Thermal Flow Sensor Signal Correction for Pulsating Air
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermal air flowmeters face challenges in accurately detecting air flow rates during pulsation, particularly in reverse flow regions where air flow direction repeatedly changes, leading to reduced accuracy and waveform distortion.
Innovation Solution
A physical quantity detection device equipped with a thermal flow sensor and a signal processing device that includes a direction determination unit, increase/decrease determination unit, correction factor storage, correction factor selection unit, and signal correction unit, which selects and applies specific correction factors based on the flow direction and rate changes to improve signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a thermal air flowmeter is used to detect air flow rate during pulsation with reverse flow, then the detection responsiveness is improved, but the measurement precision deteriorates in reverse flow regions
Solution Approach 1:
The patent applies parameter changes by selecting different correction factors (first factor through fourth factor) based on the flow state parameters (forward/reverse flow direction and increase/decrease trend). This allows the system to adapt the correction approach according to the specific pulsation phase, improving measurement precision across different flow conditions while maintaining the responsive detection capability of the thermal flow sensor.
2Measurement precision
If correction factors are applied to improve detection accuracy during pulsation, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements dynamics by dynamically selecting correction factors based on real-time flow conditions detected by the thermal flow sensor. The correction factor selection unit adjusts which factor (first through fourth) is applied according to the current pulsation phase, creating a dynamic correction system that improves precision without requiring permanently complex hardware modifications.
Solution Approach 2:
The system changes the correction parameter (selecting from four different correction factors) based on detected flow conditions. This parameter-based approach allows a single device to handle multiple flow scenarios with high precision without increasing physical complexity, as the complexity is managed through software-based parameter selection rather than hardware multiplication.
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 enhances the accuracy of air flow rate detection during pulsation, including reverse flow regions, by correcting the detection signal using appropriate correction factors, thereby improving the reliability and responsiveness of the flow rate measurement.
Implementation Method 1
a thermal flow sensor that is configured to detect a forward flow and a reverse flow of air
Data Source
AI summary
The present disclosure provides a physical quantity detection device and a signal processing device capable of improving accuracy in detecting an air flow rate by a thermal flow sensor during pulsation of air including a reverse flow region. The signal processing device 200 includes a direction determination unit 210, an increase/decrease determination unit 220, a correction factor storage unit 230, a correction factor selection unit 240, and a signal correction unit 250. The direction determination unit 210 determines a forward flow or a reverse flow of the air based on a detection signal DS of the thermal flow sensor. The increase/decrease determination unit 220 determines an increase or decrease in flow rate of the air based on the detection signal DS. The correction factor storage unit 230 stores first to fourth factors used for correction of the detection signal DS. The correction factor selection unit 240 selects any one of the first to fourth factors as a correction factor CF based on determination results of the direction determination unit 210 and the increase/decrease determination unit 220. The signal correction unit 250 corrects the detection signal DS by using the correction factor CF. The correction factor selection unit 240 selects the first factor in a case of the forward flow of the air and the increase in flow rate, selects the second factor in a case of the reverse flow and the increase in flow rate, selects the third factor in a case of the forward flow and the decrease in flow rate, and selects the fourth factor in a case of the reverse flow and the decrease in flow rate.