Brushless Bicycle Propulsion With Distributed Two-Stage Reduction
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Solution Overview
Problem
Existing electric bicycle motors face challenges with size, weight, and cost due to limitations in reduction stages, which affect torque and efficiency, especially in mountainous terrain, and mid-drive systems increase complexity and weight.
Innovation Solution
A brushless electric motor with a support body and a first and second speed reducer stage, transferring power through non-coaxial small wheels, reducing overall dimensions and weight while maintaining high power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If planetary reduction stages are added to the motor, then torque is improved, but device complexity and volume increase
Solution Approach 1:
The transmission system is divided into two independent stages: a first planetary reduction stage integrated with the motor for torque multiplication, and a second chain-driven gear reduction stage for additional torque multiplication. This segmentation allows each stage to be optimized independently and distributed across different spatial locations (motor hub and bottom bracket), reducing the complexity burden on any single component while achieving cumulative torque improvement.
2Force
If planetary reduction stages are added to the motor, then torque is improved, but the overall volume of the motor increases
Solution Approach 1:
The second reduction stage is positioned at the bottom bracket rather than within the motor hub, utilizing the vertical and longitudinal dimensions of the bicycle frame. This spatial redistribution moves the bulk of the transmission mechanism out of the constrained motor volume while maintaining the torque multiplication function, effectively decoupling torque generation from motor volume.
3Speed
If mid-drive systems are used, then optimal motor rotation speed is achieved, but device complexity and weight increase
Solution Approach 1:
The motor hub assembly serves multiple functions: it provides the primary planetary reduction stage for torque multiplication, houses the motor control electronics, and acts as the mounting point for the second reduction stage at the bottom bracket. This multi-functionality consolidates several subsystems into a single integrated unit, reducing overall device complexity while maintaining the benefits of mid-drive operation.
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
The solution results in a compact, lightweight, and cost-effective electric propulsion system with improved torque and power efficiency, suitable for various terrains.
Implementation Method 1
brushless electric motor with a support body and a first and second speed reducer stage
Implementation Method 2
first and second speed reducer stage, transferring power through non-coaxial small wheels
Data Source
AI summary
An apparatus for the electric propulsion of a vehicle, in particular of a human-powered vehicle, preferably in the form of a bicycle or the like, comprising a support body, electric propulsion means for the forwarding actuation of the vehicle, preferably in the form of an electric motor, in particular of the brushless type, having a corresponding rotatable shaft for outputting the power generated by the same electric actuation means, or motor, and means for outputting the power generated by the electric propulsion apparatus, in particular comprising means for engaging, or meshing, with said operative connection means of the transmission means of the vehicle, i.e., with an elongated and closed-loop member, or articulated link chain. Said means for transferring the power generated by said electric actuation means, or motor, to said means for outputting the power generated by the electric propulsion apparatus comprise a first and a second speed reducer stage.