Eccentric Crank System for Uniform Torque Transfer
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Solution Overview
Problem
Conventional bicycle drive train systems do not provide uniform torque throughout the pedaling cycle, leading to inefficient energy transfer from the pedals to the wheel.
Innovation Solution
A crank system with a rotating bar and wheel gear assembly that aligns with the pedals at their zenith and nadir positions, ensuring consistent torque application and efficient energy transfer through a chain or belt mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional round chain wheel is used with moveable chain interface, then the structure is simple and easy to manufacture, but the torque transfer to the wheel is not uniform throughout the pedaling cycle
Solution Approach 1:
The patent employs an eccentric crank mechanism where the crank arm length is deliberately made asymmetric relative to the wheel radius. This asymmetry creates a geometric relationship where the crank rotates at a different effective radius than the wheel, transforming the periodic pedal force into a more uniform torque distribution across the wheel rotation cycle. The eccentricity factor (crank radius divided by wheel radius) is specifically designed to optimize this torque uniformity transformation.
2Adaptability or versatility
If the chain moveably interfaces with the teeth of the wheel, then the system allows for gear rotation and wheel movement, but the torque provided to the wheel is not uniform throughout the 360° cycle
Solution Approach 1:
The patent implements a dynamic geometric relationship between the crank and wheel through the eccentric mechanism. As the crank rotates, the changing angular position and radius create a dynamic transformation of force application points. This dynamic geometry ensures that the torque is continuously adjusted during the rotation cycle to maintain uniformity, rather than applying constant force at a fixed radius.
3Productivity
If uniform torque is provided during the 360° rotation cycle, then energy transfer efficiency is improved, but the device complexity increases due to the crank mechanism alignment requirements
Solution Approach 1:
The patent achieves uniform torque through parameter optimization of the eccentric crank mechanism. By carefully selecting the crank arm length, wheel radius, and their ratio (the eccentricity factor), the system transforms variable pedal torque into uniform wheel torque. This parameter-based solution provides uniform energy transfer efficiency without requiring complex control systems or additional actuation mechanisms.
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 system achieves more uniform and higher torque transfer to the wheel, enhancing pedaling efficiency and bicycle propulsion.
Implementation Method 1
a chain or belt mechanism
Implementation Method 2
wheel gear assembly adapted for rotating the wheel
Data Source
AI summary
A crank system of the present disclosure has a first crank assembly that is coupled to a first end of a first axle and coupled to a first pedal. The crank system further has a second crank assembly coupled to a second end of the first axle and a second pedal. Additionally, the crank system has a rotating wheel fixedly coupled to the first crank assembly and the second crank assembly such that as the first and second pedals are actuated by a user, the rotating wheel rotates thereby actuating a chain and inducing motion in a vehicle.