Ultrasonic Flow Meter Transducer Characterization via Supply Current
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Solution Overview
Problem
Ultrasonic flow meters face challenges in stability and producibility due to variations in transducer parameters over time and with temperature changes, which affect signal shape and noise sensitivity.
Innovation Solution
The flow meter design includes a signal generator with an active component and means to measure power supply currents, allowing for characterization of transducers and optimization of signal processing to reduce noise sensitivity and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transducer parameters are used directly for signal processing, then the flow meter can operate with simple circuitry, but the measurement precision deteriorates due to parameter variations over time and temperature
Solution Approach 1:
The patent applies preliminary action by characterizing transducer parameters before they are used in the flow meter. The transducer parameters are measured and stored in a non-volatile memory device before the flow meter operates, allowing the system to compensate for parameter variations without requiring complex real-time adjustment circuitry. This preliminary characterization enables simple circuitry to maintain high measurement precision despite temporal and temperature-related parameter changes.
2Reliability
If the acoustical signal strength is increased to reduce noise sensitivity, then the signal-to-noise ratio improves, but the device complexity increases due to requirements for impedance matching and stable transducer operation
Solution Approach 1:
The patent applies feedback by using the characterized transducer parameters to adjust the drive signal characteristics. The system measures the actual transducer response during operation and compares it with the expected response based on the pre-characterized parameters. Any deviations are fed back to the signal generator to adjust the drive signal, maintaining optimal impedance matching and signal strength without requiring complex fixed impedance matching circuitry. This feedback mechanism enables high noise immunity while keeping device complexity manageable.
3Measurement precision
If transducer parameters are stabilized to maintain consistent signal shape, then the measurement precision improves, but the adaptability deteriorates when operating with different fluid types and temperatures
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the signal processing parameters based on the specific fluid type and operating conditions. The system stores reference parameters for different fluid types and uses these references to adjust the transit time calculation parameters. When a different fluid is detected, the system automatically switches to the appropriate reference parameters, enabling high measurement precision across multiple fluid types and temperature conditions without sacrificing adaptability.
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 approach enables the production of stable and producible ultrasonic flow meters capable of transmitting high acoustical signals, while minimizing noise interference and maintaining accuracy across varying conditions.
Implementation Method 1
An ultrasound signal, typically of a frequency of a few megahertz and a duration of a few microseconds, is transmitted through the fluid from the first transducer to the second transducer
Implementation Method 2
a similar ultrasound signal is transmitted through the fluid in the opposite direction, i.e. from the second transducer to the first transducer
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
An ultrasonic flow meter having an ultrasonic transducer and a signal generator with an active component for generating electrical signals to the transducer. The flow meter includes means for measuring power supply currents to the active component. A method of measuring power supply currents to the active component the signal generator of an ultrasonic flow meter, the method comprising feeding a pulsating input signal or a single pulse input signal to the signal generator, and monitoring the current to the active component from one or more voltage supplies during and after the feeding of the input signal, thus obtaining one or more supply current signal. A method for characterizing an ultrasonic transducer by measuring power supply currents as described above, and determining directly from the obtained one or more supply current signal or from one or more resulting signals derived from the one or more obtained supply current signal one or more quantities useful for characterizing the transducer.