Electric Bicycle Crank Recuperation via Freewheel Locking
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Solution Overview
Problem
Mid-engine electric bicycle configurations face challenges in implementing recuperation and electric braking functions due to the lack of a freewheel mechanism, which prevents the central motor from being driven when the chain disconnects during downhill riding.
Innovation Solution
A freewheel is arranged on the rear wheel with a locking device that can be actuated via a power transmission element, allowing the electric machine to operate as a generator for recuperation or eddy current braking, and a control unit manages the braking force to ensure smooth transitions and additional mechanical braking when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a central motor concept is used with a freewheel mechanism, then the electric machine can operate as a generator for recuperation, but the device complexity increases due to the additional locking device and actuation mechanism
Solution Approach 1:
The locking device is integrated into the freewheel mechanism itself, combining the functions of the freewheel and locking mechanism into a single component assembly. This reduces the number of separate parts and simplifies the overall structure while maintaining the ability to lock the freewheel for generator operation.
Solution Approach 2:
The brake lever is designed to serve dual purposes: traditional mechanical braking and actuating the locking device for recuperation. By making the brake lever multi-functional, the system eliminates the need for a separate actuating mechanism, thereby reducing device complexity while enabling generator operation.
2Use of energy by moving object
If a locking device with multiple components is used to enable generator operation, then recuperation function is achieved, but the manufacturing cost increases
Solution Approach 1:
The locking device components are integrated into the existing freewheel assembly, eliminating the need for separate locking mechanisms. This consolidation reduces the total number of parts that need to be manufactured and assembled, thereby lowering manufacturing costs while maintaining generator operation capability.
Solution Approach 2:
The brake lever is designed to serve dual purposes: traditional mechanical braking and actuating the locking device for recuperation. By making the brake lever multi-functional, the system eliminates the need for a separate actuating mechanism, thereby reducing manufacturing complexity and cost.
3Ease of manufacture
If the freewheel locking mechanism is simplified, then manufacturing cost is reduced, but the reliability of generator operation may be compromised
Solution Approach 1:
The locking device is integrated into the freewheel mechanism itself, using the existing structural elements of the freewheel. This integration maintains reliability by utilizing proven freewheel components while simplifying the overall locking mechanism design for easier manufacturing.
Solution Approach 2:
The brake lever is designed to serve dual purposes with a simple mechanical connection to the locking device. This multi-functional design maintains reliability through the robustness of the brake lever while keeping the actuation mechanism simple and easy to manufacture.
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
Enables cost-effective and space-efficient implementation of recuperation and electric braking in central motor concepts, allowing the electric machine to charge the battery or provide braking effects, with the option to switch between modes as needed.
Implementation Method 1
the electric machine (3) can be operated as a generator
Implementation Method 2
Alternatively, the electrical machine is operated as an eddy current brake in order to merely provide a braking effect
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The present invention relates to an electric bicycle that can be operated by a motor and/or muscle power, comprising a crank mechanism (2), an energy storage device (11), an electric machine (3) that can be operated as a motor and generator and is arranged on the crank mechanism (2), a power transmission element (5) for transmitting a driving force from the electric machine (3) to a drive wheel (9), a freewheel (14) on the drive wheel (9), a locking device (15) for locking the freewheel (14) on the drive wheel, and an actuating device (12; 13) for actuating the locking device (15), wherein, when the locking device (15) is locked, the drive wheel (9) drives the electric machine (3) via the power transmission element (5).