Abstract: A heater power supply control system is provided for controlling the temperature of a heater used to heat a solid electrolyte-made sensor element of a gas concentration sensor up to a desired activation temperature. The heater power supply control system measures a resistance value of the sensor element and controls an electric power supply to the heater using a PI control function. The heater power supply control system works to limit the value of an integral term of the PI control function in the course of activation of the sensor element, thereby avoiding overshoot of the resistance value of the sensor element, which avoids thermal damage of the sensor element.

Abstract: A gas sensor is disclosed comprising an oxygen pump cell having at least one exterior pump electrode and at least one interior pump electrode disposed on opposite sides of a first solid electrolyte layer. An emf cell having a first and second emf electrodes and first and second reference gas electrodes are disposed on opposite sides of a second solid electrolyte layer. At least one insulating layer is in contact with the first and second emf electrodes. At least one via hole is disposed through the first solid electrolyte layer. At least one air channel is disposed through at least one insulating layer. An air vent is disposed in at least one insulating layer in contact with the first and second reference gas electrodes. A heater is disposed in thermal communication with the sensor. And at least five electrical leads are in electrical communication with said sensor. A method of using a gas sensor is also disclosed.

Abstract: A gas sensor, comprising an oxygen pump cell with a first pump electrode and a second pump electrode disposed on opposite sides of a first solid electrolyte layer and a second pump electrode. The sensor also comprises an emf cell with an emf electrode and a reference gas electrode disposed on opposite sides of a second solid electrolyte layer. The emf electrode is disposed in fluid communication to the second pump electrode. A via hole is disposed through the first solid electrolyte layer, such that the first pump electrode is in fluid communication with the second pump electrode. A protective insulating layer, having a passage for gas to be sensed, is disposed in contact with the first pump electrode. A first insulating layer, having a conduit, is disposed in contact with the emf electrode. A second insulating layer, having an air channel, is disposed in contact with the reference gas electrode. A heater is disposed in thermal communication with the emf cell.

Abstract: According to the present invention, there is provided: a sensor element including an oxygen concentration detection section consisting of solid electrolyte for outputting a detection signal corresponding to an oxygen concentration in a hollow chamber to which an exhaust of an internal combustion engine is introduced and an oxygen pump section for controlling an electric current to be applied to a solid electrolyte wall that divides the hollow chamber from an exhaust side of the engine so that the oxygen concentration in the hollow chamber becomes a predetermined oxygen concentration, to flow oxygen into/out of the hollow chamber; an air-fuel ratio detection circuit for outputting an air-fuel ratio detection value based on the electric current applied to the solid electrolyte wall by the oxygen pump section; and a pump current cut off circuit for cutting off the power supply to the solid electrolyte wall by the oxygen pump section, and a detection value of air-fuel ratio is corrected based on an output value o

Abstract: A method and apparatus for selectively removing oxygen from a gas stream containing NOx and oxygen by contacting the gas stream with an electrochemical cell made from an electrode consisting of La1-XMXFeO3, (where M is selected from the group consisting of Sr, Ba, Ca, and combinations thereof, and X is between 0.05 and 0.5), a solid oxide electrolyte and a counter electrode, wherein the La1-XMXFeO3 electrode is on one side of a solid oxide electrolyte, and a counter electrode is on the opposite side of the solid oxide electrolyte, and applying a voltage to the electrochemical cell. The apparatus is preferably employed in a two chambered NOx sensor utilizing solid electrolyte electrochemical cells, wherein an electrochemical cell capable of catalyzing oxygen reduction without catalyzing NOx decomposition is formed as integral to the first chamber.

Abstract: A circuit configuration for generating a virtual ground includes a micro-controller, an analog circuit and a read-only memory. A pulse-width modulated signal, which is output by the micro-controller, is converted, by using the analog circuit, into the virtual ground as a common reference potential of an exhaust probe which operates according to the principle of the galvanic oxygen concentration cell with a solid electrolyte. The actual value of the virtual ground is read into the micro-controller through the use of an A/D converter and is compared with a predefined setpoint value. The potential value of the virtual ground is then controlled on the basis of the difference value. An exhaust probe configuration is also provided.

