Abstract: A gas concentration measuring apparatus for use in air-fuel ratio control of motor vehicle engines is provided which includes a laminated sensor element and a sensor circuit. The sensor circuit includes a current-measuring resistor, at least one amplifier, and A/D converters. The current-measuring resistor functions to measure a current signal flowing through the sensor element produced upon application of the voltage to the sensor element. The amplifier works to amplify the current signal to output it to one of the A/D converters to determine the concentration of the air-fuel ratio within one of a plurality of measurement ranges defined within the wide gas concentration measuring range. The amplification of the current signal results in expansion of the level of the input to the A/D converter, thus enhancing the resolution in determining the air-fuel ratio.

Abstract: Sensor assemblies for analyzing NO and NO2 concentrations in an emission gas and method for fabricating such sensor assemblies are provided. A sensor assembly comprises a first sensor having a first barium tungstate film. The first sensor is configured to detect a concentration of NOx in the gas and to provide a first signal associated with the concentration of NOx. NOx represents a combination of NO2 and NO. The sensor assembly also comprises a second sensor disposed in a stationary position relative to the first sensor and having a second barium tungstate film. The second sensor is configured to detect a concentration of one of NO2 and NO in the gas and to provide a second signal associated with the concentration of the one of NO2 and NO.

Abstract: A linear exhaust-gas probe has a measuring cell for measuring a gas concentration in a measuring chamber by determining a measuring-cell voltage, and a pump cell for pumping gas by way of a pump current. A circuit configuration for operating the prove has a comparator circuit for comparing the measuring-cell voltage with a measuring-cell setpoint voltage and for providing a corresponding analog deviation signal. A pump current source provides the pump current. The source is controlled by the deviation signal using a control circuit for the approximation of the measuring cell voltage to the measuring cell setpoint voltage. In order to reliably limit the pump voltage with no significant detrimental effect on the operation, the circuit configuration further has a second comparator circuit for comparing the pump voltage with a predefined threshold voltage and for providing a corresponding binary switching signal; and a counter coupling path between the output of the pump current source and the control circuit.

Abstract: A circuit configuration for operating a gas sensor is described, including a reference gas space in which an electrode is situated which is supplied with a reference gas pump current to maintain the concentration of the reference gas. A diagnostic system determines a concentration change of the reference gas via a change in the reference pump current and a time-based evaluation of the sensor signal of 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: In a method and with a circuit for operating a nitrogen oxide sensor for determining the nitrogen oxide (NOx) concentration in a gas mixture, in particular in post-treatment of an automotive exhaust, an electric pumping voltage (U_APE,IPE) which induces a pumping current (I_pump) being applied between an internal pump electrode (IPE) and an external pump electrode (APE) of a pumping cell, by which a constant oxygen partial pressure is established in a first test gas space by pumping oxygen in or out, the pumping voltage (U_APE,IPE) being regulated so that a constant voltage value is established at electrodes of a concentration cell, a NOx-sensitive third electrode situated in a second test gas space being operated as the second pumping cell in which a limit pumping current is established, indicating the NOx concentration, in order to minimize the influence of oxygen on the nitrogen oxide signal measured, the pumping current (I_pump) is switched off or reduced in a controlled manner within a measurement time w

Abstract: An oxygen sensor for measuring exhaust gases of an internal combustion engine is described. The sensor provides an output that has a high gain near the stoichiometric air-fuel ratio, and a lower gain in the lean and rich air-fuel ratio regions. Further, the sensor provides wide range air-fuel ratio signal to be used in engine feedback control.

Abstract: A gas sensor for detecting at least one physical magnitude of a gas, in particular of exhaust gases of an internal combustion engine, is proposed, which includes a sensor element having an electrochemical cell. The electrochemical cell includes a first solid electrolyte member on which a first electrode and a second electrode are applied. The first and the second electrode are electrically connected by means of the first solid electrolyte member. The first electrode is in contact with the gas. The area of the first electrode is smaller than the area of the second electrode.

Abstract: In order to operate an amperometric solid electrolyte sensor comprising a heating element which is separated from a sensor element by means of an electrical insulating layer, an electrical bias voltage is applied between the sensor element and the heater in such a way that the potential regions of the sensor element and the heater do not overlap.

