Mid Drive E-Bike Propulsion System Packaging
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Solution Overview
Problem
Existing electric cycles with mid drive propulsion systems face challenges in efficient packaging and integration of electric machines, gear sets, and battery arrays, which affect the overall performance and portability of the vehicles.
Innovation Solution
The integration of an electric machine, gear set, and battery array within a compact power unit, where the crankshaft extends through the electric machine and gear set, and the battery array is disposed around them, allowing for efficient packaging and intuitive pedal-based propulsion systems with regenerative capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electric machine, gear set, and battery array are integrated in a conventional separate layout, then each component can be independently designed and maintained, but the overall packaging efficiency is poor and the device occupies more space
Solution Approach 1:
The patent merges the electric machine, gear set, and battery array into a single integrated power unit. The battery array is positioned around the electric machine and gear set, with the crank shaft extending through both components, creating a compact consolidated structure that reduces overall volume while maintaining functional independence of each component
Solution Approach 2:
The battery array is arranged in a nested configuration around the electric machine and gear set, with the crank shaft passing through the center of this nested arrangement. This nesting allows the battery array to utilize the space around the other components, maximizing space utilization and minimizing the total volume of the power unit
2Loss of energy
If the crank shaft extends through the electric machine and gear set, then torque transfer efficiency is improved and noise is reduced, but the manufacturing and assembly precision requirements increase
Solution Approach 1:
The crank shaft serves multiple functions simultaneously: it acts as the rotational input for the gear set, passes through the electric machine to provide mechanical coupling, and extends to the pedals for direct torque transfer. This multi-functionality reduces the number of separate torque transfer interfaces, thereby reducing cumulative torque loss and noise while the integrated design helps manage alignment requirements
3Volume of moving object
If the battery array is disposed around the electric machine and gear set, then space utilization is maximized and portability is improved, but the heat dissipation challenges increase
Solution Approach 1:
The battery array is arranged in a three-dimensional configuration around the electric machine and gear set, utilizing radial and axial space rather than a linear arrangement. This spatial distribution in multiple dimensions maximizes space utilization while creating pathways for heat dissipation through the structure, allowing thermal management without increasing overall volume
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 configuration enhances the performance and portability of electric cycles by enabling efficient torque transfer, reduced noise and vibration, and intuitive pedal operation, while allowing for compact design and easy folding, thus improving user experience and storage convenience.
Implementation Method 1
an electric machine and a gear set that may be operatively connected with the electric machine
Implementation Method 2
a gear set that may be operatively connected with the electric machine
Data Source
AI summary
A propulsion system may include an electric machine and a gear set that may be operatively connected with the electric machine. A crank shaft may extend through the electric machine and the gear set. A battery array may be disposed around the electric machine and the gear set.