E-bike Motor Output Control for Smooth Gear Shifting
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Solution Overview
Problem
Existing electrically assisted bicycle control systems increase the load on riders during gear shifting due to limited assisting power, making the process less smooth and more strenuous.
Innovation Solution
A bicycle drive apparatus with a microcomputer-controlled output that adjusts the electric motor's assistance based on pedaling force and crank position, reducing motor output when shifting gears to minimize load on the rider and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the supply of assisting power is limited during gear shifting operation, then the gear shifting can be executed smoothly, but the load born by the rider increases
Solution Approach 1:
The patent applies dynamics by making the motor output adjustable based on crank position. The system dynamically switches between normal output mode and reduced output mode depending on whether the crank is in the dead center region, allowing optimal performance at different operational phases
Solution Approach 2:
The patent applies local quality by applying different output control strategies to different crank position regions. Normal assisting power is provided when the crank is outside the dead center range, while reduced power is applied only when the crank is within the dead center range during gear shifting
2Stress or pressure
If the motor output is reduced during gear shifting, then the load on transmission and chain decreases, but the rider experiences increased pedaling effort
Solution Approach 1:
The system dynamically adjusts motor output based on real-time crank position detection. A crank position detection unit identifies when the crank enters the dead center range, triggering automatic reduction of motor output to minimize transmission load during the critical gear shifting moment
Solution Approach 2:
The system performs preliminary detection of crank position to anticipate the gear shifting moment. By detecting when the crank approaches the dead center range, the control unit proactively reduces output before the actual gear shift occurs, preventing excessive load on the transmission
Data Source
AI summary
A bicycle drive apparatus includes a bicycle crankset, a bicycle transmission, a drive assistance electric motor and a microcomputer. The microcomputer includes an output control section. The output control section has a first control and a second control that makes an output of the drive assistance electric motor smaller than an output of the drive assistance electric motor occurring during the first control only upon determining a crank arm of the bicycle crankset is positioned within a prescribed range of at least one of a top dead center position and a bottom dead center position of the bicycle crankset. The output control section is configured to vary the output of the drive assistance electric motor according to a pedaling force. The output control section switches from the first control to the second control upon receiving a shift command to shift the transmission.