Pressure-Controlled CPAP Exhaust Vent for Stable Bias Flow
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Solution Overview
Problem
Current CPAP systems face challenges in regulating bias flow consistently across a wide range of operating pressures, leading to noise and draft disturbances for patients and their bed partners, as well as increased power consumption due to varying flow rates.
Innovation Solution
The implementation of a bias flow control system featuring a valve with varying wall section thickness and lobe configurations that constricts the flow opening as pressure increases, maintaining a relatively constant bias flow rate by altering the flow path size in response to pressure changes, thereby reducing noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed dimension hole/array is used for washout vent, then carbon dioxide removal is enabled, but bias flow increases as CPAP pressure increases causing noise and draft disturbances
Solution Approach 1:
The patent applies the Dynamics principle by using a flexible membrane with varying wall thickness that dynamically adjusts the orifice area in response to pressure changes. As CPAP pressure increases, the membrane deflects to reduce the opening area, maintaining constant bias flow and eliminating noise/draft disturbances while preserving CO2 removal functionality.
Solution Approach 2:
The patent implementsParameter changes by varying the wall thickness of the membrane from 50 to 400 microns to create different stiffness regions. This allows the membrane to deflect at specific pressures, dynamically changing the effective orifice area to maintain constant flow rate across varying CPAP pressure conditions.
2Device complexity
If fixed dimension vent is used, then simple structure is maintained, but bias flow varies with pressure requiring larger flow source dimension and power consumption
Solution Approach 1:
The patent appliesSelf-service by designing a passive pressure-regulated membrane that automatically adjusts the orifice area in response to pressure changes without requiring external control systems, sensors, or power consumption. The membrane's varying wall thickness enables it to self-regulate flow based on the pressure differential across it.
3Stability of the object's composition
If varying wall section thickness is used to regulate flow, then constant bias flow is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implementsLocal quality by creating regions of different wall thickness (50-400 microns) within the membrane structure. This allows specific areas to be more compliant than others, enabling controlled deflection patterns that maintain constant flow while using conventional manufacturing tolerances for the varying thickness regions.
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 solution significantly reduces the variance in bias flow rate over normal operating pressures, minimizing noise and draft disturbances while optimizing energy usage in CPAP systems.
Implementation Method 1
The first end of the membrane has at least one concave portion and at least one convex portion and the first end of the membrane is configured to collapse inwardly to vary a flow path size in response to changes in pressure acting on the membrane
Data Source
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.