EP1238257A1 - Procede et dispositif pour evaluer un dispositif capteur - Google Patents

Procede et dispositif pour evaluer un dispositif capteur

Info

Publication number
EP1238257A1
EP1238257A1 EP00983031A EP00983031A EP1238257A1 EP 1238257 A1 EP1238257 A1 EP 1238257A1 EP 00983031 A EP00983031 A EP 00983031A EP 00983031 A EP00983031 A EP 00983031A EP 1238257 A1 EP1238257 A1 EP 1238257A1
Authority
EP
European Patent Office
Prior art keywords
output signal
low
frequency
excitation voltage
signal
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.)
Withdrawn
Application number
EP00983031A
Other languages
German (de)
English (en)
Inventor
Bernhard Jakoby
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1238257A1 publication Critical patent/EP1238257A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/243—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the phase or frequency of ac

Definitions

  • the present invention relates to a method and a device for evaluating a sensor device, the sensor device forming an electrical resonator in a resonant circuit excited with an external excitation voltage.
  • Piezoelectric thickness shear transducers for example made of quartz, have been used for viscosity measurement for some time. See, for example, SJ Martin et. al., Sens. Act. A 44 (1994) pages 209-218. If such a Dickenscherschwinger is immersed in a viscous liquid, its resonance frequency of the natural vibration and its damping change depending on the viscosity and density of the viscous liquid.
  • 4 shows an equivalent circuit diagram of a known viscosity sensor with a quartz resonator. 4, R generally designates the viscosity sensor or “resonator”. In the electrical equivalent circuit diagram, TA designates the dry component and FA the liquid component.
  • the dry component TA there is a series connection of a capacitance Ci, an inductance Li and a resistance Ri there is a series connection of an inductor * L 2 and a resistor R 2.
  • the dry portion TA and the liquid portion FA are bridged by a further capacitance C 0 .
  • the resistance R 2 is proportional to -sj ⁇ p, where ⁇ is the dynamic viscosity and p is the density of the viscous liquid.
  • R 2 represents the viscous damping by the liquid.
  • L 2 causes the frequency shift through the viscous liquid, which is also proportional to J ⁇ p.
  • L 2 also contains fractions which result from “trapped” liquid fractions in the rough resonator surface.
  • Quartz resonator can therefore be used to determine the viscosity ⁇ .
  • these changeable electrical parameters -R 2 and L 2 can be detected by using the resonator R as a frequency-determining element in an oscillator.
  • the impedance spectrum can be determined in the vicinity of the resonance frequency. See Lee et. al., Proc. IEEE Ultrasonics Symp. (1997) pages 419-422.
  • FIG. 5 is such a known evaluation circuit for the known viscosity sensor according to FIG. 4.
  • a voltage-controlled oscillator VCO is used for this, which feeds the resonator R immersed in the liquid, the liquid being 01 in this case.
  • the output signal of the resonator R is mixed with a reference signal REF in a multiplier or multiplier M.
  • the direct current component of the resulting signal is finally determined using a low-pass filter TP.
  • the course of this output signal over the frequency of the voltage-controlled oscillator VCO is finally used to evaluate the oil viscosity.
  • This evaluation takes place in a computer 100, which also controls the voltage-controlled oscillator VCO.
  • the method according to the above publication by Lee et. al. allows at least partial compensation of the influences of Co and C s , but does not provide an output signal corresponding to the viscosity, but only serves to determine a characteristic frequency response determined by the viscosity.
  • the inventive method with the features of claim 1 and the corresponding device according to claim 6 have the advantage over the known approach that the corresponding circuits are also suitable for measuring highly viscous liquids.
  • the sensor output signal is a DC voltage which is easy to process and which is a measure of the viscosity of the liquid.
  • the idea on which the present invention is based is that the disruptive influence of the static resonator capacitance Co and the stray capacitances C s is eliminated by determining the amplitude of the resistive phase component of the resonator current at the series resonance frequency.
  • the current is detected by a measuring resistor connected to ground.
  • the amplitude of the resistive component of the resonator current is determined by multiplying a signal corresponding to the resonator current by the external excitation voltage and subsequent filtering for averaging.
  • the external excitation voltage is wobbled and the peak value of the signal corresponding to the mean value is recorded with a time constant which is greater than the period of the wobble frequency.
  • the external excitation voltage is frequency-modulated (for example with a small square wave). This causes fluctuations in the amplitude of the signal corresponding to the mean value.
