Breathing Apparatus Differential Pressure Sensor Linearization
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Solution Overview
Problem
Conventional ventilator systems face challenges in accurately determining low volumetric flow rates due to the quadratic dependence of differential pressure measurement methods, resulting in poor resolvability and potential lung tissue damage from high pressures or insufficient oxygen supply.
Innovation Solution
A ventilator apparatus with a differential pressure measuring apparatus featuring a ring-shaped flow channel and tangentially aligned measurement openings, which superimposes static and dynamic pressure components to produce an improved volumetric flow rate/differential pressure characteristic, approximating a linear relationship, enhancing resolvability at low flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional differential pressure measurement method with a simple stop or resistor is used, then the measurement arrangement is simple, but the resolvability at low volumetric flow rates is poor due to quadratic dependence
Solution Approach 1:
The patent changes the geometric parameters of the measurement path by introducing a ring-shaped flow channel with specific cross-sectional area and tangentially aligned measurement openings. This geometric modification transforms the pressure-flow relationship from quadratic to approximately linear, improving resolvability at low flow rates without adding complex external components
Solution Approach 2:
The patent introduces a tangential dimension for the measurement openings relative to the flow direction. By measuring pressure in a direction tangential to the flow rather than solely axial, the measurement path captures both static and dynamic pressure components, creating a new measurement dimension that improves low-flow detectability
2Quantity of substance
If pressure control is increased to ensure adequate oxygen supply, then oxygen supply is improved, but lung tissue damage may occur from high pressures
Solution Approach 1:
The patent enables precise feedback control by providing accurate real-time measurement of low volumetric flow rates through the improved differential pressure characteristic. The control system uses this precise feedback to adjust pressure and flow parameters, ensuring adequate oxygen delivery while preventing pressure levels that could cause lung tissue damage
Solution Approach 2:
The patent replaces coarse mechanical pressure control with precision control based on accurate differential pressure measurement. The improved measurement system allows the control system to make fine adjustments to pressure and flow, substituting imprecise mechanical control with precision control enabled by the enhanced sensing capability
3Measurement precision
If volumetric flow rate measurement accuracy is improved at low flow rates, then control precision is enhanced, but the differential pressure signal becomes smaller and harder to detect
Solution Approach 1:
The patent changes the functional relationship between differential pressure and volumetric flow rate from quadratic to approximately linear by modifying the measurement path geometry. This parameter change ensures that small changes in low volumetric flow rates produce proportionally larger changes in differential pressure, making the signals detectable while maintaining measurement accuracy
Solution Approach 2:
The patent introduces asymmetry in the measurement path design with respect to the flow direction by aligning measurement openings tangentially rather than symmetrically. This asymmetric configuration creates a measurement response that is more sensitive to low flow rates, where the tangential pressure component becomes significant relative to the static pressure
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 improved characteristic allows for precise control of volumetric flow rates, reducing the risk of lung damage and ensuring effective oxygen supply, even at low flow rates, by converting the differential pressure into digital values for accurate closed-loop control.
Implementation Method 1
the volumetric flow rate of the respiratory gas flowing through the differential pressure measurement path produces a differential pressure at measurement outputs
Implementation Method 2
the measurement openings are arranged in the flow channel in such a way that, in the case of a given flow direction, there is, on account of the wall friction between respiratory gas and flow channel occurring between the measurement openings, a lower static pressure drop at the first measurement output
Implementation Method 3
on account of the wall friction between respiratory gas and flow channel occurring between the measurement openings
Data Source
AI summary
A method and apparatus for breathing including a blower mounted in a specific part made of silicone, which reduces blower immissions and emissions. The conducting structure influences the flow of the respiratory gas in order to reduce interference when measuring the volumetric flow.