Electrical Derailleur Brake Shifter With Skip-Shift Restart Control
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Solution Overview
Problem
Existing bicycle derailleur systems struggle with inefficient shifting during high-speed braking, requiring multiple commands to achieve optimal gear ratios for restart, leading to discomfort and slower starts due to non-optimal cassette sprocket/chain ring combinations.
Innovation Solution
A bicycle derailleur system utilizing Remote Control (RC) servo apparatus with programmable controls and a microcontroller, enabling 'Skip Shift' and 'Drop Shift' capabilities, allowing riders to change gear ratios with one command and program shifter buttons for automatic or manual operation, integrated with a touchscreen interface for enhanced control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple shift commands are used to achieve optimal gear ratios during high-speed braking, then the optimal cassette sprocket/chain ring combination can be selected, but the time required for shifting increases and rider comfort decreases
Solution Approach 1:
The system pre-identifies the optimal gear combination before braking occurs by monitoring speed and cadence sensors. The microcontroller stores multiple pre-programmed gear ratio combinations and automatically selects the appropriate one in advance, so that when braking happens, the rider only needs to activate a single button to execute the pre-planned shift sequence, dramatically reducing shifting time during critical braking moments.
Solution Approach 2:
The patent implements skip-shift functionality that allows the derailleur to jump over multiple intermediate gear positions and directly land on the target gear ratio. Instead of stepping through each intermediate sprocket/chain ring combination sequentially, the system can skip directly to the optimal combination, reducing the number of shift commands needed and the total time required to achieve the desired gear ratio during high-speed braking.
2Weight of moving object
If standard worm gearing is used for speed reduction and torque amplification, then the motor size can be minimized for weight savings, but shifting speed reduces due to 30% inherent losses
Solution Approach 1:
The system employs a variable ratio transmission mechanism that can dynamically adjust the gear ratio during shifting operations. Instead of using a fixed worm gear ratio, the patent implements a programmable motor controller that can modify the motor speed and torque output in real-time based on the specific shifting requirements. This allows the system to optimize the transmission ratio for each individual shift operation, maintaining compact motor size while improving shifting speed and efficiency.
Solution Approach 2:
The patent changes the operational parameters of the motor and transmission system based on the specific shifting conditions. The microcontroller adjusts motor speed, torque, and pulse width modulation duty cycle dynamically during shifting operations. By optimizing these parameters in real-time, the system can overcome the inherent 30% losses of worm gearing and achieve faster shifting speeds while maintaining the weight advantages of compact motor design.
3Reliability
If the rider triggers multiple shift combinations during braking, then the optimal restart gear ratio can be achieved, but the rider effort and discomfort increase due to non-optimal combinations
Solution Approach 1:
The system performs self-service by automatically monitoring riding conditions through speed and cadence sensors and pre-determining the optimal gear combination without requiring active rider intervention. The microcontroller continuously evaluates current speed, cadence, and stored gear ratio data to identify the best restart gear combination, then automatically executes the shift sequence when the rider activates the brake lever, eliminating the need for the rider to manually trigger multiple shift combinations and reducing physical effort.
Solution Approach 2:
The system implements feedback control by continuously monitoring speed and cadence sensor inputs and using this information to adjust shift operations. The microcontroller receives real-time feedback from sensors about the rider's current state and braking conditions, then automatically modifies the shift timing and gear selection to ensure optimal restart gear ratio is achieved with minimal rider effort. The feedback loop ensures the system adapts to varying riding conditions and maintains optimal performance.
Data Source
AI summary
A bicycle derailleur brake shifter making use of three pushbuttons disposed in shifter brake lever and two microswitches cloaked under the shifter housing hood for a total of five switches each with programming functionality including shifting to manual, automatic and tandem modes, conventional shift ability where a rear derailleur or a front derailleur shift to a higher or lower sprocket or chain ring, drop shift ability where a rear derailleur and a front derailleur shift to a pre-defined cassette sprocket and chain ring combination for re-initiation of motion from a stopping position, with thereof functionality programmable through a rider user interface with a manual mode programming screen and an automatic and tandem mode programming screen.