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 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.

Abstract: A method of measuring oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures using a gas sensor is provided. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture.

Abstract: A method of controlling and diagnosing the heater of a sensor sensitive to the composition of the exhaust gas of an engine; the sensor having at least an electrolytic cell sensitive to oxygen ions, and supplying information relative to the ratio of the mixture supplied to the engine; the method including the steps of: calculating an internal resistance value of the cell on the basis of detected values of the voltage at the terminals of the cell before and after supplying a reference current to the cell; correcting the calculated internal resistance value as a function of the detected ratio of the mixture supplied to the engine; converting the corrected internal resistance value into a current temperature value of the sensor; feedback controlling the temperature of the sensor by regulating the current supplied to the heater by processing the deviation between the current temperature value and an objective temperature; and diagnosing the efficiency of the heater as of the corrected internal resistance value of

Abstract: A method for measurement of nitrogen oxides using a gas sensor. To reliably measure nitrogen oxides, the sensor has a reference electrode representing a constant oxygen partial pressure, at least two electrode pairs, with common a electrode associated with each pair of electrodes, and solid electrolytes arranged between the two electrodes of an electrode pair directly at the electrodes. The solid electrolyte between a first electrode pair is gas-permeable, while the solid electrolyte between a second electrode pair is gastight, whereby the second electrode pair is adapated for potentiometric or amperometric measurement of nitrogen oxides, and the first electrode pair is adapted for application of a current or a voltage to pump oxygen. The second electrode of the second electrode pair is constructed as a reference electrode on the reference gas side of the solid electrolyte of the second electrode pair. The sensor also has electrical leads for connection and for take-away of electric measurement signals.

Abstract: The present invention is an electrolyte composition in bulk, thick film and sputtered thin film form forming with different metal sensing and reference electrodes a highly stable gas component concentration sensor.

Abstract: The invention reduces the activation time of an oxygen sensor with a heater through rapid heating of an oxygen sensing element. A shaft-like heating member is inserted and fixed into an oxygen sensing element of a hollow shaft-like member while a terminal member intervenes therebetween. A heating portion is locally formed at an extreme end of the heating member. A surface of the heating portion is elastically pressed against an element inner wall, thereby establishing a laterally-abutting structure. A positioning projection is formed on an internal electrode connecting portion and projects toward the interior of the internal electrode connecting portion. The positioning projection is adapted to position the heating element within a hollow portion of the oxygen sensing element such that the axis thereof becomes substantially parallel to the axis of the hollow portion.

Abstract: A method for regulating the temperature of a sensor for determining an oxygen concentration in gas mixtures, in particular in exhaust gases of internal combustion engines, where a detection voltage that corresponds to the oxygen concentration and is supplied by a Nernst measurement cell is analyzed, the sensor is adjusted to an operating temperature by a heating device, and the instantaneous operating temperature is determined from a measurement of an internal a.c. resistance of the Nernst measurement cell. In starting and/or restarting operation of the sensor, an internal a.c. resistance of a lead of electrodes of the Nernst measurement cell is determined, and the instantaneous internal a.c. resistance thus determined is taken into account in determining the operating temperature.

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: Using a sole Nox sensor Nox concentration and oxygen concentration are measured accurately. A measurement device for measuring NOx concentration and oxygen concentration comprises an NOx sensor 2 having a first measurement chamber 20 communicating via a diffusion rate regulating layer 4d with the gas under measurement and a second measurement chamber 26 communicating with the first measurement chamber 20 via diffusion rate regulating layers 6d, 22d. A first pump cell 4 and an oxygen concentration measurement Vs cell 6 are formed on the first measurement chamber 20, while a second pump cell 8 is formed on the second measurement chamber 26. Inside of the first measurement chamber 20 is controlled to a constant low oxygen concentration by controlling the first pump current IP1 so that output of Vs cell 6 will equal a reference voltage VC0. By applying a constant voltage across the second pump cell 8 NOx in the second measurement chamber 26 is decomposed to pump out oxygen.

Abstract: A constant current Iconst is applied to an electromotive force cell which is interposed between a gap (measurement chamber) of a fixed atmosphere and an oxygen reference chamber of a constant oxygen content, for measurement of a resistance value of the electromotive force cell, whereby the resistance value can be measured accurately irrespective of an oxygen content in an atmosphere to be measured by an oxygen sensor element or cell unit. The resistance value of the electromotive force cell is measured at a predetermined timing T2 after application of a current is started, so that a measure resistance value is free of a variation of a resistance value due to deterioration of porous electrodes of an electromotive force cell, such a variation being included in the measured resistance value in case the measurement is done by using an AC current, and therefore accurate measurement can be attained.

Abstract: Disclosed is a gas sensor comprising a first internal space for making communication with the external space via a first diffusion rate-determining section, a first electrochemical pumping cell for controlling the oxygen concentration in the atmosphere in the first internal space to have a predetermined value, a second internal space for making communication with the first internal space via a second diffusion rate-determining section, a second electrochemical pumping cell for finely adjusting the oxygen concentration in the atmosphere in the second internal space to have a predetermined value, a third internal space for making communication with the second internal space via a third diffusion rate-determining section, a third electrochemical pumping cell for pumping out oxygen produced by reduction or decomposition of a component having bound oxygen in the measurement gas in the third internal space, and an ammeter Ip for detecting a pumping current which is allowed to flow in accordance with the pumping ope

Abstract: A method for measuring nitrogen oxide (NOx) in a gas by decomposing NOx in the gas and measuring an amount of oxygen generated by the decomposition includes: introducing the gas to a first inner space under a first diffusion resistance and connected with an external space, controlling an oxygen partial pressure in an atmosphere in the first inner space to be a predetermined low value at which NO is not decomposed substantially by a main pump means, introducing a controlled atmosphere of the first inner space into a second inner space which is connected with the first inner space and which is under a second diffusion resistance, and converting the atmosphere into an electric signal corresponding to the quantity of oxygen generated by decomposition or reduction of NOx contained in the atmosphere by an electric signal conversion means.

