WO2010040583A1 - Dispositif de détermination et/ou de surveillance d'une grandeur de processus d'un milieu - Google Patents

Dispositif de détermination et/ou de surveillance d'une grandeur de processus d'un milieu Download PDF

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Publication number
WO2010040583A1
WO2010040583A1 PCT/EP2009/060407 EP2009060407W WO2010040583A1 WO 2010040583 A1 WO2010040583 A1 WO 2010040583A1 EP 2009060407 W EP2009060407 W EP 2009060407W WO 2010040583 A1 WO2010040583 A1 WO 2010040583A1
Authority
WO
WIPO (PCT)
Prior art keywords
unit
medium
mechanically oscillatable
excitation signal
cleaning
Prior art date
Application number
PCT/EP2009/060407
Other languages
German (de)
English (en)
Inventor
Sergej Lopatin
Helmut Pfeiffer
Martin Urban
Original Assignee
Endress+Hauser Gmbh+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+Hauser Gmbh+Co.Kg filed Critical Endress+Hauser Gmbh+Co.Kg
Publication of WO2010040583A1 publication Critical patent/WO2010040583A1/fr

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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
    • G01F23/28—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 the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves
    • G01F23/2966—Acoustic waves making use of acoustical resonance or standing waves
    • G01F23/2967—Acoustic waves making use of acoustical resonance or standing waves for discrete levels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G01N11/10—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material
    • G01N11/16—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by moving a body within the material by measuring damping effect upon oscillatory body
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
    • G01N9/002—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis

