Time Difference Method Of Low Power Consumption Ultrasonic Flow Meter Design And Implementation

Ultrasonic flow measuring technique which is a new measuring technique, can measure the velocity of flow according to the theory that ultrasonic can carry the information of the liquid when it transits the flowing liquid. Ultrasonic flow meter has many advantages such as: non-contacting, simple fixing and maintaining, not changing the liquid’ flow state, no additional resistance etc. So ultrasonic flow meter it is widely used in industry and civilian measurement. In recent years, sensors technique, measuring technique and microelectronic technology are developing rapidly. It provides the condition for further studies on ultrasonic flow meter, at the same time, it speeds up industrialization.The main task in this thesis is to design and make an ultrasonic flow meter and study the correlation technique. By theoretical analysis on fluid-velocity measuring methods, the time difference method in the design is detailed introduced, and the hardware design of the measurement equipment of ultrasonic flow meter is made, including the hardware circuit of flow measuring device and the flow of work of ultrasonic flow meter. The key techniques of ultrasonic flow meter designing are analyzed, including the calibration method of flow, low-power design, echo operating point, and the solution is introduced. Finally, the experimental study of ultrasonic flow meter and the test dates are given, and the reasons causing measurement error are analyzed. Moreover, the methods to increase measuring accuracy are proposed. The final design of the ultrasonic flow meter’s accuracy is±1,and its response time is less than1s, the design meets the requirements of the system to its accuracy and response time. And through the low-power design, the dynamic working current of the equipment drops to12μ A, the quiescent working current can reach2～3μA and the battery life reached more than10years. The design meets the system requirement for spare battery.The ultrasonic flow meter has many advantages such as low starting flow, small pressure loss, low consume, operation reliable, fully functional and so on. It has good potential application of market.