Nested Dual-Motor E-Bike Gearbox for Compact Torque Transfer
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Solution Overview
Problem
Existing electric bicycles face challenges in optimizing space utilization and power transmission efficiency, particularly with high-weight and high-cost issues associated with drive systems.
Innovation Solution
A drive device for electric bicycles featuring a gearbox with parallel first and second drive shafts, allowing torque input from two electric motors, where one shaft is guided through the other, enabling compact configuration and efficient torque distribution on both sides of the shafts, with one motor providing primary power and the other adjusting transmission ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a dual-motor drive system is implemented to enable high power transmission, then power transmission capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent implements one drive shaft guided through the other drive shaft in the gearbox, creating a nested configuration where the first drive shaft passes through the second drive shaft. This nesting arrangement allows both motors to contribute torque to the same output path without requiring separate parallel transmission paths, thereby reducing overall device complexity and space requirements while maintaining high power transmission capability
Solution Approach 2:
The patent merges the torque transmission paths of two separate motors into a single gearbox output by having both drive shafts (one nested through the other) deliver torque to the same output element. This combining approach consolidates what would otherwise require two separate transmission systems into one integrated unit, reducing complexity while achieving the high power transmission needed for electric bicycles
2Ease of manufacture
If traditional separate drive shaft configuration is used for dual motors, then ease of manufacturing is improved, but space utilization deteriorates
Solution Approach 1:
The patent guides one drive shaft through the other drive shaft within the gearbox, creating a compact nested arrangement that significantly reduces the volume occupied by the drive device. This configuration allows both motors to be integrated into a single compact gearbox unit rather than requiring separate mounting spaces, thereby improving space utilization in the electric bicycle frame while maintaining manufacturability through standardized gearbox construction
Data Source
AI summary
A drive device for an electric bicycle has a gearbox with a first drive shaft, a second drive shaft and an output element. Torque of a first electric motor can be coupled into the gearbox via the first drive shaft. Torque of a second electric motor can be coupled into the gearbox via the second drive shaft. Torque can be removed from the gearbox via the output element. The first and second drive shafts run parallel to each other. One of the two drive shafts is guided through the other of the two drive shafts.