Patent ID: 8136396

Claim:
An apparatus for measuring and/or controlling the level of fuel stored in and eventually dispensed from a reservoir located at a gas station, said apparatus comprising a vertical support pipe positioned inside the reservoir and hermetically isolated from the fuel contained therein; a lever having a first end connected to a float and a second end joined to a pivot member fixed to said support pipe such that the lever can move angularly with respect to said support pipe as the fuel level in the reservoir raises or lowers, said pivot member comprising a stationary body fixed to an intermediate portion of said support pipe and a rotatable body joined to the second end of said lever and which can rotate relative to the stationary body around an axis; a pair of magnetoresistive sensors offset each from the other arranged in a cavity of said stationary body, a permanent magnet mounted in said rotatable body, said permanent magnet being substantially ring shaped and coaxial with said axis, said permanent magnet being diametrically magnetized; an annular yoke of magnetic material mounted in said rotatable body surrounding said permanent magnet and coaxial therewith, said yoke offering to the magnetic field a path to maximize the intensity of the magnetic field acting on the sensors and preventing dispersion of magnetic field outside said magnet, the magnetic field generated by said magnet being substantially perpendicular to said axis and of an intensity high enough to saturate the internal magnetization of said pair of magnetic sensors, independently of the position of said permanent magnet, said magnetic sensors being capable of reacting in response to changes in the angle of incidence of said magnetic field traversing said sensors and unable to react in response of changes in the intensity of said magnetic field; the respective outputs of said sensors, which depend on the angle of incidence of the magnetic field relative thereto, are transmitted to processing means external to the reservoir where readings could be made revealing the fuel level and, consequently, the volume of the fuel contained in the reservoir.