Power-Assisted Bicycle Gear Shift Smoothening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power-assisted bicycles experience sudden changes in pedaling rate and torque during gear shifting, making the riding experience uncomfortable and increasing the risk of chain overtension and shifting failures due to unpredictable gear shifts.
Innovation Solution
A power-assisted bicycle with a gear shift smoothening function that uses a microcomputer, sensors, and a gear-shift control driver to adjust assistant power output and provide a warning signal, dividing the gear-shifting process into before-shifting, in-shifting, and after-shifting time periods to manage power assistance and derailleur operation, maintaining a low assistant power during shifting to smooth the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gear shifting is performed in conventional power-assisted bicycles, then gear ratio change is achieved, but sudden changes in pedaling rate and torque occur causing rider discomfort
Solution Approach 1:
The microcomputer provides a warning signal before gear shifting occurs, allowing the rider to prepare mentally and physically. The system also performs preliminary power adjustment by reducing assistant power to a predetermined low level before the actual gear shift, preventing sudden torque changes that would cause discomfort.
Solution Approach 2:
The system cushions the impact of gear shifting by maintaining a predetermined low assistant power level during the gear shifting process. This power buffering prevents sudden torque changes and chain overtension, smoothing out the transition and eliminating the awkward sensations riders would otherwise experience.
2Extent of automation
If gear shifting occurs without rider awareness, then automatic gear control is achieved, but chain overtension and shifting failures occur
Solution Approach 1:
The system uses sensors to detect riding conditions such as wheel speed, pedaling speed, and slope, providing feedback to the microcomputer. Based on this feedback, the microcomputer determines appropriate gear shift timing and provides warning signals to the rider, ensuring shifts occur at optimal moments while maintaining reliability through continuous monitoring of system state.
Solution Approach 2:
The system performs preliminary power adjustment by reducing assistant power to a predetermined low level before gear shifting occurs. This preliminary action prevents chain overtension during the shift process, ensuring reliable and smooth gear transitions while maintaining automatic control.
3Power
If high assistant power is provided during gear shifting, then power assistance is maintained, but chain overtension occurs leading to unsmooth shifting
Solution Approach 1:
The system dynamically adjusts assistant power levels based on the gear shifting state. During gear shifting, the microcomputer maintains assistant power at a predetermined low level to prevent chain overtension and ensure smooth shifting. After the shift is complete, the power is gradually restored to the required level, creating a dynamic power management system that prioritizes shifting smoothness when needed.
Solution Approach 2:
The system cushions potential chain overtension by maintaining low assistant power before and during the gear shifting process. This power buffering prevents excessive chain tension that would cause unsmooth shifting or shifting failures, ensuring reliable gear transitions while preserving the ability to provide high power when needed for normal riding.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power-assisted bicycle(10)(60) includes a bicycle body (11) with a power assistance provider (12) and a derailleur (16), a microcomputer (21), a gear-shift control driver (31), and sensors (41). When the microcomputer (21) decides to perform gear shifting, it controls the power assistance provider (12) to provide an assistant power output and the gear-shift control driver (31) to drive the derailleur (16) to shift gears properly subject to a before-shifting time period, an in-shifting time period and an after-shifting time period. Further, the microcomputer (21) controls the power assistance provider (12) to change the current assistant power to a predetermined low assistant power during the before-shifting time period, or to maintain the predetermined low assistant power during the in-shifting time period, or to change the assistant power output to a level higher than the current assistant power and then to return to the said current assistant power after the end of the after-shifting time period.