E-Bike Chain Transfer Support Device for Wear Reduction
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Solution Overview
Problem
Electric bicycles with multiple chainrings experience increased wear during gear shifting due to the separation of pedal position and chainring by a freewheel, leading to inefficient torque application and gear wear.
Innovation Solution
A chain transfer support device is integrated into the vehicle, controlled by a sensor and electric drive, to optimize gear changes by positioning the chain transfer support device for minimal torque application during shifting, allowing for seamless transitions between chainrings without excessive wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple chainrings are used on the crank mechanism, then gear versatility is improved, but wear during shifting increases due to misaligned pedal position and chainring
Solution Approach 1:
The system performs preliminary action by using the motor to pre-position the chainrings and chain to the optimal configuration before the driver initiates a gear change. This ensures that when shifting occurs, the pedal position and chainring are properly aligned, preventing excessive wear. The control unit detects the driver's shifting intention and actuates the motor in advance to prepare the drivetrain for smooth transition.
Solution Approach 2:
The motor acts as an intermediary between the driver's gear change intention and the actual gear shifting. It mediates the interaction by independently adjusting the chainring positions relative to the pedals, decoupling the previously fixed relationship. This intermediary function allows the system to achieve proper alignment without directly controlling the driver's pedaling action.
2Ease of operation
If motor assistance is provided during gear changing, then shifting ease is improved, but torque application control becomes difficult leading to excessive wear
Solution Approach 1:
The system implements feedback by having the control unit continuously monitor the drivetrain state and adjust the motor's torque output accordingly. When gear changing is detected, the control unit modulates the motor torque to provide assistance only during the critical shifting phase, then reduces or stops assistance once the shift is complete. This feedback-based torque control prevents excessive force application while maintaining ease of operation.
Solution Approach 2:
The motor provides periodic torque assistance rather than continuous power delivery. The control unit activates the motor in specific periodic cycles: detecting gear change intention, providing torque during the shifting window, and deactivating after the shift completes. This periodic action pattern simplifies torque control by limiting motor engagement to only when needed for assisting the gear change.
3Ease of operation
If fixed climbing aids are used on chainrings, then shifting support is provided, but wear increases when pedal position and chainring are misaligned
Solution Approach 1:
The system transitions from static, fixed climbing aids to dynamic, actively controlled chainring positioning. Instead of relying on fixed mechanical features on the chainrings that work only at specific pedal positions, the motor dynamically adjusts chainring orientation to maintain optimal alignment with the pedals throughout the gear changing process. This dynamic adaptation eliminates the wear problems associated with fixed climbing aids.
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 reduces gear and chain wear by ensuring optimal support during shifting operations, enabling the use of multiple chainrings with different tooth counts without excessive torque, even with motor assistance.
Implementation Method 1
the chain transfer support device optimally supports the gear change... minimal torque application during shifting
Data Source
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AI summary
The invention relates to a vehicle that can be operated by motor and/or by muscle power, in particular an electric bicycle, comprising a crank drive (2), an electric drive (3), a power supply (6), a chain (5), a gear shift (4) having at least one first toothed gear (7a) and a second toothed gear (7b), and a chain transfer assistance device (14), which during a gear change assists with a transfer of the chain from the first toothed gear (7a) to the second toothed gear (7b), and a control unit (10) to actuate the electric drive (3). The chain transfer assistance device (14) is arranged on one of the toothed gears, wherein the control unit (10) is configured to actuate the electric drive (3) during a gear change in order to move the chain (5) such that the chain transfer assistance device (14) is brought into a gear change position, in which a gear change is assisted by the chain transfer assistance device (14).