Bicycle Drive Motor Torque Control for Smooth Shifting
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Solution Overview
Problem
Existing bicycle control systems with internal transmissions face challenges in executing smooth gear changes, especially when a large torque is applied, leading to potential difficulties during gear shifts.
Innovation Solution
A bicycle drive apparatus that includes a microcomputer controlling a drive assistance electric motor, which increases its output during gear changes, reducing the pedaling force required and ensuring a smooth transition by issuing a shift command to the motor output control section, thereby minimizing torque on the transmission gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gear change operation is executed while large torque is transmitted through the transmission, then the transmission can deliver high power to the rear wheel, but the gear change operation may not proceed smoothly
Solution Approach 1:
The microcomputer issues a motor output increasing command before or during the gear change operation to reduce the depression force on the pedal. This preliminary action reduces the torque transmitted through the chain and transmission gears before the gear shift occurs, enabling smooth gear changes while maintaining the capability for high power transmission when needed
Solution Approach 2:
The system dynamically changes the motor output parameter in response to gear shift commands. By increasing the motor output during gear changes, the system alters the torque distribution in the drivetrain, reducing the force transmitted through the chain and transmission, thereby enabling smooth gear transitions
2Ease of operation
If the depression force on the pedal is reduced during gear changes, then smooth gear operation is achieved, but the rider's pedaling effort may be insufficient to maintain momentum
Solution Approach 1:
The system merges the rider's pedaling force with the electric motor's drive force in a coordinated manner. During gear changes, the motor provides additional output to compensate for reduced rider depression force, ensuring both smooth gear operation and maintenance of driving momentum through the combination of mechanical and electrical power sources
Data Source
AI summary
A bicycle drive apparatus includes a bicycle transmission, a drive assistance electric motor and a microcomputer. The microcomputer includes an output control section that controls an output of the drive assistance electric motor, and that issues a motor output increasing command to increase the output of the drive assistance electric motor upon receiving a shift command for shifting the transmission.