Ultrasonic Flow Meter Zero Impedance Electronics
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Solution Overview
Problem
Ultrasonic flow meters face limitations in measuring transit time with high precision due to impedance differences in electronic circuits, leading to measurement uncertainty and restrictions on flow meter size, and require costly impedance matching for reciprocal operation.
Innovation Solution
An ultrasonic flow meter design with separate generator and receiver circuits having zero or near-zero output and input impedance, respectively, and controlled transducer switching to maintain consistent impedance for transducers, eliminating the need for impedance matching and allowing precise measurements without signal propagation constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If separate generator and receiver circuits are used with non-zero impedance, then the circuit can operate independently, but measurement precision deteriorates due to impedance differences between transmit and receive modes
Solution Approach 1:
The patent changes the impedance parameter of the generator and receiver circuits to be substantially zero. This parameter change ensures that both circuits present the same impedance to the transducers regardless of whether they are operating in transmit or receive mode, thereby eliminating measurement errors due to impedance differences while maintaining separate independent circuits
2Measurement precision
If switches are shifted during signal propagation to maintain impedance consistency, then measurement accuracy is improved, but the flow meter size increases due to required signal travel distance
Solution Approach 1:
The patent applies preliminary action by setting the switch positions before the ultrasonic signal propagation begins. The switching means is configured to connect specific transducers to the generator or receiver circuits in advance, eliminating the need to shift switches during signal propagation and removing the constraint on minimum flow meter size
3Reliability
If impedance matching is performed for reciprocal operation, then measurement reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the impedance parameter to be substantially zero for both generator and receiver circuits. This eliminates the need for individual impedance matching adjustments during manufacturing, as all circuits automatically present the same impedance characteristic, thereby improving ease of manufacture while maintaining measurement reliability
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 design enables highly precise, compact ultrasonic flow meters less sensitive to transducer characteristics, eliminating the need for impedance matching and allowing accurate flow rate measurements without the limitations of signal propagation time, thus improving measurement accuracy and reducing manufacturing complexity.
Implementation Method 1
The ultrasonic waves are generated by piezo-electric ultrasonic transducers
Implementation Method 2
the ultrasonic transducers act as transmitter and as receiver of ultrasonic signals
Data Source
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AI summary
The present invention discloses an ultrasonic flow meter comprising a generator circuit and a receiver circuit electrically separated from the generator circuit. The flow meter further comprises transducer switching means for controlled connection of ultrasonic transducers to either the generator circuit or to the receiver circuit. The output impedance of the generator circuit and the input impedance of the receiver circuit are controlled to be substantially zero.