to the shift command communication
path for automatically generating shift commands based on
information received from the cadence sensor.
11. The apparatus according to claim 6 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
12. An apparatus for controlling a bicycle transmission to set a
speed stage of a bicycle, comprising: a shift command communication
path for communicating electronic shift commands to select a speed
stage of the bicycle; a transmission command communication path for
communicating information for controlling the operation of the
bicycle transmission; a transmission control unit operatively
coupled to the shift command communication path and to the
transmission command communication path for receiving the shift
commands and for generating the information for controlling the
operation of the bicycle transmission; wherein, when the
transmission control unit receives at least one shift command
requesting a shift through N speed stages to a destination speed
stage, where N is an integer greater than one, the transmission
control unit generates information for causing the bicycle
transmission to move to the destination speed stage; and wherein
the shift command requesting a shift through N speed stages
comprises a first command signal and a second command signal,
wherein the first command signal and the second command signal
occur within a prescribed time interval.
13. The apparatus according to claim 12 wherein the occurrences of
the first command signal and the second command signal are not
simultaneous.
14. The apparatus according to claim 12 further comprising a
manually-operated shift control unit operatively coupled to the
shift command communication path.
15. The apparatus according to claim 14 further comprising: a speed
sensor operatively coupled to a speed communication path; and an
automatic shift control unit operatively coupled to the speed
communication path and to the shift command communication path for
automatically generating shift commands based on information
received from the speed sensor.
16. The apparatus according to claim 14 further comprising: a
cadence sensor operatively coupled to a cadence communication path;
and an automatic shift control unit operatively coupled to the
cadence communication path and to the shift command communication
path for automatically generating shift commands based on
information received from the cadence sensor.
17. The apparatus according to claim 12 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
18. A method for controlling a bicycle transmission to set a speed
stage of a bicycle, comprising the steps of: receiving, by a
transmission control unit, at least one electronic shift command
requesting a shift through N speed stages to a requested
destination speed stage, wherein N is an integer greater than one;
wherein the shift command requesting a shift through N speed stages
comprises a command signal that occurs for a time interval greater
than a prescribed value; and generating, by the transmission
control unit, information for causing the bicycle transmission to
move to the destination speed stage.
19. The apparatus according to claim 18 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
20. A method for controlling a bicycle transmission to set a speed
stage of a bicycle, comprising the steps of: receiving, by a
transmission control unit, at least one electronic shift command
requesting a shift through N speed stages to a requested
destination speed stage, wherein N is an integer greater than one;
wherein the shift command requesting a shift through N speed stages
comprises a first command signal and a second command signal,
wherein the first command signal and the second command signal
occur simultaneously; and generating, by the transmission control
unit, information for causing the bicycle transmission to move to
the destination speed stage.
21. The apparatus according to claim 20 wherein the first command
signal occurs prior to the second command signal.
22. The apparatus according to claim 20 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
23. A method for controlling a bicycle transmission to set a speed
stage of a bicycle, comprising the steps of: receiving, by a
transmission control unit, at least one electronic shift command
requesting a shift through N speed stages to a requested
destination speed stage, wherein N is an integer greater than one;
wherein the shift command requesting a shift through N speed stages
comprises a first command signal and a second command signal,
wherein the first command signal and the second command signal
occur within a prescribed time interval; and generating, by the
transmission control unit, information for causing the bicycle
transmission to move to the destination speed stage.
24. The apparatus according to claim 23 wherein the occurrences of
the first command signal and the second command signal are not
simultaneous.
25. The apparatus according to claim 23 wherein the bicycle
transmission comprises a first transmission and a second
transmission, and wherein the transmission control unit generates
information for causing at least one of the first transmission or
the second transmission to move so that the first transmission and
the second transmission are in a combined position to produce the
destination speed stage.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of copending application Ser.
No. 10/001,324, filed Nov. 23, 2001.
BACKGROUND OF THE INVENTION
[0002] The present invention is directed to bicycle control devices
and, more particularly, to a method and apparatus for shifting a
bicycle transmission.
