E-Bike Drive Assembly With Overlapping Freewheels for Compact Torque Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric bicycle drive assemblies are bulky and require complex manufacturing, lacking a compact design that allows for optimal ergonomic geometry and efficient torque transmission.
Innovation Solution
A drive assembly for electric bicycles featuring two coaxially overlapping freewheels, a bi-directional freewheel providing torque transmission and bearing functions, and a trapped roller freewheel for reliable operation, integrated with a freewheel carrier and needle bearings for a compact and robust design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separate freewheel arrangements are used, then reliable torque transmission is achieved, but the drive assembly becomes bulky and requires complex manufacturing
Solution Approach 1:
The patent combines two separate freewheels (first freewheel for motor torque, second freewheel for pedal torque) into a single integrated drive assembly with coaxial arrangement. This merging reduces the number of separate components and simplifies manufacturing while maintaining reliable torque transmission for both motor and pedal power sources.
Solution Approach 2:
The integrated drive assembly serves multiple functions: it transmits motor torque through the first freewheel, pedal torque through the second freewheel, and provides bearing support through the bi-directional freewheel mechanism. This multi-functionality reduces the overall complexity by consolidating what would otherwise require separate components.
2Reliability
If traditional separate freewheel arrangements are used, then reliable torque transmission is achieved, but the drive assembly becomes bulky
Solution Approach 1:
The patent arranges the first and second freewheels coaxially with overlapping axial positions, nesting them within the same radial space. This nested arrangement significantly reduces the axial volume of the drive assembly compared to separate freewheel arrangements, making the overall drive unit more compact while maintaining reliable torque transmission.
Solution Approach 2:
The patent transitions from a sequential arrangement of freewheels to a coaxial overlapping arrangement, utilizing the radial dimension more efficiently. By positioning freewheels at different radial positions but overlapping in the axial direction, the design reduces axial length while maintaining functional separation.
3Stability of the object's composition
If cranks are positioned far apart, then stable support is achieved, but ergonomic comfort deteriorates
Solution Approach 1:
The coaxial nesting of the first and second freewheels reduces the axial width of the drive assembly, allowing the cranks to be positioned closer together. This nested configuration maintains stable support through the bearing functions while enabling a smaller Q-factor for improved ergonomic comfort.
Data Source
AI summary
A drive assembly of an electric bicycle includes (i) an output element which is configured to transmit a motor torque, (ii) an output shaft, (iii) a first freewheel, and (iv) a second freewheel. The first freewheel and the second freewheel are disposed on the output shaft. The first freewheel and the second freewheel are disposed coaxially and at least partially overlapping in the axial direction.