EP1565733A2 - Dispositif de mesure de gaz et methode de mesure de gaz avec compensation de perturbations - Google Patents

Dispositif de mesure de gaz et methode de mesure de gaz avec compensation de perturbations

Info

Publication number
EP1565733A2
EP1565733A2 EP03785546A EP03785546A EP1565733A2 EP 1565733 A2 EP1565733 A2 EP 1565733A2 EP 03785546 A EP03785546 A EP 03785546A EP 03785546 A EP03785546 A EP 03785546A EP 1565733 A2 EP1565733 A2 EP 1565733A2
Authority
EP
European Patent Office
Prior art keywords
gas
sensor
value
measuring device
pass filter
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Withdrawn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
EP03785546A
Other languages
German (de)
English (en)
Inventor
Kurt Ingrisch
Markus Niemann
Gerald Hamm
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.)
Paragon AG
Original Assignee
Paragon AG
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 Paragon AG filed Critical Paragon AG
Publication of EP1565733A2 publication Critical patent/EP1565733A2/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Withdrawn legal-status Critical Current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
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/122—Circuits particularly adapted therefor, e.g. linearising circuits

Definitions

  • the invention relates to a gas measuring device with interference compensation according to the preamble of patent claim 1 and a method with interference compensation according to the preamble of patent claim 10.
  • Semiconductor sensors are used in the automotive sector to measure the gas concentration, in particular the concentration of carbon monoxide CO, nitrogen oxide NO and hydrocarbons CxHy.
  • the majority of semiconductor sensors are conductivity sensors based on Sn02. The measurement result can be used, for example, to open or close a recirculation air flap in a motor vehicle.
  • the sensors mentioned above are also distinguished by good sensitivity to the gas to be measured.
  • Nachteilhafter- however, they also exhibit a number of cross-effects which complicate the signal evaluation.
  • Reducing gases such as carbon monoxide
  • oxidizing gases such as nitrogen dioxide
  • the strong adsorption of water on the surface of the Sn02 semiconductor sensor leads to a disruptive cross effect.
  • the bound water significantly increases the conductivity of the gas-sensitive Sn02 layer.
  • the amount of water adsorbed by the sensitive Sn02 layer is largely dependent on the temperature. The change in the conductivity of the Sn02 layer is therefore strongly temperature-dependent.
  • the semiconductor sensor binds much larger amounts of water than at higher temperatures.
  • the amount of water adsorbed can be demonstrated by means of a TDS measurement. After a certain time, a temperature-dependent equilibrium between adsorbed and desorbed water is established. When there is a change in temperature, the time constant until a new equilibrium is reached is between a few minutes and a few hours. The time constant depends on the previous environmental conditions.
  • This effect is particularly disruptive in the phase after switching on or starting up the semiconductor sensor.
  • the equilibrium of saturation between adsorbed and desorbed water that is valid for this temperature is established during this time. This equilibrium is also referred to below as saturation equilibrium.
  • the sensor In order to be able to carry out gas measurements with the sensor, the sensor is brought to an operating temperature of approx. 330 ° C. The higher temperature of 330 ° C compared to the storage temperature means that water is desorbed until a new saturation equilibrium is formed. During this time, this has the consequence that the conductivity decreases continuously, even if the gas concentration remains constant. The resulting decrease in conductivity correlates with a change in conductivity such as is caused by a large increase in the NO concentration.
  • the gas measuring device according to the invention with interference compensation offers the advantage over the prior art of a high measuring accuracy and immediately after the gas measuring device has been put into operation, that is to say after it has been switched on. was switched.
  • the gas measuring device with interference compensation comprises a gas sensor for generating a gas concentration-dependent measurement signal, which may have an interference component.
  • a high-pass filter with an adjustable cut-off frequency is connected downstream of the gas sensor.
  • the limit frequency can be specified by means of a selection unit depending on the interference component.