Abstract: An objective gas is successively introduced into first and second chambers which are connected via a narrow passage. A first monitor cell, provided on a surface of the first chamber, generates an electromotive force representing an oxygen concentration in the first chamber. A second monitor cell, provided on a surface of the second chamber, generates an electromotive force representing an oxygen concentration in the second chamber. A voltage applied to a pump cell is controlled based on the electromotive forces obtained from the first and second monitor cells.

Abstract: A method of manufacturing a gas sensor, including a substrate electrode layer forming step, and a surface electrode layer forming step. The gas sensor includes first and second processing spaces, an oxygen concentration detection element, an oxygen pumping element, an oxidation catalyst and a combustible gas component concentration detection element.

Abstract: A gas sensor for measuring concentration of a gas component in a measured gas, including a solid electrolytic substrate and at least two electrodes fixed to the substrate. At least a first electrode of the electrodes is disposed in the environment of the measurement gas, at least one of electrodes is polarized by applying a bias current or bias voltage, and a change in the potential of the polarized electrode is measured to thereby measure the concentration of the target gas.

Abstract: A gas concentration measuring apparatus which has a gas sensor designed to measure, for example, the concentrations of O2 and HOx contained in exhaust emissions of an automotive engine is provided. The apparatus includes a signal processing circuit which converts a current signal outputted from the gas sensor as a function of the concentration of either of O2 and HOx into a voltage signal. The gas sensor and the signal processing circuit are connected electrically through a conductor. The conductor has a length which is determined as a function of a level of the current signal outputted from the gas sensor. The weaker the level of the current signal is, the shorter the length of the conductor. This minimizes addition of electrical noises to the current signal outputted from the gas sensor.

Abstract: Apparatus for detecting the NOx concentration includes a first measurement chamber 20 communicating with the gas under measurement via a diffusion rate defining layer 4d and a second measurement chamber 26 communicating with the first measurement chamber 20 via diffusion limiting layers 6d, 22d. A first pump current IP1 is controlled so that an output of a Vs cell 6 will be equal to the reference voltage VCO for controlling the oxygen concentration in the first measurement chamber 20 to a pre-set low value. A constant voltage is applied across the second pump cell 8 for decomposing the NOx component in the second measurement chamber 26 for pumping out oxygen for detecting the NOx concentration from a second pump current IP2. The sensor temperature is detected from the internal resistance of the Vs cell for controlling the current supplied to the heaters 12, 14. If the temperature of the gas under measurement is changed rapidly, the sensor temperature is changed.

Abstract: A gas sensor includes a measurement gas chamber into which a measurement gas is introduced. An oxygen pumping cell adjusts an oxygen concentration in the measurement gas chamber. An oxygen monitor cell has a monitor electrode exposed in the measurement gas chamber. The monitor electrode has an oxidizing activity with respect to a specific component of the measurement gas. A sensor cell has a sensor electrode exposed in the measurement gas chamber. The sensor electrode has an oxidizing activity with respect to the specific component of the measurement gas which is lower than the oxidizing activity of the monitor electrode. An oxygen-ion current in the oxygen monitor cell is detected. An oxygen-ion current in the sensor cell is detected. A concentration of the specific component of the measurement gas is detected from a relation between the detected oxygen-ion currents in the oxygen monitor cell and the sensor cell.

Abstract: A hydrogen gas sensor including a first electrode 3 provided on one surface of a proton conduction layer 1; a second electrode 5 provided on the other surface of the proton conduction layer 1 in opposition to the first electrode 3; and these components are supported in a support element including a first support element 9a and a second support element 9b. A conductive, elastic element 23 is disposed between a first lead portion 10a and a first electrode 3 in contact with the first lead portion 10a and the first electrode 3. The conductive, elastic element 23 is an electrically conductive, elastic sheetlike element made of metal, and has a pair of right-hand and left-hand through-holes 25 formed therein at a central portion thereof. The conductive, elastic element 23 is held between the first lead portion 10a and the first electrode 3 while being pressed inward by a first support element 9a.

Abstract: A gas sensor for measuring an amount of a measurement gas component, including a solid electrolyte having an internal space, a gas-introducing port for introducing measurement gas from an external space into the internal space, diffusion rate-determining means between the internal space and the gas-introducing port, and inner and outer pumping electrodes for pumping-processing oxygen contained in the measurement gas. The diffusion rate-determining means includes slits each having, when viewed in a plane substantially perpendicular to a longitudinal extension axis thereof, two dimensions, with at least one dimension of each slit being not more than 10 microns.

