Arrangement for establishing and/or monitoring a predetermined filling level in a container

US6148665A · kind A · utility

Assignee

• Endress+Hauser Inc. · DE

Inventors

• Igor Getman · Lörrach, DE
• Sergej Lopatin · Lörrach, DE

Key dates

• Filing date: Apr 3, 1998
• Grant date: Nov 21, 2000
• Expiry date: Apr 3, 2018

Classification

• Technology area (CPC G): Physics
• CPC primary: G01F23/2967
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An arrangement for establishing and/or monitoring a predetermined filling level is described, in which a fixed phase difference (.DELTA..phi..sub.R), which is independent of the oscillation quality of the arrangement, exists between a transmission signal and a reception signal (E) at the resonant frequency of the mechanical oscillatory structure. This arrangement comprises a mechanical oscillatory structure (1) at least one transmitter (3), which excites the oscillatory structure (1) to produce oscillations, and two piezoelectric elements as receivers (24a, 24b). In accordance with a first variant, a first signal line (241a) of the first receiver (24a) is connected to an electrode which is arranged on a surface which bounds the first receiver (24a) in a direction opposite to its polarization. A second signal line (241b) of the second receiver (24b) is connected to the transmission signal line (5) via an electrical impedance (Z). The second signal line (241b) of the second receiver (24b) is connected to an electrode which is arranged on a surface which bounds the receiver (24b) in the direction of its polarization. The reception signal (E) is equal to the difference between the two …