  • the method according to the invention for gas measurement with interference compensation with the features specified in claim 10 has the advantage over the prior art that the measurement can be carried out with high accuracy as soon as the gas measuring device is switched on.
  • the method has the following steps. By means of a gas sensor, a measurement signal that is dependent on the gas concentration is generated, which may have an interference component.
  • the measurement signal is then filtered by means of a high-pass filter with an adjustable cut-off frequency, the cut-off frequency being specified by a selection unit as a function of the interference component.
  • a low-pass filter is provided, which is connected between the evaluation unit and the gas sensor.
  • a computing unit is between the evaluation unit and the Low pass filter switched.
  • the computing unit is provided for calculating the slope of a filter output signal originating from the low-pass filter.
  • the selection unit is connected on the output side to a control input of the high-pass filter and is designed such that a value can be selected based on the slope of the filter output signal by means of which the cut-off frequency of the high-pass filter can be set.
  • the selection unit is designed in such a way that a first filter value can be specified if the difference between the sensor value and a target value exceeds a limit value.
  • a second filter value can be specified if the difference between the sensor value and the target value lies within a certain range.
  • a third filter value can be specified if the sensor value corresponds to the target value.
  • the first, the second and the third filter value are time constants.
  • a comparator is advantageously connected to the high-pass filter. This allows the filtered signal to be compared to a threshold value.
  • the gas sensor is an Sn02 gas sensor.
  • the gas sensor can be designed such that nitrogen oxide can be measured with it.
  • FIG. 1 shows the basic procedure for compensating for the disturbance in the form of a signal flow diagram.
  • Figure 2 shows in the form of a block diagram the basic structure of the gas measuring device according to the invention.
  • FIG. 3 shows the course of several signals as they can occur in the gas measuring device according to the invention.
  • a NO sensor 1 supplies a sensor sensor at its output 1.1, also referred to below as a sensor output.
  • signal Sl which in addition to the measured gas concentration can also have an interference component due to a shift in the saturation equilibrium.
  • the sensor signal S1 is evaluated by means of a run-in compensation 2 to determine whether an interference signal component caused by desorption is present and, if appropriate, how high it is. If necessary, the interference signal component in the sensor signal S1 is compensated.
  • a sensor signal S2 which has been freed from the interference signal component is present at the output of the inlet compensation 2.2 and is compared with a threshold value. For this purpose, the threshold value evaluation 3 is provided.
  • a control signal in the form of a switching signal 4 which controls a recirculating air flap, not shown in the figures.
  • the structure of the inlet compensation 2 is shown in FIG. 2 in the form of a further block diagram.
  • the NO sensor 1 is connected to a low-pass filter 5, which filters the sensor signal S1.
  • the low-pass filter 5 has a time constant tv.
  • the filtered sensor signal S5 is present at the output of the low pass 5.
  • the filtered sensor signal S5 is processed further by means of a computing unit 6.
  • the slope S ' is calculated from the filtered sensor signal S5.
  • the slope S ' is fed to a unit 12 for specifying a time constant TH.
  • the unit 12 for setting the time constant TH calculated from those pitch S 'and a parameter a is the time constant TH ⁇ .
  • a time constant TH is calculated from the sensor signal S1 of the NO sensor 1, that time constant in normal operation corresponds, this is fed to the high-pass filter 13 via its control input 13.1. This is the case if the conductance NO-S of sensor 1 lies between p2 * NO limit and NO limit. This is determined by means of a decision unit 7.
  • the time constant TH Tl is switched to the control input 13.1 of the high pass 13. This is only the case at the start of the running-in process of sensor 1. In this case, a large slope S 'of the sensor signal S1 is to be expected. Since no data is available on the start-up of sensor 1 regarding the course of signal S1 until the saturation equilibrium is reached, • based on experience, the difference between the conductance of NO sensor 1 and the limit value NO limit is fixed won cutoff frequency started.
  • the values are stored in a table, hereinafter also referred to as the look-up table. They are updated depending on the current difference during the running-in process. Tl and T2 are adjusted due to the system.
