Electric bicycle transmission systems, methods, and devices
A derailleur-based electronic transmission system for an electric bicycle comprises a wheel; a driven sprocket set coupled to the wheel via at least a first one-way clutch, the driven sprocket set comprising two or more concentric sprockets of different effective diameters; a drive chain configured to engage the driven sprocket set; an electronically controllable derailleur configured to move the drive chain among the two or more sprockets; a pedal crank configured to cause rotation of the driven sprocket set by providing a user pedal force to the driven sprocket set through at least a second one-way clutch and the drive chain; a motor configured to cause rotation of the driven sprocket set by providing an electromechanical force to the driven sprocket set through at least a the drive chain; and an electronic controller configured to, responsive to a determination that a shift should occur at a time when neither the pedal crank nor the motor is causing rotation of the driven sprocket: operate the motor to rotate the driven sprocket at a rotational speed less than or equal to a current rotational speed of the wheel; and operate the derailleur to cause the shift to occur while the driven sprocket is being rotated by the motor.
1. A derailleur-based electronic transmission system for
an electric bicycle, the system comprising:
a wheel;
an electronically controllable derailleur;
a driven sprocket set coupled to the wheel, the driven sprocket set comprising two or more sprockets;
a drive chain configured to engage the driven sprocket set; and
a mid-drive assembly comprising:
a pedal crank configured to cause rotation of the driven sprocket set by providing a user pedal force to the driven sprocket set through at least the drive chain;
a motor assembly comprising a motor configured to cause rotation of the driven sprocket set by providing an electromechanical force to the driven sprocket set through at least the drive chain; and
an electronic controller configured to, responsive to a determination that a shift should occur at a time when neither the pedal crank nor the motor is causing rotation of the driven sprocket:
operate the motor to rotate the driven sprocket at a rotational speed less than or equal a rotational speed of the wheel.
2. The derailleur-based electronic transmission system of claim 1 , wherein the electronic controller is further configured to operate the derailleur to cause the shift to occur while the driven sprocket set is being rotated by the motor at the rotational speed less than or equal the current rotational speed of the wheel.
3. The derailleur-based electronic transmission system of claim 1 , wherein the driven sprocket set is coupled to the wheel via a clutch.
4. The derailleur-based electronic transmission system of claim 3 , wherein the clutch includes a one-way free-wheel clutch.
5. The derailleur-based electronic transmission system of claim 1 , wherein the motor is positioned adjacent the pedal crank.
6. The derailleur-based electronic transmission system of claim 1 , wherein the motor is configured to drive a front sprocket to cause rotation of the drive chain, and wherein the pedal crank is configured to drive the front sprocket to cause rotation of the drive chain.
7. The derailleur-based electronic transmission system of claim 1 , wherein the motor assembly is integrated with the pedal crank.
8. The derailleur-based electronic transmission system of claim 1 , wherein the electronic controller is configured to determine that the shift should occur by determining that a stop event is occurring.
9. The derailleur-based electronic transmission system of claim 8 , wherein the electronic controller is configured to determine that the stop event is occurring by monitoring, directly and/or indirectly one or more of the following: the rotational speed of the wheel, a rotational speed of the pedal crank, a rate of deceleration of the rotational speed of the wheel, a braking force, a rate of translational deceleration, or a pedal cadence.
10. The derailleur-based electronic transmission system of claim 2 , wherein the electronic controller is further configured to:
monitor the rotational speed of the wheel as the shift is occurring; and adjust the operation of the motor, responsive to a determination that the rotational speed of the wheel has changed, to increase or decrease the rotational speed of the driven sprocket to maintain the rotational speed of the driven sprocket set at a speed less than or equal to the rotational speed of the wheel.
11. The derailleur-based electronic transmission system of claim 8 , wherein the electronic controller is further configured to:
estimate a remaining amount of revolutions of the wheel before the stop event completes; and
operate the motor to rotate the driven sprocket set at a rotational speed less than or equal to the rotational speed of the wheel, but sufficiently fast to complete the shift within the estimated remaining amount of revo-lutions of the wheel.
12. The derailleur-based electronic transmission system of claim 1 , further comprising a bicycle frame.
13. Amid-drive assembly for an electric bicycle having an electronically controllable derailleur, the mid-drive assem-bly comprising:
a motor assembly configured to be positioned adjacent to or integrated with a pedal crank, the motor assembly comprising a motor, the motor configured to cause rotation of a driven sprocket coupled to a wheel of the electric bicycle by providing an electromechanical force to the driven sprocket set through at least a drive chain of the electric bicycle; and
an electronic controller configured to, responsive to a determination that a shift should occur at a time when neither the motor nor the pedal crank is causing rotation of the driven sprocket:
operate the motor to rotate the driven sprocket at a rotational speed less than or equal a rotational speed of the wheel.
14. The mid-drive assembly of claim 13 , wherein the electronic controller is further configured to operate the electronically controllable derailleur to cause the shift to occur while the driven sprocket is being rotated by the motor.
15. The mid-drive assembly of claim 13 , wherein the driven sprocket is coupled to the wheel via a clutch.
16. The mid-drive assembly of claim 15 , wherein the clutch includes a one-way freewheel clutch.
17. The mid-drive assembly of claim 13 , wherein the motor is configured to drive a front sprocket to cause rotation of the drive chain, and wherein the pedal crank is configured to drive the front sprocket to cause rotation of the drive chain.
18. The mid-drive assembly of claim 13 , wherein the electronic controller is configured to determine that the shift should occur by determining that a stop event is occurring.
19. The mid-drive assembly of claim 18 , wherein the electronic controller is configured to determine that the stop event is occurring by monitoring, directly and/or indirectly one or more of the following: the rotational speed of the wheel, a rotational speed of the pedal crank, a rate of deceleration of the rotational speed of the wheel, a braking force, a rate of translational deceleration, or a pedal cadence.
20. The mid-drive assembly of claim 18 , wherein the electronic controller is further configured to:
estimate a remaining amount of revolutions of the wheel before the stop event completes; and
operate the motor to rotate the driven sprocket set at a rotational speed less than or equal to the rotational speed of the wheel, but sufficiently fast to complete the shift within the estimated remaining amount of revo-lutions of the wheel.