A segmented capacitive liquid level sensor and its liquid level measurement method

Abstract

A segmented capacitive liquid level sensor and a liquid level measuring method thereof, comprising a microprocessor, a sine wave generating circuit connected with the microprocessor, and a multiplex switch connected with the microprocessor and the sine wave generating circuit, A segmented capacitor connected to the multi-way switch, the segmented capacitor is composed of at least two mutually insulated capacitor arrangements, the multi-way switch is connected to each segment of the capacitor in the segmented capacitor respectively, and the microprocessor A leakage resistance detection circuit and a phase difference detection circuit are respectively connected between the multi-way switch and the multi-way switch; the microprocessor controls the multi-way switch to connect the input terminals of each segment capacitor in the segmented capacitor to the sine wave through a charging resistor The generating circuit is connected to the leakage resistance detection circuit and the phase difference detection circuit respectively at the output end. The invention adopts a leakage resistance detection circuit and a phase difference detection circuit to accurately measure the capacitance of each segment of the segmented capacitor, so that the liquid level measurement is more accurate, the reliability is high, and the anti-interference ability is strong.

Description

technical field [0001] The invention relates to a liquid level sensor and a liquid level measuring method thereof, in particular to a segmented capacitive liquid level sensor suitable for multi-interface liquid level measurement and a liquid level measuring method thereof. Background technique [0002] At present, most capacitive sensors used in multi-interface liquid level measurement are composed of two metal round tubes, and the liquid enters between the two tubes to form a capacitive dielectric, so that when there are two different liquids, it is regarded as Two capacitors are connected in parallel, thus the height of the liquid level can be measured. This capacitive sensor has the following disadvantages: [0003] (1) The measurement accuracy is not high and the error is large [0004] This single-stage liquid level sensor needs to know the dielectric constant of different liquids in advance, and these two parameters need to be set as constants during the measurement ...

AI Technical Summary

Problems solved by technology

[0003] (1) The measurement accuracy is not high and the error is large

[0004] This single-stage liquid level sensor needs to know the dielectric constant of different liquids in advance, and these two parameters need to be set as constants during the measurement process, but in actual production, these two parameters are not constant, so the measurement error Moreover, in a variety of practical applications, there is often a transition layer with different thickness and indeterminate density gradient between the two liquid layers, and the composition is complex, so that the measurement error of the interface will be greater

[0005] (2) The measurement circuit is complicated and the communication is inconvenient

However, since the accuracy of liquid level detection depends on the accurate measurement of the capacitance of each section of the sensor, and most of the existing public liquid level sensors use the traditional direct measurement of capacitance, the measured capacitance value will contain the resulting Larger errors, which in turn affect the accuracy and reliability of the measured liquid level height, and the existing sensors including the above two patents have not given a better solution to this problem

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