Bicycle Drive Device Control for Rapid Gear Ratio Adjustment
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Solution Overview
Problem
Existing electric bicycle drive systems exhibit indirect driving behavior, leading to low pedal resistance and delayed reaction to changes in pedaling force or speed, resulting in rotor slipping and an unsatisfactory riding experience.
Innovation Solution
A control procedure for a bicycle drive device that records the speed of the crank axis and adjusts the motor speed of an electric motor to optimize the translation ratio of a planetary gear, ensuring quick adaptation to changes in speed or pedaling force within milliseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planetary gear system with electric motor control is used to enable gear ratio variation, then the adaptability of the drive system is improved, but the device complexity increases
Solution Approach 1:
The planetary gear system employs dynamic adjustment of gear ratios through electric motor control, allowing the transmission ratio to vary continuously or in discrete steps based on riding conditions. The planet carrier can be selectively coupled to or decoupled from the pedal axle, enabling smooth transitions between different gear ratios without manual intervention.
Solution Approach 2:
The patent replaces traditional mechanical derailleur-based gear shifting with an electrically controlled planetary gear system. Instead of using cable-pulled derailleurs that require manual operation, the system uses electric motors to automatically adjust the gear ratio by controlling the planet carrier's connection to the pedal axle, thereby substituting mechanical adjustment mechanisms with an automated electromechanical system.
2Ease of operation
If the control system responds quickly to changes in pedaling force, then the directness of riding behavior is improved, but the loss of time for control response must be minimized
Solution Approach 1:
The control system continuously monitors riding conditions including pedaling force, speed, and gear ratio, and uses this feedback to automatically adjust the planetary gear configuration. Sensors detect changes in rider input and system state, and the control unit processes this information to command the electric motor to adjust the gear ratio in real-time, creating a closed-loop control system that responds dynamically to rider needs.
Solution Approach 2:
The system anticipates rider needs by continuously monitoring pedaling characteristics and proactively adjusting gear ratios before the rider would need to manually shift. The control algorithm analyzes trends in pedaling force and speed to predict optimal gear changes, executing adjustments in advance to maintain optimal riding conditions without noticeable delay.
3Reliability
If the pedal axle is directly supported by the drive wheel to prevent rotor slipping, then the reliability of power transmission is improved, but the device complexity increases
Solution Approach 1:
The patent merges the function of the drive wheel with the planetary gear system by integrating the electric motor and gear mechanism into a unified assembly. The motor shaft is directly coupled to the planet carrier, which in turn connects to the pedal axle, creating a consolidated power transmission path that eliminates separate rotor components and reduces the number of potential failure points while maintaining reliable power transfer.
Data Source
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AI summary
The invention relates to a method for controlling a drive device (200) of a bicycle (100), the drive device (200) comprising a planetary gearbox (220), an actuating electric motor (210) and a speed-reducing gearbox (260), the actuating electric motor (210) being engagingly connected to a first input component (224) of the planetary gearbox (220) by means of the speed-reducing gearbox (260), the pedal shaft (106) of the bicycle (100) being connected, for conjoint rotation or engagingly, to a second input component (223) of the planetary gearbox (220), and an output component (221) of the planetary gearbox different from the input components being connected, more particularly for conjoint rotation, to an output pinion (108) of the drive device (200), the method comprising the following method steps: sensing (610) a rotational speed of the pedal shaft (106); and producing (650) an actuating motor rotational speed by means of the actuating electric motor (210) in accordance with the sensed rotational speed of the pedal shaft (106) in order to set a transmission ratio of the planetary gearbox (220) between the pedal shaft (106) and the output pinion (108), the actuating motor rotational speed being adjusted within a time period of less than or equal to twenty milliseconds after a change in the sensed rotational speed of the pedal shaft (106).