Abstract: A heating device for a gas sensor, in particular for use in the exhaust gas analysis of internal combustion engines, including a heating element having an electrical resistor layer. The heating element is embedded in a first insulation which in turn is surrounded, at least in part, by a second insulation. The first and the second insulation have different porosities.

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 NOx 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: A gas flow measuring device and gas flow measuring method are disclosed wherein specific gas component of measuring object gas or target gas composed of gas different from the specific gas component are added to or extracted from the measuring object gas, and concentrations C1 and C2 of the specific gas component before and after the target gas is added to or extracted. A detector (111, 121) is provided to calculate the flow rate Q1 in response to the detected concentrations C1, C2 or to detect the flow rate Q1 of the measuring object gas, and the flow rate Q3 of added or extracted target gas is detected in response to the flow rate Q1 and the concentrations C1, C2 which are detected.

Abstract: A combined oxygen and NOx sensor is provided. Generally, the combined sensor employs a sensor body that includes two different types of electrodes—oxygen-porous electrode layers and dissociative oxygen-porous electrode layers. In accordance with one embodiment of the present invention, the sensor comprises a sensor body, an oxygen content electrical signal output, and a NOx content electrical signal output. The sensor body is disposed in the gas and comprises a plurality of oxygen-porous electrode layers and a plurality of dissociative oxygen-porous electrode layers. The dissociative oxygen-porous electrode layers comprise a material selected to catalyze dissociation of NOx into nitrogen and oxygen.

Abstract: A sensor is described for measuring the concentration of a gas component in a gas mixture, particularly a lambda probe for measuring the oxygen concentration in the exhaust gas of an internal combustion engine, having a solid electrolyte and having two electrodes separated by the solid electrolyte, of which an outer electrode is exposed to the gas mixture and an inner electrode is situated in a cavity separated from the gas mixture by a diffusion barrier. To achieve a broadband measuring of the air ratio &lgr; and a simplified construction compared to a known lambda broadband probe having a pump cell and a Nernst cell, the sensor is operated according to predefined criteria, alternately as lean operation probe according to the limiting current principle and as transition probe having a pumped reference.

Abstract: A probe is described for determining an oxygen concentration in a gas mixture, in particular in the exhaust gas of internal combustion engines, having a Nernst measuring cell, which has a first electrode (Nernst electrode) which is exposed to the gas mixture to be measured via a diffusion barrier, a second electrode (reference electrode) which is exposed to a reference gas, and a solid electrolyte body arranged between the first and the second electrode, and having a pump cell, which has a first electrode (inner pump electrode) which is exposed to the gas mixture via the diffusion barrier, a second electrode (outer pump electrode) which is exposed to the gas mixture, and a solid electrolyte body arranged between the first and the second electrode. The Nernst electrode and the inner pump electrode are connected at least in some sections via a joint supply conductor to a circuit arrangement for controlling and evaluating the probe.

Abstract: A sensor element for determining the concentration of a gas component in a gas mixture, particularly for determining the oxygen concentration in exhaust gases of internal combustion engines. The sensor element includes at least one pump cell, which has at least one first pump electrode located in a measuring gas chamber and at least one second pump electrode, located on a surface of the sensor element facing the gas mixture, as well as at least one concentration cell, which has at least one reference electrode located in a reference gas chamber and at least one measuring electrode, located in the measuring gas chamber, which cooperates with the reference electrode. The measuring gas chamber and the reference gas chamber are essentially located in the same layer level (plane) of the sensor element which has a layered construction.

Abstract: In order to raise accuracy of measurement, a compound layered type of sensing device is provided. The device comprises a plurality of solid electrolyte plates and first to third electrochemical cells. Each cell has a single pair of electrodes disposed on the solid electrolyte plates. A concentration of a gas specified from a gas to be measured pre-processed based on oxygen pumping by the first electrochemical cell is detected by the second electrochemical cell. A difference in electromotive force between the gas to be measured and a reference gas is detected by the third electrochemical cell. The single pair of electrodes of the third electrochemical cell is disposed on the same surface of one of the solid electrolyte plates, and both of the first and third electrochemical cells are located with different ones of the solid electrolyte plates.

