THERMAL INDICATOR OF LIQUID LEVEL Russian patent published in 2002 - IPC

FIELD: control of fuel level in fuel tank of aircraft. SUBSTANCE: thermal indicator has two temperature-sensitive resistors connected in series and installed in level detector located in fuel tank. Temperature-sensitive resistors are connected to power supply source, have temperature coefficients of resistance of same sign and equal coefficients of convective heat exchange in gas, but their rated values of resistance differ. Thermal indicator has controlled two-position switching key, each immobile contact of key is connected to one of temperature-sensitive resistors and switching contact is connected to input of analog-to-digital converter whose body is grounded, for example, is connected to fuselage of aircraft. Output of converter is connected to input of divider and output of the latter is connected to measurement input of comparator, reference input of it is connected to output of source of reference signal and output of comparator is coupled to input of indicator. Controlling inputs of controlled key and divider are connected to output of generator of controlling signals. Common point of temperature-sensitive resistors is grounded. EFFECT: exclusion of possibility of generation of false signal on absence of liquid in tank when indicator operates in wide range of uncorrelated temperatures of liquid and gas, inflammable liquids included. 1 dwg