High-precision time-difference single-pulse ultrasonic flowmeter system and method for measuring flow

Abstract

The invention discloses a high-precision time difference type single-pulse ultrasonic flowmeter system and a flow measurement method thereof. The method comprises the following steps of: sending a control signal to a transceiving switch unit and a single-pulse signal transmitting and driving unit; sending a standard time delay signal to a phase discrimination integral unit; calculating to obtain a time difference of the ultrasonic sequential stroke transmission and the ultrasonic return stroke transmission in a flowmeter pipeline by measured ultrasonic sequential stroke transmission time and the measured ultrasonic return stroke transmission time; selecting an ultrasonic energy converter; generating a single-period sine wave signal; sending the signal to the ultrasonic energy converter; sending an ultrasonic signal to an ultrasonic signal processing unit; filtering and amplifying the ultrasonic signal; determining an arrival signal by zero detection and threshold value detection; comparing the arrival signal with the standard time delay signal to obtain the ultrasonic sequential stroke transmission time and ultrasonic return stroke transmission time; and according to the time difference of the ultrasonic sequential stroke transmission and the ultrasonic return stroke transmission as well as the pipeline diameter, calculating to obtain the unit time flow of pipeline fluid.

Description

technical field [0001] The invention relates to the technical field of flow measurement equipment, in particular to a high-precision time-difference single-pulse ultrasonic flowmeter system and a method for measuring flow. Background technique [0002] Compared with mechanical and electromagnetic flow meters, ultrasonic flow meters have the advantages of strong adaptability to pipe diameter, large range ratio, no moving parts, non-contact measurement, zero pressure loss, and easy maintenance. Promising flow metering equipment, especially in recent years, has been widely used in heating heat metering. [0003] Ultrasonic flow measurement as a volume measurement method is mainly carried out through the following five steps: [0004] 1) The ultrasonic probe inside the pipeline emits sound waves in the fluid, starts the timing, and receives the ultrasonic signal after a certain period of time. [0005] 2) Perform preprocessing on the received ultrasonic signal, judge the arriv...

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Problems solved by technology

However, the energy of the multi-pulse transmitting circuit is not concentrated, the amplitude of the first wave of the received signal is small, the signal-to-noise ratio is poor, the receiving signal processing circuit is complex, and the cost is high; and when the ultrasonic wave is transmitted with a high-voltage narrow-band pulse signal, the transducer cannot completely convert the pulse signal. There is high-order resonance inside the energy, that is, it cannot completely convert and send out all the frequency components in the pulse signal, resulting in high-frequency resonance inside the transducer, which will cause interference when receiving signals, and can only be used for transmission or reception alone; The sound channel layout plan measures the forward and reverse time difference, which increases the number of devices and complicates the circuit, and requires more layout space due to the increase of sound channels, so it is not suitable for small pipe diameter flow velocity measurement

[0011] 2) Existing ultrasonic flowmeters use FPGA or CPLD circuit with crystal oscillator for timing, the system is complex and the timing resolution is only 5-10ns; or the timing chip TDC-GP2 is used to develop the timing circuit, although the timing resolution can reach 65ps, but Expensive, accounting for a large proportion of the flow meter cost, which is not conducive to cost control

In addition, when using a dedicated timing chip for time difference, the A / D function of the micro-processing control chip in the flowmeter circuit is idle, and the utilization rate of the chip is low

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