[0003] Electrically controlled bicycles usually include a front
transmission associated with the front pedal assembly, a rear
transmission associated with the rear wheel, a motor for each
transmission, a control unit for controlling each motor, and a
shift control device such as a lever or switch that provides
electrical shift command signals to the control unit. The control
unit operates the motors for each transmission based on the
electrical signals received from the shift control device. In known
electrically controlled bicycles, the transmission increases or
decreases only one speed stage or gear for each shift command
received from the shift control device, and the front or rear
transmission operates at least once for each shift command. This
can substantially delay the speed change operation and create
considerable mechanical noise and wear on the components if the
rider wants to shift multiple speed stages at one time.
SUMMARY OF THE INVENTION
[0004] The present invention is directed to a method and apparatus
for shifting a bicycle transmission. In one embodiment, a control
mechanism for controlling a bicycle transmission to set a speed
stage of a bicycle comprises a shift command communication path for
communicating electronic shift commands to select a speed stage of
the bicycle, a transmission command communication path for
communicating information for controlling the operation of the
bicycle transmission, and a transmission control unit operatively
coupled to the shift command communication path and to the
transmission command communication path for receiving the shift
commands and for generating the information for controlling the
operation of the bicycle transmission. When the transmission
control unit receives at least one shift command requesting a shift
through N speed stages to a destination speed stage, where N is an
integer greater than one, the transmission control unit generates
information for causing the bicycle transmission to move to the
destination speed stage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a side view of a bicycle that includes a
particular embodiment of an apparatus according to the present
invention for shifting a bicycle transmission;
[0006] FIG. 2 is a block diagram of a particular embodiment of the
apparatus according to the present invention for shifting a bicycle
transmission;
[0007] FIG. 3A is a timing diagram illustrating a possible
electrical shift command signal received by the control unit shown
in FIG. 2;
[0008] FIG. 3B is a timing diagram illustrating another possible
electrical shift command signal received by the control unit shown
in FIG. 2;
[0009] FIG. 3C is a timing diagram illustrating another possible
electrical shift command signal received by the control unit shown
in FIG. 2;
[0010] FIG. 3D is a timing diagram illustrating a possible
composite electrical shift command signal received by the control
unit shown in FIG. 2; and
[0011] FIG. 3E is a timing diagram illustrating another possible
composite electrical shift command signal received by the control
unit shown in FIG. 2.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0012] FIG. 1 is a side view of a bicycle 10 that incorporates a
particular embodiment of an apparatus according to the invention
for shifting a bicycle transmission. Bicycle 10 may be any type of
bicycle, and in this embodiment bicycle 10 includes a typical frame
18 comprising a top tube 22, a head tube 24, a down tube 26
extending downwardly from head tube 24, a seat tube 30 supporting a
seat 32 and extending downwardly from top tube 22, a bottom bracket
(not shown) disposed at the junction of down tube 26 and seat tube
30, a pair of seatstays 34 extending rearwardly and downwardly from
top tube 22, and a pair of chainstays 38 extending rearwardly from
the bottom bracket. A fork 42 is rotatably supported within head
tube 24, and a front wheel 46 is rotatably supported to the lower
end of fork 42. Handlebars 50 control the rotational direction of
fork 42 and front wheel 46 in a well-known manner. A rear wheel 54
having a plurality of coaxially mounted rear (freewheel) sprockets
56 is rotatably supported at the junction of seatstays 34 and
chainstays 38, and a pedal assembly 58 supporting a plurality of
front (chainwheel) sprockets 62 is rotatably supported within the
bottom bracket. Typically, two or three front sprockets 62 rotate
coaxially and integrally with pedal assembly 58. A chain 66 engages
one of the plurality of front sprockets 62 and one of the plurality
of rear sprockets 56. A front derailleur 70 moves chain 66 from one
front sprocket 62 to another, and a rear derailleur 74 moves chain
66 from one rear sprocket 56 to another. These operations are well
known.