Abstract: A concentration detector comprises oxygen-forming means for forming oxygen by decomposing the particular component in the gas, first output means for producing an output value proportional to the oxygen concentration in the gas of before oxygen is formed by the oxygen-forming means, second output means for producing an output value proportional to the oxygen concentration in the gas after oxygen is formed by the oxygen-forming means, concentration calculation means for calculating the concentration of the particular component in the gas based upon the output value from the first output means and upon the output value from the second output means by using a coefficient for bringing the output characteristics of the first output means into agreement with the output characteristics of the second output means, and means which feeds at least two kinds of gases containing the particular component at a constant concentration and containing oxygen at different concentrations to said first output means and calculates

Abstract: In a method for operating a measuring probe for measuring a gas concentration in a measuring gas with the aid of a solid electrolyte which conducts oxygen ions and has a measurement cavity for holding the measuring gas, a measuring electrode and an external electrode, a pumping current flowing between the measuring electrode and external electrode transporting oxygen ions from the measuring electrode to the external electrode, the measuring electrode being checked by determining the electrode area effectively available for oxygen diffusion.

Abstract: A vehicle control apparatus and methodology relate to an exhaust gas sensor and sensor heater associated with an exhaust passage of a vehicle engine. The exhaust gas sensor is selectively heated to an applicable activation temperature by the heater so that the sensor may output a normal and accurate sensing signal. The heating must take place, however, without causing damage to the sensor such as that resulting from condensation that may occur within the exhaust passage as a result of engine operation and environmental conditions.

Abstract: A sensor for determining the concentration of particulates in gas mixtures is described, a soot sensor in particular, having a ceramic sensor body surrounded by a metallic housing and having a first and a second measuring electrode. In this instance, the first measuring electrode is connected to the metallic housing of the sensor or the metallic housing of the sensor is designed as the first measuring electrode. By additional electrodes on the ceramic body, the sensor is operable also as a lambda sensor.

Abstract: There is provided a gas sensor for measuring the concentration of a specific gas component in a gas under measurement, including a gas diffusion rate limiting portion, a measurement chamber communicating with an atmosphere of the gas under measurement through the gas diffusion rate limiting portion, a sensor element having an ion-conductive layer with first and second surfaces, a first electrode disposed in contact with the first surface of the ion-conductive layer within the measurement chamber and a second electrode disposed in contact with the second surface of the ion-conductive layer and communicating exclusively with the atmosphere of the gas under measurement and a cylindrical support member installing therein the sensor element with the first and second surfaces of the ion-conductive layer directed toward front and base end sides of the support member, respectively.

Abstract: In a gas concentration measuring apparatus, a measurement substrate is provided. A conductive pattern portion is formed in the measurement substrate. The conductive pattern portion includes a signal input pattern constituting the signal processing circuit and electrically connected to the connection terminal, said signal input pattern having direct current impedance with respect to the connection terminal, said direct current impedance being 10 percent or less of the input impedance of the connection terminal; a different potential pattern having a potential difference of 2 V or over from a potential of the signal input pattern; and a guard pattern having a substantially constant potential and a potential difference of less than 0.5 V from the potential of the signal input pattern, said guard pattern being arranged on at least a portion of the measurement substrate, said at least portion of the measurement substrate being located between the signal input pattern and the different potential pattern.

Abstract: An oxygen concentration detection system including an oxygen sensor which outputs a plurality of types of measurement signals and anomaly detection means and modification means. The anomaly detection means detects a sensor anomaly by determining whether the respective levels of the plurality of types of measurement signals fall within predetermined ranges. When a sensor anomaly is not detected, the modification means outputs the plurality of types of measurement signals as is. When a sensor anomaly is detected, the modification means outputs at least one of the plurality of types of measurement signals at a level outside the corresponding range within which the level of the measurement signal varies in a normal state.

Abstract: A current detection resistance in a sensor control device is connected to a sensor element. The current flowing in the sensor element is detected through the current detection resistance. The current detection resistance is connected to an inverting amplification circuit for outputting an air/fuel output voltage to be transferred to a microcomputer. An offset setting circuit is connected to one input terminal of an operational amplifier in the inverting amplification circuit. The offset setting circuit is comprised of a switching element, a resistance connected in series to the switching element, and two dividing voltage resistances whose common node is connected to the resistance. The offset setting circuit generates and gives an offset to the A/F output voltage. The switching element is turned ON and OFF based on an offset switching signal transferred from the microcomputer.

Abstract: A common current sensing resistor is used to monitor the current supplied to the heater elements of multiple heated oxygen sensors of an engine exhaust gas emission control system. Two or more sensor heater elements are coupled to a single current sensing resistor to produce a single current feedback signal for analysis by a programmed controller. The controller synchronizes its current monitoring function with its heater activation control to diagnose heater element fault conditions.

