초록 ▼

The device for determining and/or monitoring a predetermined filling level in a container has two oscillatory rods secured with spacing adjacent one another on a diaphragm the edge of which is connected to a screw-in part. By means of the screw-in part the device is so secured in a screw-threaded ap

The device for determining and/or monitoring a predetermined filling level in a container has two oscillatory rods secured with spacing adjacent one another on a diaphragm the edge of which is connected to a screw-in part. By means of the screw-in part the device is so secured in a screw-threaded aperture of the container wall at the height of the filling level to be detected that the oscillatory rods project into the container. At the side of the diaphragm remote from the oscillatory rods a bridging member is held spaced from the diaphragm by flexurally elastic rod-shaped supports. Each of the rod shaped supports is rigidly connected at one end to an oscillatory rod. Between the bridging member and the diaphragm there is held, with preloading of the diaphragm, a transducer column comprising in a stack a piezoelectric excitation transducer and a piezoelectric reception transducer. The piezoelectric transducers are connected to one another via an amplifier in a self-excitation circuit so that the mechanical oscillatory system is excited with its natural resonance frequency. An evaluation circuit responds to changes in frequency of the oscillations and initiates indicating and/or switching operations in accordance with such frequency changes.

대표청구항 ▼

A device for monitoring a predetermined filling level in a container, comprising a mechanical oscillatory structure having a diaphragm held at its edge region, two oscillatory rods secured to said diaphragm in a spaced relationship so as to project into said container, and a bridging member held at

A device for monitoring a predetermined filling level in a container, comprising a mechanical oscillatory structure having a diaphragm held at its edge region, two oscillatory rods secured to said diaphragm in a spaced relationship so as to project into said container, and a bridging member held at a spacing from said diaphragm at the side remote from said oscillatory rods by flexurally elastic rod-shaped supports each connected rigidly at one end to an oscillatory rod, further comprising an excitation arrangement for imparting to said oscillatory rods oscillations in opposite directions transversely to the longitudinal direction of said rods, said excitation arrangement having an excitation transducer with at least one piezoelectric element excitable by an AC voltage and a reception transducer with at least one piezoelectric element converting the oscillations of the mechanical oscillatory structure into an electrical output signal, the piezoelectric elements of said excitation transducer and of said reception transducer being arranged in a stack which is held, with preloading of said diaphragm, between said bridging member and the portion of said diaphragm which is situated between said oscillatory rods, and further comprising an evaluation circuit for initiating at least one of a display and switching operation in response to the output signal of said reception transducer.