Electric Bicycle Drive Torque Limiting for Wear Reduction
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Solution Overview
Problem
The service life of electric bicycle drives varies significantly due to different user driving behaviors, leading to uneven wear and potential sudden failures, as existing designs are based on assumed torque loads rather than actual usage patterns.
Innovation Solution
A method and device that detect the mechanical load on components of an electric bicycle using a load parameter set, calculating a resultant mechanical load over time, and limit torque when this load exceeds a predefined value to extend the service life of the drive train components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive is designed to withstand the maximum assumed torque load, then the reliability is improved, but the service life varies significantly due to different user driving behaviors
Solution Approach 1:
The control unit continuously monitors the actual mechanical load on the drive train components and uses this feedback to dynamically adjust the torque provided by the drive. This closed-loop control ensures that the drive operates within safe load limits while adapting to different user driving behaviors, thereby extending service life without compromising reliability
Solution Approach 2:
The system transitions from a static torque design based on maximum assumed loads to a dynamic torque control that adapts to actual usage patterns. The control unit continuously adjusts the torque output based on real-time load monitoring, allowing the drive to operate optimally across varying conditions and extend component service life
2Productivity
If the drive provides maximum torque during regular operation, then the productivity is improved, but the mechanical load on components increases leading to reduced service life
Solution Approach 1:
The system applies partial torque limitation only when the cumulative mechanical load approaches the limiting value, rather than continuously limiting torque. This allows the drive to provide maximum torque during normal operation for optimal productivity, while intervening selectively to prevent excessive wear and extend service life
3Duration of action of moving object
If the torque is limited to extend service life, then the duration of action is improved, but the maximum torque provided by the drive is reduced
Solution Approach 1:
The system dynamically adjusts torque limitation based on the current mechanical load state. When the cumulative load is below the limiting value, the drive provides full maximum torque for optimal performance. When the limit is approached, torque is reduced only to the extent necessary to extend service life, minimizing the impact on power output
Data Source
AI summary
A method for operating an electric bicycle. The method includes: detecting a mechanical load of a component of the bicycle in a load parameter set caused by a drive of the electric bicycle, ascertaining a resultant mechanical load, which results from the mechanical load of the component caused by the drive since a start of the detection of the mechanical load, based on the load parameter set, and limiting a torque provided by the drive when the resultant mechanical load exceeds a limiting value.