EP1941247A1 - Dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d un produit - Google Patents

Dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d un produit

Info

Publication number
EP1941247A1
EP1941247A1 EP06807357A EP06807357A EP1941247A1 EP 1941247 A1 EP1941247 A1 EP 1941247A1 EP 06807357 A EP06807357 A EP 06807357A EP 06807357 A EP06807357 A EP 06807357A EP 1941247 A1 EP1941247 A1 EP 1941247A1
Authority
EP
European Patent Office
Prior art keywords
amplitude
level
response signal
approach
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP06807357A
Other languages
German (de)
English (en)
Inventor
Igor Getman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Endress and Hauser SE and Co KG
Original Assignee
Endress and Hauser SE and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Endress and Hauser SE and Co KG filed Critical Endress and Hauser SE and Co KG
Publication of EP1941247A1 publication Critical patent/EP1941247A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
    • G01F23/266—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors measuring circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/20—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of apparatus for measuring liquid level

Definitions

  • the invention relates to a device for capacitive determination and / or monitoring of the level of a medium in a container, with at least one probe unit, with at least one control unit, which acts on the probe unit with a drive signal, and with at least one evaluation unit, which from the probe unit receives at least one response signal, and which determines from the response signal at least one statement about the level, wherein the response signal has at least one amplitude and one phase relative to the drive signal and / or to a reference signal.
  • the medium may be, for example, a liquid or a bulk material.
  • Capacitive level gauges are known in the art. The
  • Measuring principle is that a measuring probe and a second probe or the wall of the container in which the medium is located, form the two electrodes of a capacitor with the medium as a dielectric.
  • the capacity of the capacitor is dependent on the level of the medium, and therefore allows the determination of the level.
  • the probe is usually subjected to a drive signal, which is an electrical alternating voltage of a predeterminable frequency.
  • the response signal is usually a current signal, which is usually converted to an AC voltage. From the response signal then the level is determined.
  • Probe can form, which adversely affects the measurement. Especially very viscous material tends to adhere to the probe unit and thus forms an approach. Under certain circumstances, the approach can lead to the fact that a level measurement is no longer possible because the approach acts as a kind of metallic insulation around the probe.
  • the object of the invention is to propose a capacitive measuring device with which the level can be determined as reliably as possible even when approaching prone media.
  • the evaluation unit determines from the response signal and / or from the temporal behavior of the response signal a statement about an approach to the probe unit that in the evaluation at least a first and a second formula or a first and a second evaluation In the case that the approach is below a predetermined limit value, the evaluation unit determines the statement about the fill level via the first formula and / or via the first evaluation algorithm from the response signal, and that in the case that the Approach is above the predetermined limit, the evaluation determines the statement about the level of the second formula and / or the second evaluation algorithm from the response signal.
  • the evaluation unit is designed such that it first determines a statement about the approach from the response signal.
  • the evaluation unit determines a statement about an approach from a combination of the phase and the amplitude of the response signal.
  • the response signal is a signal with a mostly complex amplitude and a phase relative to the drive signal or to another reference signal.
  • phase and amplitude under the influence of the approach depending on the level is different in each case.
  • An evaluation of phase and imaginary and real part of the amplitude, or a combination of these variables allows a statement about the approach.
  • a calculation of the quantities with corresponding factors allows, for example, the specification of a tolerance band within which only a negligible approach occurs. However, if the approach is negligible, then one can continue to calculate with the formula or with the algorithm, which or which also finds use without an approach. For example, the amplitude or a part, eg the imaginary part, is evaluated. However, if the approach is greater than the value associated with the tolerance band limit, then a formula less affected by the approach must be used.
  • the phase in the case of the strong approach, the phase can be evaluated preferentially, since, in contrast to the amplitude, this also shows a dependency on the fill level when used.
  • the phase is ideally about 90 ° for each level, so without an inclusion of the phase in the determination of the level is not helpful. Therefore, depending on the case, the appropriate formula is too use.
  • An embodiment includes that in the event that the approach is below a predetermined threshold, the evaluation determines the statement about the level of the amplitude or from a portion of the amplitude of the response signal, and that in the case that the approach is above the predetermined limit, the evaluation determines the statement about the level of the phase of the response signal.
  • the amplitude or part of the amplitude e.g. the imaginary part or a combination of imaginary and real part - for example, the difference between the two values - ideal for determining the level. If, however, approach is given, then the phase is to be preferred.
  • Level between a minimum and a maximum level value is that at least one lower level value and / or an upper level value can be specified as switching points / switching point, the lower level value and / or the upper level value between the minimum and the maximum level value is / is ,
  • the meter is thus used as a two-point switch or serves to control the level between a lower and an upper value. This is advantageous, for example, to regulate the level of the medium in a buffer.
  • the minimum level value is usually given by the lower end of the probe unit.
  • the maximum level value is usually close to the attachment of the probe unit. The fill level values to be monitored are therefore between these two extreme values.
  • An embodiment includes that at least one memory unit is provided, wherein in the memory unit, an upper phase value and an upper amplitude value or an upper Operaamplituwertwert, which are assigned to the upper level value, are stored, and / or wherein in the memory unit, a lower phase value and a lower amplitude value or a lower partial amplitude value, which are assigned to the lower fill level value, are stored, that the evaluation unit for determining the statement on the level of the phase and / or amplitude and / or the part of the amplitude and / or a combination of the phase and the amplitude and / or a part of the amplitude of the response signal with the corresponding values, which are associated with the switching points, and compares that upon reaching one of a switching point associated value by the response signal, the evaluation unit signals the reaching of the associated switching point.
