Flow Regulation Vent for CPAP Noise and Gas Wastage
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Solution Overview
Problem
Existing vent valves in CPAP systems are inefficient at higher pressures, leading to excessive noise and gas wastage, and fail to maintain adequate gas flow at lower pressures, limiting the pressure range and patient compliance due to incompatible vent characteristics with different masks and control algorithms.
Innovation Solution
A flow regulation vent with a movable portion pivotally connected to a fixed portion, using a spring force to adjust the gas flow area based on pressure, allowing for tailored flow rate curves across a specified pressure range, and optionally incorporating a strain gauge for flow measurement and a flexible flap to manage exhalation gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large vent size is selected to achieve adequate gas washout flow at low pressures, then gas washout efficiency is improved, but noise level increases excessively at higher pressures
Solution Approach 1:
The vent incorporates a movable portion that dynamically adjusts the gas flow area based on pressure changes. At low pressures, the movable portion remains in a relaxed position maintaining a large flow area for adequate gas washout. At higher pressures, the movable portion pivots to a pressurized position reducing the flow area to minimize noise, thus adapting the vent characteristics to different operating conditions.
2Reliability
If a large vent size is selected to ensure adequate gas flow at low pressures, then gas washout is improved, but gas wastage increases at higher pressures
Solution Approach 1:
The vent dynamically adjusts its flow area in response to pressure changes. At low pressures, the large flow area ensures adequate gas washout. At higher pressures, the movable portion reduces the flow area, preventing excessive gas flow and thereby reducing gas wastage of treatment gas and humidified gas.
3Device complexity
If a fixed vent size is used, then device complexity is minimized, but the vent cannot maintain adequate flow across a wide pressure range
Solution Approach 1:
The vent includes a movable portion connected by a hinge that pivots between relaxed and pressurized positions based on pressure changes. This dynamic structure allows the vent to maintain adequate flow characteristics across a wide pressure range (4 cm H2O to 30 cm H2O), improving adaptability while adding only minimal structural complexity.
Solution Approach 2:
The vent changes its flow area parameter in response to pressure changes. The movable portion's position changes with pressure, dynamically adjusting the flow area to maintain optimal flow characteristics across different pressure levels, enabling compatibility with various masks and control algorithms.
4Speed
If the movable portion is made highly flexible to respond to pressure changes, then flow regulation responsiveness is improved, but manufacturing precision becomes more difficult
Solution Approach 1:
The movable portion is constructed from a flexible material such as a thin sheet of stainless steel or plastic that can pivot in response to pressure changes. This flexible construction allows responsive flow regulation while using common manufacturing techniques for forming and pivoting flexible components, balancing responsiveness with manufacturability.
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 solution reduces operating noise, gas wastage, and rebreathing of CO2, enhances patient compliance by maintaining effective gas flow across a wide pressure range, and allows for faster air pressure rise, making CPAP treatment more effective.
Implementation Method 1
a spring force biased movable portion connected by a hinge to the fixed portion
Implementation Method 2
the pressurized gas offsets the spring force to pivot the movable portion to the fully pressurized position adjacent the fixed portion
Data Source
AI summary
A flow regulation vent includes a fixed portion adapted to engage a gas supply conduit and a spring force biased movable portion connected by a hinge to the fixed portion and flowingly connected to the pressurized gas supply. The fixed portion includes a gas flow orifice. The movable portion is pivotally movable between 1) a relaxed position, whereby at a specified minimum operating pressure, the movable portion is pivoted by the spring force away from the fixed portion to a position to establish a first gas washout flow area between the movable portion and the gas flow orifice; and 2) a fully pressurized position, whereby at a specified maximum operating pressure, the pressurized gas offsets the spring force to pivot the movable portion to a position adjacent the fixed portion to establish a minimum gas washout flow area between the movable portion and the gas flow orifice.