Abstract: Disclosed is a gas sensor comprising a main pumping cell including a solid electrolyte layer contacting with an external space, and an inner pumping electrode and an outer pumping electrode formed on inner and outer surfaces of the solid electrolyte layer, for pumping-processing oxygen contained in a measurement gas introduced from the external space on the basis of a control voltage applied between the electrodes; a feedback control system for adjusting the control voltage to give a predetermined level of a voltage between the inner pumping electrode and a reference electrode disposed at a reference gas-introducing space; and a heater for heating at least the main pumping cell to a predetermined temperature; wherein the outer pumping electrode is connected to a negative side lead wire of the heater.

Abstract: An oxygen concentration-detecting device for an internal combustion engine includes an oxygen concentration sensor arranged in the exhaust system of the engine, for detecting concentration of oxygen present in exhaust gases emitted from the engine. Energization of a heater for heating the oxygen concentration sensor is started when the ignition switch is turned on. The energization of the heater is stopped after a predetermined time period has elapsed after the turning-on of the ignition switch.

Abstract: An air/fuel ratio sensor is controlled such that the oxygen concentration of the measurement gas can be detected from a pump current substantially instantaneously after a heater turns on. In the air/fuel ratio sensor an oxygen pumping cell and an oxygen concentration measuring cell are each formed of a solid electrolytic layer interposed between a pair of porous electrodes. One of the electrodes of each cell defines a measurement gas chamber in which the diffusion of the measurement gas is controlled. After a micro current is supplied to the other electrode of the oxygen concentration measuring cell for a predetermined period of time, thereby forming an internal reference oxygen source, the supply of the micro current is stopped and at the same time a pump current in the oxygen pumping cell starts to be controlled until the interelectrode voltage of the oxygen concentration measuring cell reaches a target voltage. After the air/fuel ratio sensor is activated, the supply of the micro current is restarted.

Abstract: Oxygen sensor element (ZrO.sub.2 solid electrolyte etc) for detecting oxygen concentration in an exhaust gas has a protective layer which is made of a heat-resistant metal oxide and which carries a component of a IIa subgroup element (Ca, Mg etc) on the side exposed to the exhaust gas of the sensor element, at least a part of the protective layer being present as a nonstoichiometric compound (Ti oxide etc) with respect to the heat-resistant metal oxide. Si-poisoning is prevented. Heater for heating the sensor element is provided for preventing Si-poisoning at low temperatures.

Abstract: To achieve change-over from detection of an internal resistance of an oxygen sensor S to detection of a threshold current effectively in a short time, a positive desired voltage for measuring a threshold current is applied to an oxygen sensor S to detect the threshold current and then a negative voltage for measuring a temperature is applied to the oxygen sensor S for a short time to detect an internal resistance of the oxygen sensor. After that, when the voltage applied to the oxygen sensor S is restored to a positive desired voltage for measuring the threshold current, by applying a voltage higher than this positive desired voltage temporarily to the oxygen sensor S, discharge or recharge of electric charges due to electrostatic capacitance components of the oxygen sensor S is completed quickly to reduce the time required for convergence to the threshold current when the voltage is changed. As a result, it is possible to reduce the time during which the threshold current cannot be detected.

Abstract: A shaft-like heating member is inserted into and fixed to an oxygen sensing element of a hollowed shaft-like member, together with of a terminal member. A heating portion is located at a portion of the heating member closer to the extreme end thereof. The surface of the heating portion is resiliently pressed on the element inner wall in a side-abutting fashion. In this case, a guide mainly gives rise to the elastic force. With such a side-abutting structure, heat generated in the heating portion is directly transferred to the oxygen sensing element, and heats it. Heat radiated from a portion in the vicinity of its contact position additively heats the oxygen sensing element. Temperature of the oxygen sensor quickly reaches an activation temperature.

Abstract: An oxygen sensor according to the present invention has battery element and a pump element in each of which porous electrodes are disposed on both faces of a solid electrolyte substrate. A minute current is supplied to the battery element after the start of energizing a heater and the activation of the sensor elements are judged on the basis of an interelectrode voltage generated at this energizing. A heater voltage is set to be 12V at the start of energizing. When the time period necessary for the interelectrode voltage to reach a predetermined voltage is short, the applied voltage is lowered to 11V. As a result, the time period necessary for judging the sensor elements to be activated can be made substantially constant irrespective of variations in sensor characteristics. After the activation judgment, the variation of the temperature of the sensor element is monitored on the basis of the interelectrode voltage.

Abstract: A continuous oxygen content monitor has a reference electrode embedded in a powdered chrome-chrome-oxide mixture and a counter electrode embedded in an elongate alumina-graphite sleeve which acts as the probe support body. Two hallow and spacer ablative steel domes encase the reference electrode and an intermediate air gap spacing and provide insulation to prevent thermal shock from damaging the monitor during insertion into the metal melt. A circuit provides counter emf across the sensing electrodes to prevent ion depletion of the reference material.

Abstract: A method for correcting an output from an electrochemical cell sensor, having an output responsive to a concentration of sensed species in a stream, a pressure and a temperature in an interactive non-linear relationship, comprising the steps of providing a pressure sensor for producing an output responsive to a pressure in proximity to the electrochemical sensor; providing a temperature sensor for producing an output responsive to a temperature of said electrochemical sensor; and processing the outputs of the electrochemical sensor, pressure sensor and temperature sensor in a neural network having an output function which compensates said electrochemical sensor for changes in pressure and temperature to indicate a concentration of the sensed species.