Cavity Array Gas Flow Sensor Using MEMS Pressure Mapping
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Solution Overview
Problem
Existing methods for determining the speed and direction of gas flow, such as mechanical and acoustical anemometers, face issues with wear and tear, cost, and power consumption, necessitating a more reliable and cost-effective solution.
Innovation Solution
A monitoring device with a cavity assembly and micro-electromechanical systems (MEMS) pressure sensors that measure absolute pressure to determine gas flow speed and direction, using logarithmic pressure differences and pressure sensor rankings mapped via pre-determined mappings or lookup tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical anemometers are used to measure gas flow speed and direction, then cost is reduced, but reliability deteriorates due to wear and tear of moving parts
Solution Approach 1:
The patent replaces the mechanical anemometer system with a pressure sensor-based measurement system. Multiple pressure sensors are positioned at different locations on a probe to detect pressure differences caused by gas flow. This substitution eliminates moving parts while maintaining measurement capability, resolving the contradiction between cost and reliability.
2Reliability
If ultrasonic anemometers are used to measure gas flow speed and direction, then reliability is improved by eliminating moving parts, but cost and power consumption increase
Solution Approach 1:
The patent substitutes ultrasonic transducers with pressure sensors for flow measurement. Pressure sensors are simpler, more cost-effective devices that can detect flow-induced pressure differences without requiring complex ultrasonic transmission infrastructure, thereby reducing cost while maintaining the non-mechanical reliability advantage.
Solution Approach 2:
The patent changes the measurement parameter from ultrasonic time-of-flight to static pressure difference. By measuring pressure at multiple points and calculating gradients, the system achieves flow velocity measurement using simpler, lower-cost pressure sensors instead of expensive ultrasonic transducers.
3Reliability
If ultrasonic anemometers are used to measure gas flow speed and direction, then moving parts are eliminated, but power consumption increases
Solution Approach 1:
The patent replaces the power-intensive ultrasonic transmission system with passive pressure sensing. Pressure sensors require minimal power to operate compared to ultrasonic transducers that must continuously generate and receive acoustic waves, thereby reducing power consumption while maintaining the moving-parts-free reliability advantage.
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
Provides accurate and reliable measurements of gas flow speed and direction without moving parts, offering a cost-effective and durable alternative to existing technologies.
Implementation Method 1
The pressure sensors, which may be a micro-electrical mechanical systems (MEMS) based sensor, may measure the absolute pressure of the gas within each of the cavities
Data Source
AI summary
A monitoring device includes a cavity assembly with a plurality of cavities. Openings of the plurality of cavities are distributed about a flow-facing surface of the cavity assembly. A gas pressure sensor is disposed within each of the cavities, and is configured to measure an absolute pressure of a gas flow which flows past the monitoring device. Gas pressure measurements from the pressure sensors may be used to determine a flow speed and a flow direction of the gas flow. More specifically, a mapping may be used to map the logarithm of the difference between the maximum and minimum pressures to a flow speed. Further, a lookup table may be used to map a pattern of pressure measurements to a flow direction.