Definitions

  • the invention relates to a device for determining and / or monitoring at least one process variable of a medium, comprising at least one mechanically oscillatable unit, with at least one drive unit, which excites the mechanically oscillatable unit to mechanical vibrations based on an excitation signal, and with at least one Eiektronikhim which acts on the drive unit with the Anreungssignai.
  • the process variable is, for example, the level, density or viscosity of a medium which is, for example, a liquid or a fluid in general.
  • the medium is, for example, in a container.
  • vibration forks for example EP 0 444 173 B1
  • rods for example EP 2004/094964 A1
  • membrane vibrators membrane vibrators.
  • the characteristics of the mechanical vibrations vary on the contact with the medium and also on its properties.
  • the frequency or amplitude of the vibrations decreases as the medium reaches and at least partially covers the vibratable unit. Therefore, it can be concluded from the decrease in the oscillation frequency or the amplitude that the medium has reached a level dependent on the design and the position of the attachment of the device.
  • the oscillation frequency is also dependent, for example, on the viscosity (see, for example, EP 1 325 301) and the density of the medium.
  • the mechanically oscillatable unit is confined to a membrane, i. In particular, there are no forks available.
  • the deposition of gas bubbles on the membrane causes shifts in the oscillation frequency in the direction of the freely oscillating membrane (referred to as the air resonance frequency of the membrane).
  • the gas bubbles deposited on the membrane can strongly attenuate the oscillatable unit and thus reduce the oscillation amplitude. Therefore, measurement uncertainties result e.g. in the case of strongly degassing media (such as, for example, in fresh water shortly before cooking or in soda water).
  • the invention has for its object to provide a measuring device, which allows a reliable measurement even with outgassing liquids.
  • the invention solves the problem in that the electronic unit is designed such that the electronics unit, at least during a cleaning phase, the drive unit with a cleaning excitation signal applied.
  • a cleaning phase is provided for the mechanically oscillatable unit, in which, in particular, gas bubbles of the medium, which have formed on the mechanically oscillatable unit, are detached from it.
  • the mechanically oscillatable unit is excited by the drive unit, starting from an excitation signal to mechanical vibrations.
  • Embodiment forms a unit with the drive unit or is identical in a further embodiment with the drive unit receives the mechanical vibrations and generates a received signal whose characteristics - amplitude, frequency, phase relative to the excitation signal - allow a statement about the process variable.
  • the excitation signal has a measurement frequency and a measurement amplitude. The amplitude depends, for example, on the energy with which the device is operated.
  • the frequency is usually the resonance frequency of the mechanically oscillatable unit.
  • Excitation signal during a measurement phase is.
  • the cleaning amplitude is thus substantially equal to the measurement amplitude, i. in both cases, the same excitation energy is used in terms of amplitude.
  • Cleaning excitation signal is greater than an amplitude of the excitation signal during a measurement phase.
  • the mechanically oscillatable unit is thus in this embodiment with achessanregungssigna! applied, whose amplitude is above the measurement amplitude. If the drive unit of the mechanically oscillatable unit is excited with a high voltage, i. if the amplitude is increased, the mechanical movements of the mechanically oscillatable unit, which in one embodiment is a membrane, increase sharply. By a corresponding Wahi the excitation frequency during the cleaning phase, it is possible to stimulate the gas bubbles to vibrate.
  • the resonant frequency of the gas bubbles is advantageously to be used as the frequency of the cleaning excitation signals. If the vibrational forces exceed the postural forces by which the gas bubbles adhere to the membrane, for example, then the bubbles dissolve
  • An embodiment of the device according to the invention includes that the frequency of the cleaning excitation signal is substantially equal to the resonant frequency of at least a portion of gas bubbles forming and / or in the medium.
  • the mechanically oscillatable unit is configured such that the resonant frequency of the mechanically oscillatable unit is substantially equal to the resonant frequency of at least a portion of gas bubbles forming and / or in the medium.
  • An embodiment of the device according to the invention includes that the electronics unit is configured such that the electronics unit varies the frequency of the cleaning excitation signal within a predefinable range, at least during the cleaning phase.
  • the frequency is in one embodiment, the resonant frequency of the gas bubbles, which can occur in the medium and which primarily the
  • Vibration behavior of the mechanically oscillatable unit influenced.
  • a so-called frequency sweep is performed, i. During excitation, a frequency range is traversed.
  • the occurring signals - excitation signal, cleaning signal and received signal - are in particular electrical voltage signals.
  • the cleaning signals Rectangular configured, in one embodiment, in particular, are sinusoidal signals.
  • the frequency of the mechanically oscillatable unit is substantially equal to the resonant frequency of the gas bubbles, which have the strongest influence on the vibration behavior of the mechanically oscillatable unit.
  • the energy is used optimally because the vibrations have maximum amplitude.
  • the measuring device is thus adapted to the medium and especially to its outgassing behavior or the gas bubbles occurring in the process.
  • the electronics unit is configured such that the electronics unit varies the frequency of the cleaning excitation signal within a predefinable range, at least during the cleaning phase.
  • the swept area it is preferable to have the resonance frequency of the gas bubbles of the medium or at least part of the gas bubbles of the medium.
  • an area is subjected to a frequency sweep by 10% to 20% about the resonance frequency of the oscillatable unit.
  • the membrane oscillator in principle, it is possible to excite the membrane oscillator at its resonant frequency by a corresponding resonant circuit, which results from the electronics unit, and to free by the periodic or permanent lifting of the transmission voltage and thus the Ampütude of gas bubbles.
  • the cleaning phase coincides with the measurement phase and that preferably in particular the resonance frequency of the mechanically oscillatable unit is equal to the resonance frequency of the gas bubbles.
