Shielding system for capacitance type fuel quantity gauge
AssigneeSimmonds Precision Products, Inc.
InventorIrwin Wallman
Life of this patent
Estimating the term…
Abstract
A capacitance type fuel quantity gauge for an aircraft fuel tank including a probe capacitor whose capacitance varies in accordance with the level of fuel in the tank with a Lo-Z oscillator connected to the probe capacitor together with a pair of diodes for producing a DC output signal which is fed to signal processing circuitry, the diodes being disposed in a metal enclosure for isolation from interfering signals and the interconnecting leads to the diodes passing through feedthrough capacitors to block the entry of such interfering signals into the metal enclosure.
Claims11
A capacitance type fuel quantity gauge for a fuel tank comprising, in combination, a first capacitor arranged to be mounted within a fuel tank and having a capacitance corresponding to the level of fuel in the tank, an enclosure having a wall defining an interior associated with said first capacitor, remotely located indicating means, an oscillator having an output, means for connecting said oscillator output to one side of said first capacitor, a pair of oppositely poled diodes disposed within the said enclosure interior, means for connecting one side of both of said diodes to the other side of said first capacitor, a pair of conductors each connected at one end to the other side of one of said diodes, and extending through openings in said enclosure wall, a pair of feedthrough capacitors in said enclosure wall, each arranged to accommodate one of said conductors for bypassing interfering signals on said conductors to a level below the threshold of said diodes and means for connecting the other ends of said diodes to said indicating means for indicating the quantity of fuel in the fuel tank.
Dependencies are inferred from the claim text.