Electric Bicycle Gear Selection Optimizing Motor Power
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Solution Overview
Problem
Electric bicycles with automatic shift mechanisms often prioritize vehicle speed over electrical energy efficiency and user comfort, leading to suboptimal energy consumption and reduced battery life.
Innovation Solution
A method and device that assess instantaneous pedal frequency and travel speed to determine the gear with the lowest electric motor power consumption, using a consumption characteristic map and actuator for automatic shifting to optimize energy use while maintaining user comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automatic shift mechanisms prioritize vehicle speed, then speed performance is improved, but electrical energy consumption increases
Solution Approach 1:
The shift mechanism dynamically adjusts gear selection based on real-time operating conditions (pedal frequency, vehicle speed, power demand) rather than following fixed speed-based shifting rules. The control unit continuously monitors multiple parameters and adapts gear changes to optimize the balance between speed maintenance and energy consumption, selecting gears that keep the motor operating in efficient power ranges.
Solution Approach 2:
The system changes the decision parameters for gear shifting from solely speed-based to a multi-parameter approach including pedal frequency, vehicle speed, and power demand. By incorporating power consumption characteristics and motor efficiency maps, the system selects gears based on optimal power delivery ranges rather than fixed speed intervals, thereby reducing electrical energy consumption while maintaining acceptable speed performance.
2Ease of operation
If traditional shift mechanisms maintain pedal frequency in comfort range, then user comfort is improved, but electrical energy consumption increases
Solution Approach 1:
The gear selection system serves multiple functions simultaneously: it maintains pedal frequency within the comfort range for the cyclist while also optimizing electrical energy consumption. The control unit evaluates both comfort criteria (pedal frequency ranges) and energy efficiency criteria (motor power consumption, operating points) to make unified gear decisions that satisfy both requirements, making the system universally optimized for both user experience and energy efficiency.
Solution Approach 2:
The system implements feedback control by continuously monitoring pedal frequency and comparing it against comfort range thresholds. When pedal frequency deviates from the optimal comfort range, the system adjusts gear selection to bring it back into the comfortable zone. This feedback mechanism ensures user comfort is maintained while the system simultaneously considers power consumption implications of each gear change.
3Device complexity
If gear selection is based on speed and pedal frequency only, then shifting simplicity is improved, but energy optimization is insufficient
Solution Approach 1:
The system performs preliminary calculations and evaluations of multiple gear options before executing a shift decision. The control unit pre-computes power consumption for each candidate gear based on current operating conditions and motor characteristics, then selects the optimal gear in advance. This preliminary analysis enables energy-optimized shifting without requiring complex real-time calculations during the actual shift moment, maintaining manageable system complexity.
Solution Approach 2:
The patent replaces traditional mechanical or simple electronic shift mechanisms with an intelligent control system that uses computational algorithms to optimize gear selection. Instead of relying on fixed mechanical linkages or simple speed-based electronics, the system substitutes a microcontroller-based decision-making process that evaluates motor power consumption, efficiency maps, and operating conditions to determine optimal gear changes, thereby achieving superior energy optimization.
Data Source
AI summary
A method and device for operating an electric bicycle that has an electric motor and a transmission with at least two gears is provided. The method includes ascertaining a current pedal frequency that is generated by a user of the electric bicycle and checking whether the ascertained current pedal frequency lies within a specified pedal frequency interval. The method also includes ascertaining a current travel speed of the electric bicycle, ascertaining at least two transmission gears within the specified pedal frequency interval depending on the ascertained travel speed, and ascertaining a respective output of the electric motor for each of the ascertained at least two gears. The method also includes ascertaining the lowest ascertained output of the electric motor by comparing the two ascertained outputs of the electric motor, and ascertaining the transmission gear for which the lowest output was ascertained.