[0013] In this embodiment, front derailleur 70 is controlled by
pulling and releasing a conventional Bowden-type control cable 78
coupled to a front derailleur motor 82 (FIG. 2) disposed in a motor
assembly 84, and rear derailleur 74 is controlled by pulling and
releasing a Bowden-type control cable 86 coupled to a rear
derailleur motor 88 disposed in motor assembly 84. Of course, in
some embodiments a single motor may be coupled to separate cable
pulling structures through clutches or otherwise to perform the
same function, and such also could be deemed distinct motors. A
front derailleur position sensor 87 and a rear derailleur position
sensor 88 are provided for sensing the operational positions of the
front and rear derailleurs 70 and 74, respectively. These position
sensors provide signals that, in turn, determine which front
sprocket 62 and rear sprocket 56 is currently engaged by chain 66.
Such position sensors may comprise, for example, known
potentiometers for sensing the positions of the output shafts of
front derailleur motor 82 and rear derailleur motor 88, but there
are many other known structures that can perform these functions. A
speed sensor 91 is mounted to fork 42 for receiving signals from a
magnet 89 mounted to front wheel 46 for sensing the speed of the
bicycle in a well-known manner, and a cadence sensor 92 is mounted
to pedal assembly 58 for receiving signals from a magnet 93 mounted
to one of the chainstays 38 for sensing the pedal cadence in a well
known manner.
[0014] A transmission control unit 90 is operatively coupled to
motor assembly 84 through a transmission command communication path
94 and to position sensors 87 and 88 through a transmission
position communication path 96 for generating transmission command
(TC) signals for controlling the operation of motor assembly 84 in
accordance with the information from position sensors 87 and 88. A
manually operated shift command unit 98, comprising a shift-up
switch 98A and a shift-down switch 98B, is operatively coupled to
transmission control unit 90 through a shift command communication
path 102 for communicating electrical shift commands (described in
more detail below) to transmission control unit 90. Furthermore, an
automatic shift command unit 103 is operatively coupled to
transmission control unit 90 through shift command communication
path 102, to position sensors 87 and 88 through transmission
position communication path 96, to speed sensor 91 through a speed
communication path 105, and to cadence sensor 92 through a cadence
communication path 106 for communicating electrical shift commands
to transmission control unit 90 in accordance with signals received
from position sensors 87 and 88, speed sensor 91 and/or cadence
sensor 92. Such shift commands may comprise the shift commands
described below for shift command unit 98, or they may comprise
digital messages. Automatic shift command unit 103 includes a
parameter memory 107 for storing wheel circumference, cadence
tables, speed tables and/or acceleration tables for generating
shift commands based on cadence, speed and/or acceleration in
accordance with known programming techniques. Parameter memory 107
may be a hardware table memory, a software table memory, or some
other structure that provides the same information. Other inputs
110 may be operatively coupled to automatic shift command unit 103
through a communication path 112 for communicating other
information such as from a heart rate sensor, a slope sensor, a
pedal or other torque sensor, etc. Parameter memory 107 and the
programming of automatic shift command unit 103 may be configured
accordingly to generate shift commands in accordance with these
other inputs in any combination. Of course, in some embodiments
only manually operated shift command unit 98 may be provided, and
in other embodiments only automatic shift command unit 103 may be
provided. In this embodiment, communication paths 94, 96, 102, 105
and 106 have the form of electrical wires, but in other embodiments
such communication paths may comprise fiber optic devices, wireless
communication paths, or some other mechanism.
[0015] According to the present invention, when the transmission
control unit 90 receives at least one shift command requesting a
shift through N speed stages to a destination speed stage, wherein
N is an integer greater than one, transmission control unit 90
generates TC signals (digital or analog) for causing front
derailleur 70 and rear derailleur 74 in combination to move a total
of M times to reach the destination speed stage, wherein M is an
integer less than N. To accomplish this, transmission control unit
90 comprises a table memory 110 for storing a table containing the
information for controlling the operation of front derailleur 70
and rear derailleur 74. Table memory 110 may be a hardware table
memory, a software table memory, or some other structure that
provides the same information. The content of table memory 110
depends upon the configuration of the bicycle. Three examples will
be provided below, and other configurations will be readily
apparent to one of ordinary skill in the art.