Abstract: To determine the oxidizable portion of exhaust gases in the presence of the reducible portion with the legally required precision, a method and a sensor are disclosed for analyzing a flow of exhaust gas components. The sensor includes a limit current measurer, one limit current pump for reducible gases and, downstream from this pump in the direction of diffusion, another limit pump for oxidizable gases. The electrodes of the limit current pump for reducible gases are made of a material that does not catalyze the reaction between oxidizable and reducible gases.

Abstract: A hydrogen sensor includes a solid electrolyte made of a barium cerium oxide, and a first electrode and a second electrode that are formed on the surface of the solid electrolyte. The first and the second electrodes are made of a material having a catalytic effect with respect to an oxidation reaction of hydrogen and are made of the same material. Thus, the hydrogen sensor can be inexpensive and has good hydrogen selectivity and responsiveness to detection, and thus it is possible to measure hydrogen in a high concentration region.

Abstract: A method and apparatus which enable accurate measurement of the concentration of NOx in a gas under measurement, even when the NOx concentration is low. A gas under measurement is introduced into a first chamber 3 through a first diffusion passage 2. A pump voltage V1 is applied from a direct-current power source E1 to a first oxygen ion pump cell 6 such that the electric potential of an oxygen-concentration-measuring cell 7 is held constant. As a result, oxygen is pumped out from the first chamber 3 such that the oxygen concentration measured at an inlet to a second chamber 5 becomes constant. A first pump current Ip1 flowing to the first oxygen ion pump cell 6 is measured. Next, the gas under measurement contained in the first chamber 3 is introduced into the second chamber 5 through a second diffusion passage 4.

Abstract: An electrochemical gas sensor and a method for determining the concentration of gaseous components in a gas mixture, particularly of NOx in exhaust gases of internal combustion engines. The gas sensor includes a first measuring-gas compartment which is in communication with the measuring gas, and two additional measuring-gas compartments which are connected to the first measuring-gas compartment via diffusion barriers. The first measuring-gas compartment contains a first pump cell which, with the aid of pump electrodes arranged on a solid electrolyte, transports oxygen into and out of the measuring-gas compartment. The second and third measuring-gas compartments contain further pump cells, the second measuring-gas compartment being used for measuring the oxygen concentration of the mixture, and the third measuring-gas compartment being used for measuring the sum of the oxygen concentration and the concentration of the gaseous component in the gas mixture.

Abstract: A heater control apparatus used for a gas concentration sensor is provided which heats a sensor element a solid electrolyte body of up to a desired activation temperature. The heater control apparatus determines an actual resistance value of the sensor element, controls a power supply to the heater as a function of a difference between the actual resistance value and a target one, determines a power supplied to the heater, and determines a reference resistance value of the sensor element based on a predetermined fundamental relation between a power used in the heater and a resistance value of the sensor element to correct the target resistance value as a function of a difference between the reference resistance value and the actual resistance value.

Abstract: A CO gas sensor is equipped with a detecting unit in which a solid electrolyte membrane is held between a detection electrode and a counter electrode, and a voltage applying unit which applies voltage between the detection electrode and the counter electrode and changes the voltage. The detection electrode includes an electrochemically active first catalyst in an electrically conductive porous body, a reaction layer having a density of 1 ng/cm2-100 &mgr;g/cm2 and having a thickness of 0.3 nm-15 &mgr;m, and the counter electrode includes an electrochemically active second catalyst carried on an electrically conductive porous body.

Abstract: A limit-current type A/F sensor produces element current responsive to oxygen concentration in the exhaust gas when a voltage is applied to its sensor element portion. An application voltage control circuit comprises an operational amplifier and resistors. An output of the control circuit is applied to one terminal of the A/F sensor via a driver circuit. The other terminal of the A/F sensor is connected to an output terminal of an operational amplifier via a current-detecting resistor. The element current value, detected by the current-detecting resistor, is returned to the application voltage control circuit via a buffer. In the application voltage control circuit, adjustment of the gain is performed in such a manner that the inclination of the application voltage line on the V-I coordinate becomes larger than the inclination equivalent to the A.C. impedance of the sensor element in the sensor activated condition.

