Bicycle Electric Assist Drive Roller Pivoting Engagement
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Solution Overview
Problem
Current electric assistance devices for bicycles lack efficient mechanisms for engaging and disengaging the drive roller with the bicycle wheel, leading to inefficiencies and potential wear due to sudden contact and separation, and do not effectively utilize control systems to optimize torque delivery based on speed and pedal rotation.
Innovation Solution
An electric assistance device with a support arm and drive roller that pivots to engage and disengage with the bicycle wheel, utilizing a freewheel mechanism and control means including sensors for speed, rotation, and position to manage torque delivery and pivot positioning, ensuring smooth operation and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive roller is constantly in contact with the bicycle wheel, then continuous power transmission is achieved, but wear and energy loss increase due to sudden contact and separation
Solution Approach 1:
The support arm pivots to bring the drive roller into contact with the bicycle wheel before power transmission begins, and maintains contact during operation. This preliminary engagement ensures smooth power transfer without sudden contact, reducing wear and energy loss while maintaining continuous transmission reliability.
2Speed
If the support arm is quickly pivoted to engage the drive roller, then rapid engagement is achieved, but impact and noise increase
Solution Approach 1:
The return means (spring) is pre-loaded to provide a cushioning effect during the pivoting motion of the support arm. This cushioning absorbs impact forces during engagement and disengagement, reducing noise and harmful vibrations while maintaining rapid positioning capability through the stored elastic energy.
3Power
If the electric machine continuously delivers torque, then constant assistance is provided, but energy consumption increases
Solution Approach 1:
The control system operates the electric machine in periodic cycles: delivering driving torque when the support arm is engaged with the bicycle wheel, then delivering reaction torque to pivot the arm away for disengagement. This periodic operation provides continuous assistance during cycling while reducing overall energy consumption by allowing the system to coast during disengagement phases.
4Object-affected harmful factors
If the drive roller is positioned away from the wheel, then reduced wear is achieved, but power transmission is interrupted
Solution Approach 1:
The support arm is designed as a dynamic component that can pivot between engaged and disengaged positions. During normal operation, the arm maintains engagement for continuous power transmission; during coasting or braking, it pivots away to reduce wear. The return means ensures the arm automatically returns to the engaged position when needed, dynamically balancing wear reduction with power transmission continuity.
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
The solution enables efficient and controlled engagement and disengagement of the drive roller, optimizing torque delivery based on bicycle speed and pedal rotation, thereby enhancing the assistance provided while minimizing wear and noise.
Implementation Method 1
a rotor shaft (16) which carries a drive roller (5) by means of a freewheel (19) in such a way that the electric machine (4) can, when supplied with electrical energy, produce a driving torque
Implementation Method 2
a return means (26) acting on said support arm (7) in said first direction of pivoting
Implementation Method 3
delivering an electrical impulse to the machine electric to produce a reaction torque in a direction opposite to said motor torque, causing the support arm to pivot in said second pivot direction
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to an electric assist device for a bicycle, comprising an electric machine (4) provided with a support arm (7) and comprising a rotor shaft (16) on which a roller (5) for driving by means of a free wheel is supported, the support arm being mounted on the bicycle by means of a pivot shaft (8) for pivoting between a drive position and a spaced-apart position, positioning means (28) which can be actuated for releasably holding the support arm in a spaced-apart position, means (44) for controlling the operation of the electric machine that are capable of supplying power to the electric machine in order to produce a motor torque in the direction in which the wheel of the bicycle is driven when moving forward, and that are capable of outputting an electrical pulse to the electric machine in order to produce a reaction torque in a direction opposite that of said motor torque, causing the support arm to pivot and actuating said positioning means.