Venturi Flow Sensor Bypass Chamber for Low-Pressure Medical Airflow
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Solution Overview
Problem
Existing flow sensors for medical devices like ventilators and CPAP machines require significant pressure changes to measure airflow, which can be uncomfortable for patients and inefficient, and are often too expensive for many medical facilities.
Innovation Solution
A venturi flow sensor system with a tapered venturi region and a parallel bypass flow chamber that measures flow rate without causing a significant system-wide pressure change, using a micro-electromechanical system (MEMS) or other airflow sensor to detect flow without inducing discomfort or operational issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional flow sensors are used to measure airflow, then flow rate control can be achieved, but significant pressure changes are required which cause patient discomfort and reduce fan performance
Solution Approach 1:
The flow sensor system is segmented into a main chamber with venturi region and a separate bypass flow chamber. The bypass chamber contains the flow sensor and is connected to the main chamber through taps, allowing flow measurement to occur in a separate pathway rather than directly in the main airflow path.
Solution Approach 2:
The venturi region creates a localized pressure change only in specific areas (upstream and downstream of the venturi) rather than system-wide pressure changes. This localized pressure differential is sufficient to drive flow through the bypass chamber for measurement without affecting overall system pressure.
2Measurement precision
If expensive electronic flow controllers are used, then accurate flow rate control is achieved, but the cost becomes prohibitive for many medical facilities
Solution Approach 1:
The system uses pneumatic principles through the venturi effect to create pressure differentials that drive flow through the bypass chamber. This eliminates the need for expensive electronic flow controllers by using passive fluid dynamic mechanisms for both flow measurement and control.
Solution Approach 2:
The venturi flow sensor system is self-regulating through the natural pressure differentials created by the venturi effect. The localized pressure changes automatically drive flow through the bypass chamber proportional to the main airflow, providing self-service flow measurement without requiring expensive external control systems.
3Difficulty of detecting and measuring
If adequate pressure drop is created for flow sensing, then flow detection is enabled, but system-wide pressure changes occur which are detrimental to device operation
Solution Approach 1:
The flow sensing function is extracted from the main airflow path and placed in the bypass flow chamber. The bypass chamber is connected through taps upstream and downstream of the venturi region, allowing the sensor to measure flow based on pressure differentials without creating significant pressure drop in the main system.
Solution Approach 2:
The bypass flow chamber acts as an intermediary pathway that translates the localized pressure differential from the venturi region into measurable flow through the bypass chamber. This intermediary system allows flow detection without requiring significant pressure drop in the main airflow path.
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
Enables accurate airflow measurement in medical devices without significant pressure changes, improving patient comfort and device performance while being cost-effective for use in resource-constrained medical facilities.
Implementation Method 1
The venturi region creates a local increase in flow velocity, which in turn creates a local change in static pressure
Data Source
AI summary
A venturi flow sensing method, system, and apparatus. A tube or chamber may be tapered from a larger to smaller diameter to create a venturi region within the tube or chamber. The venturi region causes a local increase in flow velocity. The change in velocity creates a local change in pressure which is, in turn, used to drive flow through a parallel bypass tube or chamber. Inside this bypass, a flow sensor can be located, and in some cases, a pressure sensor as well. The flow is then either exhausted back into the original tube or the bypass tube may alternatively dead end. In either case, flow can be measured without causing a significant overall pressure drop in the system.