Abstract: The invention relates to a waste gas probe which is disposed in an internal combustion engine, comprising a plurality of cylinders and injection valves associated with the cylinders, in order to measure fuel. The waste gas probe is arranged in a waste gas tract and the measuring signal thereof is characteristic for the air/fuel ratio in the respective cylinder. The measuring signal is detected in relation to a reference position of the piston of the respective cylinder at a predefined crankshaft angle and associated with a respective cylinder. A manipulated variable which is used to influence the air/fuel ration in the respective cylinder according to the measuring signal detected for the respective cylinder is produced by a controller. The predefined crankshaft angle is adapted according to an instability criterion of the controller.

Abstract: A method for real-time determination of the mass of particles in a particle filter fitted to the exhaust line of an internal combustion engine. The following data—temperature T(t) of the exhaust gas at the filter input, oxygen [O2 (t)] and nitrogen oxide [NOx(t)] concentration of the exhaust gases entering the filter—is used to calculate the rate of combustion of the particles in the particle filter with the aid of kinetic laws of chemical reactions of particle combustion. The rate, the rate emission of particles from the engine F(t), and the mass of particles in the filter mc(t??,.t) obtained during the cycle of operations prior to the moment t??t, is then used to calculate the mass of particles in the filter, mc(t):=mc(t??t)+[F(t) V(t)]*?t.

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 deterioration detection apparatus for an oxygen sensor is able to detect an abnormality of the oxygen sensor constantly with high precision, without being affected by the temperature characteristic of the element impedance. The apparatus applies a voltage V to the oxygen sensor, and calculates an element impedance real value Rsr=V/1 of a sensor element based on the applied voltage and the current I caused to flow by the voltage. The apparatus calculates an element temperature estimated value Tex of the oxygen sensor from a factor that affects the temperature of the oxygen sensor. The apparatus determines whether the oxygen sensor has an abnormality on the basis of whether the relationship between the element impedance real value Rsr and the element temperature estimated value Tex can be regarded as a relationship that agrees with a normal temperature characteristic.

Abstract: In detecting a deterioration of an air-fuel ratio sensor, a sensor output change speed integrated value is calculated when an element temperature of a solid electrolyte is stabilized at a low temperature. Successively, a sensor output change speed integrated value is calculated when the solid electrolyte element is stabilized at a high temperature. Finally, a deviation between the change speed integrated values is calculated. By comparing the deviation amount with a predetermined determinant, presence or absence of the deterioration is determined.

Abstract: A deterioration detecting apparatus for an exhaust gas sensor of an internal combustion engine, the exhaust gas sensor including a sensor element and a heater that heats the sensor element, computes a first sensor characteristic parameter, which is related to a characteristic of the sensor element, by estimating an interchange state of thermal energy between the sensor element and a periphery of the sensor element. The deterioration detecting apparatus senses impedance of the sensor element. The deterioration detecting apparatus computes a second sensor characteristic parameter, which is related to the characteristic of the sensor element, based on the sensed impedance. The deterioration detecting apparatus determines a degree of deterioration of the exhaust gas sensor by comparing the first sensor characteristic parameter and the second sensor characteristic parameter.

Abstract: A diagnostic testing system for a vehicle comprising an oxygen sensor having a heating element for heating the oxygen sensor to its minimum operational temperature, an analyzer having a user interface, a communications link between the analyzer and the vehicle to obtain data from the oxygen sensor, and a diagnostic heuristic analyzing the data and confirming proper operation of the heating element, the diagnostic heuristic being adapted to generate an output and transmit the output to the user interface, the output including the results generated by analysis of the data by the diagnostic heuristic.

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: A control system for a plant is disclosed. The control system includes a controller which controls the plant based on a controlled object model which is obtained by modeling the plant. The controlled object model is modeled using an input and an output of the plant which are sampled at intervals of a period which is longer than a control period of the controller. The controller carries out a control process of the plant at intervals of the control period.

