High-Frequency Ventilation Oxygen Control Dead Zone
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Solution Overview
Problem
High-frequency ventilation systems face challenges in maintaining stable oxygen concentration control due to the dead zone characteristics of proportional valves, leading to fluctuations in oxygen concentration, especially at settings below 40% or above 80%, which is critical for patient care.
Innovation Solution
The proposed ventilation adjustment method and system include determining gas flow rate control values and maintaining controllers on to ensure stable operation within dead zones, using a high-frequency pressure reduction module with a valve and turbine to generate oscillations, and an oxygen concentration detector for feedback adjustments, ensuring accurate oxygen concentration control within set ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional control method is used during high-frequency ventilation, then the proportional valve can respond quickly to pressure oscillation requirements, but the proportional valve cannot continuously provide stable flow rate when flow rate is close to dead zone, causing oxygen concentration fluctuation
Solution Approach 1:
The patent divides the control system into two independent proportional valves (first proportional valve for oxygen flow rate, second proportional valve for air flow rate) instead of using a single proportional valve. This segmentation allows each valve to operate in its optimal range and avoids the dead zone problem by distributing the control burden across multiple valves working in parallel.
Solution Approach 2:
The patent changes the control parameters by introducing separate control signals for two different proportional valves, each with its own flow rate control value. By independently adjusting the flow rates of oxygen and air through separate valves, the system can maintain stable mixed gas oxygen concentration even when individual valve flow rates approach their dead zones.
2Productivity
If the flow rate of proportional valve is controlled quickly during pressure oscillation, then high-frequency ventilation requirements are met, but oxygen concentration fluctuates when oxygen concentration is arranged below 40% or above 80%
Solution Approach 1:
The patent segments the gas flow control into two independent channels: one for oxygen (first proportional valve) and one for air (second proportional valve). Each channel can be controlled independently at high frequency, enabling the system to meet high-frequency ventilation requirements while maintaining precise oxygen concentration control through coordinated adjustment of both valves.
Solution Approach 2:
The patent implements a feedback control mechanism where the control device continuously monitors the mixed gas flow rate and oxygen concentration, then adjusts the flow rate control values of both proportional valves in real-time. This closed-loop feedback ensures that even during rapid pressure oscillations, the oxygen concentration remains within the required accuracy range.
3Device complexity
If a single proportional valve is used for flow rate control, then the system structure is simple, but the system cannot provide stable flow rate in dead zone range
Solution Approach 1:
The patent replaces a single proportional valve with two proportional valves working in parallel, each controlling a different gas source (oxygen and air). Although this increases the number of components, it eliminates the dead zone instability problem by allowing each valve to operate in its linear range and providing redundant control capability.
Solution Approach 2:
The patent merges the functions of two proportional valves into a unified control system where both valves work together to control the mixed gas flow rate. The control device coordinates both valves to achieve the desired total flow rate and oxygen concentration, combining their individual capabilities into a stable and reliable 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 approach stabilizes oxygen concentration control within the desired range, reducing fluctuations and maintaining accuracy to within 3% clinical requirements, even at challenging concentration settings.
Implementation Method 1
Both implementation methods generate high-frequency pressure oscillation
Implementation Method 2
Valve-controlled high-frequency ventilation needs to generate a pulsed gas flow by quickly opening and closing of the valve
Implementation Method 3
an oxygen concentration of the high-frequency ventilation system is also controlled by a flow rate of the proportional valve
Data Source
AI summary
A ventilation adjustment method and a high-frequency ventilation system, which ensure stable and accurate oxygen concentration control within an oxygen concentration setting range, are disclosed. The ventilation adjustment method includes: determining a first gas flow rate control value and a second gas flow rate control value according to a target output flow rate and an oxygen concentration setting value; determining whether the first gas flow rate control value falls into a first dead zone range and whether the second gas flow rate control value falls into a second dead zone range; if the first gas flow rate control value falls into the first dead zone range, maintaining a first gas flow rate controller turned on in an expiratory phase; and if the second gas flow rate control value falls into the second dead zone range, maintaining a second gas flow rate controller turned on in the expiratory phase.