  • the signal corresponding to the mean value is used together with the modulation signal to regulate the excitation center frequency to the resonance frequency.
  • the sensor means is a viscosity sensor and has a Be * - sti determining unit for determining viscoelastic effects based on the output signal of the first low-pass filter and the output signal of the control means.
  • At least one of the multiplication devices is implemented in terms of circuitry by means of a switched inverter.
  • the detection device has a transimpedance amplifier for detecting the current in the resonant circuit.
  • FIG. 2 shows a block diagram of a second embodiment of the evaluation device according to the invention
  • FIG. 3 shows the output voltage of the first low-pass filter as a function of the VCO frequency in the second embodiment of the evaluation device according to the invention as shown in FIG. 2;
  • FIG. 5 shows a known evaluation circuit for the known viscosity sensor according to FIG. 4.
  • FIG. 1 shows a block diagram of a first embodiment of the evaluation device according to the invention.
  • reference symbol W denotes a wobble device for wobbling the external supply voltage.
  • VCO is a voltage-controlled oscillator, which is controlled by a sawtooth generator SZ.
  • R denotes all common to the resonator, C s is a stray capacitance, and R m is a detection resistor connected to ground.
  • M is a multiplier which mixes the output signal of the detection resistor R m and the output signal of the wobble device W.
  • TP is a low pass, which receives the output signal of the multiplier M
  • SWD is a peak detector which receives the output signal of the low-pass filter TP and ultimately corresponds the viscosity * returns speaking output signal OUT.
  • the resonator current is determined by the measuring resistor R m and multiplied by the applied resonator voltage.
  • the mean value of the resulting signal is proportional to the amplitude of the phase component of the resonator current and can be determined by filtering with a low pass. In this way, the influence of C 0 and C s determined reactive current components is eliminated.
  • the exact function of the circuit constructed in this way for determining the viscosity is as follows.
  • the resonator R is fed by the wobble device W.
  • there is a maximum at the series resonance frequency of the resonator R in the output signal of the low-pass filter TP which can be used to determine the resistance R 2 determined by the viscosity (cf. FIG. 4).
  • This maximum at the output of the low-pass filter TP is detected by the peak value detector SWD and used as the output signal AUS to determine the viscosity.
  • the memory time constant of the peak value detector SWD is greater than the period of the wobble frequency of the wobble device W.
  • FIG. 2 shows a block diagram of a second embodiment of the evaluation device according to the invention.
  • a first multiplier TPl a first low pass
  • U_TP1 the output signal of the first low pass TPl
  • M2 a second multiplier
  • TP2 a second low pass
  • I an integrator
  • U_VCO the output signal of the integrator I
  • ADD an adder
  • RE a square-wave signal generating device for generating a modulation voltage U_R and AI or A2 a respective first and second output signal.
  • the frequency of the voltage-controlled oscillator VCO is periodically varied by a center frequency f_c, ie frequency-modulated.
  • f_c center frequency
  • FIG. 3 shows a representation of the output voltage of the first low pass as a function of the VCO frequency in the second embodiment of the evaluation device according to the invention shown in FIG. 2.
  • both the output signal AI, ie U_TP1, and the output signal A2, ie U_VCO can be used as an analog output signal corresponding to the viscosity.
  • the output signals AI and A2 correspond to the damping or the resonance frequency of the resonator. Both sizes represent the viscosity of the measured liquid. The simultaneous observation of these sizes also allows the detection of viscoelastic (i.e. not purely viscous) liquid behavior, in this case the ⁇ e ratio of the two sizes changes compared to the purely viscous case.
  • the multiplier can be implemented in terms of circuitry by a switched inverter. This is because the evaluation of the phase relationships is essential for the functionality of the circuit. With all multipliers M, Ml, M2 used one of the two input variables has a constant amplitude (excitation voltage at M and Ml, square wave voltage at M2).
  • the first input variable namely the excitation voltage at M and Ml or the square-wave voltage at M2
  • the second input variable is inverted (first input variable negative) or not (first input variable positive).
  • the invention is not limited to viscosity sensors, but can be applied to all sensors which serve as the element determining the resonance frequency in a resonant circuit excited with an external excitation voltage.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