Abstract: A detecting element is described, in particular a gas sensor for detecting the concentration of a gas component in a measuring gas, including a sensor element which is exposable to the measuring gas and has a connecting end section which is contacted by connecting cables and is exposed to a reference gas atmosphere. The end section is accommodated in a protective sleeve having a radial opening over which a gas-permeable diaphragm covering the at least one radial opening is provided, the diaphragm, in turn, being engaged by a clamping sleeve having at least one radial opening. To avoid the axial penetration of liquids between the clamping sleeve and the diaphragm, which would cause the detecting element to malfunction, the clamping sleeve is caulked axially above and below the radial openings. Both caulking zones are designed in such a way that the diaphragm is compressed with increasing force from the inner caulking edges facing each other to the outer caulking edges facing away from each other.

Abstract: Electronic circuitry and control algorithms are described to automatically establish the output voltage of a linear exhaust gas oxygen sensor (e.g., a UEGO sensor) corresponding to an exhaust air-fuel ratio of stoichiometry. The apparatus and control logic herein described may be used to adaptively correct the setpoint of an air-fuel ratio control system in which a UEGO sensor is used in a feedback loop to adjust the fuel injection quantity of an internal combustion engine.

Abstract: The present invention relates to a system and method for controlling electrical heating of an element to maintain a constant electrical resistance, by adjusting electrical power supplied to such element according to an adaptive feedback control algorithm, in which all the parameters are (1) arbitrarily selected; (2) pre-determined by the physical properties of the controlled element; or (3) measured in real time. Unlike the conventional proportion-integral-derivative (PID) control mechanism, the system and method of the present invention do not require re-tuning of proportionality constants when used in connection with a different controlled element or under different operating conditions, and are therefore adaptive to changes in the controlled element and the operating conditions.

Abstract: Of a gas detector 100, a chamber 105 formed between a center cover 150 and a cover 160 is a part of an air flow channel AF. A first shielding plate 165 is provided in the chamber 105. Water droplets that have entered the chamber from a chamber entrance 103 with air hit and adhere to an entrance-opposed surface 165E of the first shielding plate 165. The water thus adhering to the surface is pushed by the air flowing along the entrance-opposed surface 165E and by gravity, to thereby advance downward. The water then drips downward and is accumulated on a bottom wall surface 105WD which serves as an upper surface of a bottom wall section 161WD. The water is pushed by the flow of air, to thereby advance toward a chamber exit 104. The water is then drained downward from the chamber exit 104.

Abstract: The present invention provides a gas sensor element and its production method, in which poisons are trapped in a porous protective layer to prevent them from reaching a measured gas side electrode, thereby making it possible to maintain a stable sensor output over a long period of time. The gas sensor element of the present invention is composed of a solid electrolyte 10, and a measured gas side electrode 12 that contacts a measured gas and a reference gas side electrode 11 that contacts a reference gas provided on said solid electrolyte 10; wherein, the above measured gas side electrode 12 is covered with a porous protective layer 14 composed of a heat-resistant metal oxide containing a getter, and the above getter is an alkaline silicate.

Abstract: An air fuel ratio control system includes an exhaust gas sensor to sense an oxygen concentration in an exhaust passage of an internal combustion engine, and a controller. The controller is configured to judge that the exhaust gas sensor is in an active state, by monitoring a decrease of an output of the exhaust gas sensor from a level greater than a first predetermined value, to a level smaller than or equal to the predetermined first predetermined value, and to allow the air fuel ratio control when the exhaust gas sensor is judged to be in the active state.

Abstract: The invention relates to a method for artificially ageing a catalyst device for use on a catalyst test bench for converting exhaust gases comprising at least one constituent from the group consisting of C-, HC- and NOx-containing constituents, in which method hot ageing gas which comprises at least one constituent from the group consisting of C-, HC- and NOx-containing constituents is allowed to flow through the catalyst device, and to a corresponding apparatus.

Abstract: An improved engine control system using a NOx sensor is disclosed. In one example, the NOx sensor structure and/or signals are modified to improve distance transmission of NOx sensor output signals so that at least some processing electronics can be relocated remote to the sensor and in an engine control unit, or other such control unit utilizing the NOx sensor signals, and controlling the NOx sensor heaters, if applicable.

Abstract: The present invention relates to a method of estimating the fuel/air ratio in each cylinder of a multicylinder internal-combustion engine comprising an exhaust circuit in which a single detector measures the fuel/air ratio of the exhaust gas. The estimator comprises a physical model (RTM) representing the expulsion of the gases from the cylinders and the travel thereof in the exhaust circuit to the detector, the model being coupled with a non-linear state observer of Extended Kalman Filter (KF) type.