Abstract: A CO sensor and a CO-concentration measurement method which enables accurate measurement of CO concentration irrespective of the hydrogen concentration of a gas under measurement. By applying a first predetermined voltage between first and second electrodes 7 and 8, hydrogen contained in a gas under measurement which has been introduced into a first measurement space 2 via a first diffusion-controlling section 1 dissociates, decomposes, or reacts with another element to generate protons. The thus-generated protons are transported from the first electrode 7 to the second electrode 8 via a first proton-conductive layer 5 or protons are transported from the second electrode 8 to the first electrode 7 via the first proton-conductive layer 5 (when the hydrogen concentration of the measurement gas is extremely low), so that the hydrogen concentration within the first measurement space 2 is controlled to a constant level.

Abstract: A method for operating a mixed-potential exhaust-gas probe for an internal combustion engine having a heatable probe ceramic 1.3 with a first electrode 1.5, which is arranged in a chamber 1.6 and is subjected to the reference atmosphere and with a second electrode 1.4 which detects gas molecules and is arranged in the exhaust gas of the internal combustion engine, a pump voltage being applied between the first and second electrodes by means of a pump voltage source, so that, in the interior of the chamber 1.6, a somewhat reduced oxygen partial pressure is adjusted by the electrochemical pumping off of the oxygen molecules, characterized in that one applies a constant external voltage to the electrodes (1.4, 1.5) with this voltage deviating from the thermodynamic equilibrium voltage of the wanted reaction, measuring and evaluating the current dropping across the electrodes (1.4, 1.5).

Abstract: The present invention discloses a NOx sensor for accurately detecting the total concentration of nitrogen oxides in a measured gas without being affected by interference gases. The sensor comprises a gas treatment chamber 5 arranged at the prior stage of the gas detection chamber 3, an inorganic porous member 25 loaded in the gas treatment chamber, and a NOx conversion pumping cell 14, 15 and/or an oxygen supplying pumping cell which supplies oxygen into the gas treatment chamber. When the measured gas is introduced in the gas treatment chamber, the interference gases contained in the measured gas are effectively oxidized by the supplied oxygen under the assistance of the catalytic activity of inorganic porous member. The total amount of the nitrogen oxides is measured in the gas detection chamber while NOx in the measured gas are converted into a single component (NO2 or NO) by the NOx conversion pumping cell after the interference gases are oxidized.

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: An electrochemical sensor for determining a gas concentration of a measuring gas using a sensor element that has at least one electrode situated on an ion-conducting solid electrolyte body, an electrode lead leading to the electrode. The electrode lead is made of a material possessing no ionic conductivity or an ionic conductivity that is significantly less in comparison with the material of the electrode, and/or having a low resistance.

Abstract: A sensor element for determining the concentration of gas components in gas mixtures, particularly for determining the oxygen concentration in exhaust gases of internal combustion engines. It contains a pump cell, which pumps oxygen into or out of a measuring gas chamber, as well as a concentration cell, which has a reference electrode situated in the reference gas channel, and has a measuring electrode. The measuring gas chamber and the reference gas channel are situated in the same layer plane of the sensor element, and are separated from each other by a partition, which is produced by applying a ceramic paste to an adjacent, solid electrolyte foil.

Abstract: Method for operating a sensor for determining the concentration of oxidizing gases in gas mixtures, especially of the nitrogen oxide concentration in exhaust gases of internal combustion engines, wherein the sensor includes: at least one chamber (1; 2) mounted in a solid state electrolyte (20), the chamber being connected to the gas mixture via a first diffusion barrier (4); a second chamber (3) arranged in the solid state electrolyte (20) and the chamber having a pregivable constant oxygen partial pressure; on the solid state electrolyte, an oxygen pump electrode (9) subjected to the exhaust gas; a further oxygen pump electrode (7; 8) as well as an NO pump electrode (10) in the at least one chamber (1; 2); and an oxygen reference electrode (6) arranged in the second chamber (3); and at least a voltage is made available at the electrodes and at least a pump current is evaluated as a measurement signal.

