Improved low power consumption two-wire system vortex shedding flowmeter

Abstract

The invention relates to the field of flow detection, as an advanced low power consumption two-wire system vortex-shedding meter, comprising a piezo-electric transducer, a differential charge amplifier, a voltage amplifier, a programmable amplifier, a low pass filter, a voltage follower, a band-pass filter set, a band-pass select switch circuit, a peak detection circuit, a wave shaping circuit, a singlechip, a human-computer interface circuit, a 4-20mA output and power management circuit, a constant flow source, a temperature sensor, a pressure sensor, a differential amplifier and a 16-bit analog-to-digital converter. Mini FFT spectral decomposition is used to be combined with the analog band-pass filter set to process signals of a vortex sensor and a multicycle frequency measurement method of precision is used, thereby having temperature and pressure compensating circuit and function, outputting 4-20mA direct current and having two-wire system work. The advanced low power consumption two-wire system vortex-shedding meter has greatly improved measure ratio, measurement precision and capacity of resisting disturbance.

Description

technical field [0001] The invention relates to the field of flow detection, and is a low-power two-wire vortex flowmeter, in particular a low-power, Two-wire vortex flowmeter signal processing system. Background technique [0002] A Chinese invention patent announced a low-power two-wire vortex flowmeter (Xu Kejun, Zeng Xianjun, Zhu Zhihai, Liu Sanshan, etc. Low-power two-wire vortex flowmeter, application for invention patent, 200710162074.5, application date: 2007.11.14.). This flowmeter consists of piezoelectric sensor, charge amplifier, voltage amplifier, program-controlled amplifier, low-pass filter, voltage follower, peak detection circuit, band-pass filter bank, multi-way switch gating circuit, shaping circuit, single-chip microcomputer, human It is composed of computer interface circuit, 4-20mA output and power management circuit. The single-chip microcomputer detects the peak value and frequency of the vortex signal, and accordingly controls the program-controlle...

AI Technical Summary

Problems solved by technology

However, this low-power two-wire vortex flowmeter has the following disadvantages: (1) The calculation of the pulse frequency adopts the method of counting the number of pulses within 2 seconds, which may cause one pulse to be counted more or less, resulting in 0.5Hz frequency calculation error; (2) using a Schmitt trigger as a shaping circuit, its threshold level and trigger amplitude cannot be adjusted, which is not conducive to shaping the signal in the case of noise and small signal amplitude; (3 ) The bandpass filter designed can only be applied to a liquid or a gas flowmeter of a caliber, and the application area is narrow; (4) The analog ground of the circuit is directly connected to the instrument shell to achieve shielding, but such a connection cannot Passed safety performance test

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