  • This embodiment of the two-point signal relates to the fact that in particular the phase in the case of the approach and the amplitude in the case of the only small approach are used to determine the filling level.
  • the evaluation unit monitors the corresponding values of the response signal and reports an exceeding or falling short of the assigned limit values.
  • the size to be used for monitoring the fill level results from the response signal. This means that the evaluation unit initially derives from the response signal whether there is an approach. From this information follows whether phase or amplitude is to be used to monitor the level. Finally, the metric matching the situation is compared with the associated limits.
  • This embodiment is therefore particularly advantageous for the control of the level of a medium, which tends to formation of deposits in a container.
  • the maximum and the minimum level value are above or below the two fill level values to be monitored, additional monitoring is still provided, even if the reaching of these extreme values is monitored.
  • an embodiment includes that the effective in the container probe length of the probe unit is smaller than 1 meter. In one embodiment, the probe length within the container is less than 50 cm.
  • the container is thus, for example, an intermediate tank, which is interposed between the actual medium tank and, for example, a bottling plant.
  • Fig. 1 a schematic representation of a measurement with the invention Mes s device.
  • an intermediate container 2 is filled by a superordinate tank 7 with medium 1. From the container 2 then the filling into individual containers as here as an example bottles 8. The height of such intermediate container is often only between 30 cm and 50 cm.
  • the medium 1 is thus for example liquid soap or liquid foods such as mustard or ketchup.
  • a problem of such highly viscous and at the same time very conductive media is the formation of deposits on the probe unit 3.
  • the probe unit 3 is, for example, a probe rod or a probe cable. Due to the approach, the probe 3 is virtually shielded. This problem is related to the fact that the actual electrically conductive probe is surrounded by an insulating layer.
  • the probe unit 3 is acted upon by a control unit 4 with a drive signal.
  • This is usually an electrical alternating voltage of a predefinable frequency.
  • the frequency of the drive signal also has effects on the prior art and thus also has an effect on the limit and tolerance values which are predetermined for the determination of the approach.
  • a response signal is tapped from the probe unit. This is usually a current signal, which is converted for example via a resistor into a voltage signal.
  • the control unit 4 and the evaluation unit 5 are summarized in one embodiment in a single unit. This unit is preferably an electronic unit controlled by a microprocessor.
  • the evaluation unit 5 is designed such that it digitizes the response signal and thus the entire signal of the Evaluation makes accessible. In the evaluation unit 5, a statement about an approach to the probe unit 3 is first obtained from the response signal.
  • phase is about 90 °
  • the level is in the vicinity of the maximum level or the upper switching point. Therefore the amplitude has to be examined. If the amplitude indicates a low level, the phase of about 90 ° results from the normal phase on the capacitor and there is no approach.
  • Corresponding considerations between phase and amplitude or part of the amplitude - imaginary or real part - or from a combination of phase and amplitude can also be set up for all other cases. Overall, a statement about the approach and with this knowledge can then use the appropriate formula or the appropriate evaluation algorithm for the determination and / or monitoring of the level. If no approach is given, then the evaluation of the amplitude is recommended, eg the evaluation of the imaginary part. If the approach adheres, the evaluation of the phase is advantageous.
  • the meter is used to control the level of the
  • the aim is that the level is always between a lower and an upper value. Because this range is within the range between maximum and minimum level, the extreme values are still monitored even at the beginning, thus providing increased safety, i. even if the switching values are exceeded, the extreme values are still limiting.
  • pumps or valves can be controlled such that reaching the lower switching point to an inflow of medium 1 in the container 2 and reaching the upper switching point serves to stop another filling.
  • Such a control has the advantage that the switching ranges do not produce any sharp boundaries.
  • Such switching zones thus also take into account that the approach is not always possible with high-precision statements. However, if, for example, it is recognized that the approach is too large and thus further measurements are not meaningful, a warning is output, for example.
  • the switching points 6 corresponding limits and tolerance ranges are stored here in the memory unit. Depending on the evaluation, i. depending on the case, if approach is given, these are also appropriate values. In the case of the approach, the phase is evaluated, so that stored in the memory unit 6 the switching points associated phase values.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L'invention concerne un dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d'un produit (1) dans un contenant (2), muni d'une unité de sonde (3), d'une unité de commande (4), appliquant à l' unité de sonde (3) un signal de commande, et d'une unité d'interprétation (5), recevant un signal de réponse de l'unité de sonde (3) et déterminant une valeur du niveau de remplissage à partir du signal de réponse. Selon l'invention, l'unité d'interprétation (5) calcule à partir du signal de réponse et/ou à partir du comportement temporel du signal de réponse une valeur avec une équation de l'unité de sonde (3), de sorte que l'unité d'interprétation (5) comporte au moins une première et une seconde formule ou bien un premier et un second algorithme d'interprétation, et que si l'équation était inférieure à une valeur seuil donnée, l'unité d'interprétation (5) détermine la valeur du niveau de remplissage avec une première formule, et si l'équation est supérieure à la valeur seuil donnée, l'unité d'interprétation (5) détermine la valeur du niveau de remplissage avec une seconde formule.
EP06807357A 2005-10-27 2006-10-17 Dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d un produit Ceased EP1941247A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102005051794A DE102005051794A1 (de) 2005-10-27 2005-10-27 Vorrichtung zur kapazitiven Bestimmung und/oder Überwachung des Füllstands eines Mediums
PCT/EP2006/067514 WO2007048739A1 (fr) 2005-10-27 2006-10-17 Dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d’un produit

