Aircraft fuel measuring and controlling system with self compensation capacitance type level sensor

Abstract

The invention discloses an aircraft fuel measuring and controlling system with a self compensation capacitance type level sensor. The system comprises a measuring circuit and the self compensation capacitance type level sensor comprising an electrode AA, an electrode AB, an electrode BB and an electrode CC; during measurement, the electrode AA is grounded and serves as an external electrode for measuring the capacitance, the electrode BB and electrode CC serve as internal electrodes, and aircraft fuel medium is capable of entering the cavity between the electrode AA and the electrode AB. A processing chip of the measuring circuit is provided with a capacitance compensation relationship (img file = 'DDA0000612921630000011.TIF' wi = '336' he = '126' / ), and the height h of the measured level can be calculated through a capacitance compensation ratio K. By the aid of the capacitance type level sensor, influence caused by temperature and medium change and fuel dielectric constant change can be eliminated, and the complex process of repeated calibrations is reduced.

Description

technical field [0001] The invention relates to the technical field of aircraft fuel oil measurement and control systems, and more particularly refers to an aircraft fuel oil measurement and control system with a self-compensating capacitive liquid level sensor. The self-compensating capacitive liquid level sensor is used to collect the amount of aircraft fuel, which can eliminate the influence of temperature and the change of the measured liquid medium (aircraft fuel) on the sensor measurement. Background technique [0002] The aircraft fuel quantity measurement and control system is an important device of the aircraft fuel guarantee system, and its measurement results are one of the basis for the pilot to determine the flight range of the aircraft. The function of the fuel oil measurement system sensor is to accurately measure the remaining fuel volume of each group of fuel tanks to maintain automatic fuel supply to the aircraft engine when the aircraft is flying horizonta...

AI Technical Summary

Problems solved by technology

When the edge effect is not considered, the total capacitance characteristic equation of the capacitor is From the relationship between the capacitance value C and the height of the liquid level x, it can be known that if the external ambient temperature changes during the measurement process, or when different fuel grades are used, the dielectric constant ε of the fuel will be 1 , the dielectric constant ε of the mixture above the fuel 0 Therefore, there is no linear change between the capacitance value C and the liquid level x, and the influence of this change cannot be compensated from the aircraft fuel oil quantity measurement and control system or the calibration calibration test

Therefore, the sensor must be calibrated and calibrated before each measurement, which is cumbersome and difficult to implement

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