Abstract: A control circuit unit which enables an existing NOx sensor to serve not only as an NOx sensor but also as an oxygen concentration sensor by attachment to an existing NOx sensor. A control circuit unit 31 is connected to an NOx sensor 1. A first pump element control circuit 56 controls a voltage applied to a first pump element 3 so as to control the partial pressure of oxygen in a first processing chamber 9 such that an output voltage of an oxygen concentration detection element becomes substantially constant. A first pump current is detected using a current detection resistor 101 and is then output via an A/D converter circuit 65. A second pump element control circuit 57 applies a constant voltage to a second pump element 5 in a direction so as to pump out oxygen from a second processing chamber 10. A second pump current is detected using a current detection resistor 107 and is then output via an A/D converter circuit 65.

Abstract: A combined gas sensor of the invention is equipped with a second oxygen sensing electrode 5 active only to oxygen, which is disposed on a solid electrolyte substrate 3a such that it is directly exposed to detection gases. Sensor disorder is detected by measuring an electromotive force (signal output 2) generated between a reference electrode 7 and the second oxygen sensing electrode 5 as an oxygen concentration in an exhaust gas atmosphere, and comparing and judging the detected result with a signal output 1 corresponding to an electromotive force between a first oxygen sensing electrode 4 and the sit reference electrode 7, or with a signal output of an oxygen pump current.

Abstract: A hardened powder ring, being a hardened block of talc powder, is inserted into an annular end space between a housing and a sensing element. A pushing member presses and crashes the hardened powder ring into talc powder, thereby stuffing the talc powder into the annular end space. An inner radius rp and an outer radius Rp of the pushing member have the relationship 0.275 mm≦rp−R&thgr;≦0.375 mm and 0.15 mm≦rh−Rp≦0.25 mm with respect to an outer radius R&thgr; of the sensing element and an inner radius rh of the housing. A press portion of pushing member has an inner curved surface having a curvature radius of 0.3˜0.4 mm and an outer curved surface having a curvature radius of 0.3˜0.5 mm.

Abstract: A modified universal exhaust gas oxygen sensor, referred to herein as a CEGA sensor, is provided which can be used to measure the concentration of a variety of components of a gaseous fuel emission including CO, CO2, O2, H2, and H2O. The CEGA sensor-employs at least one additional electrode on a ceramic substrate which possess a different catalytic activity relative to the electrodes that normally found on a UEGO sensor. The ceramic substrate may be made of any suitable ceramic and is preferably made of zirconia. The difference in catalytic activity between the additional electrode(s) and the electrodes native to the UEGO sensor create an oxygen gradient which enables a measure of combustion completeness to be calculated. In combination with an air/fuel ratio measured by the sensor, the concentrations of different components in the emission can be calculated.

Abstract: A detector for an air/fuel ratio sensor, which is comprised of a structure formed by stacking an oxygen reference electrode, a dense zirconia solid electrolyte, a negative electrode, a porous zirconia solid electrolyte, a positive electrode and a porous protection film on one another, is formed over a ceramic substrate having a heater built therein. Thus, a combined air/fuel ratio sensor can be obtained which is operated in a short time (about 5 seconds or less) after power-on so as to comply with emission control applied immediately after startup and provides low power consumption and a high degree of reliability.

Abstract: A circuit configuration for controlling a pump current includes a microcontroller, an analog circuit and a read-only memory. A pulse-width modulated signal, which is output by the micro-controller, is converted, by using the analog circuit, into the pump current for a pump cell of an exhaust probe which operates according to the principle of the galvanic oxygen concentration cell with a solid electrolyte. A pump current actual value is determined from a voltage drop across a measuring resistor, and a pump current setpoint value is determined from a voltage difference between an actual value of a Nernst voltage in the corresponding measuring cell and a predefined setpoint value. An exhaust probe configuration is also provided.

Abstract: A modified universal exhaust gas oxygen sensor, referred to herein as a CEGA sensor, is provided which can be used to measure the concentration of a variety of components of a gaseous fuel emission including CO, CO2, O2, H2, and H2O. The CEGA sensor-employs at least one additional electrode on a ceramic substrate which possess a different catalytic activity relative to the electrodes that normally found on a UEGO sensor. The ceramic substrate may be made of any suitable ceramic and is preferably made of zirconia. The difference in catalytic activity between the additional electrode(s) and the electrodes native to the UEGO sensor create an oxygen gradient which enables a measure of combustion completeness to be calculated. In combination with an air/fuel ratio measured by the sensor, the concentrations of different components in the emission can be calculated.