Abstract: The reference air channel of a gas sensor or a lambda probe having a laminate body produced by printing technology is provided. The laminate body is produced by printing a suitably structured layer onto a neighboring layer, for example, by screen printing.

Abstract: A fault detecting apparatus for a gas concentration sensor is provided. The apparatus includes a storage device and a fault detecting circuit. The storage device stores therein fault detectable conditions in which preselected different types of faults of the gas concentration sensor are allowed to be detected, respectively. The fault detecting circuit works to detect a selected one of the faults stored in said storage device. When one of the fault detectable conditions is encountered during operation of the gas concentration sensor, the fault detecting circuit initiates detection of a corresponding one of the faults based on an output of the gas concentration sensor, thereby enabling the fault detecting circuit to identify the type of one of the faults to be detected correctly.

Abstract: In a gas sensor internally including a sensing element for measuring a specific gas concentration of a measured gas, an outer surface thereof has a measured gas surface exposed to a measured gas and an atmosphere surface exposed to the atmosphere, and at least a portion of the atmosphere surface has an emissivity equal to or lower than 0.3. Preferably, this emissivity is a value with respect to an electromagnetic wave having a wavelength of 0.5 to 1 ?m, and the a region of the atmosphere surface, contributing 60% or more of the atmosphere surface, has an emissivity equal to or lower than 0.3. This provides a gas sensor less susceptible to radiant heat and less temperature-increasable.

Abstract: A hydrocarbon sensor and collector. An element that is capable of absorbing and releasing hydrocarbons is positioned in the air intake system of a vehicle, upstream from the engine and wholly in the airflow. The element has a plurality of chambers defined in it that allow air to pass through the element. The hydrocarbon sensor and collector also includes a means for detecting the level of hydrocarbons absorbed by the element.

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 target value Vtgt for an output Vout of an O2 sensor 8 (an exhaust gas sensor) disposed downstream of a catalytic converter 4 is set variably depending on a temperature TO2 of an active element 10 of the O2 sensor 8 by a target value setting unit 18, and the air-fuel ratio of an exhaust gas is controlled by an air-fuel ratio control unit 17 to converge the output Vout to the target value Vtgt. An exhaust gas temperature Tgd is estimated by an exhaust temperature observer 19, and the temperature TO2 of the active element 10 is sequentially estimated by an element temperature observer 20 using the estimated value of the exhaust gas temperature Tgd. A heater 13 of the O2 sensor 8 is controlled by a heater controller 22 to keep the temperature TO2 of the active element 10 at a predetermined target value R. The air-fuel ratio is thus controlled to maintain a desired exhaust gas purifying capability of the catalytic converter irrespective of the temperature of the active element of the exhaust gas sensor.

Abstract: A poison resistant combustible gas sensing element, a method for its production and a method for determining poisoning of the element. The element includes an electric heating element, an inner layer coated on the electric heating element and containing a precious metal catalyst supported on a porous oxide, the precious metal catalyst catalyzing combustion of a combustible gas to be detected by the element, and an outer layer overlaying the first layer, and containing a catalytic compound capable of trapping gases which poison the precious metal catalyst, the catalytic compound being supported on a porous oxide.

Abstract: The invention provides a control strategy and a control system to control a gas sensor to a target operating temperature. It relies upon both feedback and model-based feedforward control systems to achieve and then maintain the sensor at the target operating temperature. The mechanization includes a gas sensor with a heating element in a feedstream. The control strategy employs a control system for the heating element that is based upon the target operating temperature, the temperature of the heating element, and an effect of the feedstream and mounting structure on the temperature of the sensor. The control strategy enables the control system to optimize the heating of a sensor during warm-up and steady state operations.

Abstract: There is provided an air/fuel ratio gauge for monitoring an engine exhaust mixture of an engine having a plurality of oxygen sensors. The gauge of the present invention comprises a gauge housing. A gauge controller is disposed within the gauge housing and is electrically communicated with the engine. The gauge controller is operative to receive a sensor voltage output signal from each of the plurality of oxygen sensors. Furthermore, at least two gauge displays are each electrically communicated with the gauge controller and an associated oxygen sensor. Each gauge display is operative to independently display sensor information representative of the associated oxygen sensor operation.

