Power-assisted bicycle with a gear shift smoothening function

1. A power-assisted bicycle, comprising:

a bicycle body comprising a power assistance provider and a derailleur;

a microcomputer electrically coupled with said power assistance provider and adapted for controlling said power assistance provider to provide an assistant power output;

a gear-shift control driver electrically connected to said microcomputer and physically connected to said derailleur for driving said derailleur to shift gears subject to the control of said microcomputer;

at least one sensor mounted at said bicycle body at a respective selected location and electrically connected to said microcomputer for sensing at least one of the conditions of wheel speed, pedaling speed, pedaling force and slope and providing at least one sensing signal for causing said microcomputer to generate at least one detection result and to determine gearshift timing subject to said at least one detection result, said at least one sensor including at least one of a wheel speed sensor and a pedaling speed sensor; and

wherein when the wheel speed meets a first condition or the pedaling speed meets a second condition during the operation of said microcomputer to judge gearshift timing, said microcomputer divides the time period of the gear-shifting process into a before-shifting time period, an in-shifting time period and an after-shifting time period, and controls said power assistance provider to provide an assistant power output and said gear-shift control driver to drive said derailleur to shift gears during the three time periods of before-shifting time period, in-shifting time period and after-shifting time period; and

wherein:

said microcomputer controls said power assistance provider to change the current assistant power output thereof to a predetermined low assistant power during said before-shifting time period;

said microcomputer controls said power assistance provider to maintain said predetermined low assistant power and said gear-shift control driver to drive said derailleur to shift gears during said in-shifting time period;

said microcomputer controls said power assistance provider to change the assistant power output from said predetermined low assistant power to a level higher than the current assistant power output thereof when gearing up during said after-shifting time period, and then controls said power assistance provider to return to said current assistant power output after the end of said after-shifting time period.

2. A power-assisted bicycle, comprising:

a bicycle body comprising a power assistance provider and a derailleur;

a microcomputer electrically coupled with said power assistance provider and adapted for controlling said power assistance provider to provide an assistant power output;

a gear-shift control driver electrically connected to said microcomputer and physically connected to said derailleur for driving said derailleur to shift gears subject to the control of said microcomputer;

at least one sensor mounted at said bicycle body at a respective selected location and electrically connected to said microcomputer for sensing at least one of the conditions of wheel speed, pedaling speed, pedaling force and slope and providing at least one sensing signal for causing said microcomputer to generate at least one detection result and to determine gearshift timing subject to said at least one detection result, said at least one sensor including at least one of a wheel speed sensor and a pedaling speed sensor; and

wherein when the wheel speed meets a first condition or the pedaling speed meets a second condition during the operation of said microcomputer to judge gearshift timing, said microcomputer divides the time period of the gear-shifting process into a before-shifting time period, an in-shifting time period and an after-shifting time period, and controls said power assistance provider to provide an assistant power output and said gear-shift control driver to drive said derailleur to shift gears during the three time periods of before-shifting time period, in-shifting time period and after-shifting time period; and

wherein:

said microcomputer controls said power assistance provider to change the current assistant power output thereof to a predetermined low assistant power during said before-shifting time period;

said microcomputer controls said power assistance provider to maintain said predetermined low assistant power and said gear-shift control driver to drive said derailleur to shift gears during said in-shifting time period;

said microcomputer controls said power assistance provider to change the assistant power output from said predetermined low assistant power to a level higher than the current assistant power output thereof when gearing up during said after-shifting time period, and then controls said power assistance provider to return the assistant power output to said current assistant power output after the end of said after-shifting time period;

said microcomputer controls said power assistance provider to change the assistant power output from said predetermined low assistant power to said current assistant power output when gearing down during said after-shifting time period.

3. The power-assisted bicycle as claimed in claim 1 , wherein said predetermined low assistant power is below 20% of the maximum assistant power output of said power assistance provider.