Abstract: An emission control system for determining a concentration of oxygen in a flow of gas which has a sensor. The sensor has a diffusion barrier, an electrolyte material, and a counter-electrode. The counter-electrode is configured to support the diffusion barrier, and the electrolyte material is disposed between the diffusion barrier and the counter-electrode.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: A gas sensor, comprising an oxygen pump cell with a first pump electrode and a second pump electrode disposed on opposite sides of a first solid electrolyte layer and a second pump electrode. The sensor also comprises an emf cell with an emf electrode and a reference gas electrode disposed on opposite sides of a second solid electrolyte layer. The emf electrode is disposed in fluid communication to the second pump electrode. A via hole is disposed through the first solid electrolyte layer, such that the first pump electrode is in fluid communication with the second pump electrode. A protective insulating layer, having a passage for gas to be sensed, is disposed in contact with the first pump electrode. A first insulating layer, having a conduit, is disposed in contact with the emf electrode. A second insulating layer, having an air channel, is disposed in contact with the reference gas electrode. A heater is disposed in thermal communication with the emf cell.

Abstract: The present invention discloses a gas sensing device, an oxygen pumping cell, and a gas detection apparatus using the same for detecting lower ranges of gas concentration with high accuracy and stability. An under layer made of oxygen-ion-conductive solid electrolyte was formed between an electrolyte substrate and a sensing electrode, a conversion electrode or a gas treatment electrode. This allows the physical and chemical adhesion between these electrodes and the electrolyte substrate, thereby improving the sensing properties and stability.

Abstract: A gas sensor is disclosed comprising an oxygen pump cell having at least one exterior pump electrode and at least one interior pump electrode disposed on opposite sides of a first solid electrolyte layer. An emf cell having a first and second emf electrodes and first and second reference gas electrodes are disposed on opposite sides of a second solid electrolyte layer. At least one insulating layer is in contact with the first and second emf electrodes. At least one via hole is disposed through the first solid electrolyte layer. At least one air channel is disposed through at least one insulating layer. An air vent is disposed in at least one insulating layer in contact with the first and second reference gas electrodes. A heater is disposed in thermal communication with the sensor. And at least five electrical leads are in electrical communication with said sensor. A method of using a gas sensor is also disclosed.

Abstract: A method for making a sensor is disclosed comprising using a sensing electrode having a first and second side. Using a reference electrode having a first and second side and a second electrical lead in electrical communication with the reference electrode. Disposing an electrolyte between the first side of sensing electrode and the first side of reference electrode. Disposing a first side of a protective layer adjacent to the side of sensing electrode. Mixing a metal oxide, a fugitive material, and a solvent to form a mixture. Applying the mixture to a second side of the protective layer and calcining the sensor to form the protective coating on the protective layer second side.

Abstract: A gas detector equipped with a sensor-monitoring feedback function includes a casing and a base board housing a circuit board therein. The circuit board supports a plurality of electronic elements, including a processor unit consisting of a micro control chip (MCU), two output units including a plurality of LED lights and a buzzer, an input unit including a power supply, a voltage stabilizer and a power breaker circuit, an amplification circuit, a sensor and a detection circuit. The detection is capable of monitoring the sensor for normal function and service, and providing feedback constantly so that users will be alerted immediately to malfunction or out of order condition that necessitate repairs and replacement thereby giving users the best possible protection. The gas detector of the invention will also automatically cutoff electricity supply to the sensor for preventing a gas explosion.

Abstract: A limiting-current-type hydrocarbon sensor of the present invention comprises a solid electrolyte formed of a barium-cerium-based oxide, capable of detecting hydrocarbon stably and accurately regardless of whether no oxygen is present or a high concentration of oxygen is present. The cathode on the surface of the solid electrolyte is formed of an alloyed layer including Au and Al. In particular, an alloyed layer including an Al—Au intermediate phase is suited for the alloyed layer of the cathode. The alloyed layer comprises a first layer including an Al—Au intermediate phase that is in contact with the surface of the solid electrolyte, and a second layer including a metal Al phase that covers the first layer. The Al phase of the alloyed layer blocks oxygen, and the Al—Au intermediate phase smoothens hydrogen association and reduces the resistance of the electrode. The hydrocarbon sensor can thus detect hydrocarbon accurately even when oxygen is included in an atmosphere.