Abstract: A gas sensor suitable for measuring hydrogen concentration, including a proton conductive layer (1); a first electrode (3) and a second electrode (5) provided on the proton conductive layer (1); a gas diffusion-limiting inlet (19) provided between the first electrode (3) and a measurement gas atmosphere (6) containing hydrogen gas; and a gas diffusion-limiting outlet (21) provided between the second electrode (5) and the atmosphere (6); wherein the ratio (a/b) between the diffusion resistance (a) of the diffusion limiting portion (19) and the diffusion resistance (b) of the gas outlet portion (21) is not greater than 2.

Abstract: A gas sensor has improved electrical properties. In the top view of the layer planes of the body of the sensor, printed circuit traces for electrodes are arranged outside of cavities in the body, e.g., outside of the reference air duct. Furthermore, the electrodes are enlarged in the direction of the exhaust-side end of the sensor. Also, the printed circuit traces have an increased layer thickness or are formed as a double layer.

Abstract: A wide range oxygen sensor comprising a first oxygen pump cell, the first pump cell comprising: a first and a second electrode, with a first communication zone therebetween, the first electrode being exposed to exhaust gas, the second electrode being exposed to a heat source; and wherein at least one element of said first pump cell incorporates a gas-diffusion limiting characteristic; a second oxygen pump cell, operating at opposite polarity from said first oxygen pump cell, electrically isolated from said first oxygen pump cell, and disposed within a sensor substrate, the second cell comprising: a third and a fourth electrode, with a second communication zone therebetween, the third electrode being exposed to exhaust gas, the fourth electrode being exposed to a heat source; and wherein at least one element of said second pump cell incorporates a gas-diffusion limiting characteristic; at least one heating element for providing heat to said second electrode and said fourth electrode; and an electrical circuit

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected. Finally, the effect of the amount of moisture in the exhaust gas is removed or reduced from the detected value of gas concentration.

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: A gas sensor includes a sensor element formed of a solid electrolyte having an oxygen ion conductivity; a cathode and an anode, each formed of a porous metal material and each formed on the sensor element, to produce a pumping current reflecting a concentration of a detection component in a measurement gas when a predetermined voltage is applied between the cathode and the anode. The detection component contains oxygen. The measurement gas contacts the cathode. The gas sensor also includes a gas diffusion control to vary the oxygen pumping current in accordance with a pressure of the measurement gas by controlling a diffusion of the measurement gas. The measurement gas moves from a measurement atmosphere toward the cathode by way of the gas diffusion control. Thereby, information on the pressure of the measurement gas is obtained based on the oxygen pumping current.

Abstract: The present invention relates a gas concentration detecting apparatus capable of appropriately making a decision on activation of each of a pump cell, a monitor cell and a sensor cell of its gas concentration sensor. In the apparatus, a control circuit outputs an oxygen concentration value on the basis of a current flowing when a voltage is applied to the pump cell and outputs an NOx concentration value on the basis of a current flowing at the voltage application to the sensor cell. Moreover, the control circuit separately makes a decision on activation of the pump cell and a decision on activation of the sensor cell in the middle of the activation of the sensor. Still moreover, the control circuit makes the decision on the activation of the sensor cell after the activation of the pump cell reaches completion.