Abstract: A flat limiting-current sensor 10 includes a solid electrolyte substrate 22, a negative electrode 34a and a positive electrode 32a. The negative and positive electrodes 34a and 32a, respectively, are disposed on the same side of the solid electrolyte substrate 22. A voltage of 0.8 V is applied between the negative electrode 34a and the positive electrode 32a in order to determine oxygen concentration. The ratio between the area of the negative electrode 34a and the area of the positive electrode 32a is set to 1:2, thereby reducing element resistance to 74% that of the case where the negative electrode and the positive electrode assume the same area. Thus, the measurement accuracy of the flat limiting-current sensor 10 is improved.

Abstract: A gas sensing element has at least a sensor cell consisting of a measured gas side electrode positioned in a measured gas chamber, a reference electrode being operative association with the measured gas side electrode, and a solid electrolytic substrate having surfaces on which the measured gas side electrode and the reference electrode are formed. The measured gas side electrode of the sensor cell contains at least one additive selected from the group consisting of Au, Ag, Cu, and Pb by an amount of 0.01 wt % to 2.0 wt % (external wt %) when an overall amount of the measured gas side electrode is 100 wt %.

Abstract: A set of methods controls the pumping action of and provides leak checking of a solid electrolyte oxygen sensor having internal and external electrodes. A first method performs a leak check on the sensor by forcing the sensor internal reference chamber to an evacuated state while seeking a minimum pumping current able to maintain this state. Further pumping control methods apply current pulses to the sensor electrodes to achieve a balanced state between an external oxygen partial pressure and an internal reference oxygen partial pressure. Reduction expressions modify the pulse parameters as a function of the sensor voltage output. A further expression modifies the pulse magnitude as a function of the internal reference chamber oxygen partial pressure. A further expression modifies the initial value of the pulse magnitude as a function of the oxygen partial pressure in a calibration gas during a calibration process.

Abstract: A concentration detector for detecting the concentration of a particular component in a gas based upon the amount of oxygen formed by the decomposition of the particular component, comprising oxygen-forming means for forming oxygen by decomposing the above particular component, oxygen-discharging means for discharging oxygen from the gas before oxygen is formed by the oxygen-forming means, and oxygen-discharging capability-increasing means for increasing the oxygen-discharging capability of the oxygen-discharging means when the rate of increase of the oxygen concentration in the gas is greater than a predetermined rate before oxygen is formed by the oxygen-forming means.

Abstract: Provided is a multilayer gas sensing element having a high measurement accuracy and less susceptible to a leakage current. The element comprises an oxygen pump cell for adjusting an oxygen concentration in a measured gas chamber, a sensor cell for detecting a specified gas concentration in the measured gas chamber, and a heater for heating the cells up to an activating temperature. The heater includes a heat generator for generating heat when energized, a heater terminal provided externally and a heater lead for making electrical connection therebetween. When the electrical resistance value of the heat generator is taken as RH and the electrical resistance value of the heater lead is taken as RL, these values are set to satisfy the relationship of 1.5?RH/RL.

Abstract: A gas sensor based on solid electrolyte is proposed for measuring a gas component in a gas mixture, having at least one sensitive region, which has a first means for producing a reaction gas from an additional gas component of the gas mixture. A second means is situated in the sensitive region of the gas sensor, using which the residual content of the reaction gas may be determined, after a reaction that takes place between the reaction gas and the gas component to be measured.

Abstract: In a limiting current type oxygen sensor, a plane cathode layer and a plane anode layer are arranged on both sides of a solid electrolyte layer, and a porous diffusion layer for controlling gaseous diffusion rate is arranged on the other side of the cathode layer. Additionally, the cathode layer has a bonding pad portion for connecting electrically to an external lead wire. A part of the bonding pad is in contact with the solid electrolyte layer, and the other part of the bonding pad is exposed to an atmosphere of the sensor. A patterned gas barrier film is disposed in between a boundary between the part of the bonding pad being in contact with the patterned solid electrolyte layer and the other part of the bonding pad exposed to the atmosphere, and surroundings thereof so as not to expose the boundary directly to the atmosphere.

