Pressure-Controlled CPAP Vent for Stable Bias Flow
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Solution Overview
Problem
Existing CPAP systems face issues with carbon dioxide accumulation due to fixed dimension washout vents, leading to increased bias flow that causes noise, drafts, and higher power consumption, as well as impacting the flow and humidity sources.
Innovation Solution
A patient interface with a valve system that regulates gas flow based on applied pressure, using a membrane with varying wall thickness and concave-convex portions to control flow path size, and an array of valves to maintain consistent flow rates across varying pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a patient interface includes a bias flow vent configured to deform with the application of pressure, then the orifice size can vary dynamically to match patient breathing patterns, but the structure becomes more complex compared to fixed orifice vents
Solution Approach 1:
The bias flow vent employs a dynamic orifice that changes size in response to pressure variations during breathing. The vent transitions from a static component to a dynamic one that automatically adjusts its opening based on real-time pressure conditions, enabling adaptation to varying breathing patterns without requiring complex electronic sensors or actuators.
Solution Approach 2:
The vent operates by changing the physical parameter of orifice size in response to pressure changes. As pressure increases during inhalation, the orifice expands to allow greater airflow; as pressure decreases during exhalation, the orifice contracts. This parameter-based control mechanism provides adaptive breathing support through simple physical responsiveness rather than complex control systems.
2Object-generated harmful factors
If the bias flow vent fully collapses under high pressure, then maximum flow restriction occurs, but the vent loses its ability to provide consistent bias flow during normal breathing
Solution Approach 1:
The vent design incorporates a structural configuration that prevents complete collapse before excessive pressure buildup occurs. The geometry and material properties are selected to ensure the orifice maintains a minimum open state even under high pressure conditions, cushioning against the harmful effect of complete closure while preserving bias flow delivery.
Solution Approach 2:
The vent converts the potentially harmful effect of pressure-induced collapse into a beneficial feature by designing the collapse characteristics to provide progressive flow restriction. Rather than abrupt closure, the controlled deformation under pressure creates a smooth transition that maintains breathing support while preventing over-pressurization, turning a mechanical limitation into a safety feature.
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
Reduces flow rate variance, minimizes noise and drafts, and decreases power consumption by maintaining a consistent bias flow, thus improving user comfort and system efficiency.
Implementation Method 1
The bias flow vent is configured to deform with the application of pressure but not fully collapse such that an orifice size defined by the bias flow vent can vary with the application of pressure
Data Source
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AI summary
A patient interface includes a mask body, an elbow, a connector and a conduit. Any one or more of the mask body, the elbow, the connector and the conduit includes a bias flow vent. The bias flow vent is configured to deform with the application of pressure but not fully collapse such that an orifice size defined by the bias flow vent can vary with the application of pressure.