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
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/403—Cells and electrode assemblies
  • G01N27/406—Cells and probes with solid electrolytes
  • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
  • G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
• • 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
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/28—Electrolytic cell components
  • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
• • 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
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/403—Cells and electrode assemblies
  • G01N27/406—Cells and probes with solid electrolytes
  • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
  • G01N27/4073—Composition or fabrication of the solid electrolyte
  • G01N27/4074—Composition or fabrication of the solid electrolyte for detection of gases other than oxygen
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/0004—Gaseous mixtures, e.g. polluted air
  • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
  • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
  • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
  • G01N33/0037—NOx
• • 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
  • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
  • G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
  • G01N2027/222—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties for analysing gases
• • 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
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/403—Cells and electrode assemblies
  • G01N27/406—Cells and probes with solid electrolytes
  • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

• YSZ yttrium-stabilized zirconia
• electrodes of the same material for example platinum.
• the principle of operation is based on a two-chamber system with simultaneous measurement of oxygen and NOx.
• the disadvantage here is still a complex structure and thus high price.
• mixed potential sensors which contain electrodes made of different materials and evaluate the potential difference between them as a sensor signal.
• US 2005/0284772 A1 discloses a measuring method in which zirconium oxide-based lambda probes or mixed potential sensors are used to construct a NOx sensor.
• the measurement principle here is a dynamic method in which defi ned ⁇ voltage pulses applied to the sensor and the jewei ⁇ celled gas-dependent depolarization is measured is used.
• the discharge curves recorded in this way have a strong dependence on the surrounding gas atmosphere. Nitrogen oxides can be distinguished well from other gases.
• a central principle of the oxygen sensor is that one of the electrodes must be the face to be measured gas mixture, while the other electrode is facing a gas having a defi ned ⁇ oxygen partial pressure.
• the sensors used per se, ie the lambda probes point in the process Furthermore, the known and initially mentioned disadvantages.
• Object of the present invention is to provide a gas sensor and an operating method for the gas sensor, with which a simplified construction of the sensor can be achieved.
• the gas sensor according to the invention for the detection of nitrogen oxides in a gas mixture comprises an oxygen ion-conducting material and at least two electrodes arranged on the ion-conducting material, wherein the electrodes consist of the same material.
• the gas sensor is designed in such a way that, during operation of the gas sensor, both electrodes come into contact with the gas mixture.
• the electrodes make it surprisingly possible to simplify the construction of the NOx gas sensor considerably.
• the reference gas is usually the surrounding ⁇ ambient air, for this is in the prior art example ⁇ as an access for the ambient air to a formed as a chamber inside created in zirconia, which requires a considerable effort in the production.
• the sensor has a much better potential to be made very small.
• the gas sensor according to the invention can be constructed comparatively simply, since both electrodes are made of the same material and both electrodes only have to come into direct contact with the gas mixture.
• the gas sensor includes electrical connections to the electrodes and means, propose this with a voltage to beauf ⁇ and means for measuring the voltage be- see the electrodes during the subsequent Depola- risation.
• the ion-conducting material may, for example
• YSZ yttrium stabilized zirconia
• the ion-conducting material can be applied as a layer on a support, for example of aluminum oxide.
• the electrodes are then suitably applied again on the layer of the ion-conducting material.
• the electrodes themselves are expediently made of platinum.
• the gas sensor comprises a heating device which is designed to heat the sensor, in particular the ion-conducting material and the electrodes, to a temperature at which an oxygen-ion line is present.
• the heater can be used, for example, as Rischer heater be configured in the form of a flat layer of, for example, platinum. It is suitably electrically separated from ion-conducting material and of course the electrodes by an insulator layer, for example by the carrier.
• the ion-conducting material may be embodied as a porous material.
• the ion-conducting material adjoins both the gas mixture to be measured and, for example, ambient air
• the gradients in the partial pressure of the various gases lead to a diffusion of the gases through the ion-conducting material leads to Ver ⁇ deterioration of the sensor signal. Since the ion-conducting material is no longer present at the adjacent sensor to the Conversely ⁇ ambient air, but is suitably surrounded on all sides by the gas to be measured, passes no such Diffu ⁇ sion more and a porous, in particular open-pored material may be used.
• a porous ion-conducting material is easier to manufacture, more stable against the stresses of changing temperatures and has a higher specific surface area, which brings advantages for the interaction with gases and thus for the sensor signal.
