초록 ▼

The invention relates to a device for determining and/or monitoring the level of a filling material in a container. According to the invention, an oscillatable unit is provided which is fastened to a membrane, whereby said oscillatable unit is mounted at the height of the predetermined level. An emi

The invention relates to a device for determining and/or monitoring the level of a filling material in a container. According to the invention, an oscillatable unit is provided which is fastened to a membrane, whereby said oscillatable unit is mounted at the height of the predetermined level. An emitting-receiving unit is provided which, with a given emit frequency, causes the membrane and the oscillatable unit to oscillate, and which receives the oscillations of the oscillatable unit. A control/evaluation unit is provided, which identifies once the predetermined level is obtained upon a given change in frequency or which, with the aid of the oscillation frequency of the oscillatable unit, determines the density of the filling material.

대표청구항 ▼

1. An apparatus for determining and/or monitoring the filling level of a filling material in a container and for determining a process variable of a filling material in the container, comprising:a membrane which can oscillate being fitted at the same level as the predetermined filling level; a unit

1. An apparatus for determining and/or monitoring the filling level of a filling material in a container and for determining a process variable of a filling material in the container, comprising:a membrane which can oscillate being fitted at the same level as the predetermined filling level; a unit which can oscillate and is attached to said membrane said unit which can oscillate being fitted such that it enters the filling material to a defined immersion depth; a transmitting/receiving unit which causes said membrane and said unit which can oscillate to oscillate at a pre-determined transmission frequency and which receives the oscillations from said unit which can oscillate; a control/evaluation unit which identifies that the predetermined filling level has been reached as soon as a predetermined frequency change occurs, or which determines the density of the filling material on the basis of the oscillation frequency of the unit which can oscillate; and a differential amplifier, wherein: said transmitting/receiving unit is a piezoelectric element in the form of a disk, on whose first face an electrode structure is provided, with the electrode structure having at least two transmitting electrodes and two receiving electrodes, and with the first transmitting electrode being opposite the second transmitting electrode, and with the first receiving electrode being opposite the second receiving electrode, essentially in each case symmetrically about a point, the inputs of said differential amplifier have the electrical signals which are tapped off from said two receiving electrodes applied, and said first transmitting electrode and said second transmitting electrode, as well as said first receiving electrode and said second receiving electrode are of opposite polarity. 2. The apparatus as claimed in claim 1, wherein:said transmitting electrodes and/or said receiving electrodes of said transmitting/receiving unit are essentially of the same shape. 3. The apparatus as claimed in claim 1, wherein:said transmitting electrodes and/or said receiving electrodes are in the form of 90° circle segments. 4. The apparatus as claimed in claim 1, further comprising:an inverter, which inverts the electrical signal which is applied to one of said two transmitting electrodes of said transmitting/receiving unit. 5. The apparatus as claimed in claim 1, wherein:said piezoelectric element is provided at least partially with a conductive coating on said second face, which is opposite said first face to which said electrode structure is fitted. 6. The apparatus as claimed in claim 5, further comprising:a connecting electrode provided on said first face, to which said electrode structure is fitted, of the piezoelectric element and is connected in at least one area to said conductive coating, which forms the ground electrode, on said second face of said piezoelectric element. 7. An apparatus for determining and/or monitoring the filling level of a filling material in a container and for determining a process variable of a filling material in the container, comprising:a membrane which can oscillate being fitted at the same level as the predetermined filling level; a unit which can oscillate and is attached to said membrane said unit which can oscillate being fitted such that it enters the filling material to a defined immersion depth; a transmitting/receiving unit which causes said membrane and said unit which can oscillate to oscillate at a pre-determined transmission frequency and which receives the oscillations from said unit which can oscillate; a control/evaluation unit which identifies that the predetermined filling level has been reached as soon as a predetermined frequency change occurs, or which determines the density of the filling material on the basis of the oscillation frequency of the unit which can oscillate; and a connecting electrode, wherein; said transmitting/receiving unit is a piezoelectric element in the form of a disk, on whose first face an electrode structure is provided, with the electrode structure having at least two transmitting electrodes and two receiving electrodes, and with the first transmitting electrode being opposite the second transmitting electrode, and with the first receiving electrode being opposite the second receiving electrode, essentially in each case symmetrically about a point, said piezoelectric element is provided at least partially with a conductive coating on said second face, which is opposite said first face to which said electrode structure is fitted, and said connecting electrode is provided on said first face, to which said electrode structure is fitted, of the piezoelectric element, and is connected in at least one area to said conductive coating, which forms the ground electrode, on said second face of said piezoelectric element.