[0016] FIGS. 3A-3E are timing diagrams indicating various
embodiments of shift commands generated by shift control unit 98
and the timing of TC signals generated by transmission control unit
90. In each diagram, the shift command signals are low active. FIG.
3A illustrates a situation wherein a shift command signal is
generated by shift control device 98 for a time interval P that is
less than a predetermined time interval X. In this embodiment, such
a shift command signal is assumed to be a spurious signal, and no
operation is performed. Of course, in other embodiments such a
shift command signal could perform some kind of function. FIG. 3B
illustrates a situation wherein a shift command signal is generated
by shift control device 98 for a time interval Q that is greater
than time interval X. In this embodiment, such a shift command
signal requests a shift by one speed stage, and the TC signal is
generated accordingly. FIG. 3C illustrates a situation wherein a
shift command signal is generated by shift control device 98 for a
time interval R that is greater than time interval X and also
greater than a time interval Y, wherein, for the purposes of
measurement, time interval Y begins at the same instant as time
interval X but is greater than time interval X. In this embodiment,
such a shift command signal requests a shift by two speed stages,
and the TC signal is generated accordingly.
[0017] FIG. 3D illustrates a situation wherein a composite shift
command signal appearing on two channels is generated by shift
control device 98. In this example, the shift command signal
appearing on channel 1 is generated for a time interval S that is
greater than time interval X. A shift command signal is generated
on channel 2 prior to the expiration of time interval Y. In this
embodiment, such a composite shift command signal requests a shift
by two speed stages, and the TC signal is generated accordingly.
Such a composite signal could be generated by two separately
operated switches, but in most cases it would be more convenient to
generate such signals by a plunger with an electrical contact which
successively and cumulatively contacts two other electrical
contacts. Such a switch also could be used to generate the signal
shown in FIGS. 3A-3C by depressing the plunger only enough to
activate one of the two other electrical contacts. Of course, many
ways of generating such signals could be devised. FIG. 3E
illustrates a situation wherein sequential shift command signals
are generated by shift control device 98. In this example, two
sequential shift command signals are generated within a time
interval T of each other. Such an action is similar to
double-clicking a computer mouse. In this embodiment, such
sequential shift command signals request a shift by two speed
stages, and the TC signal is generated accordingly. Each shift-up
switch 98A and shift-down switch 98B may use any of the techniques
illustrated in FIGS. 3A-3E to suit the application.
[0018] Automatic shift command unit 103 may generate the signals
illustrated in FIGS. 3B-3E for the same purposes described for
them, or it may generate digital messages. Digital messages would
be particularly useful to request a shift through more than two
speed stages, although manual shift command unit 98 could be
configured to provide signals for that purpose as well. The signals
generated by automatic shift command unit 103 representing shifts
through multiple speed stages could be generated based on cadence,
speed, acceleration, or some other criteria.
[0019] Table 1 illustrates a bicycle with two front sprockets 62
and eight rear sprockets 56, and Table 2 illustrates the shift
commands and TC signals for operating front derailleur 70 and rear
derailleur 74 for this configuration. Transmission control unit 90
is programmed, whether through hardwired logic, software or
otherwise to generate the appropriate TC signals on communication