• For surveying is preferred for a definable first
• the gas sensor comprises three or four electrodes.
• two of the electrodes may be arranged on one side of the ion-conducting material, while the third or the third and fourth te electrode are arranged on the other side of the ion-conducting material.
• the impressing of a voltage during a respective first period of time for the different pairs of electrodes can take place with a time offset, in other words phase-shifted.
• pairs of electrodes can be connected in series and thus an improvement in signal strokes can be achieved.
• the electrodes can be geometrically designed to achieve signal quality enhancement.
• the electrodes can be designed as finger electrodes (interdigital electrodes).
• FIG. 2 shows a diagram for the measuring method for operating the gas sensor
• FIG. 3 shows a second variant of a gas sensor according to the He ⁇ invention with three electrodes
• FIG. 1 shows a highly schematic diagram of a first gas sensor 10 according to the invention. This comprises a block 11 of YSZ material. On a first side of this block 11, a first platinum electrode 12 is arranged, while a second platinum electrode 13 is applied on a two ⁇ th side, which is opposite the first side.
• FIG. 1 means with which the first gas sensor 10 in an nen filled with the gas mixture to be measured space can be introduced, for example, a flange for screwing into a correspondingly shaped opening.
• These means and the gas sensor 10 are designed such that, after arrival bring the gas sensor 10, both the first as well as the two ⁇ te platinum electrode 12, 13 are directly connected to the gas mixture in Kon ⁇ clock. A contact of the block 11 with, for example, the ambient air, however, is thereby expediently avoided.
• a voltage US between the platinum electrodes 12, 13 is applied alternately by means of the device 14 and the voltage profile is measured.
• An exemplary profile of the voltage US is shown in FIG. So a firm, positive voltage is from left to right in Figure 2 during ei ⁇ ner first period tO be ⁇ sets.
• the voltage used here is preferably between 0.5 V and 2 V.
• the duration of the first period of time tO is be ⁇ vorzugt s between 0.1 and 1 s.
• the voltage US in terms of magnitude
• a fixed voltage is applied with a negative polarity and following it, followed in a further second time ⁇ span the course of the voltage US during another first period of time tO.
• a measurement value can be taken in ⁇ nerrenz the second period of time tl, for example, after a fixed time, ⁇ example, after 1 s or 3 s.
• FIG. 3 likewise shows very schematically a second gas sensor 20 according to the invention, which is constructed and operated similarly to the first gas sensor 10. It comprises a block 11 of YSZ material.
• a first platinum electrode 12 is arranged, while on a second side, which lies opposite the first side, a second platinum electrode 13 is applied.
• the platinum electrodes 12, 13 are, as in the case of the first gas sensor 10, electrically connected to a device 14 for generating and measuring voltage US.
• the second platinum electrode 13, in contrast to the first gas sensor 10 is not exactly as large as the first platinum electrode 12, but has a smaller area.
• a third platinum electrode 21 is provided.
• the device 14 for generating a voltage which is no longer shown in FIG. 2, has a correspondingly more complex configuration, so that different potentials can be generated between the electrodes 12, 13, 21.
• a positive potential can be generated in the first period between the first and second electrodes 12, 13, while a negative potential is generated between the first and third electrodes 12, 21.
• two independent measurement signals can be recorded in the course of the after ⁇ second time period. So that the signal ge ⁇ accuracy for example, can be improved. If one sets the respective first and second time periods, ie also the times at which the measurement signals are recorded, with a time offset, the temporal resolution of the measurement signals is improved.
• FIG. 4 shows a third gas sensor 30 according to a further exemplary embodiment of the invention.
• the third gas sensor 30 is constructed on an alumina substrate 31.
• a layer 33 of zirconium oxide is applied by screen printing, for example.
• the first and second platinum electrode 12, 13 are arranged.
• ei ⁇ ne platinum heating structure 32 is applied. This is designed to heat the third gas sensor to 350 ° C.
• the heating structure 32 itself can be used.
• an additional temperature sensor is provided for this purpose. If the temperature of the gas mixture itself significantly above 350 ° C, it can operate the heating structure 32 only as a temperature sensor also be sufficient since additional Behei ⁇ wetting is unnecessary.
• Substratmate- rials can be used as long as they are functional non-ion ⁇ conductive.
• an aerosol landfill can be used sition ⁇ al ternatively for screen printing. This produces a dense layer in contrast to screen printing.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Pathology (AREA)
• General Physics & Mathematics (AREA)
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• Electrochemistry (AREA)
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• Combustion & Propulsion (AREA)
• Food Science & Technology (AREA)
• Medicinal Chemistry (AREA)
• Measuring Oxygen Concentration In Cells (AREA)

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• 2013
  • 2013-10-31 DE DE201310222195 patent/DE102013222195A1/de not_active Withdrawn
• 2014
  • 2014-10-23 EP EP14795570.2A patent/EP3042189A1/de not_active Withdrawn
  • 2014-10-23 WO PCT/EP2014/072712 patent/WO2015062955A1/de active Application Filing
  • 2014-10-23 KR KR1020167014054A patent/KR101833370B1/ko active IP Right Grant
  • 2014-10-23 JP JP2016527187A patent/JP6234568B2/ja not_active Expired - Fee Related
  • 2014-10-23 US US15/033,790 patent/US20160282297A1/en not_active Abandoned
  • 2014-10-23 CN CN201480059018.7A patent/CN105683744A/zh active Pending

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