Quadrilateral Linkage Drive System for Elliptical Foot Motion
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Solution Overview
Problem
Existing drive systems for human-powered devices, such as bicycles and watercrafts, do not effectively minimize vertical foot motions while guiding feet in natural, elliptical motions, which can lead to inefficient energy transfer and user discomfort.
Innovation Solution
A drive system comprising two arm assemblies and two chain assemblies, where the motion of rotatable pedals drives the arm assemblies, which in turn drive chain assemblies, utilizing a quadrilateral linkage to minimize vertical motions and replicate natural walking motions, incorporating a frame, extension members, crank shaft, and sprocket mechanisms for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional single chain drive system is used, then the device complexity is reduced, but the ability to minimize vertical foot motions and guide feet in natural elliptical motions is insufficient
Solution Approach 1:
The drive system is segmented into two independent arm assemblies (first and second arm assemblies), each with its own chain assembly. This segmentation allows each arm to independently guide foot motion along an elliptical path while minimizing vertical movements, thereby improving ease of operation without requiring a single overly complex integrated mechanism.
Solution Approach 2:
The patent employs a nested structure where the quadrilateral linkage mechanism is integrated within each arm assembly, and the chain assembly is nested within the arm assembly structure. This nesting allows the complex elliptical motion guidance to be contained within a compact form factor, reducing the overall device complexity while maintaining the natural foot motion guidance capability.
2Loss of energy
If a quadrilateral linkage mechanism is implemented to minimize vertical foot motions, then energy transfer efficiency is improved, but the device complexity increases
Solution Approach 1:
The quadrilateral linkage mechanism is segmented and distributed across two separate arm assemblies rather than being implemented as a single complex mechanism. Each arm assembly contains its own quadrilateral linkage (first frame arm, first connecting arm, first main arm, first crank arm for the first arm; similarly for the second arm). This segmentation improves energy transfer efficiency by optimizing each arm's motion path while keeping individual arm assembly complexity manageable.
Solution Approach 2:
The patent merges the functions of motion guidance and drive transmission by integrating the quadrilateral linkage mechanism directly within each arm assembly structure. The linkage mechanism is combined with the arm assembly components (frame arms, connecting arms, main arms, crank arms) rather than being separate add-on elements, thereby improving energy transfer efficiency without proportionally increasing overall device complexity.
3Ease of operation
If two chain assemblies are used to drive the second chain assembly from the first, then the ability to guide feet in elliptical motions is enhanced, but the device complexity increases
Solution Approach 1:
The chain drive system is segmented into a first chain assembly and a second chain assembly, with each chain assembly associated with a specific arm assembly. The first chain assembly is driven by the first arm assembly, and the second chain assembly is driven by the second arm assembly. This segmentation enhances elliptical foot motion guidance by allowing independent optimization of each chain's path while maintaining a manageable configuration through modular organization.
Data Source
AI summary
A drive system comprises a frame, a first extension member, a second extension member, a crank shaft, a hub, a bearing, a cross shaft, a first arm assembly, a second arm assembly, a first chain assembly, a second chain assembly, a first rotatable pedal, a second rotatable pedal, and a steering column. The first arm assembly comprises a first frame arm, a first connecting arm, a first main arm, and a first crank arm. The second arm assembly comprises a second frame arm, a second connecting arm, a second main arm, and a second crank arm. The first arm assembly further comprises a first roller track assembly. The second arm assembly further comprises a second roller track assembly.