Abstract: A Method and device for the measurement of exhaust gas from internal combustion engines using a full-flow dilution method in which the exhaust volume flow is mixed with dilution air so that in specified test cycles, a defined total volume flow results, from which a partial sampling volume flow is extracted, on which a measurement of particulate emissions and/or gaseous components in the exhaust is conducted, and wherein a smoothed curve (II) of the exhaust flow (I) that is varied during the test cycles is determined, and the total volume flow (III) is adjusted in proportion to the variations in the measured smoothed curve of the exhaust flow.

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 poison resistant combustible gas sensing element, a method for its production and a method for determining poisoning of the element. The element includes an electric heating element, an inner layer coated on the electric heating element and containing a precious metal catalyst supported on a porous oxide, the precious metal catalyst catalyzing combustion of a combustible gas to be detected by the element, and an outer layer overlaying the first layer, and containing a catalytic compound capable of trapping gases which poison the precious metal catalyst, the catalytic compound being supported on a porous oxide.

Abstract: An air-fuel ratio sensor includes a sensor element inserted through a cylindrical housing for detecting an air-fuel ratio in an atmosphere of unburnt gas, and a measured gas side cover disposed on an end of the cylindrical housing so as to cover the sensor element and defining an inside chamber for storing therein a gas to be measured. The cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each cover member having a gas inlet hole formed in a side wall thereof and a bottom hole formed in a bottom wall thereof. The gas inlet hole of an innermost one of the plural cover members that directly faces the sensor element is offset from an air-fuel ratio detecting portion of the sensor element toward the housing in an axial direction of the sensor.

Abstract: Disclosed herein is a ceramic part, gas sensor, and method for making the gas sensor. The ceramic part comprises: an insulating layer affixed to a substrate wherein the insulating layer comprising Al2O3 particles; and a glass comprising about 45 to about 69 mole percent SiO2, 0 to about 9 mole percent B2O3, 0 to about 26 mole percent Al2O3, 0 and 25 mole percent SrO, and about 10 to about 26 mole percent RE2O3, where RE2O3 is selected from the group consisting of Y2O3, three valent rare earth oxides, and combinations comprising at least one of the foregoing. In one embodiment of a ceramic part, a gas sensor comprises: an electrolyte layer having disposed on opposite sides thereof a first electrode and a second electrode; and an insulating layer that is in intimate contact with the second electrode, wherein the insulating layer comprises alumina and frit.

Abstract: A system for generating electricity includes a generator and an interface. The generator is coupled to the interface and provides data to the interface regarding electricity generation. The interface is coupled to a control node for monitoring and controlling the generator. The control node may be coupled to the generator through a medium such as the internet. In some aspects of the invention, a continuous emissions monitoring system is provided for fossil-fuel based generators to enhance operation and reduce emissions of such generators.

Abstract: At a time point at which an ignition switch is made OFF and an engine is stopped, an output of a downstream gas sensor is read, thereafter, at a time point at which a predetermined time period has elapsed from stopping the engine, the output of the downstream gas sensor changed by flowing the atmosphere back into an exhaust pipe is read. Thereafter, a change in the output of the downstream gas sensor until the predetermined time period has elapsed from stopping the engine is calculated, the change in the output is compared with an abnormality determinant and when the change in the output is smaller than the abnormality determinant, response of the downstream gas sensor is determined to be abnormal.

Abstract: In a low rotation speed and low load operation region of an internal combustion engine, the heating of an air-fuel ratio sensor by a heater is stopped, and also an air-fuel ratio feedback control is stopped, and just after the heating of the air-fuel ratio sensor by the heater and the air-fuel ratio feedback control are started, a smoothing degree of a detection signal of the air-fuel ratio sensor is set to be small, to perform the air-fuel ratio feedback control based on the smoothed detection signal.

