Fluidic Oscillator Flow Meter Using Piezoelectric Sensors
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Solution Overview
Problem
Existing flow meters are inaccurate, prone to noise, and have limited operating ranges for temperature and pressure, particularly failing to measure non-conductive fluids like oils and gases, and are complex and costly to assemble.
Innovation Solution
A feedback type hydrodynamic oscillator flow meter utilizing a meter body with a nozzle, flow conditioner, and bluff body, combined with piezoelectric sensor assemblies and feedback paths, operating on the Coanda effect to measure fluid flow independently of fluid properties, with noise cancellation and robust construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnetic field sensors are used to measure oscillation frequency, then the flow meter can detect fluid flow, but it cannot measure non-conductive fluids like oils and gases and becomes clogged by magnetic particles
Solution Approach 1:
The patent replaces magnetic field sensors with piezoelectric sensors that detect pressure fluctuations caused by fluid oscillation. This mechanical substitution eliminates the requirement for fluid electrical conductivity, enabling measurement of oils, gases, and other non-conductive fluids without magnetic particle interference or clogging issues
Solution Approach 2:
The patent introduces piezoelectric sensors as an intermediary measurement mechanism that converts fluid oscillation into electrical signals through pressure detection rather than magnetic field interaction. This intermediary approach allows universal fluid measurement while avoiding direct magnetic field exposure that causes clogging
2Measurement precision
If temperature sensitive sensors are used to sense oscillatory flow, then the sensor can detect fluid fluctuations, but it requires external power and complicated electronic circuitry with limited operating range
Solution Approach 1:
The piezoelectric sensors generate electrical signals directly from the mechanical stress of fluid oscillation without requiring external power supply. This self-service capability eliminates the need for external power and complex electronic circuitry, simplifying the device while maintaining measurement precision across wide temperature and pressure ranges
Solution Approach 2:
The patent utilizes the piezoelectric effect where mechanical stress (from fluid oscillation) directly generates electrical charge. This parameter transformation from mechanical to electrical domain enables precise detection without external power, contrasting with temperature-sensitive sensors that require active heating and complex compensation circuits
3Measurement precision
If differential pressure sensors are used to measure oscillation frequency, then the flow rate can be determined, but the sensing ports and tubes add hydraulic capacitance causing delay and signal attenuation
Solution Approach 1:
The patent extracts the sensing function directly into the main flow passage using piezoelectric sensors that detect pressure fluctuations at the oscillation source. This eliminates the need for separate sensing ports, tubes, and diaphragms that introduce hydraulic capacitance and time delays in differential pressure measurement systems
Solution Approach 2:
The patent segments the sensing function from the traditional differential pressure measurement system by placing piezoelectric sensors directly in the flow path. This segmentation removes the intermediate tubing and ports that create hydraulic capacitance, enabling real-time detection of oscillation frequency without signal attenuation or delay
4Measurement precision
If inductive sensors with coils and movable core are used, then the oscillatory frequency can be sensed, but the device becomes sensitive to noise and performs poorly at low and high frequencies
Solution Approach 1:
The patent replaces inductive sensors with piezoelectric sensors that directly convert mechanical pressure fluctuations into electrical signals. This substitution eliminates the movable core and coil arrangement that are inherently sensitive to electromagnetic noise and have limited frequency response, achieving superior noise immunity and broader frequency measurement capability
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 flow meter provides accurate, noise-insensitive measurements across a wide range of fluid types and conditions, reducing costs by 25-50% and simplifying construction, with piezoelectric sensors offering a wide temperature and pressure range without the need for external power.
Implementation Method 1
at least one sensor assembly comprising a sensor body having at least two sensing segments, leads extending from the sensing segments to a metering device located outside the meter body
Implementation Method 2
A feedback type hydrodynamic oscillator flow meter utilizing a meter body with a nozzle, flow conditioner, and bluff body, combined with piezoelectric sensor assemblies and feedback paths, operating on the Coanda effect to measure fluid flow
Data Source
AI summary
The present invention discloses a feedback type, hydrodynamic oscillator flow meter for measuring the flow of fluids such as gas, air, water and oil, flowing through a conduit. This flow meter gives very accurate measurements over a long period of time since piezoelectric sensors are employed. The working principle of this flow meter is based on the Coanda Effect, which guides the flowing fluid to pass through two feedback paths (103, 129) alternatively and a linear relationship is obtained between the fluidic oscillation frequency and the flow rate.