Electric Bicycle Kick-Back Reduction via Anti-Phase Motor Control
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Solution Overview
Problem
Electric bicycles with rear suspension experience an uncomfortable kick-back effect due to oscillating chain tension, leading to energy loss and variable propulsion, which existing designs like sprung rear structures and multi-pivot triangles fail to completely mitigate.
Innovation Solution
An anti-phase control method using an evaluation unit to regulate the motor force relative to the pedal force, generating a chain force with reduced periodic fluctuations, and dynamically adjusting the damper's hardness to maintain a constant chain force, thereby minimizing the kick-back effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rear suspension with damper is added to improve driving characteristics on undulating ground, then riding comfort is improved, but kick-back effect occurs causing energy loss and uncomfortable pedaling
Solution Approach 1:
The control unit continuously monitors pedal force and motor force, and dynamically adjusts the motor force to counteract chain force fluctuations. This closed-loop feedback system detects the kick-back effect and applies compensating forces in real-time, resolving the energy loss problem while maintaining suspension benefits
Solution Approach 2:
The system dynamically changes the motor force parameter based on pedal phase and force magnitude. By varying motor torque in antiphase to pedal force oscillations, the system eliminates chain force fluctuations and prevents kick-back effect while maintaining continuous pedaling comfort
2Loss of energy
If pivot point is placed along catenary to reduce leverage caused by chain tension, then kick-back effect is reduced, but variability of chain line in different gears prevents complete elimination
Solution Approach 1:
The control unit receives feedback about current gear position and chain line configuration, and dynamically adjusts motor force compensation accordingly. This allows the system to maintain effective kick-back reduction across all gear ratios and chain line positions without mechanical redesign
Solution Approach 2:
Instead of a fixed mechanical pivot point configuration, the system uses dynamic motor force adjustment that adapts to changing gear and chain line conditions. The motor torque is continuously varied to counteract kick-back effect regardless of mechanical configuration, providing gear-independent solution
3Ease of operation
If multi-pivot rear triangle with virtual pivot points is used, then suspension performance is improved, but kick-back effect still occurs
Solution Approach 1:
The control unit monitors chain force fluctuations generated by the multi-pivot suspension geometry and applies real-time motor force compensation. This feedback-based approach counteracts the specific oscillation patterns created by virtual pivot points, eliminating kick-back while preserving suspension performance
Solution Approach 2:
The motor force acts as an intermediary that mediates between the pedal force and the suspension system. By introducing this active compensating force, the system decouples the kick-back effect from the suspension mechanics, allowing both to coexist without negative interaction
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
Significantly improves the handling and range of electric bicycles by reducing energy loss and allowing for more design flexibility in rear triangle constructions, while saving weight and costs.
Implementation Method 1
Generation of a chain force of reduced periodic fluctuations by means of an anti-phase control of the motor force to the pedal force by the evaluation unit
Implementation Method 2
The chain tension has an influence on the damper of the rear triangle. Due to the oscillation of the chain tension, the damper is continuously compressed and released again.
Data Source
Figure 1~2
AI summary
The present invention relates to a method for reducing the kick-back effect of a damper (3) on the sprung rear frame (2) of an electric bicycle (1), wherein the electric bicycle (1) has an electric drive device (4) for generating a motor force, pedals (5) for generating a pedal force, a bicycle chain (6) for power transmission and an evaluation unit, comprising the following step: - generation of reduced periodic fluctuations in chain force by means of an antiphase control of the motor force to the pedal force by the evaluation unit.