path 94 in response to the indicated shift command. TABLE-US-00001
TABLE 1 Rear Sprocket Teeth 11 13 15 17 21 25 29 33 Front 46 4.18
3.54 3.07 2.71 2.19 1.84 1.59 1.39 Sproc- 34 3.09 2.62 2.27 2.00
1.62 1.36 1.17 1.03 ket
[0020] TABLE-US-00002 TABLE 2 Signal Recongnized By Control Unit
Present Gear Position Two Steps Two Steps One Step Front Rear Up
One Step Up Down Down 46 11 Alarm Alarm front - 1 rear - 1 46 13
rear + 1 rear + 1 front - 1 rear - 1 46 15 rear + 2 rear + 1 front
- 1 rear - 1 46 17 rear + 2 rear + 1 front - 1 rear - 1 46 21 rear
+ 2 rear + 1 front - 1 rear - 1 46 25 rear + 2 rear + 1 front - 1
rear - 1 46 29 rear + 2 rear + 1 front - 1 rear - 1 46 33 rear + 2
rear + 1 front - 1 front - 1 rear + 1 34 11 front + 1 front + 1,
rear - 2 rear - 1 rear - 1 34 13 front + 1 rear + 1 rear - 2 rear -
1 34 15 front + 1 rear + 1 rear - 2 rear - 1 34 17 front + 1 rear +
1 rear - 2 rear - 1 34 21 front + 1 rear + 1 rear - 2 rear - 1 34
25 front + 1 rear + 1 rear - 2 rear - 1 34 29 front + 1 rear + 1
rear - 1 rear - 1 34 33 front + 1 rear + 1 Alarm Alarm
[0021] Table 3 illustrates a bicycle with three front sprockets 62
and eight rear sprockets 56, and Table 4 illustrates the shift
commands and TC signals for operating front derailleur 70 and rear
derailleur 74 for this configuration. TABLE-US-00003 TABLE 3 Rear
Sprocket Teeth 11 13 15 17 21 25 29 33 Front 46 4.18 3.54 3.07 2.71
2.19 1.84 1.59 1.39 Sproc- 34 3.09 2.62 2.27 2.00 1.62 1.36 1.17
1.03 ket 24 2.18 1.85 1.60 1.41 1.14 0.96 0.83 0.73
[0022] TABLE-US-00004 TABLE 4 Signal Recognized By Computer Present
Gear Position Two Steps Two Steps One Step Front Rear Up One Step
Up Down Down 46 11 Alarm Alarm front - 1 rear - 1 46 13 rear + 1
rear + 1 front - 1 rear - 1 46 15 rear + 2 rear + 1 front - 1 rear
- 1 46 17 rear + 2 rear + 1 front - 1 rear - 1 46 21 rear + 2 rear
+ 1 front - 1 rear - 1 46 25 rear + 2 rear + 1 front - 1 rear - 1
46 29 rear + 2 rear + 1 front - 1 rear - 1 46 33 rear + 2 rear + 1
front - 1 front - 1 rear + 1 34 11 front + 1 front + 1, rear - 1
front - 1 rear - 1 34 13 front + 1 rear + 1 front - 1 rear - 1 34
15 front + 1 rear + 1 front - 1 rear - 1 34 17 front + 1 rear + 1
front - 1 rear - 1 34 21 front + 1 rear + 1 front - 1 rear - 1 34
25 front + 1 rear + 1 front - 1 rear - 1 34 29 front + 1 rear + 1
front - 1 rear - 1 34 33 front + 1 rear + 1 front - 1 front - 1,
rear + 1 24 11 front + 1 front + 1, rear - 1 rear - 2 rear - 1 24
13 front + 1 rear + 1 rear - 2 rear - 1 24 15 front + 1 rear + 1
rear - 2 rear - 1 24 17 front + 1 rear + 1 rear - 2 rear - 1 24 21
front + 1 rear + 1 rear - 2 rear - 1 24 25 front + 1 rear + 1 rear
- 2 rear - 1 24 29 front + 1 rear + 1 rear - 1 rear - 1 24 33 front
+ 1 rear + 1 Alarm Alarm
[0023] Table 5 illustrates the shift commands and TC signals for
operating front derailleur 70 and rear derailleur 74 for the same
configuration when implementing the concept of a prohibited range
of sprocket combinations. Such prohibited sprocket combinations
typically comprise the combination of the large front sprocket with
the large rear sprockets, which results in excessive chain tension,
and the small front sprocket with the small rear sprockets, which
results in excessive chain looseness. TABLE-US-00005 TABLE 5 Signal
Recognized By Computer Present Gear Position Two Steps Two Steps
One Step Front Rear Up One Step Up Down Down 46 11 Alarm Alarm
front - 1 rear - 1 46 13 rear + 1 rear + 1 front - 1 rear - 1 46 15
rear + 2 rear + 1 front - 1 rear - 1 46 17 rear + 2 rear + 1 front
- 1 rear - 1 46 21 rear + 2 rear + 1 front - 1 front - 1, rear + 1
46 25 Prohibited Prohibited Prohibited Prohibited 46 29 Prohibited
Prohibited Prohibited Prohibited 46 33 Prohibited Prohibited
Prohibited Prohibited 34 11 front + 1 front + 1, rear - 1 rear - 2
rear - 1 34 13 front + 1 rear + 1 rear - 2 rear - 1 34 15 front + 1
rear + 1 rear - 2 rear - 1 34 17 front + 1 rear + 1 front - 1 rear