  • the drive unit preferably excited periodically with a frequency sweep at a high amplitude and thus a high voltage.
  • the frequency sweep comprises in particular the expected measuring range and is preferably also devisrauf from the higher to the lower frequency.
  • An embodiment provides that the mechanically oscillatable unit is a vibratable membrane.
  • An embodiment of the device according to the invention includes that the surface of the mechanically oscillatable unit, which comes into contact with the medium, at least partially substantially smooth, in particular polished, is.
  • An embodiment includes that the surface of the mechanically oscillatable unit, which comes into contact with the medium, at least partially has an anti-corrosion coating.
  • An embodiment provides that the surface of the mechanically oscillatable unit, which comes into contact with the medium, has at least one region which is rough.
  • sacrificial surface in the form of a roughened, for example, sandblasted area, for example in the form of a ring, can be produced at the edge of the membrane, at which the gas bubbles preferentially arrange.
  • An embodiment provides that the surface of the mechanically oscillatable unit, which comes into contact with the medium, at least partially coated with a polymer, in particular with a hydrophobic plastic.
  • the mechanically oscillatable unit is a membrane with a circular border which has a ring with a rough surface.
  • An embodiment of the device according to the invention includes that the drive unit receives mechanical vibrations from the mechanically oscillatable unit and converts them into a received signal.
  • the drive unit comprises at least one piezoelectric element.
  • FIG. 1 shows a schematic representation of a measuring device according to the invention
  • FIG. 2 shows a plan view of a mechanically oscillatable unit in the form of a membrane
  • FIG. 3 is a schematic representation of the application of a measuring device according to the invention for measuring a process variable
  • FIG. 4 shows a plan view of a membrane of a measuring device according to the invention.
  • the mechanically oscillatable unit 1 is here a membrane, which is mounted on one side of a housing 4 such that the medium to determine the at least one process variable and / or to monitor, can interact with the membrane.
  • the membrane is preferably circular.
  • the drive unit 2 On the inside of the membrane is the drive unit 2, which is, for example, a piezoelectric element.
  • the drive unit 2 is acted upon by the electronic unit 3 with an electrical signal and executes thereof starting from mechanical vibrations, which excite the membrane as a mechanically oscillatable unit 1 to mechanical vibrations.
  • a piezoelectric element of the drive unit 2 also serves to receive the mechanical vibrations of the membrane 1, which are converted into a received signal and further processed or evaluated by the electronic unit 3.
  • the electronic unit 3 acts on the drive unit 2 with an excitation signal and during a cleaning phase with a cleaning excitation signal.
  • the cleaning excitation signal in one embodiment has a predetermined, fixed frequency, which preferably corresponds to the resonant frequency of the mechanically oscillatable unit 1 and / or the resonant frequency of a portion of the gas bubbles which are or form in the medium to be measured or monitored. Preferably, these are the gas bubbles which most affect the vibrations of the mechanically oscillatable unit 1.
  • the frequency of the cleaning excitation signal is varied within a predefinable frequency range, wherein the frequency range is preferably selected such that the resonance frequencies of the gas bubbles occurring in the medium are in this range.
  • the cleaning excitation signal By the cleaning excitation signal, the gas bubbles are excited to vibrate to thereby detach from the membrane 1.
  • the measuring phase and the cleaning phase are identical in one embodiment, so that the vibrations which are used for the measurement at the same time also contribute to the completion of the gas bubbles. In another embodiment is alternated regularly between these two phases.
  • FIG. 2 shows a plan view of a circular membrane 1. You can see the proportion that comes in contact with the medium.
  • the membrane 1 is designed predominantly smooth, so that as little as possible
  • a strip which is designed to be rough, so that the gas bubbles settle preferentially at this location.
  • the medium 10 is in particular a liquid which tends to outgas.
  • the measuring device is attached to the wall of the container 11.
  • the resonance frequency of the mechanically oscillatable unit is tuned such that this frequency is at the same time the resonance frequency of at least part of the gas bubbles of the medium and preferably of the part of the gas bubbles, which mainly influence the vibration behavior of the mechanically oscillatable unit. That Depending on the nature of the medium 10 or as a function of the outgassing behavior, a corresponding sensor is to be selected or its resonant frequency is to be designed appropriately.
  • FIG. 4 shows a plan view of the underside, ie the side of a membrane facing the medium or the process, which shows the mechanically oscillatable unit 1 of the measuring device in this embodiment Design is. Dashed lines show an imaginary symmetry axis.
  • the surface of the membrane 1 is mainly roughened in this embodiment, or in this case to two places.
  • the surface of the membrane 1 within the two arranged symmetrically to the axis of symmetry and outlined by dashed lines ovals is polished and thus serves as sensitive membrane areas. On the rough surface area there is a faster bias growth, so this is a "sacrificial surface.”
  • the smooth areas, or with a different expression: the "vibrating surfaces” are therefore less affected by the gas bubbles.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Acoustics & Sound (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L'invention concerne un dispositif de détermination et/ou de surveillance d'au moins une grandeur de processus d'un milieu (10), comprenant au moins une unité (1) apte à produire des vibrations mécaniques, au moins une unité d'entraînement (2) qui, à partir d'un signal d'excitation, excite l'unité (1) pour l'amener à produire des vibrations mécaniques, et au moins une unité électronique (3) qui cède le signal d'excitation à l'unité d'entraînement (2). Selon l'invention, l'unité électronique (3) est conçue de telle façon que, au moins pendant une phase de nettoyage, l'unité électronique (3) cède un signal d'excitation de nettoyage à l'unité d'entraînement (2).
PCT/EP2009/060407 2008-10-08 2009-08-12 Dispositif de détermination et/ou de surveillance d'une grandeur de processus d'un milieu WO2010040583A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008050445.9 2008-10-08
DE200810050445 DE102008050445A1 (de) 2008-10-08 2008-10-08 Vorrichtung zum Bestimmen und/oder Überwachung einer Prozessgröße eines Mediums

