Development And Design Of Ultrasonic Household Water Meter Based On Phase Difference Method

At present,the traditional water meter flowmeter basically adopts the mechanical metering method,which has the problems of high initial flow rate,low accuracy and large pressure loss.With the progress of new measurement sensing technology,ultrasonic measurement technology has achieved continuously improvement and application.In contrast with the mechanical water meter,ultrasonic flowmeter has the advantages of high accuracy,wide measurement range,small pressure loss and complete output communication function in the field of water meter measurement.In this thesis,ultrasonic measurement technology is applied to the flow measurement of small caliber household water meter.In particular,the problems of low accuracy and poor reliability of ultrasonic water meter in low flow area are solved.In order to solve the defect of low accuracy of ultrasonic water meter with small flow rate,the following two measures are proposed:1.The pipe flow field of water meter is analyzed,U-shaped pipe structure is designed,the diameter design of plastic pipe is adopted,and the ultrasonic transducer with better performance is selected,and the measurement precision is effectively guaranteed from the hardware structure;2.Aiming at the nonlinear problem caused by temperature,the thermistor temperature sensor for real-time acquisition of water temperature is added to the circuit.Based on the nonlinear mapping relationship between temperature and flow rate,the improved BP neural network compensation algorithm is applied.In the software program,the error of water velocity at different temperature is corrected,thus the reliability of flow velocity measurement for small flow rate is improved effectively.In addition,the micro-power MSP430 control chip and the special chip UTA6905 based on phase difference method are applied in the hardware circuit to obtain more accurate time difference and guarantee the accuracy of flow measurement.Meanwhile,the RF card technology is applied to realize the prepaid function,which makes the meter more suitable for the step water price and reasonable utilization and saving of water resources.Finally,a large number of function tests,flow accuracy tests and reliability tests are measured for prototype and corresponding experimental results are analyzed.The obtained results show that the ultrasonic meter has the advantages of high accuracy of small flow,high reliability,low power consumption and good real-time performance,which can satisfy the requirements of the initial design and the overall design.The research results in this thesis improve the accuracy and stability of ultrasonic flowmeter and promote the development of independent core technology.