Measuring and testing – Liquid level or depth gauge
Reexamination Certificate
2002-02-08
2004-04-27
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Reexamination Certificate
active
06725718
ABSTRACT:
TECHNICAL FIELD
The presence invention relates in general to a method for the automatic coarse differentiation between a liquid or a bulk material of a filling product present in a receptacle by analyzing an echo signal, in particular by analyzing the therefrom generated envelope curve of a filling level measuring device. The present invention further relates in general to devices for the automatic coarse differentiation between a liquid or a bulk material of a filling product present in a receptacle by analyzing an echo signal, in particular by analyzing the therefrom generated envelope curve, as well as filling level measuring devices working in particular on the pulse echo principle and scanning a reflected echo signal.
Filling level measuring devices working on the pulse echo principle and scanning a reflected echo signal, generate from the scanned echo signal a series of data for each echo in the echo image or the so-called envelope curve. Generating an envelope curve from echo signals is sufficiently known and, accordingly, further explanations as to this technology are not required here (cf., for example, German Patent DE 44 07 369 C2; M. Scholnik “Introduction to Radar Systems”, 2
nd
edition, 1980, McGraw-Hill; Peter Devine “Radar level measurement—the user's guide”, VEGA Controls Ltd., 2000, ISBN 0-9538920-0-X).
BACKGROUND INFORMATION
Conventional filling level measuring devices or sensors detect the filling level by measuring individual echoes in the envelope curve. A method for the filling level measurement according to the radar principle is described in European Patent Application EP 1 039 273 A1, by means of which a non-planar, in particular arched bottom can be determined by examining the measurement signal or the envelope curve for a typical noise signal behavior. When this typical noise signal behavior is determined, the empty state of the receptacle is detected. A characteristic feature for the noise signal behavior of the measurement signal consists in erratic random changes of the local peaks or in an increasing amplitude of the local minimum or maximum points with a rising frequency. German Patent DE 43 32 071 A1 described a method for the filling level measurement according to the radar principle is known, wherein the actual echo function is compared to memorized undisturbed echo function, which corresponds to an undisturbed measurement, and deviations ascertained in the antenna zone and the short range following the antenna, are evaluated for recognizing an initial formation and/or other disturbances. Furthermore, Great Britain Patent Application GB 2 123 237 A shows a filling level detector working with microwaves, which does not work according to the echo principle, but causes the reflected beam to interfere with a beam branched off using a waveguide.
With the conventional devices, it is, however, necessary for improving the evaluation of the envelope curve, to manually input whether the filling product to be measured is a liquid or a bulk material. Through this manual input, the type of the envelope curve measurement, and hence the determination of the filling level, is changed. Thus, if it is predetermined that the filling product is a liquid, the amplitude to be measured is placed at a predetermined amplitude before the maximum of the envelope curve with prior art. In case the operator has predetermined that the filling product is a bulk material, the beginning of the envelope curve up to the maximum is measured as the amplitude to be measured.
In summary, it has to be stated that according to prior art, an improved measurement of the individual echoes of an envelope curve of an echo signal depending on the type of filling product, is only then possible when a coarse manual differentiation on the filling level measuring device is carried out by an operator.
SUMMARY OF THE INVENTION
The present invention relates to a method and a device for carrying out an automatic coarse differentiation between a liquid or a bulk material of a filling product present in a receptacle. A possibility is therewith supposed to be created that a filling level measuring device working in particular on the pulse echo principle and scanning a reflected echo signal, automatically carries out a coarse differentiation between a liquid or a bulk material of the filling product.
In particular, according to a first exemplary embodiment of the present invention, a method for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle is described, where a filling level measuring device is used scanning a reflected echo signal, and the coarse differentiation is made in dependence on the width of the individual echoes of an envelope curve in an echo signal.
According to a further exemplary embodiment of the present invention, a method for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle using a filling level measuring device scanning an echo signal is described, where the coarse differentiation is made in dependence on the number of equidistant echoes in an echo signal.
According to yet another exemplary embodiment of the present invention, a method for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle, using a filling level measuring device scanning an echo signal, is described, where the coarse differentiation is made in dependence on the detection of a stirring apparatus.
A preferred exemplary embodiment of a device according to the present invention for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle, includes an arrangement for detecting the echo widths of echoes of a generated envelope curve, an arrangement for detecting the number of echoes having an echo width larger than a reference echo width, and the number of echoes having an echo width smaller than the reference echo width, and a signal outputting arrangement for the type of filling product, which signal outputting arrangement outputs a signal representative of a liquid when the number of echoes having an echo width larger than a reference echo width is greater than the number of echoes having an echo width smaller than a reference echo width.
A further preferred exemplary embodiment of a device according to the present invention for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle, includes an arrangement for determining the number of equidistant echoes of a generated envelope curve, and an arrangement for outputting a signal determining the type of filling product in dependence on the determined number of equidistant echoes.
Still another preferred exemplary embodiment of a device according to the present invention for the coarse differentiation between a liquid and a bulk material of a filling product present in a receptacle, includes an arrangement for detecting a stirring apparatus by evaluating the echoes of a generated envelope curve, and an arrangement for outputting a signal representative of the type of filling product in dependence on the detection of a stirring apparatus.
Furthermore, according to yet another exemplary embodiment of the present invention, a filling level measuring device is described. The filling level measuring device utilizes a pulse echo principle which evaluates an envelope curve generated from the reflected echo signal, and including a device according to the above configurations. The device may also be modified according to one or more of the following configurations.
As indicated above, the present invention utilizes an idea of examining for the first time the individual echoes of an envelope curve for determined characteristics providing at least an indication as to the type of the filling product, namely liquid or bulk material. Thus, it is possible to make this coarse differentiation in dependence on the width of the individual signals of an envelope curve in an echo signal. Profit is thereb
Fay Kaplun & Marcin LLP
Vega Grieshaber KG
Williams Hezron
Wilson Katina
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