Ultrasonic Flow Metering Waveform Control
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Solution Overview
Problem
Ultrasonic time-of-flight flow meters face issues with induced ringing voltages, which cause unwanted coupling, interference, and increase the minimum required separation distance between transducers, leading to larger and less efficient flow meters.
Innovation Solution
The method involves driving ultrasonic transducers with a first waveform configured to cause oscillation, followed by a second waveform with a discontinuity that maintains the voltage within a predetermined range, reducing coupling and interference by filtering the oscillations and allowing for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic transducers are driven with continuous oscillation to maintain signal strength, then measurement sensitivity is improved, but induced ringing voltages cause unwanted coupling and interference between transducers
Solution Approach 1:
The patent applies periodic action by using pulsed excitation signals instead of continuous oscillation. The transducer is excited with short pulses at resonant frequency, allowing the oscillation to naturally decay between pulses. This periodic pulsed action maintains sufficient signal strength for measurement while eliminating the continuous ringing voltages that cause harmful coupling and interference between transducers.
Solution Approach 2:
The patent implements preliminary anti-action by applying a reverse polarity pulse immediately after the excitation pulse. This counter-pulse actively cancels out the residual oscillations and ringing voltages in the transducer, preventing them from coupling to adjacent transducers. The anti-action is applied in advance to suppress the harmful effects before they can cause interference.
2Reliability
If transducer separation distance is increased to reduce coupling and interference, then signal quality is improved, but device size and complexity increase
Solution Approach 1:
The patent converts the harmful ringing voltages into a beneficial signal by using the transducer's natural resonant oscillation as the measurement signal. The same oscillation that was previously considered harmful noise is now utilized as the carrier wave for time-of-flight measurements. This allows compact transducer spacing while maintaining signal quality, as the oscillation is precisely controlled and measured rather than treated as unwanted interference.
Solution Approach 2:
The patent applies parameter changes by modifying the excitation signal characteristics - using short pulses at specific resonant frequencies rather than continuous signals. This changes the temporal and spectral parameters of the driving signal, allowing the system to achieve sufficient signal-to-noise ratio with smaller transducer separation distances, thereby reducing device size while maintaining reliability.
3Object-generated harmful factors
If additional components are added to filter and manage ringing voltages, then interference is reduced, but device complexity increases
Solution Approach 1:
The patent implements self-service by utilizing the transducer's inherent resonant properties to naturally suppress ringing voltages. The transducer's mechanical resonance acts as a natural filter, and the control system uses the transducer's own electrical characteristics to manage the oscillations. This eliminates the need for additional external filtering components, reducing device complexity while effectively managing interference.
Solution Approach 2:
The patent uses the control system and signal processing algorithms as intermediaries to manage ringing voltages. Rather than adding physical filtering components, the system employs digital signal processing to identify and suppress ringing artifacts in the received signals. This software-based intermediary approach reduces hardware complexity while maintaining effective interference management.
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 effectively manages induced ringing voltages, reducing interference and maintaining a low zero-flow offset, enabling a compact and efficient ultrasonic time-of-flight flow meter with minimal additional components.
Implementation Method 1
driving an ultrasonic transducer using a first waveform for a first duration, the first waveform configured to cause oscillation of the ultrasonic transducer
Implementation Method 2
Ultrasonic time-of-flight flow meters have been constructed which measure a flow velocity of a liquid or gas based on time-of-flight measurements
Implementation Method 3
induced ringing voltages, which cause unwanted coupling, interference
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A method for an ultrasonic time-of-flight flow meter (1) includes driving an ultrasonic transducer (2, 3) using a first waveform (V 1 (t)) for a first duration (Δt 1 ), the first waveform ( V 1 ,(t)) configured to cause oscillation (21) of the ultrasonic transducer (2, 3), The method also includes driving the ultrasonic transducer (2, 3) using a second waveform (V 2 (t)) for a second duration (Δt 2 ). There is a discontinuity between the first waveform (V 1 (t)) and the second waveform (V 2 (t)). The second waveform (V 2 (t)) and the second duration (Δt 2 ) are configured to maintain a voltage (V t -(t)) across the ultrasonic transducer (2, 3) within a predetermined range (V h , V L ).