Modular Stator Assembly for Compact High-Torque Bicycle Motors
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Solution Overview
Problem
Electric motors for bicycles face challenges in providing high torque at low rotational speed while maintaining a compact size, minimizing noise, and ensuring compatibility with the bicycle's design, particularly at the bottom bracket assembly.
Innovation Solution
A stator design featuring separate teeth with connectors and a central module with connecting frames that allow for easy assembly and reduced bulk, using a star or Delta coil configuration, and a method of manufacturing involving winding coils around bobbins and connecting them via clip-fastening, which enables high torque production and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor is designed to provide high torque at low rotational speed, then the motor produces effective assistance for cycling, but the motor size increases making it difficult to install in the bottom bracket assembly
Solution Approach 1:
The stator is divided into separate modular components: individual teeth with coils that can be independently assembled onto a central module. This segmentation allows for optimized torque production through strategic coil placement while maintaining a compact overall structure that fits bicycle bottom bracket constraints.
Solution Approach 2:
The connecting frames are nested within the central module structure, with connecting tabs extending radially and inserting into connectors on the teeth. This nested arrangement consolidates multiple functional elements into a compact configuration, reducing overall motor volume while maintaining torque-generating components.
2Force
If the electric motor is designed to provide high torque, then effective assistance is achieved, but the noise produced by the motor increases
Solution Approach 1:
The segmented tooth structure with individually wound coils allows for optimized magnetic field distribution that reduces motor noise while maintaining high torque output. The separation of coil assemblies enables precise positioning for noise reduction without sacrificing torque-generating capability.
3Strength
If traditional stator assembly methods are used, then structural integrity is maintained, but assembly time increases reducing mass production capability
Solution Approach 1:
The stator is segmented into pre-assembled modular units (teeth with coils) that can be independently manufactured and then quickly connected to the central module using the connecting frames and tabs system. This modular approach maintains structural integrity through designed connection interfaces while enabling parallel manufacturing and rapid assembly for mass production.
Solution Approach 2:
The coils are pre-wound around the teeth and the connecting frames are pre-positioned on the central module before final assembly. This preliminary preparation of components allows for rapid final assembly while ensuring proper structural connections, thereby increasing productivity without compromising structural integrity.
4Volume of moving object
If the motor is designed for compact size to fit bicycle bottom bracket, then installation compatibility is improved, but torque production capability is reduced
Solution Approach 1:
The connecting frames are positioned at specific radial locations on the central module, with connecting tabs extending to precise positions where they insert into connectors on the teeth. This localized optimization of component placement maximizes the efficiency of the compact structure, ensuring high torque production within the constrained volume of the bottom bracket assembly.
Data Source
AI summary
The present invention relates to a stator for an electric motor, comprising a plurality of separate teeth comprising a first connector and a second connector, a plurality of coils which are configured to be wound respectively around the plurality of separate teeth, a first end of the wire of the winding being configured to be positioned in the first connector and a second end of the wire of the winding being configured to be positioned in the second connector, a central module configured to receive the separate teeth, said central module comprising connecting frames comprising connecting tabs extending radially and configured to be inserted in a first connector or in a second connector of a separate tooth, the connecting frames being configured to provide electrical connections between the coils.