Abstract: A gas sensor is created comprising an electrochemical cell having a solid electrolyte layer disposed between an exhaust gas electrode and a reference electrode. A resistor is disposed in electrical communication with a heater and the reference electrode. The resistor can be disposed on a side of the gas sensor; on a side of the gas sensor such that the resistor is electrically connected through a via hole; over at least a portion of at least two sides of the gas sensor; or disposed in a void extending at least from the heater to the pump electrode, such that the void extends to at least a surface of the gas sensor, extends to at least partially through the gas sensor, or extends completely through the gas sensor. A method for using this gas sensor comprises applying a voltage to the heater within the gas sensor. A current is directed through the resistor to the reference electrode to pump oxygen into the reference electrode.

Abstract: A heater control apparatus used for a gas concentration sensor heats a sensor element including a solid electrolyte body 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: The invention is directed to a circuit arrangement for operating an exhaust-gas probe including a NOx double chamber sensor. The exhaust-gas probe includes: a heatable solid-state electrolyte body having first and second pump chambers and diffusion barriers for separating the chambers from each other and from the exhaust gas. A third chamber communicates with the atmosphere. An external pump electrode is exposed to the exhaust gas and a first oxygen pump electrode is disposed in the first pump chamber. A second oxygen pump electrode is disposed in at least one of the first and second pump chambers and a nitrogen oxide pump electrode is disposed in the second pump chamber. An air reference electrode is disposed in the third chamber. Only one pump voltage generating circuit unit is provided and a switching device switches the pump voltage generating circuit unit between respective ones of the pump electrodes.

Abstract: A device according to the present invention is provided with element temperature measurement voltage application circuit for temporarily applying a predetermined voltage for element temperature measurement to a sensor element of an air-fuel ratio sensor equipped to an exhaust system of an internal combustion engine, first sensor output reading circuit for reading in a sensor output just before applied with the voltage, and second sensor output reading circuit for reading in a sensor output being applied with the voltage, wherein the element temperature of the air-fuel ratio sensor is estimated based on the sensor output just before applied with the voltage and the sensor output being applied with the voltage. Further, during internal resistance measurement of the sensor element of the air-fuel ratio sensor equipped to the exhaust system of the internal combustion engine, a voltage applied to the heater for heating the sensor element is maintained to be constant.

Abstract: A control system for a gas sensor element capable of lessening the effect of variations in sensor properties among gas sensor elements as well as the effect of environmental factors, such as temperature and humidity, to thereby accurately detect variation in the concentration of a specific gas. In a control system 10 for a gas sensor element 11 whose sensor resistance Rs varies with the concentration of NOx gas, a pulse signal Sc which alternates between 0 V and +5 V is input to a pulse input terminal 17. When a voltage of 5 V is applied to the pulse input terminal 17, a capacitor 14 is charged via a fixed resistor 15 having a resistance Rc and a diode 16. When a voltage of 0 V is applied, the capacitor 14 discharges via the gas sensor element 11. An output voltage Vout is A/D-converted and processed by means of a microcomputer 20, thereby controlling an electronic control assembly 21.

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: Methods automatic process control of biasing and testing a heated-electrode refrigerant sensor for use in a refrigerant detector. An unbiased sensor may be mounted in a manufacturing station, and while mounted may be biased by applying current to electrically heat the sensor and by applying a voltage potential between the sensor's anode and cathode, thereby generating a bias current at the cathode, and after the sensor is at least partially biased, the bias current is used to electrically test the sensor's construction. If the temperature of the sensor is held constant at a bias temperature, the acceptability of the sensor may be determined based on the time that elapses before the bias current decreases from an initial value to a threshold value, or determined based on the noise present on a signal which is representative of an operating condition other than the bias current magnitude.

Abstract: A measured gas side electrode is provided on one surface of a solid electrolytic substrate so as to be exposed to a measured gas. A reference gas side electrode is provided on an opposite surface of the solid electrolytic substrate so as to be exposed to a reference gas stored in a reference gas chamber. A water-vapor absorbing member is provided in the reference gas chamber.