Abstract: A noiseless circuit structure of a gas concentration measuring apparatus is provided. The gas concentration measuring apparatus includes a control circuit and a gas sensor including a solid electrolyte body, a cell, and a heater serving to heat the solid electrolyte body up to an activation temperature. The control circuit is designed to cancel or remove electric noises arising from an on-off operation of the heater added to a sensor output.

Abstract: In a planar oxygen sensor having a pump cell, a reference cell, a sensor chamber and a heating device, a ground plane electrode is provided and includes a sensing portion having a first sense lead and a second sense lead and a measuring portion having a first measuring lead and a second measuring lead, wherein the first measuring lead and the second measuring lead have increased surface area relative to said sensing portion such that the resistance between the first measuring lead and the second measuring lead is reduced and wherein the first measuring lead is disposed so as to be communicated with the first sense lead and the second measuring lead is disposed so as to be communicated with the second sense lead.

Abstract: A hydrogen gas sensor capable of accurately measuring hydrogen concentration of a measurement gas atmosphere in the presence of a variety of interfering gasses such as H2O and CO. In the hydrogen gas sensor, the flow sectional area of a diffusion-rate limiting portion 6 is rendered small; the electrode surfaces of first and second electrodes 3 and 4 are rendered large; and/or a solution containing a polymer electrolyte which may be identical to that of a proton-conductive layer 2 is applied onto the surfaces of the first and second electrodes 3 and 4 to thereby form a layer containing the polymer electrolyte. Thus, the rate of conduction of protons from the first electrode 3 to the second electrode 4 becomes greater than the rate at which protons are derived from hydrogen which is introduced onto the first electrode 3 via the diffusion-rate limiting portion 6.

Abstract: In an oxygen sensor that measures a limiting current of when a voltage is applied between pumping electrodes, and also performs a rich/lean judgment based on an electromotive force generated between one of the pumping electrodes and a reference electrode, an oxygen supply voltage for supplying oxygen to the reference electrode is applied, and the reference electrode is covered with a dense layer.

Abstract: The invention relates to an air/fuel ratio detection apparatus. This apparatus includes (a) a heater portion having an elongate cylindrical shape and heating by applying electricity thereto from outside; (b) a solid electrolyte layer surrounding the heater portion and being activated by heat to conduct oxygen ions therethrough; (c) first and second electrodes in contact with the solid electrolyte layer and being away from each other such that pumping voltage is applied by the first and second electrodes to the solid electrolyte layer; (d) a reference electrode for outputting an air/fuel ratio detection signal, the reference electrode being formed on the solid electrolyte layer and being away from the first and second electrodes; and (e) a diffusion layer made of a porous material and surrounding periphery of the solid electrolyte layer to cover the first and second electrodes and the reference electrode.

Abstract: Species detection techniques are described based on measurement of a dynamic response to an external stimulus. One embodiment includes a voltage stimulus applied to a polymer electrolyte fuel cell (PEFC), with the response to said stimulus used to measure CO concentration on the anode catalyst. The principles of symbolic dynamics, finite state machines or a simplified peak response-to-asymptotic value measurement can be used to achieve a high degree of precision for measuring CO concentrations. Using the techniques of the present invention, CO poisoning of a fuel cell can be monitored and diagnosed before reaching a critical condition, thereby allowing early implementation of mitigation or graceful degradation strategies.

Abstract: A gas sensor (1a) having a laminate including an alumina substrate (11) having a heating resister (115) embedded in the alumina substrate (11); a first oxygen-ion conductive solid electrolyte layer (131) containing zirconia and alumina and partly constituting an oxygen-detecting cell (13) and the first solid electrolyte layer (131) being laminated with said alumina substrate (11); a second oxygen-ion conductive solid electrolyte layer (121) containing zirconia and alumina and partly constituting an oxygen-pumping cell (12); an ion-leakage preventing ceramic spacer (143) for preventing oxygen-ions from leaking from the second oxygen-ion conductive solid electrolyte layer (121) to the first oxygen-ion conductive solid electrolyte layer (131), the spacer (143) being laminated between the first and second oxygen-ion conductive solid electrolyte layers (131, 121); and a gas-diffusion space (141) formed between an electrode (133) of the oxygen-detecting cell (13) and an electrodes (126) of the oxygen-pumping cell (

Abstract: Disclosed is a gas sensor for controlling a concentration of oxygen and/or measuring NOx by allowing a current to flow through an ion-conductive member for conducting oxygen ion, by the aid of a current supply circuit, wherein the current, which is outputted from the current supply circuit, has a pulse waveform (current signal) having a constant crest value, and the current supply circuit comprises a rectangular wave-generating circuit for controlling a frequency of the current signal on the basis of an electromotive force generated in the ion-conductive member to which the current signal is supplied. Accordingly, it is possible to highly accurately measure the predetermined gas component while scarcely being affected by the electric noise or the like.

