DD213995A1 - FURNITURE MEASUREMENT DEVICE IN PANELS - Google Patents

Abstract

The invention has for its object to design a Fuellstandsmesseinrichtung, which excludes the known disadvantages of measuring devices with mechanically moving parts and can be used in containers that do not allow radioactive Fuellstandsmessverfahren due to the goods to be stored. According to the invention, the object is achieved in that, by suitable means, the volume of air in the container is deliberately excited at a selectable frequency. In addition, means are provided which allow the exciter frequency to be matched to the resonant frequency, and thus the resonant frequency can be determined. By means of a once established Füllstandsresonenzfreqenzkennlinie can be closed to the filling level and thus to the quantity in the container. The measuring device can be used in all containers, preferably silos and bunkers, in which the exciter and sound pressure transducer can be installed.

Description

Title of the invention;

Si'nrioiituns for level measurement in containers

Field of application of the invention

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Containers for storage and transport of various goods are used in almost all branches of industry. 3s is often the current level of interest, depending on the purpose for which they are used. A wide range of methods and devices allows the control of the level according to the respective requirements, For example, sight glasses, level switches of various designs and sensing devices are known,

For filling level measurements in bulk containers, in addition to the first-time arrangement of fill level switches, predominantly scanning devices of the bulk material surface are used,

For example, multiple arrangements of Füllstandsschaltem der.verschiedensten. Principles of operation possible, in addition to the considerable device-technical expenditure, the occurring uncertainty between two level switches and the formation of an uneven bulk material surface can cause erroneous measurement results. To the known state, the technique include, further various mechanical scanning devices that use a attached to a rope Tastkörper- to determine the level «Various such measuring devices either the ¹ Iastkörper the bulk material surface nachnach or keys at regular intervals from a starting position from the bulk material surface and thus the level of, These measuring devices has a total of the lack of, several mechanically moving and so much trouble-prone 'line to contain and scan through their sample the bulk material surface only punctiform. For uneven bulk material surfaces, therefore, significant errors occur.

Particularly in recent times, contactless measuring methods have increasingly been used for level measurement tasks in bulk containers. Thus, for example, an echosounding method is becoming increasingly popular. This method uses the transit time of a pulse for determining the fill level in the container. Various solutions are now available, which this procedure according to the. , apply the respective application. All these facilities are liable for the defect that they have to be detected incorrectly by detecting the surface of the rubbish surface, the fill level being incorrectly determined and / or realized by expensive technical means »

Another solution is described in DE 2417734. It uses for the acoustic excitation of the air in the container a jet of air in the corresponding manner against the

Tank opening is directed, The thus generated acoustic vibrations are converted into electrical signals, thus allowing a. Conclusion on the level in the container, complicated container conditions, in particular; large and closed containers in this way can not stimulate the Luftstromes-. Likewise, the detection of the resonance state in the manner described is difficult.

Object of the invention

The aim of the invention is a device for continuous and Bedarfsv / iron determination of the level in preferably closed containers, in which, justified by the material to be stored, no radioactive measuring methods and measuring methods with mechanical in the container 'moving' healing can be used.

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The invention is based on the idea to design a level measuring device, which excludes the known laughing parts of measuring devices with mechanically moving healing by the use of a -acoustical measurement and at the same time can be used in containers that do not permit radioactive Füllstandsmeßverfahren due to 'the goods to be stored * doing at the same time a measuring method is to be used which is also suitable under complicated conditions, such as in pressure vessels, open containers and containers with complicated geometrical dimensions,

By extensive experiments it was found that the oscillation frequency of the excited volume of air to the resonance case in a container clearly a level and

Thus, the object of the invention is to solve the problem of stimulating the air volume in the container to resonate in a suitable, purposeful manner, to achieve the resonance case and to evaluate this in a suitable manner in order to make a statement on the level receive. According to the invention, the object is achieved in that a pathogen is expediently arranged in the container above, with which the volume of air in the container is excited at a selectable frequency. The frequency must be continuously variable in a frequency range corresponding to the container.

It is also part of the essence of the invention that expediently in the container above a sound pressure transducer, preferably a microphone, is attached, which receives the sound pressure and converts it into electrical signals * The sound pressure transducer is followed by an amplifier and this a meter.

solved.

According to the invention, the object is further solved in that by monitoring the meter by the operator or an automatic device, the excitation frequency is adjusted to a maximum of the sound pressure, by means of a once recorded level resonance frequency characteristic can on the basis of the determined resonance frequency :, a statement on the level of the container hit '// earth. It also belongs to the invention that a plurality of exciters and sound pressure transducers can be connected to a control device and to a measuring device via a switching device. to be able to minimize the technical complexity of several containers.

The advantages of the invention consist in the application of a simple suitable method, in particular for measuring tasks, the radioactive Püllstandsmeßverfahren due to

Do not allow requirements of the contents. Furthermore, the advantages of the invention in the creation of a cost, rubusten and reliable measuring device by detecting the total volume of air in the container, the true mean level and. Thus, the true quantity of stock, especially on bulk material, with uneven interface bulk material - air determined. The invention will be explained in more detail below with an exemplary embodiment.

_ 3

In a 3o m silo aggregates are stored for mineral mixtures, Due to the feeding of these mineral mixtures to animals no radioactive Füilstandsmeßverfahren allowed. It is therefore used the device described. For this purpose, a loudspeaker and a microphone is mounted in the cylindrically shaped container above, so that both are acoustically coupled only over the entire air space in the container * With a recorded once-level resonance frequency characteristic is adjusted by hand to a pressure minimum, the resonance frequency and thus the Level determined in the container, The exciter was coupled in the frequency range used between 600 and 800 Hz. With a tunable tone generator. On a small scale, a characteristic curve was determined which unambiguously assigns the resonance frequency to the fill level, and experimental measurements were made on the basis of this characteristic curve. It was possible to determine the level with ^T 3 m accuracy within the scope of these test measurements.

Claims (5)

Jj rf indung s ans jgruch. 1. Apparatus for carrying out the method of level measurement by determining the befindlicher in a hollow body air volume by means of acoustic resonance, characterized in that by, a pathogen, the volume of air in the container at a frequency in the range: the sound waves excited, which is in a variable frequency range, in order to be able to determine the resonant frequency by means of measuring the sound pressure and frequency adjustment to the maximum sound pressure level, which allows an unambiguous determination of the filling level. « 2. Device by point; 1, characterized in that the exciter, preferably a speaker, and the Schai! Druckaufnehmer »preferably a microphone, are arranged in the container above such that both are acoustically coupled only via the remaining air volume in the container. 3. Device according to item 1 and. 2, characterized in that the frequency of the sound waves emitted by the exciter by a control device, preferably an ion generator, is continuously variable, is displayed and adjusted by hand or a Automatikeinr.ich.tung in. Dependence of the measured sound pressure to a maximum sound pressure « 4. Device after. Points 1,2 and 3, characterized in that the frequency display scale of the control unit is calibrated in filling units, 5. The device according to item I ₅ 3 and 4, characterized in that the frequency range of the control unit is selected so that in each Füll33zustand of the container a resonant frequency, can be determined, which clearly determine the level in the container IaBt. η /: S3 η a ft O 0 -ί, Π Q Λ '-λ »1"'