Abstract: Method and sensor for measuring accurate measurement of NOx concentration in an exhaust gas containing O2,H2O, CO2 and NOx and a NOx gas concentration sensor. A first oxygen pump cell sufficiently pumps out oxygen in a measurement gas such as not to decompose NOx. A pair of electrodes is provided on an inner side and an outer side of a second measurement chamber into which the gas is introduced from a first measurement chamber via a diffusion resistance. A voltage is impressed across the paired electrodes for decomposing NOx in the second measurement chamber to dissociate oxygen which causes the current to flow in a second oxygen ion pump cell. The NOx gas concentration is measured for this current. The voltage impressed across the paired electrodes of the second oxygen ion pump cell is set so as not to dissociate H2O and CO2 present in the second measurement chamber.

Abstract: An electronic control unit of an internal combustion engine performs preheat energization control before activation energization control. In the activation energization control, a gas sensor is energized with electric power capable of heating the gas sensor to activation temperature. In the preheat energization control, the gas sensor is energized with low electric power, which is not enough to heat the gas sensor to the activation temperature. Thus, while there is a possibility that water adheres to a sensor main body of the gas sensor, the sensor main body is prevented from being heated to high temperature. Meanwhile, even if water droplets exist in the sensor main body of the gas sensor, the water is vaporized gradually, while preventing the bumping of the water.

Abstract: A NOx sensor for measuring NOx concentration including a main pumping cell and a detecting electrode, the main pumping cell-including an electrode having no decomposing/reducing ability for NOx or a low decomposing/reducing ability for NOx, to be used to control oxygen concentration in a measurement gas 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. Accordingly, it is possible to suppress the oxidation of Rh and the reconversion into the metal contained in the detecting electrode, stabilize the impedance, and stabilize the sensitivity to NOx.

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 concentration measuring apparatus is provided which includes a gas concentration sensor consisting of a pump cell, a sensor cell, and a monitor cell. The pump cell works to determine the concentration of O2. The sensor cell works to decompose an oxygen containing gas such as NOx and provide an output indicative of the concentration of NOx. The apparatus also includes an applying voltage determining circuit which looks up a predetermined voltage-to-current relation to determine a target voltage to be applied to the pump cell as a function of the current produced by the pump cell so as to preclude the pump cell from decomposing the oxygen containing gas component, thereby minimizing an error in determining the concentration of oxygen containing gas as a function of the output of the sensor cell.

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: The NOx concentration in a gas is determined with a thick-film measuring sensor which has two measuring cells. The raw measured value of the measuring sensor is corrected by a multiplicative correction value and an additive correction value, which are both taken from a characteristic map. The characteristic map depends on the oxygen-ion pumping current in the second measuring cell, the measured gas temperature, and the measuring sensor temperature.

Abstract: An electrochemical gas sensor for determining the concentration of gas components in a gas mixture, in particular for determining NOx and HC. The gas sensor includes a first measuring gas space which is connected to the measuring gas, and a second measuring gas space which is connected to the first measuring gas space by a connecting channel. Furthermore, a first electrode and a second electrode, arranged in the first measuring gas space, and at least one third electrode arranged in the second measuring gas space, and at least one fourth electrode are provided. The two measuring gas spaces are arranged in layer planes on top of one another and are separated from one another by at least one oxygen ion conducting layer, the connecting channel passing through the oxygen ion conducting layer.

Abstract: A hydrogen sensor and process for measuring hydrogen gas concentrations includes a pump cell and a measuring cell. The pump cell includes a first conducting electrolyte layer having a top and a bottom surface, and an electrode disposed on the top and bottom surfaces, wherein the top electrode is in communication with an unknown concentration of hydrogen gas. The measuring cell includes a second conducting electrolyte layer having a top and a bottom surface, and an electrode disposed on the top and bottom surfaces, wherein the bottom electrode is in communication with a reference gas source. A diffusion-limiting barrier is disposed between the pump cell bottom electrode and the measuring cell top electrode, wherein hydrogen diffusion through the diffusion-limiting barrier is controlled by a Knudsen diffusion mechanism at hydrogen concentrations greater than about 40%.

