Mid Drive E-Bike Planetary Gear Torque Measurement
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Solution Overview
Problem
Existing electric cycles with planetary drive mechanisms lack efficient torque measurement and control systems, limiting their ability to provide intuitive pedal-assisted propulsion and regenerative braking modes effectively.
Innovation Solution
The implementation of a gear set with a carrier and crank assembly connected to a torque measurement device, allowing for the measurement of rider input torque and enabling various operational modes such as pedal assist, regenerative braking, and electronic coaster modes by controlling the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a planetary drive mechanism is implemented in electric cycles, then power transmission efficiency is improved, but torque measurement capability deteriorates
Solution Approach 1:
A dedicated torque measurement device is introduced as an intermediary component between the crank assembly and the planetary gear system. This separate measurement device accurately captures rider input torque without interfering with the power transmission path, resolving the contradiction between maintaining efficient power transmission and enabling precise torque measurement.
Solution Approach 2:
The power transmission system is segmented into distinct functional components: a crank assembly for input, a planetary gear set for power transmission, and a separate torque measurement device for sensing. This segmentation allows each component to perform its specific function optimally without compromising the others, enabling both efficient power transmission and accurate torque measurement.
2Adaptability or versatility
If multiple operational modes (pedal assist, regenerative braking) are added, then system versatility is improved, but device complexity deteriorates
Solution Approach 1:
The planetary drive mechanism is designed with multi-functionality to handle different operational modes (pedal assist, regenerative braking, electronic coaster) through a single integrated system. The same mechanical components serve multiple purposes by adjusting control parameters and torque flow directions, achieving versatility without proportionally increasing complexity.
Solution Approach 2:
A feedback control system is implemented that uses torque measurement data to automatically adjust motor control strategies for different operational modes. The system continuously monitors rider input torque and dynamically switches between pedal assist, regenerative braking, and electronic coaster modes, providing versatility through intelligent control rather than complex mechanical switching mechanisms.
Data Source
AI summary
A product may include a gear set that may have a first gear, a second gear that may be engaged with the first gear and a third gear. The third gear may be held from rotation and may be engaged with the second gear. A carrier may carry the second gear for rotation. A crank may be continuously connected with the carrier to provide input thereto. A torque measurement device may be connected to the third gear.