Capteur de niveau d'un liquide à absorption d'ondes élastiques

Abstract
This new type of liquid level sensor is based on the attenuation of elastic waves guided in a hollow cylinder partially immersed in the liquid. The cylinder (10 cm long) is suspended at one end of a few meter long magnetostrictive wire. The acoustic waves are launched in the wire by a pulse of current in a coi1 and after propagating are transmitted through a cylindrical horn to the hollow cylinder. The carrier frequency of the wave trains and the thickness of the tube are chosen so that the waves strongly leak into the liquid when the cylinder is immersed. Then, this sensor is automatically maintained just immersed by winding or unwinding the wire so that the waves can leak. The level is finally determined by measuring the time-of-flight of the echo reflected at the junction between the wire and the horn.