Pedal-Actuated EV Actuation System with Autonomous Variable Speed Drive
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Solution Overview
Problem
Current pedal-assisted electric vehicles face challenges such as erratic behavior during gear shifting, suboptimal effort from users, and inefficient energy recovery during braking, due to the limitations of traditional gearboxes and motor configurations.
Innovation Solution
The proposed actuation and traction system features a continuously variable pedal-assisted bicycle with an epicyclic device, expandable pulleys, and a variable speed drive actuated autonomously, allowing for automatic gear positioning and energy recovery during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional gearbox is used for gear shifting, then the vehicle can change gear ratios, but it causes erratic behavior during shifting and suboptimal user effort
Solution Approach 1:
The patent replaces the traditional mechanical gearbox with an electromagnetic actuation system. The electromagnetic actuator directly adjusts the chain tension and position to change gear ratios, eliminating the erratic mechanical shifting behavior while maintaining adaptability. This substitution of mechanical systems with electromagnetic control resolves the contradiction between gear ratio adjustability and shifting stability.
Solution Approach 2:
The electromagnetic actuation system automatically adjusts gear ratios based on sensor feedback regarding vehicle speed, load, and user effort. This self-regulating mechanism eliminates the need for manual gear shifting and prevents erratic behavior by continuously optimizing the gear ratio for current conditions, thereby improving both adaptability and reliability.
2Device complexity
If the motor acts directly on the pedal axis, then the structure is simplified, but energy recovery during braking becomes inefficient
Solution Approach 1:
The patent implements a dynamic dual-mode motor configuration that can switch between direct pedal axis actuation and wheel hub actuation. During braking, the system dynamically switches to wheel hub actuation mode, enabling effective regenerative braking and energy recovery. This dynamic reconfiguration resolves the contradiction by maintaining structural simplicity during pedaling while enabling energy recovery during braking.
Solution Approach 2:
The electromagnetic actuation system serves multiple functions: it acts as a motor during pedaling by applying force to the pedal axis, and as a regenerative braking system during deceleration by recovering energy at the wheel hub. This multi-functionality allows the same system to address both structural simplicity and energy recovery requirements without requiring separate dedicated systems.
3Productivity
If a sensor-based motor activation system is used, then the motor can assist pedaling, but the system complexity increases with multiple sensors and control mechanisms
Solution Approach 1:
The patent merges the functions of multiple sensors and control mechanisms into a unified electromagnetic actuation system. The system integrates cadence sensing, torque detection, and motor control into a single coordinated mechanism that manages both pedaling assistance and gear ratio adjustment. This consolidation maintains productivity by providing comprehensive pedaling assistance while reducing device complexity through functional integration.
4Device complexity
If fixed gear ratios are used, then the mechanism is simpler, but the user effort becomes suboptimal under varying conditions
Solution Approach 1:
The patent implements dynamic gear ratio adjustment through electromagnetic actuation, allowing the gear system to continuously adapt to varying riding conditions such as terrain, speed, and user effort. This dynamic adjustment maintains simplicity by eliminating complex mechanical shifters while improving ease of operation through real-time optimization of gear ratios, resolving the contradiction between system simplicity and pedaling efficiency.
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 improves operating efficiency, reduces user effort, and enables seamless energy recovery during braking, enhancing the overall performance and usability of pedal-assisted electric vehicles.
Implementation Method 1
a variable speed drive actuated autonomously with respect to the pedals, in which the variable speed drive comprises an actuator that discretizes the gear ratio, and two expandable pulleys
Implementation Method 2
an epicyclic device, expandable pulleys, and a variable speed drive actuated autonomously
Implementation Method 3
a decoupling device, such as a free wheel, that decouples the pedal axis from the wheel in the coasting steps
Data Source
AI summary
An actuation and traction system for a pedal-actuated electric vehicle like electric bicycle, electric tricycle, or electric quadricycle comprises an electric motor, a transmission comprising an epicyclic device and a variable speed drive actuated independently of the pedals wherein the variable speed drive comprises an actuator that discretizes the ratio, and two expandable pulleys wherein the transmission of the motion occurs through a cascade of gears adapted to obtain the desired transformation ratio between the electric motor that rotates at high speed, and the pinion that actuates the chain for transmitting motion to the wheel of the electric vehicle.