  • the time constant TH T2 is applied to control input 13.1 of the High pass 13 placed. From the slope S 'of the filtered sensor signal S5, the interference amplitude of the signal S2 can be estimated after the high-pass filter 13.
  • the time constant TH for the high pass 13 is set such that a defined limited interference amplitude of the signal S2 occurs at the output of the high pass filter 13. The interference amplitude is selected so that a recirculation damper that can be controlled with signal S2 is not inadvertently closed.
  • the running-in process of the sensor 1 is a monotonous process, which ends when the saturation equilibrium, that is to say the balance between adsorption and desorption of the water, has been reached by the NO sensor 1.
  • the signal form of the logarith ized resistance Ine can be approximated by the function from the time of switching on
  • the measurement signal has a useful signal component and an interference signal component, the latter, due to the desorption of water, having the characteristic of a PTI step function.
  • PT1 a First order delay element understood. In the frequency spectrum of this step function, there are high frequency components at the beginning, which decrease and disappear with increasing time.
  • the interference signal component hereinafter also referred to as interference signal, which is caused by the desorption of water, can therefore be suppressed at the beginning by the high-pass filter 13 with a suitably high selected cutoff frequency for a certain period of time.
  • the high frequency components in the interference signal decrease. This is taken into account by continuously lowering the cut-off frequency of the high-pass filter 13.
  • the cut-off frequency of the high-pass filter 13 remains constant and the initially attenuated measurement signal, which is now a pure useful signal, comes into its own.
  • the signal that can be tapped at the output of the high pass 13 is used to control the recirculation flap.
  • the approximate knowledge about the running-in of the NO sensor 1 is used.
  • a conductivity is established which is referred to as the NO limit.
  • the conductivity of the NO limit thus occurs when there is a balance between desorption and adsorption at the operating temperature of the NO sensor ' 1.
  • the value of the conductivity must be approximately determined by filtering the sensor signal S1 using a low-pass filter 5.
  • the time constant tv is about 30 minutes. The conductivity value obtained in this way is constantly stored in a non-volatile memory during operation.
  • the slope S 'of the sensor signal S1 is shortly after startup of the NO sensor 1, as mentioned, strongly dependent on the storage period of the NO sensor 1. However, the storage period can be provided in the control unit only with great effort Observe the sensor signal Sl for a certain time after switching on the sensor 1 and then conclude that the sensor signal Sl continues. In order to minimize the influence of briefly high gas concentrations, the sensor signal S1 is first filtered by means of the low pass 5 and then its slope S 1 is determined.
  • the amplitude of the interference signal component due to the shift in equilibrium, drops monotonously in the course of the running-in process.
  • the experimental parameters a, b and T depend on the storage period of the sensor 1 ′′ and the sensor itself. These parameters can therefore not be determined in experiments and kept in the run-in compensation.
  • the different signal dynamics between a signal change generated by the gas to be measured and a signal change generated by the desorption of water are used.
  • a change in the concentration of the gas to be measured usually has a time constant between 2 and 30 s.
  • the interference signal caused by the desorption of water has a time constant between a few minutes and several hours, depending on the previous storage period of the sensor.
  • FIG. 3 shows a number of signal curves using a time diagram.
  • the time is plotted on the x-axis of the diagram and the amplitude on the y-axis of the diagram. It can be seen that the amplitude of the —not compensated NO sensor signal S1 initially increases strongly and only slightly increases later.
  • the course of the compensated sensor signal is also shown in FIG. 3 and provided with the reference symbol S2.
  • the threshold value SW, the filtered signal 23, the control signal 24 for the air recirculation flap and the time constant 26 are also shown in FIG. 3.
  • the growing time constant 26 shows how the cut-off frequency of the high-pass filter is adjusted by leasing lower values and thus the system becomes more sensitive to gas pulses.

