Rear Derailleur Actuator Using Spur Gearing for Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bicycle derailleur systems face inefficiencies due to reliance on worm gearing, leading to reduced motor efficiency, increased battery drain, and shorter component life, despite advancements in actuation mechanisms and shifting technologies.
Innovation Solution
The use of a high-efficiency spur gearing reduction transmission package from wireless remote control servo units, combined with a digitally commutated brushless AC motor and magnetic encoders for precise positioning, eliminates the need for auxiliary gears and minimizes backlash, while enabling wireless control through Bluetooth Low Energy connections for semi-automatic and fully automatic shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If worm gearing is used in derailleur actuation, then substantial gearing reduction ratio is achieved to amplify motor output torque, but power transmission efficiency decreases to around 70% due to sliding motion between worm and worm gear
Solution Approach 1:
The patent replaces the traditional worm gear mechanism with a planetary gear system. This substitution eliminates the sliding motion inherent in worm gears that causes energy loss, while maintaining the torque amplification function through the planetary gear arrangement with sun, planet, and ring gears.
Solution Approach 2:
The patent changes the mechanical parameters of the gear system by using a planetary configuration with specific tooth counts and gear ratios. This allows optimization of both torque multiplication and efficiency by selecting appropriate planetary gear parameters rather than relying on worm gear geometry.
2Force
If multiple stage proprietary gearing reduction sets are used, then needed torque amplification is achieved, but device complexity increases with multiple stages required
Solution Approach 1:
The patent merges multiple gear reduction functions into a single planetary gear stage. The planetary configuration inherently provides high reduction ratios in one compact stage, eliminating the need for multiple sequential gear stages and reducing overall system complexity.
Solution Approach 2:
The planetary gear system serves multiple functions simultaneously: it provides torque amplification, achieves the required reduction ratio, and maintains compact size. This multi-functionality replaces what would otherwise require separate components for each function.
3Force
If worm gearset is used for substantial reduction, then torque amplification is achieved, but motor efficiency decreases and battery drain increases
Solution Approach 1:
The patent substitutes the worm gearset with a planetary gear system that has significantly lower energy losses. This replacement reduces the power required from the motor, thereby decreasing battery drain while maintaining the necessary torque output for derailleur actuation.
4Measurement precision
If auxiliary gears are used in the actuation mechanism, then positioning is achieved, but backlash increases and precision decreases
Solution Approach 1:
The patent removes auxiliary gears from the actuation mechanism, using only the essential planetary gear components. This extraction eliminates the backlash and positioning errors introduced by additional gear interfaces, while the planetary system itself provides sufficient reduction and control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances power conservation, reduces heat losses, and provides minimal weight and fast response times, achieving improved efficiency and durability in bicycle derailleur systems.
Implementation Method 1
a high-efficiency spur gearing reduction transmission package typically used in wireless remote control (RC) servo units
Implementation Method 2
with output shaft thereof coupled to a magnetic 12-bit quadrature encoder for high positioning accuracy
Implementation Method 3
a small cored or coreless DC motor acting through a triple or quadruple spur gearing reduction set
Data Source
AI summary
An electrical actuator for a bicycle rear derailleur making use of a standard wireless remote control (RC) servo unit relying exclusively on highly efficient spur gearing reduction and facilitating highly accurate derailleur positioning thereof through an integral digital magnetic rotary encoder with assembly thereof sealed in a two-piece housing with a lateral extension for an auxiliary spur gear serving to transmit actuation effort thereof to actuation shaft of a rear derailleur.