fluessigkeitsniveauschalter, based on elastic lamb waves for the detection of the presence of.

摘要

The switch device detects the presence or absence of a liquid (2) at a predetermined level (N) in a tank (1). The device consists of a transmitting transducer (51; 51'; 61), a receiving transducer (52, 52', 62) and an electronic circuit (100) for processing the signals applied to the transmitting transducer (51; 51', 61) and delivered by the receiving transducer (52, 52', 62). …??The device includes, near the said predetermined level (N) of the said tank (1), a detector plate (50; 50', 60), of which at least one surface (58) is capable of being put into contact with the liquid (2) and which carries on the one hand the transmitting transducer (51; 51'; 61) arranged so as to create Lamb waves locally in the said plate (50; 50'; 60) and on the other hand the receiving transducer (52; 52'; 62) arranged so as to detect the presence or absence of the Lamb waves transmitted along the said plate (50; 50'; 60). …??The receiving transducer (52; 52'; 62) is connected to a high-gain amplifier whose output is connected to the transmitting transducer (51; 51'; 61) to form a closed oscillating loop, the oscillations of which are interrupted when the liquid reaches the predetermined level (N). …IMAGE…