- 1 34 21 front + 1 rear + 1 front - 1 rear - 1 34 25 rear + 2 rear
+ 1 front - 1 rear - 1 34 29 rear + 2 rear + 1 front - 1 rear - 1
34 33 rear + 2 rear + 1 front - 1 front - 1, rear + 1 24 11
Prohibited Prohibited Prohibited Prohibited 24 13 Prohibited
Prohibited Prohibited Prohibited 24 15 Prohibited Prohibited
Prohibited Prohibited 24 17 front + 1 front + 1, rear - 1 rear - 2
rear - 1 24 21 front + 1 rear + 1 rear - 2 rear - 1 24 25 front + 1
rear + 1 rear - 2 rear - 1 24 29 front + 1 rear + 1 rear - 1 rear -
1 24 33 front + 1 rear + 1 Alarm Alarm
[0024] In all examples, it should be noticed that some shift
commands that request a change through two speed stages require
only one movement of one derailleur. For example, assume in the
first configuration that chain 66 is disposed on the 34-tooth front
sprocket 62 and the 33-tooth rear sprocket 56, thus producing a
speed stage having a gear ratio of 1.03. If shift control device 98
generates a signal indicating a two-step-up shift command (two
sequential rear ratios), then transmission control unit 90 may
generate a TC signal to move front derailleur 70 a single step so
that chain 66 engages the 46-tooth front sprocket 62, thus
producing the speed stage having a gear ratio of 1.39. Prior art
electrically controlled bicycles would move rear derailleur 74 from
the 33-tooth rear sprocket 56 to the 29-tooth rear sprocket 56, and
then to the 25-tooth rear sprocket 56, thus producing the speed
stage having a gear ratio of 1.36. Such a technique requires a
total of two movements, rather than the one movement taught
herein.
[0025] The method and apparatus according to the present invention
takes advantage of the fact that many front/rear sprocket
combinations produce substantially the same gear ratio. The TC
signals are generated based on which combination of front and rear
sprockets require the least number of movements of the front
derailleur 70 and/or rear derailleur 74 to achieve the desired gear
ratio. In general, particularly good results can be achieved by
selecting the front and rear sprockets such that, for a given
combination of front and rear sprockets, the change in gear ratio
that results when switching from one front sprocket to another
front sprocket is substantially an integral number of the change in
gear ratio when switching from one rear sprocket to another rear
sprocket. In the embodiment disclosed above, the change in gear
ratio that results when switching from one front sprocket to
another front sprocket is substantially twice the change in gear
ratio when switching from one rear sprocket to another rear
sprocket. If a shift command signal is received that cannot be
accommodated, such as a shift-up command to when the chain 66
currently engages the largest front sprocket 62 and the smallest
rear sprocket 56, then table memory 110 can instruct the system to
sound an audible alarm indicating an illegal request. In such a
situation front derailleur 70 and rear derailleur 74 remain
stationary.
[0026] While the above is a description of various embodiments of
the present invention, further modifications may be employed
without departing from the spirit and scope of the present
invention. For example, the size, shape, location or orientation of
the various components may be changed as desired. The functions of
one element may be performed by two, and vice versa. It is not
necessary for all advantages to be present in a particular
embodiment at the same time. Every feature which is unique from the
prior art, alone or in combination with other features, also should
be considered a separate description of further inventions by the
applicant, including the structural and/or functional concepts
embodied by such feature(s). Thus, the scope of the invention
should not be limited by the specific structures disclosed or the
apparent initial focus on a particular structure or feature.
* * * * *