Publications (1)

Publication Number Publication Date
WO2010040583A1 true WO2010040583A1 (fr) 2010-04-15

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WO (1) WO2010040583A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010003733B4 (de) * 2010-04-08 2020-08-13 Endress+Hauser SE+Co. KG Verfahren zur Detektion von Gasblasen in einem flüssigen Medium
DE102010003734B4 (de) * 2010-04-08 2021-06-17 Endress+Hauser SE+Co. KG Verfahren zur Detektion von Gasblasen in einem flüssigen Medium
DE102010028161B4 (de) 2010-04-23 2023-08-17 Endress+Hauser SE+Co. KG Verfahren und Vorrichtung zur Bestimmung und/oder Überwachung eines Grenzfüllstands
EP2604987A1 (fr) * 2011-12-16 2013-06-19 Harro Höfliger Verpackungsmaschinen GmbH Capteur, récipient et procédé de determination du niveau d'un matériau
DE102015100417A1 (de) 2015-01-13 2016-07-14 Krohne Messtechnik Gmbh Verfahren zur Bestimmung des Füllstands eines Mediums in einem Behälter
DE102015100415A1 (de) 2015-01-13 2016-07-14 Krohne Messtechnik Gmbh Vorrichtung zur Bestimmung des Füllstands eines Mediums
DE102015100414A1 (de) 2015-01-13 2016-07-14 Krohne Messtechnik Gmbh Vorrichtung zur Bestimmung des Füllstands eines Mediums in einem Behälter
DE102019105302A1 (de) * 2019-03-01 2020-09-03 Vega Grieshaber Kg Grenzstandsensor für anhaftende Medien und Verfahren zum Betreiben eines solchen Grenzstandsensors

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US5051645A (en) * 1990-01-30 1991-09-24 Johnson Service Company Acoustic wave H2 O phase-change sensor capable of self-cleaning and distinguishing air, water, dew, frost and ice
DE19850801A1 (de) * 1998-11-04 2000-05-11 Bosch Gmbh Robert Verfahren und Vorrichtung zum Betrieb einer mikroakustischen Sensoranordnung
WO2008012317A1 (fr) * 2006-07-27 2008-01-31 Continental Automotive Gmbh Capteur acoustique de fluide avec mode nettoyage

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JPS5825214B2 (ja) * 1978-01-18 1983-05-26 株式会社日立製作所 粉粒体レベル検出装置
DE3931453C1 (fr) 1989-09-21 1991-02-28 Endress U. Hauser Gmbh U. Co, 7864 Maulburg, De
DE4203967C2 (de) * 1992-02-11 1995-06-22 Endress Hauser Gmbh Co Vorrichtung zur Feststellung und/oder Überwachung eines vorbestimmten Füllstands in einem Behälter
DE4327167C2 (de) * 1993-08-13 1996-07-04 Grieshaber Vega Kg Verfahren und Vorrichtung zum Feststellen eines vorbestimmten Füllstandes in einem Behältnis
US5438230A (en) * 1994-02-28 1995-08-01 Motorola, Inc. Piezoelectric material detector
DE10050299A1 (de) 2000-10-10 2002-04-11 Endress Hauser Gmbh Co Vorrichtung zur Bestimmung und/oder Überwachung der Viskosität eines Mediums in einem Behälter
DE10318705A1 (de) 2003-04-24 2004-11-18 Endress + Hauser Gmbh + Co. Kg Vorrichtung zur Bestimmung und/oder Überwachung mindestens einer physikalischen oder chemischen Prozessgröße eines Mediums

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5051645A (en) * 1990-01-30 1991-09-24 Johnson Service Company Acoustic wave H2 O phase-change sensor capable of self-cleaning and distinguishing air, water, dew, frost and ice
DE19850801A1 (de) * 1998-11-04 2000-05-11 Bosch Gmbh Robert Verfahren und Vorrichtung zum Betrieb einer mikroakustischen Sensoranordnung
WO2008012317A1 (fr) * 2006-07-27 2008-01-31 Continental Automotive Gmbh Capteur acoustique de fluide avec mode nettoyage

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Publication number Publication date
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