Abstract: An on-board diagnostic system and method for directly monitoring the efficiency of a catalyst having negligible oxygen storage capacity is provided. The monitoring system includes an oxygen sensor mounted at a first end of the conditioning catalyst, and an exhaust gas catalyst bypass. The oxygen sensor includes a first side and a second side. The first side detects oxygen levels in the exhaust gas at or near the first end of the catalyst and the second side detects oxygen levels at or near the second end of the catalyst. The oxygen sensor simultaneously compares exhaust gas from the first end of the catalyst to the exhaust gases from the second end of the catalyst. The oxygen sensor produces a voltage signal which is proportional to the difference in oxygen levels between the upstream gases and the downstream gases.

Abstract: Disclosed is a method for controlling a gas sensor comprising the steps of pumping-processing oxygen contained in a measurement gas introduced from external space into a first chamber by using a main pumping cell so that a partial pressure of oxygen in the first chamber is controlled to have a predetermined value at which a predetermined gas component as a measurement objective is not decomposable; decomposing the predetermined gas component contained in the measurement gas in a second chamber by the aid of a catalytic action and/or electrolysis by using a detecting pumping cell to pumping-process oxygen produced during the decomposition; and measuring the predetermined gas component contained in the measurement gas on the basis of a pumping current which flows during the pumping process; wherein the oxygen to be pumped out by the detecting pumping cell is pumped out toward an inner pumping electrode which is fixed to have a base electric potential (ground electric potential), of the main pumping cell.

Abstract: In order to correct the characteristic of a linear lambda probe which is arranged in an emission control system of an internal combustion engine upstream of a catalytic converter, in an overrun fuel cut-off phase the throttle valve and/or at least one gas exchange valve of the internal combustion engine is opened, and the signal of the lambda probe is assigned to the lambda value corresponding to the oxygen concentration of the ambient air. It is then possible, together with a conventional trimming controller which corrects the assignment of the signal to lambda=1, to correct the gradient of the characteristic.

Abstract: An electrochemical sensor measures a gas concentration of a measured gas with an electrochemical element. The electrochemical sensor includes an electrochemical pump cell with a first solid electrolyte body, a first and a second electrode, and a gas chamber, which is connected to a measured gas chamber via a gas inlet opening and in which one of the two electrodes is located. The electrochemical sensor also includes a second solid electrolyte body with an electrochemical sensor cell (e.g., a Nernst cell), which has a third electrode and a reference gas chamber in which a fourth electrode is located, with the electrodes having a supply conductor for electrical contacting. A supply conductor of the fourth electrode is provided with an electrically insulating layer to insulate it against the second solid electrolyte body.

Abstract: A Nernstian-type gas sensor for monitoring changes in a concentration of oxygen present in an environment. One embodiment includes a mass of solid-electrolyte material, and first and second electrodes. The first and second electrodes are each in fluid communication with the environment and are arranged to generate a signal therebetween indicative of a difference between an oxygen concentration at the first electrode and an oxygen concentration at the second electrode. The sensor may be free of a temperature control device.

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: In a method for testing a measuring sensor for the determination of an oxygen concentration in a gas mixture, the measuring sensor supplies a detection voltage furnished by a Nernst measuring cell and corresponding to the oxygen concentration. The detection voltage is evaluated by a circuit arrangement and is picked off between a first electrode exposed to the gas mixture and a second electrode exposed to a reference gas. The measuring sensor is heated to operating temperature. The Nernst measuring cell is exposed to a constant test voltage and a gas mixture with a well-defined oxygen concentration and a measuring current of the Nernst measuring cell is evaluated.

Abstract: In a CO gas sensor composed of a CO gas sensing electrode 3 being made of Au or an Au alloy and a reference electrode 2 electrically connected to at least part of a surface of a solid electrolyte having an oxygen ion transfer property, which is superior in CO gas selectivity, in particular, reducing the affect of the co-existing oxygen to CO, and which works with a high precision at a high temperature, and in a CO gas measuring device using the gas sensor, the gas sensor being capable of determining a CO gas concentration by measuring a electromotive force change due to adsorption/oxidization of the carbon monoxide gas in the sensing electrode 3 when a constant current is caused to flow between the reference electrode 2 and the sensing electrode 3 or a current value caused by the oxidizing reaction of the carbon monoxide gas in the sensing electrode when a voltage is kept constant between the reference electrode 2 and the sensing electrode 3.