4. The power-assisted bicycle as claimed in claim 1 , wherein said before-shifting time period is shorter than 2 seconds; said in-shifting time period is shorter than 1 second; said after-shifting time period is shorter than 2 seconds.

5. The power-assisted bicycle as claimed in claim 1 , wherein said power assistance provider is controllable to change the assistant power output thereof subject to different slopes or different gear ratios when operating under an assistant mode; said at least one sensor includes a slope sensor.

6. The power-assisted bicycle as claimed in claim 1 , wherein said microcomputer controls said power assistance provider to change the current assistant power output thereof to a predetermined medium assistant power and then to said predetermined low assistant power during said before-shifting time period.

7. The power-assisted bicycle as claimed in claim 6 , wherein said predetermined medium assistant power is directly proportionally changeable subject to the pedaling force or chain tension.

8. The power-assisted bicycle as claimed in claim 1 , wherein the assistant power output of said power assistance provider is increased or reduced during said before-shifting time period and said after-shifting time period in a linear relationship relative to time.

9. The power-assisted bicycle as claimed in claim 1 , further comprising an alarm electrically connected to said microcomputer and controllable by said microcomputer to give off a warning signal.

10. The power-assisted bicycle as claimed in claim 9 , wherein said alarm is selected from the group of buzzer, light-emitting diode and display device.

11. The power-assisted bicycle as claimed in claim 2 , wherein the operation of upshifting is limited to upslope during said before-shifting time period, and prohibited when the power-assisted bicycle is running down a slope or on a flat ground; said at least one sensor includes a slope sensor.

12. The power-assisted bicycle as claimed in claim 1 , wherein said first condition is that the wheel speed is greater than a predetermined first speed and said second condition is that the pedaling speed is greater than a predetermined second speed when said microcomputer judges the gear-shift operation is to gear up; said first condition is that the wheel speed is lower than said predetermined first speed and said second condition is that the pedaling speed is lower than said predetermined second speed when said microcomputer judges the gear-shift operation is to gear down.

13. The power-assisted bicycle as claimed in claim 2 , wherein said predetermined low assistant power is below 20% of the maximum assistant power output of said power assistance provider.

14. The power-assisted bicycle as claimed in claim 2 , wherein said before-shifting time period is shorter than 2 seconds; said in-shifting time period is shorter than 1 second; said after-shifting time period is shorter than 2 seconds.

15. The power-assisted bicycle as claimed in claim 2 , wherein said power assistance provider is controllable to change the assistant power output thereof subject to different slopes or different gear ratios when operating under an assistant mode; said at least one sensor includes a slope sensor.

16. The power-assisted bicycle as claimed in claim 2 , wherein said microcomputer controls said power assistance provider to change the current assistant power output thereof to a predetermined medium assistant power and then to said predetermined low assistant power during said before-shifting time period.

17. The power-assisted bicycle as claimed in claim 16 , wherein said predetermined medium assistant power is directly proportionally changeable subject to the pedaling force or chain tension.

18. The power-assisted bicycle as claimed in claim 2 , wherein the assistant power output of said power assistance provider is increased or reduced during said before-shifting time period and said after-shifting time period in a linear relationship relative to time.

19. The power-assisted bicycle as claimed in claim 2 , further comprising an alarm electrically connected to said microcomputer and controllable by said microcomputer to give off a warning signal.

20. The power-assisted bicycle as claimed in claim 19 , wherein said alarm is selected from the group of buzzer, light-emitting diode and display device.

21. The power-assisted bicycle as claimed in claim 2 , wherein said first condition is that the wheel speed is greater than a predetermined first speed and said second condition is that the pedaling speed is greater than a predetermined second speed when said microcomputer judges the gear-shift operation is to gear up; said first condition is that the wheel speed is lower than said predetermined first speed and said second condition is that the pedaling speed is lower than said predetermined second speed when said microcomputer judges the gear-shift operation is to gear down.