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

Abstract

L'invention concerne un dispositif de mesure de gaz équipé d'une compensation de perturbation et fournissant, dès sa mise en fonctionnement, des mesures de haute précision. Ce dispositif de mesure de gaz comprend un capteur de gaz (1) qui génère un signal de mesure (S1) dépendant de la concentration de gaz, ce signal pouvant contenir une composante perturbatrice. L'invention est caractérisée en ce qu'en aval du capteur de gaz est monté un filtre passe-haut (13) à fréquence limite réglable, laquelle est déterminée par une unité de sélection en fonction de la composante perturbatrice.
EP03785546A 2002-11-29 2003-11-28 Dispositif de mesure de gaz et methode de mesure de gaz avec compensation de perturbations Withdrawn EP1565733A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10255704 2002-11-29
DE10255704A DE10255704A1 (de) 2002-11-29 2002-11-29 Gasmessvorrichtung und Verfahren mit Störkompensation
PCT/DE2003/003951 WO2004051245A2 (fr) 2002-11-29 2003-11-28 Dispositif de mesure de gaz et procede associe avec compensation de perturbation

Publications (1)

Publication Number Publication Date
EP1565733A2 true EP1565733A2 (fr) 2005-08-24

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP03785546A Withdrawn EP1565733A2 (fr) 2002-11-29 2003-11-28 Dispositif de mesure de gaz et methode de mesure de gaz avec compensation de perturbations

Country Status (7)

Country Link
US (1) US7231807B2 (fr)
EP (1) EP1565733A2 (fr)
JP (1) JP2006508355A (fr)
KR (1) KR20050085225A (fr)
AU (1) AU2003294642A1 (fr)
DE (1) DE10255704A1 (fr)
WO (1) WO2004051245A2 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH701654B1 (fr) 2007-02-15 2011-02-28 Neroxis Sa Capteur de gaz.
DE102010044142A1 (de) * 2010-11-18 2012-05-24 Robert Bosch Gmbh Verfahren zum Ausblenden einer Störung
CN105416170B (zh) * 2015-12-25 2017-10-20 河南师范大学 空气质量提升装置
KR20230015100A (ko) 2021-07-22 2023-01-31 재단법인대구경북과학기술원 입출력 데이터 기반 제어 시스템 외란 추정 방법 및 장치

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US2926524A (en) * 1956-01-12 1960-03-01 John C Sanders Method and mechanism for detecting stall and surge of gas engines
GB1567284A (en) * 1976-12-27 1980-05-14 Nissan Motor Closed loop control system equipped with circuitry for temporarirly disabling the system in accordance with given engine parameters
DE3126238A1 (de) * 1981-07-03 1983-01-20 Robert Bosch Gmbh, 7000 Stuttgart Vorrichtung zum betrieb einer sauerstoffsonde in einem grossen temperaturbereich
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DE3311350A1 (de) * 1983-03-29 1984-10-04 Robert Bosch Gmbh, 7000 Stuttgart Regeleinrichtung fuer die gemischzusammensetzung einer brennkraftmaschine
DE3768944D1 (de) * 1986-10-11 1991-05-02 Heinz Hoelter Sensor zur steuerung von umluftklappen von kraftfahrzeugen.
US5319921A (en) * 1992-08-04 1994-06-14 Ford Motor Company Catalytic converter efficiency monitoring
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US6567738B2 (en) * 2001-01-30 2003-05-20 Ford Global Technologies, Llc Fueling control system
DE10202869A1 (de) * 2002-01-24 2003-08-21 Volkswagen Ag Verfahren zur Korrektur des NOx-Signals eines in der Abgasanlage einer Brennkraftmaschine anordenbaren NOx-Sensors
EP1543291A4 (fr) * 2002-09-26 2006-05-10 Prime Photonics Inc Stabilisation du point q actif destine a des capteurs interferometriques lineaires

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See references of WO2004051245A2 *

Also Published As

Publication number Publication date
AU2003294642A1 (en) 2004-06-23
DE10255704A1 (de) 2004-06-17
JP2006508355A (ja) 2006-03-09
WO2004051245A2 (fr) 2004-06-17
US7231807B2 (en) 2007-06-19
AU2003294642A8 (en) 2004-06-23
KR20050085225A (ko) 2005-08-29
WO2004051245A3 (fr) 2004-09-30
US20060155490A1 (en) 2006-07-13

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