Abstract: The present invention relates to an apparatus for measuring and displaying a noxious waste gas exhausted from a vehicle in real time through an electrical method instead of conventional chemical one, and controlling an amount of fuel to feed an engine with based on the measurement result to adjust an amount of noxious gas generated. A sensor, which is an element of the present invention, comprises a porous ceramic and a pair of electrodes to apply a voltage across two sides of the porous ceramic.

Abstract: Disclosed is a NOx sensor for measuring a NOx concentration comprising a main pumping cell and a detecting electrode, the main pumping cell including an electrode (an inner pumping electrode and an outer pumping electrode) having no decomposing/reducing ability for NOx or a low decomposing/reducing ability for NOx, to be used so that an oxygen concentration in a measurement gas is controlled to have a predetermined value at which NO is not substantially decomposable, and the detecting electrode having a certain decomposing/reducing ability for NOx or a high decomposing/reducing ability for NOx, to be used so that NOx is decomposed to measure the NOx concentration by measuring an amount of oxygen produced during this process, wherein a cermet electrode composed of a Pt—Rh alloy and a ceramic component is used as the detecting electrode.

Abstract: A nitrogen oxide gas sensor wherein an alloy electrode of platinum and rhodium or a cermet electrode of platinum, rhodium, and zirconia or of a rhodium alloy and zirconia is used as the gas sensing electrode. The electrode of the sensor is suitable for measuring nitrogen oxide such as NO and NO2 in an exhaust gas.

Abstract: A gas analyzer monitors concentration of discharged NOx even if an air ratio X is less than 1. The gas analyzer has three internal spaces and four electro-chemical pumps. The first space effects combustion of combustible gases and has a first pump to adjust oxygen partial pressure. The second space has a second pump to decrease oxygen partial pressure. The third space has a third electro-chemical pump to control oxygen partial pressure and a fourth pump to draw out oxygen generated when object gas is reduced or decomposed. An air introducing duct is provided so the outside pump electrodes of the first and second pumps are isolated and not directly exposed to object gas. This duct serves as oxygen source when oxygen is introduced into the first space. The gas analyzer has an operating section for operating the pumps, a calculating section, and a displaying/outputting section. A calibrating method is disclosed also.

Abstract: A sensor for determining gas components and/or gas concentrations in gag mixtures, in particular, in the exhaust gas of an internal combustion engine, includes an inner pump electrode, an inner pump electrode supply conductor, a measuring electrode and a measuring electrode supply conductor. The inner electrode and the measuring electrode are in contact with the measuring area. In addition, separation is maintained between the measuring electrode supply conductor and the inner pump electrode supply conductor at least in the hot area of the sensor. At least in the hot area at least one of the electrode supply conductors is in contact with at least one oxygen reservoir, there being an at least largely gas-tight barrier between this and the measuring area.

Abstract: A gas sensor for measuring an amount of a measurement gas component, including a solid electrolyte having an internal space, a gas-introducing port for introducing measurement gas from an external space into the internal space, diffusion rate-determining means between the internal space and the gas-introducing port, and inner and outer pumping electrodes for pumping-processing oxygen contained in the measurement gas. The diffusion rate-determining means includes slits each having, when viewed in a plane substantially perpendicular to a longitudinal extension axis thereof, two dimensions, with at least one dimension of each slit being not more than 10 microns.

Abstract: The time profile of the output signal of an NOx measurement transducer arranged downstream of the NOx storage catalyst is used, during and after the regeneration phase, to derive a criterion as to whether the quantity of regeneration agent to be supplied to the NOx storage catalyst in a regeneration phase must be changed in order to achieve an optimum action of the exhaust-gas purification system. The output signal is picked off at the amperometric NOx measurement transducer at two electrodes. The measurement transducer exhibits the two-position behavior necessary for the method.