Publications (1)

Publication Number Publication Date
EP1941247A1 true EP1941247A1 (fr) 2008-07-09

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP06807357A Ceased EP1941247A1 (fr) 2005-10-27 2006-10-17 Dispositif de détermination capacitive et/ou de surveillance du niveau de remplissage d un produit

Country Status (5)

Country Link
US (1) US8117910B2 (fr)
EP (1) EP1941247A1 (fr)
CA (1) CA2627210C (fr)
DE (1) DE102005051794A1 (fr)
WO (1) WO2007048739A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120067119A1 (en) * 2009-05-26 2012-03-22 Diba Industries, Inc. Pressure-sensor based liquid-level measuring device with reduced capillary effect
DE102010042624A1 (de) * 2010-10-19 2012-04-19 Krones Aktiengesellschaft Verfahren zum Betreiben einer Abfüllanlage
US9261395B2 (en) 2012-02-13 2016-02-16 Goodrich Corporation Liquid level sensing system
US9574928B2 (en) 2012-02-13 2017-02-21 Goodrich Corporation Liquid level sensing systems
DE102014115635A1 (de) * 2014-10-28 2016-04-28 Endress + Hauser Gmbh + Co. Kg Verfahren zur Messwertverarbeitung
DE102018127458A1 (de) 2017-11-14 2019-05-16 Miele & Cie. Kg Verfahren und Steuergerät zum Steuern eines wasserführenden Reinigungsgerätes und Reinigungsgerät

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4347741A (en) * 1980-07-17 1982-09-07 Endress & Hauser, Inc. Control system for a capacitive level sensor
US5245873A (en) * 1982-08-25 1993-09-21 Berwind Corporation Capacitance-type material level indicator and method of operation
DE19916979A1 (de) * 1999-04-15 2000-11-02 Sican Gmbh Verfahren zur Füllstandsmessung und Füllstandssensor
DE10161069A1 (de) 2001-12-12 2003-06-18 Endress & Hauser Gmbh & Co Kg Feldgeräteelektronik mit einer Sensoreinheit für kapazitive Füllstandsmessungen in einem Behälter
DE10322279A1 (de) 2003-05-16 2004-12-02 Endress + Hauser Gmbh + Co. Kg Kapazitive Füllstandmessung
DE102004008125A1 (de) 2004-02-18 2005-09-01 Endress + Hauser Gmbh + Co. Kg Verfahren und Vorrichtung zur kapazitiven Füllstandsbestimmung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2007048739A1 *

Also Published As

Publication number Publication date
CA2627210A1 (fr) 2007-05-03
US8117910B2 (en) 2012-02-21
US20100005879A1 (en) 2010-01-14
WO2007048739A1 (fr) 2007-05-03
CA2627210C (fr) 2013-02-12
DE102005051794A1 (de) 2007-05-03

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