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

Abstract: The present invention relates to a limiting-current type hydrocarbon sensor comprising a solid-electrolytic layer made of a Ba—Ce-based oxide, and provides a sensor capable of stably detecting hydrocarbon at high sensitivity, regardless of the concentration of oxygen in an atmosphere. A material mainly containing Al is used for at least one of two electrodes on the solid-electrolytic layer made of a Ba—Ce-based oxide to block oxygen at the electrode, i.e. cathode, whereby a hydrocarbon sensor being stable, high in sensitivity, compact, easy to use and low in cost can be provided. Furthermore, the other electrode, anode, of the limiting-current type hydrocarbon sensor is made of a material mainly containing Ag.

Abstract: A gas sensor, in particular for determining the oxygen content in exhaust gases of internal combustion engines, is described. The gas sensor includes a sensing element sealedly fastened in a housing, whose segment on the measured gas side has at least one electrode exposed to a measured gas, at least one electrode exposed to a reference gas, and a reference gas conduit, extending in the longitudinal direction of the sensing element, which terminates at the segment of the sensing element remote from the measured gas and is connected to a reference gas source; and having contacts remote from the measured gas for making contact to the electrodes of the sensing element. Provision is made for the reference gas conduit to terminate at a large surface of the sensing element and to be sealed with a planar sealing fit.

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: An oxygen measuring sensor is proposed, having a pump cell (20) with outer and inner pump electrodes (17, 19) disposed on a solid electrolyte (11) which conducts oxygen ions, of which the inner pump electrode (17) is exposed in a diffusion conduit (15) to the gas to be measured. A further electrode (18) of a measuring cell (21) is disposed in the diffusion conduit (15) behind the inner pump electrode (17) in the direction of diffusion, at which a partial oxygen pressure, which lies at least approximately in the vicinity of lambda=1, can be set by means of the pump cell (20), so that the pump cell (20) operates outside of the limiting current range of the current/voltage characteristic curve.

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: The invention is directed to a method for detecting the oxygen content in a gas to be measured. At least one concentration cell operating in accordance with the Nernst principle is provided. The concentration cell includes a measuring electrode communicating with the gas and a solid electrolyte and a reference electrode connected to the measuring electrode through the solid electrolyte. A pump-current pulse is applied between the reference electrode and the measuring electrode and, directly after the end of each pump-current pulse, the current flow between the reference electrode and the measuring electrode is reversed in a pulse-like manner.

Abstract: A sulfur dioxide gas sensor having a high selectivity of SO2 gas, and an operability at a high temperature which comprises: a solid electrolyte having oxygen ion conductivity; a detecting electrode for measuring sulfur dioxide gas, electrically connected to at least a part of a surface of the solid electrolyte and containing glass and either gold or a gold alloy; and a basic electrode for measuring sulfur dioxide gas, electrically connected to at least a part of a surface of the solid electrolyte and containing Pt.

Abstract: A zirconium oxide shell forms a chamber of fixed volume, and a controller monitors voltage across the shell indicative of difference between inside and outside oxygen levels, applying a signal to pump oxygen. Pumping is effected to empty the chamber, to develop an internal reference, for example by comparison to ambient air, for calibration, and thereafter to substantially continuously null the difference, i.e., to track the oxygen level of a sample environment. Integrated pump current yields a measure of the oxygen added to or removed from the chamber. A suitable material for forming the sensor is a mixture of about 91% zirconium oxide and 9% yttrium oxide, which is formed to shape as a paste or slurry and sintered at about 1400° C., and then platinum coated, for example by a CVD process, to form porous electrodes on each surface. The controller may apply a sequence of current pulses, and check the Nernst cell output indicative of &Dgr;P across the wall, until &Dgr;P=0.

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