Abstract: Electrode having high activity to oxygen gas and low activity to flammable gas is provided. An oxygen pump includes oxide-ion conductive solid electrolyte 2, electrode 8 which is an inactive electrode, and active electrode 10. Electrode 8 is an electrode that includes Ce0.8Sm0.2O2-?. Electrode 8 is disposed on the gas detection chamber 12 side of solid electrolyte 2. Active electrode 10 is disposed on the open space side of solid electrolyte 2. Gas detection chamber 12 is an enclosed space defined by solid electrolyte 2, insulation layers 6, and diffusion control layer 4.

Abstract: A nitrogen oxide sensor system for measuring the amount of nitrogen oxide in a gas. A first electrode is exposed to the gas. An electrolyte is positioned in contact with the first electrode. A second electrode is positioned in contact with the electrolyte. A means for applying a fixed current between the first electrode and the second electrode and monitoring the voltage required to maintain the fixed current provides a measurement of the amount of nitrogen oxide in the gas.

Abstract: A detecting electrode comprises a first cermet electrode layer formed directly on a solid electrolyte layer and a second cermet electrode layer formed on the first cermet electrode layer. The ratio between Pt and Rh in the first cermet electrode layer ranges from 100:0 to 25:75 by weight. The ratio between Pt and Rh in the second cermet electrode layer ranges from 25:75 to 0:100 by weight.

Abstract: A compensation circuit (KS) is provided between the output of a differential amplifier (Diff_Amp) and the input of a controller (R). The compensation circuit generates a compensation signal, whose characteristic curve approximates to that of the parasitic signal, with the same amplitude and frequency (Phi1) as the parasitic signal, but by 180 DEG out of phase. The compensation signal is subtracted from the differential signal (DELTA Vs) and allows the parasitic signal to be eliminated to a great extent.

Abstract: The invention relates to an air/fuel ratio detection apparatus for a gas. This apparatus includes (a) a heater portion having an elongate cylindrical shape; (b) a solid electrolyte layer surrounding the heater portion and activated by heat to conduct oxygen ions therethrough; (c) a first electrode positioned between the heater portion and the solid electrolyte layer; (d) second and third electrodes in contact with an outer surface of the solid electrolyte layer and away from each other; (e) a first voltage applying device for applying a first voltage between the first and second electrodes; (f) a second voltage applying device for applying a second voltage between the first and third electrodes, the second voltage being higher than the first voltage; and (g) a diffusion layer made of a porous material and covering the second electrode to adjust transmission of the gas to the second electrode.

Abstract: The pumping current source (P) required for operating the linear lambda probe is wired in such a manner that its inverting input is connected to the third probe terminal (Vp+), its non-inverting input is connected to the potential of the mean voltage (VM), and that its output is connected to the second probe terminal (Vp?/Vs?).

Abstract: A gas sensor for determining the concentration of gas components in gas mixtures is used in particular to measure the concentration of nitrogen oxides in exhaust gases of internal combustion engines or in the interiors of motor vehicles. It contains an electrochemical measuring cell which includes a first electrode situated on a solid electrolyte and an additional electrode. The electrode is made of an oxide material containing lanthanum which at least catalytically decomposes nitrogen oxides. The pump current flowing between the electrodes is used as a measure of the nitrogen oxide concentration in the gas mixture.

Abstract: A gas sensor element which may be employed in measuring the concentration of gas such O2, NOx, or CO. The gas sensor element consists of an electrochemical cell made up of a solid electrolyte body formed by a partially stabilized zirconia and a pair of electrodes disposed on the solid electrolyte body. The electrochemical cell is subjected to an aging treatment in which the dc current is applied to the electrodes at a given voltage to enhance the activation of the electrochemical cell.

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 solid electrolyte-based sensor element of a gas sensor for determining a gas component in a gas mixture is described, in particular for determining the concentration of oxygen and/or nitrogen oxides in exhaust gases of internal combustion engines. The sensor element has an electrochemical cell that includes a first and a second electrode, both electrodes being located in internal gas spaces of the sensor element. The internal gas space in which the first electrode is located is largely in the same layer plane of the sensor element as at least one other internal gas space of the sensor element in which the second electrode or a reference electrode are located.

