Ultrasonic Flow Meter Clock Control for Low Power Precision
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Solution Overview
Problem
Conventional flow measuring instruments face challenges in achieving precise measurements at low flow velocities due to the small difference in travel times of ultrasonic waves, leading to measurement errors, especially when flow velocities change cyclically, and require high power consumption for frequent sampling and data integration.
Innovation Solution
The flow measuring instrument employs a digital and analog electronic circuit with a Z-path configuration, using a high rate clock and an auxiliary clock to measure travel times with high accuracy, reducing power consumption by optimizing clock usage and incorporating a verification section to ensure precise oscillating cycles, and includes a shut-off valve for safety in gas meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If repeated measurements are carried out at regular intervals to average travel times, then measurement precision is improved, but power consumption increases and cyclic flow changes cause errors
Solution Approach 1:
The patent applies periodic action by using two different measurement intervals (first interval and second interval) to capture flow velocity at different phases of cyclic changes. Multiple measurements are performed periodically at these different intervals and then averaged to obtain an accurate flow velocity that accounts for cyclic variations, thereby improving measurement precision while managing power consumption through controlled measurement frequency.
2Measurement precision
If multiple measurement sets are performed to capture all phases of varying waveform, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement process into distinct measurement sets, each performing a specific number of measurements (e.g., four measurements per set). The control section is configured to execute a predetermined number of these measurement sets sequentially. This segmentation allows the system to capture all phases of cyclic flow variations through multiple sets while maintaining manageable complexity through structured, repetitive measurement patterns.
3Measurement precision
If high rate clock is used for precise travel time measurement, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent uses periodic action by activating the high rate clock only during specific measurement periods when travel time measurements are being performed, rather than keeping it continuously running. The clock operates at high frequency during the actual measurement windows to achieve precise travel time resolution, then enters lower power states between measurements, thereby reducing overall power consumption while maintaining measurement precision when needed.
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 precise flow volume measurement with reduced power consumption, effectively capturing cyclic changes in flow velocity and ensuring reliable operation with improved accuracy and maintainability, suitable for applications like gas meters.
Implementation Method 1
first oscillator 52 for transmitting an ultrasonic wave, second oscillator 53 for receiving the ultrasonic wave transmitted
Implementation Method 2
measurement control section 54 for measuring a travel time of the ultrasonic wave between oscillators 52 and 53
Data Source
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AI summary
Measurement control section (4) for controlling an operation of measuring a travel time of an ultrasonic wave, which operation is done by time measuring section (11), works based on a high rate clock supplied from ceramic oscillation circuit (16) during the time measuring operation. Clock control section (18) stops the high rate clock supplied from ceramic oscillation circuit (16) every time when time measuring section (11) finishes its time measuring operation, and controls a standby time between an end of measuring the travel time and a start of carrying out the next measuring step by using a low rate clock supplied from quartz oscillation circuit (15).