Time difference measuring method of time difference type ultrasonic flow meter

Abstract

The invention discloses a time difference measuring method of a time different type ultrasonic flow meter. According to the method, on the basis of measuring the time difference through pulse counting, conversion measuring is performed on the error part of the pulse counting through a phase discriminator, an integrating circuit and an ADC, so that the time difference is measured accurately through the flow meter. According to the method, a clock signal which is output by a flow meter control unit MSP430 is adopted as a pulse counting signal. Counting errors exist in the pulse counting and are converted into voltage through the integrating circuit after being recognized by the phase discriminator. The voltage is transmitted to the ADC inside the flow meter control unit MSP430, and through the combination of an ADC conversion result and a pulse counting result, the time difference of the time difference type ultrasonic flow meter can be finally obtained. According to the method, by the utilization of the ADC inside the time difference type ultrasonic flow meter control unit MSP430 and the clock signal, a timing chip of an existing time difference type ultrasonic flow meter can be omitted, and therefore cost is well reduced.

Description

technical field [0001] The present invention relates to the technical field of flow measurement equipment, in particular to a method for measuring the difference of a time-difference ultrasonic flowmeter. Background technique [0002] Transit-time ultrasonic flowmeters have high requirements for time-difference measurement accuracy when measuring small flow rates. Existing pulse timing circuits that use FPGA or CPLD circuits with crystal oscillators cannot be used for small flow rate measurements, and can only be used for large flow rates or low precision requirements. occasions. In the case of high flow measurement accuracy or low flow rate, to improve the flow measurement accuracy, the counting pulse frequency must be increased accordingly. However, it is difficult to increase the counting pulse frequency in the later stage, and the cost is also high. [0003] In the transit-time ultrasonic flowmeter, the research and application of improving the flow measurement accuracy...

AI Technical Summary

Problems solved by technology

This method utilizes the internal ADC and output clock signal of the time-difference ultrasonic flowmeter control unit MSP430, and uses the output clock signal to count the pulses of the forward and reverse flow time differences, and convert the time into a voltage for the measurement error of less than one cycle that cannot be measured by pulse counting. Combined with the internal ADC of MSP430, the time difference value of this part is obtained, so as to obtain the final forward and reverse flow time difference

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