Ultrasonic Flow Rate Measuring Device Reference Voltage Adjustment
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Solution Overview
Problem
Conventional flow rate measuring devices using ultrasonic transducers face accuracy issues when measuring gases with significantly different waveforms from air, leading to incorrect detection of zero cross points and poor measurement of propagation time and flow rate.
Innovation Solution
A flow rate measuring device with a reference-voltage changing part that adjusts the reference voltage as a linear function of the amplifier's amplification degree, ensuring stable detection of zero cross points for various gases by maintaining the reference voltage at the center point between peak voltages, and incorporating a learned data storage part to calculate optimal reference voltages for different gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed reference voltage is used for comparison in the reference comparator, then the device structure remains simple, but measurement accuracy degrades when measuring gases with waveforms significantly different from air due to incorrect zero cross point detection
Solution Approach 1:
The reference voltage is changed from a fixed value to a dynamic value that varies according to the amplification degree. The reference-voltage changing part adjusts the reference voltage based on the amplification degree from the amplifier, allowing the reference voltage to adapt to different gas types and waveform characteristics, thereby maintaining accurate zero cross point detection across various measurement conditions.
Solution Approach 2:
The patent changes the parameter of reference voltage from a constant fixed value to a variable value that depends on the amplification degree. By establishing a functional relationship between reference voltage and amplification degree (reference voltage = k × amplification degree + b), the system can adjust the reference voltage parameter to match different gas measurement conditions, resolving the accuracy issue without requiring complex additional hardware.
2Measurement precision
If the reference voltage is adjusted manually for each gas type, then measurement accuracy can be maintained, but the ease of operation deteriorates due to manual intervention requirements
Solution Approach 1:
The system performs self-adjustment of the reference voltage based on the amplification degree automatically obtained during signal processing. The reference-voltage changing part uses the amplification degree information already available in the measurement system to dynamically adjust the reference voltage, eliminating the need for manual intervention while maintaining measurement accuracy across different gas types.
Solution Approach 2:
The system establishes a feedback mechanism where the amplification degree information is fed back to the reference-voltage changing part, which then adjusts the reference voltage accordingly. This closed-loop approach ensures that the reference voltage automatically adapts to different measurement conditions based on the actual signal characteristics, maintaining accuracy without user intervention.
3Measurement precision
If device-to-device variations are not accounted for, then manufacturing precision remains high, but measurement precision deteriorates due to variations in zero cross point detection across different devices
Solution Approach 1:
The patent introduces device-specific parameters (k and b) in the linear relationship between reference voltage and amplification degree (reference voltage = k × amplification degree + b). These parameters can be calibrated for each device during manufacturing or initial setup, allowing the system to compensate for device-to-device variations. This approach maintains high manufacturing precision while achieving consistent measurement precision across different devices.
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
This solution stabilizes the measurement of propagation time and flow rate for various gases, preventing degradation in measurement accuracy and accounting for device-to-device variations.
Implementation Method 1
first ultrasonic transducer 22 and second ultrasonic transducer 23 disposed on flow path 21... transmitting/receiving an ultrasonic signal
Data Source
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AI summary
To measure the propagation time of an ultrasonic signal, the flow rate measuring device of the present invention has amplifier (6) for amplifying a received signal, reference-voltage changing part (11), reference-voltage setting part (12), and reference comparator (7) for comparing between the received signal waveform and reference voltage. Reference-voltage changing part (11) changes the reference voltage according to the amplification degree of the amplified waveform of the received signal in amplifier (6). Comparing the changed reference voltage with the received signal waveform enhances stability in calculation of the propagation time. This prevents measurement accuracy of the flow velocity and the flow rate of fluid to be measured from degradation.