La présente invention concerne un procédé et un dispositif pour évaluer un dispositif capteur, le dispositif capteur formant un résonateur électrique dans un circuit oscillant excité par une tension d'excitation extérieure. Selon l'invention, il est procédé à une mesure du courant dans le circuit oscillant, dans la plage de la fréquence de résonance, puis à une multiplication du courant mesuré par la tension d'excitation extérieure. Enfin, la valeur moyenne du signal résultant de la multiplication est formée.
EP00983031A 1999-12-07 2000-10-18 Procede et dispositif pour evaluer un dispositif capteur Withdrawn EP1238257A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19958769A DE19958769A1 (de) 1999-12-07 1999-12-07 Verfahren und Vorrichtung zur Auswertung einer Sensoreinrichtung
DE19958769 1999-12-07
PCT/DE2000/003652 WO2001042762A1 (fr) 1999-12-07 2000-10-18 Procede et dispositif pour evaluer un dispositif capteur

Publications (1)

Publication Number Publication Date
EP1238257A1 true EP1238257A1 (fr) 2002-09-11

Family

ID=7931602

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00983031A Withdrawn EP1238257A1 (fr) 1999-12-07 2000-10-18 Procede et dispositif pour evaluer un dispositif capteur

Country Status (5)

Country Link
US (1) US6765392B1 (fr)
EP (1) EP1238257A1 (fr)
JP (1) JP2003516535A (fr)
DE (1) DE19958769A1 (fr)
WO (1) WO2001042762A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005007544A1 (de) * 2005-02-18 2006-08-24 Robert Bosch Gmbh Verfahren und Vorrichtung zur Erfassung zweier Parameter eines Fluids
DE102005009143A1 (de) * 2005-03-01 2006-09-07 Robert Bosch Gmbh Vorrichtung und Verfahren zur Messung von Eigenschaften eines fluiden Mediums
DE102005043036B4 (de) * 2005-09-09 2011-03-24 Siemens Ag Vorrichtung zur Ermittlung der viskosen Eigenschaften einer Flüssigkeit
JP4943171B2 (ja) * 2007-01-30 2012-05-30 東芝機械株式会社 振幅検出装置
AT516556B1 (de) * 2014-12-03 2017-11-15 Dipl Ing Niedermayer Alexander Messsystem mit resonanten Sensoren und Verfahren zum Betrieb eines Resonators
DE102015215330A1 (de) * 2015-08-11 2017-02-16 Continental Teves Ag & Co. Ohg Induktive Sensoren mit Betriebsfrequenz nahe der Resonanz
WO2024122308A1 (fr) * 2022-12-06 2024-06-13 三井化学株式会社 Dispositif de traitement de signal de capteur

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0600357A1 (fr) * 1992-11-30 1994-06-08 Rim Tech, Inc. Appareil et méthode de détection et de mesure de couches d'eaux liquide et du verglas sur des surfaces solides
EP0683382A3 (fr) * 1994-05-20 1996-08-14 Ford Motor Co Procédé et système pour calculer l'économie effective en carburant.
US6397661B1 (en) * 1998-12-30 2002-06-04 University Of Kentucky Research Foundation Remote magneto-elastic analyte, viscosity and temperature sensing apparatus and associated methods of sensing
CA2300250A1 (fr) * 1999-03-10 2000-09-10 Barco N.V. Methode et appareil de detection de matieres etrangeres dans des textiles en mouvement

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0142762A1 *

Also Published As

Publication number Publication date
US6765392B1 (en) 2004-07-20
WO2001042762A1 (fr) 2001-06-14
DE19958769A1 (de) 2001-06-13
JP2003516535A (ja) 2003-05-13

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