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 gas sensor having a laminate structure composed of thin sheets of solid electrolyte and including a cavity portion 21 and an oxygen concentration cell 5. The oxygen concentration in the cavity portion 21 is held constant. The oxygen concentration cell 5 includes an active electrode 12 having a relatively high catalytic capability with respect to NOx or combustible gas and an inner common electrode 13/15 (serving as an inactive electrode and an oxygen-concentration-sensing electrode) having a relatively low catalytic capability with respect to NOx or combustible gas. The oxygen concentration cell 5 is disposed in the gas sensor so as to be exposed to the interior of the cavity portion 21. The concentration of NOx or combustible gas is determined based on an electromotive force (of the order of mV) generated between the active electrode 12 and the inner common electrode 13/15 by a concentration cell effect.

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: 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: A NOx gas detecting apparatus including an oxygen pumping cell for removing oxygen from a measurement gas, and a NOx detecting cell positioned downstream from the oxygen pumping cell to detect concentration of NOx in the measurement gas, the NOx detecting cell being configured to measure current which flows when oxygen generated from reducing NOx is pumped, wherein the NOx detecting cell has a NOx detecting cathode made of an electrode material including at least one alloy selected from the group consisting of a Pt-Pd alloy, a Pt-Au-Pd alloy, and a Pt-Pd-Rh alloy.

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: A low cost amperometric oxygen sensor which utilizes a plurality of oxygen ion conductor layers interposed between a plurality of oxygen-porous electrode layers is provided. Oxygen from a sample gas enters the sensor at porous cathode electrodes, is pumped through the ion conductor layers, and exits through the anode electrodes. The amperometric current generated is representative of the partial pressure of oxygen in the sample gas. In accordance with one embodiment of the present invention, an amperometric oxygen sensor is provided for determining the oxygen partial pressure of a gas. The sensor comprises a sensor body defined by a plurality of oxygen-porous electrode layers and at least one oxygen ion conductor layer. The plurality of oxygen-porous electrode layers include at least one cathode layer and at least one anode layer. Each of the cathode layers define first and second major cathode surfaces and each of the anode layers defining first and second major anode surfaces.

Abstract: In a maltilayer exhaust gas component sensor for measuring NOX (nitrogen oxide) and HC (hydrocarbon), the reliability and the productivity are improved without degrading the detecting sensitivity. A gas sensing portion is formed by laminating porous solid electrolyte layers having gas permeability together with an electrode protecting film, porous electrodes having catalytic activity, a porous electric insulating layer and a closely-compacted (dense) solid electrolyte layer, and by placing a heater as a temperature control means in contact with or near the laminated layer body.

Abstract: The invention presents a hydrocarbon sensor excellent in yield and high in detection precision. To achieve the object, the invention includes a solid electrolyte layer (1) contained barium-cerium oxide, a pair of electrodes, cathode (2) and anode (3), provided on the solid electrolyte layer (1), a ceramic substrate (4) having a coefficient of thermal expansion nearly same as that of the solid electrolyte layer (1), and a heater (7) provided on the ceramic substrate (4), in which the solid electrolyte layer (1) and ceramic substrate (4) are bonded to each other.

Abstract: An objective gas to be measured is introduced into first and second chambers which are connected via a diffusion resistive passage. A first electrochemical cell is provided in the first chamber for pumping in and out oxygen in accordance with an applied voltage. A second electrochemical cell is provided in the second chamber and responsive to application of a predetermined voltage for generating a sensor current representing a specific gas concentration in the objective gas. The first electrochemical cell is located between the first chamber and a reference gas chamber so that oxygen pumping in and out operation can be performed between the first chamber and the reference gas chamber.

Abstract: A gas concentration measuring apparatus has a gas sensor consisting of 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 monitor cell upon the sweep of the initial value of the voltage applied to the pump cell, thereby keeping a gas concentration measuring accuracy free from, for example, aging of the sensor.