Polycentric Knee Joint With Adjustment-Free Multi-Stage Air Cylinder

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional prosthetic knee air cylinders require frequent adjustments to accommodate different walking speeds, leading to discomfort or injury due to inadequate cushioning, and existing solutions are mechanically complex, costly, and lack adjustability for varying gait phases.

Innovation Solution

An adjustment-free multi-stage prosthesis air cylinder with a polycentric knee joint, featuring a piston assembly, multi-stage air pressure valve, and check valves that automatically adjust airflow resistance based on walking speed, providing a comfortable and stable cushioning effect without user intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional cushioning air cylinders are used for specific walking speeds, then cushioning function is provided for that speed, but multiple air cylinders are needed for different walking speeds

Engineering Contradiction:

Improveadaptability to different walking speedsVSAvoidnumber of air cylinders required

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The air cylinder is designed with multiple cushioning modes (first, second, and third modes) that provide different cushioning forces for different walking speeds. The same air cylinder structure serves multiple functions by switching between different cushioning modes, eliminating the need for multiple separate air cylinders for different speed conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The air cylinder incorporates adjustable cushioning modes that can be dynamically switched based on walking speed requirements. The cushioning force is made variable through different operational modes rather than fixed, allowing the system to adapt to changing conditions without physical replacement of components.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If cushioning mode is manually adjusted, then cushioning force can be adapted to walking speed, but user intervention is required and wrong settings may cause damage or injury

Engineering Contradiction:

Improveadaptability to different walking speedsVSAvoiduser intervention required

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The air cylinder automatically determines and switches between cushioning modes based on detected walking speed conditions without requiring user intervention. The system self-adjusts the cushioning force by selecting appropriate operational modes, eliminating the need for manual adjustment and preventing wrong settings that could cause injury.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system incorporates speed detection capability that provides feedback about the user's walking speed, which is then used to automatically select the appropriate cushioning mode. This closed-loop control ensures the cushioning force matches the actual walking conditions without user input.

Inventive Principle:

Principle #23Feedback

3Device complexity

If mechanical friction is used for swing phase control, then simplicity is maintained, but adjustment of walking speed is limited

Engineering Contradiction:

Improvesimplicity of control mechanismVSAvoidadjustment of walking speed

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention replaces pure mechanical friction control with a pneumatic system using an air cylinder that provides resistance during the swing phase. This pneumatic approach maintains relative simplicity while enabling adjustable walking speed control through the air cylinder's cushioning modes, offering better adaptability than mechanical friction alone.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 allows for comfortable walking at various speeds without frequent adjustments, offering a simple, cost-effective, and long-lasting prosthetic knee joint with precise movement, ensuring user safety and comfort across different gait phases.

Implementation Method 1

air can be compressed by the piston and be accumulated in the air cylinder. As an external forces applied to the piston is removed, the compressed air pushes the piston to slide backwardly

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

air can be compressed by the piston and be accumulated in the air cylinder. As an external forces applied to the piston is removed, the compressed air pushes the piston to slide backwardly

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

multi-stage air pressure valve that automatically adjusts airflow resistance based on walking speed

Methodology Applied

Scientific EffectAirflow resistance: Drag

Data Source

PatentUS11413168B2Polycentric knee joint having an adjustment-free multi-stage air cylinder

Publication Date: 2022.08.16 PRO LIMB INT

AI summary

A polycentric knee joint including an adjustment-free multi-stage prosthesis air cylinder. The air cylinder has an air cylinder body, a piston assembly slidably mounted on the air cylinder body, a first check valve mounted in the piston, and a multi-stage air pressure valve mounted inside a lower air way of the air cylinder body. The multi-stage air pressure valve automatically cushions movements of the piston assembly without being adjusted whenever a user of the prosthesis joint walks slowly or quickly, for improved comfort.