Abstract: A gas concentration sensing apparatus includes a gas introducing portion for introducing a measurement gas. A first cell opposed to the gas introduction portion operates for pumping oxygen from the measurement gas in the gas introducing portion. A second cell opposed to the gas introducing portion operates for sensing a concentration in a specific component of the measurement gas from which oxygen has been pumped by the first cell. There is a reference gas chamber to which at least one of the first cell and the second cell is exposed. The one of the first cell and the second cell which is exposed to the reference gas chamber includes an electrode facing the gas introducing portion. A current flowing through the first cell is sensed. A voltage is applied to the first cell in response to the sensed current through the first cell. A current flowing through the second cell is sensed. A voltage is applied to the second cell in response to the sensed current through the second cell.

Abstract: A sensor element for limiting-current sensors for determining the lambda value of gas mixtures, in particular of exhaust gases from internal combustion engines. The sensor element has inner and outer pump electrodes arranged on a solid electrolyte foil. The inner pump electrode is arranged in a diffusion channel that is bordered by a diffusion barrier, the pump electrode lying in the diffusion direction of the gas mixture downstream of the diffusion barrier. The gas entry hole, essentially perpendicular to the surface of the solid electrolyte foil, is led through the solid electrolyte foil into the diffusion channel. The diffusion barrier is arranged so as to be set back in the diffusion channel from the interior wall of the gas entry hole. For manufacturing the sensor element, a chamber created upstream of the diffusion barrier is filled with a cavity-creating material, which evaporates in the sintering of the sensor element and thus forms a cavity in the diffusion channel.

Abstract: A nitrogen oxide concentration detector has a first measurement chamber 2 into which is introduced a measurement gas via a first diffusion resistance 1; an oxygen concentration detection electrode 7a for measuring the oxygen concentration in the measurement gas in said first measurement chamber 1; a first oxygen ion pump cell 6 for pumping out oxygen in the measurement gas from said first measurement chamber 2 based on the potential of said oxygen concentration detection electrode 7a; a second measurement chamber 8 into which the gas is introduced from said first measurement chamber 2 via a second diffusion resistance 3; and a second oxygen ion pump cell 8 having a pair of electrodes 8a,8b across which a voltage is applied to decompose NOx in the second measurement chamber 4 to pump out dissociated oxygen to cause a circuit Ip2 corresponding to the NOx concentration to flow in the second oxygen ion pump cell 8. Variation of NOx concentration is a function of variation of Ip2.

Abstract: To determine the oxidizable portion of exhaust gases in the presence of the reducible portion with the legally required precision, a method and a sensor are disclosed for analyzing a flow of exhaust gas components. The sensor includes a limit current measurer, one limit current pump for reducible gases and, downstream from this pump in the direction of diffusion, another limit pump for oxidizable gases. The electrodes of the limit current pump for reducible gases are made of a material that does not catalyze the reaction between oxidizable and reducible gases.

Abstract: A NOx concentration of a gas is measured with a NOx measuring sensor which has two measuring cells. An oxygen concentration is respectively corrected by a oxygen-ion pumping current. A controller is used for correcting a transitional resistance through which the first oxygen-ion pumping current flows at the first measuring cell, the controller correcting at least partially a correction value for the transitional resistance by using the second oxygen-ion pumping current at the second measuring cell.

Abstract: Provided is a CO sensor which comprises a solid electrolyte 11 having oxygen ion conductivity and a standard electrode 15 and a sensing electrode 16 for measurement of carbon monoxide and at least one standard electrode 15 and sensing electrode 17 for measurement of at least one different gas other than carbon monoxide, especially sulfur dioxide, these electrodes being formed on at least a part of the surface of the solid electrolyte 11. This CO sensor is excellent in selectivity for carbon monoxide, can exclude the influence of the coexisting sulfur dioxide and oxygen on the carbon monoxide measured value, and, besides, can be used at high temperatures. A method for making the sensor and a method of using it are also provided.

Abstract: A detecting element is configured such that a second electrode is disposed on one side of a plate-like first electrode with a first solid electrolyte layer positioned therebetween and a third electrode is disposed on the other side of the first electrode with a second solid electrolyte layer positioned therebetween, thereby detecting migration of oxygen ions between the first electrode and the second electrode and migration of oxygen ions between the first electrode and the third electrode. Since the second electrode is disposed on one side of the plate-like first electrode with the first solid electrolyte layer positioned therebetween and the third electrode is disposed on the other side of the first electrode with the second solid electrolyte layer positioned therebetween, both planes of the detecting element functions as detecting planes and, to thus extend the directivity of detection in two directions.