Hydraulic Knee Joint Valve for Sensorless Damping Control

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Solution Overview

Problem

Conventional prosthesis knee joints with hydraulic valves require complex and costly sensor systems to manage different phases of the gait cycle, leading to increased size, weight, and energy consumption, while also being prone to errors.

Innovation Solution

A valve design where the influx exerts a total force perpendicular to the valve body in the first position, blocking or reducing fluid connection between the extension and flexion chambers, and allowing fluid flow only when the knee is almost fully stretched, eliminating the need for sensors by using a combination of a one-way valve, a switching pin, and a spring mechanism to control the valve's position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional sensor systems are used to manage different phases of the gait cycle, then the knee joint can provide appropriate damping control, but the device becomes larger, heavier, more expensive, and more complex

Engineering Contradiction:
Improvedamping control reliabilityVSAvoidsensor system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The valve body automatically detects knee extension state through hydraulic pressure generated by knee movement itself, eliminating the need for external sensors. The system uses its own operating fluid and pressure changes to trigger valve switching, achieving self-service control without additional electronic components

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent uses hydraulic pressure generated during knee movement to automatically switch the valve between closed and open positions. The influx channel directs fluid to exert force on the valve body, utilizing hydraulic principles to replace electronic sensing and control systems

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Measurement precision

If multiple sensors are used to detect gait phase and knee extension, then accurate control is achieved, but the knee joint becomes larger, heavier, and requires more energy

Engineering Contradiction:
Improvegait phase detection accuracyVSAvoidknee joint weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The system uses the hydraulic fluid already present in the knee joint for both damping control and position sensing. The fluid pressure generated during normal operation automatically triggers valve switching, eliminating the need for separate sensors and their associated power requirements

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The hydraulic serving fluid performs multiple functions: providing damping force, enabling valve switching, and serving as the sensing medium. This multi-functionality eliminates the need for additional components for detection and control

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If sensors and electronic components are used for valve control, then precise gait phase detection is possible, but manufacturing costs increase

Engineering Contradiction:
Improveknee extension detection accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The valve switching mechanism uses hydraulic pressure from the knee joint's own operation to trigger state changes. This eliminates expensive electronic sensors and control systems, significantly reducing manufacturing costs while maintaining functional precision

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces electronic sensing and control systems with a purely mechanical-hydraulic switching mechanism. The valve body responds directly to hydraulic pressure changes through mechanical force, eliminating the need for electronics and reducing manufacturing complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This design simplifies the system, reduces manufacturing costs, and ensures stable and safe movement by providing appropriate resistance and damping, eliminating the need for electronic components and sensors, while allowing for adjustable flow resistance.

Implementation Method 1

a fluid that occurs through the inflow exerts a total force on the valve body

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

fluid connection between an extension chamber and a flexion chamber of the hydraulic system

Methodology Applied
Scientific EffectHydraulic force transmission: Hydraulic Press

Implementation Method 3

a valve body that is blocked by moving along a layer in a first position in which the fluid connection is blocked, and in one The second position is brought in, in which the fluid connection is open

Methodology Applied
Scientific EffectMechanical blocking: Valve

Implementation Method 4

The flow is preferably equipped with a one-way valve to prevent the fluid from the fluid from the fluid to prevent the chamber of extension

Methodology Applied
Scientific EffectOne-way flow control: Valve

Implementation Method 5

The valve preferably has a switching spring that is set up, a force from the switching pin to the valve body is transferred when the switching pin is operated

Methodology Applied
Scientific EffectElastic restoring force: Spring

Implementation Method 6

there is an increased friction between the valve body and the housing wall on which it lies. As a result, a holding force arises that counteracts a shift in the valve body

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3793486B1Valve and prosthetic knee joint having such a valve
Publication Date: 2022.12.07 OTTOBOCK SE & CO KGAA
  • EP3793486B1 patent drawingFigure 1~2
  • EP3793486B1 patent drawingFigure 3~4
  • EP3793486B1 patent drawingFigure 5~6

AI summary

The invention relates to a valve (20) with an inlet (28), an outlet (30), which is connected to the inlet (28) by a fluid connection, and a valve body (26) which, by displacement along a displacement direction, can be brought to a first position, in which the fluid connection is blocked, and to a second position, in which the fluid connection is opened, wherein the inlet (28) is configured and arranged in such a way that a fluid entering through the inlet (28) applies a total force to the valve body (26), which total force at least also acts in a force direction perpendicular to the displacement direction when the valve body (26) is located in the first position.