Abstract: A coating system and a method for its manufacture are provided. An electrically conductive base coat and a porous overcoat lying over the base coat are arranged on a ceramic substrate. At least one additional deposited layer is arranged on the base coat in such a way that the additional layer is formed in the pores of the porous overcoat adjacent to the base coat. The additional layer is deposited either by currentless or electrolytic deposition. For electrolytic deposition of the additional layer, the ceramic substrate sintered with the base coat and the overcoat is submerged in an electrolytic bath and the base coat is connected as a cathode. The currentless deposition takes place from a solution of the metal to be deposited with the addition of a reducing agent.

Abstract: A sensor element including an insulative base (11), a heating resistor (12), an oxygen pump cell (13), an oxygen detection cell (14), and a diffusion-chamber-forming member (161) having a rate-controlling introduction portion (163) and defining a diffusion chamber (16) in cooperation with electrodes (1321, 1421), wherein these components have been subjected to simultaneous firing (i.e., cofiring) to form a unitary sensor element. A partition wall (162), which extends from the diffusion-chamber-forming member and is made of alumina, is joined to a surface of a solid electrolyte (131) between two electrodes (1321, 1322) of an Ip cell. Preferably, a region within 20 ?m from the plane of junction joining the partition wall (162) to the solid electrolyte (131) contains no portion whose amount of non-alumina substances exceeds by 2% by mass (by weight) or more the amount of non-alumina substances of the diffusion-chamber-forming member (161).

Abstract: A gas concentration detecting apparatus comprises a gas concentration sensor and a gas concentration calculator. The sensor has first to third cells. A gas to be detected is introduced in a chamber and the first cell is responsible for discharging and changing oxygen from and into the chamber. The second cell detects a concentration of a specific gas component of the gas that has passed along the first cell. The third cell detects a concentration of residual oxygen in the gas that remains after discharge of the oxygen through the first cell. The calculator takes in a current acquired from the second cell measured with a voltage applied thereto and calculates the specific gas component concentration based on the current. The calculator includes plural concentration calculating means whose concentration detecting ranges are mutually different in a scale. The specific gas component concentration is calculated every concentration calculating means.

Abstract: A sensor element and a method for determining the concentration of at least one gas component, especially of a nitrogen oxide, in a gas, mixture. For this purpose, the sensor element includes at least one first electrode exposed to the gas component to be analyzed and at least one reference electrode, which are electrically interconnected by a first solid electrolyte. Furthermore, an electric current between the first electrode and a further electrode is measured continuously or in sampling fashion in response to the application, especially the setting, of an electric voltage between first electrode and the reference electrode due to a chemical reaction proceeding at the first electrode, by which the concentration of the gas component to be analyzed in the gas mixture can be determined. During this process, the application or setting of the electric voltage takes place only during recurring time intervals.

Abstract: A gas concentration measuring apparatus has a gas sensor consisting of pump, sensor, and monitor cells. The apparatus works to determine the value of voltage applied to the pump cell when a change in current produced by the monitor cell or the sensor cell changes upon a change in the voltage applied to the pump cell varies greatly and uses it to determine a control point to which the voltage applied to the pump cell is to be controlled. This keeps a gas concentration measuring accuracy free from, for example, aging of the sensor.

Abstract: A gas concentration measuring apparatus has a gas sensor including pump, sensor, and monitor cells. The apparatus works to look up a predetermined voltage-to-current relation to determine an initial value to be applied to the pump cell as a function of a current output of the pump cell, apply the initial value of the voltage to the pump cell, and to sweep it temporarily. The apparatus works to correct the initial value of the voltage as a function of a current output of the sensor cell upon the sweep of the initial value of the voltage applied to the pump cell, thereby better maintaining gas concentration measuring accuracy with respect to, for example, aging of the sensor.

Abstract: An electrochemical gas sensor determining the concentration of oxidizable gas components which has an electrochemical measuring cell having a measuring electrode and a reference electrode. Measuring electrode is made of a material which is not able, or not completely able to catalyze the establishment of gas equilibrium. In addition to the electrochemical measuring cell, at least one electrochemical pumping cell, having at least one inner pumping electrode, is provided, which, together with measuring electrode, is positioned in a measuring gas compartment. Oxygen is pumped into or out of measuring gas compartment by pumping cell, the partial pressure of oxygen in measuring gas compartment being set to a lambda value of ?1.3.