Marwal Systems

Karim Benghezal

Christophe Gouzou

Olivier Vaillant

Karim Ouenniche

The invention provides a piezoelectric liquid gauge system in particular for a motor vehicle fuel tank, the system comprising piezoelectric means suitable for transmitting a sound wave in a liquid and for detecting said wave in order to determine the distance traveled by the wave in the liquid on the basis of the time between transmission and reception, said piezoelectric means comprising two distinct active piezoelectric portions suitable respectively for directing a sound wave towards a reference obstacle and a sound wave towards the surface of the liquid to be gauged, the system being wherein the pellet is contained in a housing suitable for being fixed in position in the tank in which measurement is to be performed, the reference obstacle extending over a face of the housing which faces one of the active portions, said face also having a measurement opening placed facing the other active portion and suitable for allowing the measurement sound waves to pass through.

Depth gauge

The invention concerns a device for measuring liquid level, comprising a detection set (Si) including two piezoelectric cells ( ) associated with control means for transmitting ultrasonic waves respectively opposite a reference reflector ( ), located at a known distance (D) from the associated cell, and from the top surface ( ) of the liquid, and processing means for determining the level of liquid by operating on the respective propagation times of the ultrasounds emitted by each of the two cells ( ). The invention is characterised in that it comprises means for defining, after the device has been charged, an initialising phase ( bis) during which the control means control the piezoelectric cells ( ) such that the ratio between the excitation rate of the reference cell ( ) and that of the level-measuring cell ( ) is higher than the ratio between those same rates during the subsequent stabilised measuring phase ( ).

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Chalons en Champagne, France

Karim Benghezal