Abstract: A self contained field sampling system for measuring engine exhaust emissions includes a mini-dilution tunnel adapted for the collection of proportional samples of emissions to be analyzed, an engine air intake flow measurement instrument, a system controller and data acquisition system, and an optionally portable generator to provide electrical power. Several probes withdraw dilute and undiluted exhaust for emission analysis. Various engine emissions may be isolated. As well, engine emissions mass rate may be calculated by reference to engine RPM, inlet flow rate, exhaust temperature and emissions output rate.

Abstract: A novel abnormality detection device for an air-fuel ratio sensor able to more accurately detect an abnormality, provided with an air-fuel ratio sensor arranged in an exhaust passage of an internal combustion engine for detecting an air-fuel ratio based on a current generated in accordance with a concentration of oxygen in the exhaust gas along with application of voltage and an air-fuel ratio sensor activating means for activating the air-fuel ratio sensor, wherein the activity of the air-fuel ratio sensor is maintained even after the internal combustion engine is stopped and an abnormality of the air-fuel ratio sensor is detected based on an output of the air-fuel ratio sensor upon and/or after the elapse of a first predetermined time after the internal combustion engine is stopped.

Abstract: A gas sensing element includes a solid electrolytic substrate having oxygen ion conductivity, a measured gas side electrode provided on a surface of the solid electrolytic substrate so as to be exposed to a measured gas, and a reference gas side electrode provided on another surface of the solid electrolytic substrate so as to be exposed to a reference gas. The measured gas side electrode is covered by a porous electrode protecting layer. A limit current density of the electrode protecting layer is in a range from 0.04 mA/mm2 to 0.15 mA/mm2 on a unit area of the reference gas side electrode.

Abstract: An exhaust gas cleaning system has two catalysts and three sensors. The target voltage of a second sensor arranged upstream of a downstream catalyst is set according to the output voltage of the second sensor and the output voltage of a third sensor. Thus, even if the output voltage of the second sensor shows a stoichiometric condition and the output voltage of the third sensor shows a rich condition, it is possible to restrict the unnecessary correction of the target voltage and to optimize the cleaning rate of the downstream catalyst. Therefore, it is possible to reduce emission from being impaired by an expected variation in the air-fuel ratio.

Abstract: A gas sensor for determining a physical quantity of a gas component, e.g., in an exhaust gas of an internal combustion engine, including a sensor element which contains at least one electrochemical cell. The electrochemical cell includes a first electrode and a second electrode that are arranged at a distance on at least one solid electrolyte, the second electrode is arranged in a reference gas space. A third electrode which is in contact with a gas located in the gas space is provided. The gas component may be exchanged between the gas space and the reference gas space using a voltage applied between the second electrode and the third electrode.

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: 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: Oxygen sensors (3, 13) are provided upstream and downstream of a three-way catalytic converter (10) in an exhaust passage (9) of an internal combustion engine (1). A controller (2) performs feedback correction of an air-fuel ratio of an air-fuel mixture burnt in the engine (1) by proportional/integral control based on the output of the upstream oxygen sensor (3). In this process, the controller (2) corrects a proportional part by a correction value based on the output of the downstream oxygen sensor (13) (S11, S12). The feedback correction is performed based on a feedback correction coefficient calculated using the proportional part and an integral part. The controller (2) further determines if there is a leak in the exhaust passage (9) based on the correction value (S61) (S62). Higher diagnostic precision is obtained than in the case where the determination is performed based directly on the feedback correction coefficient.

Abstract: A signal processing apparatus for detecting and displaying the properties of diesel fuel powered compression-ignition engines senses strain pulses in the fuel injection rail structure to perform a variety of testing functions. Among other capabilities, the apparatus permits the user to establish stroboscope timing, to measure engine RPM, to view the relationship between crankshaft position and injection time, and to examine the time-dependent properties of strain pulses on individual fuel injectors in order to evaluate the condition of the diesel engine.

Abstract: Intended for application on ducts through which flow a fluid at a high temperature, and particularly at a high pressure, comprising two bodies (4) and (8) which axially screw onto each other, one body (4) provided with a threaded neck (5) for attachment to the orifice of duct wall (3), which body (4) houses within it sensor element (2) of the probe which is thus placed inside the duct, with second body (8) screwed onto first body (4) and exerting on sensor element (2) the pressure required to secure it in its housing, with second body (8) further provided with an axial orifice through which passes a metallic tube (9) open to the exterior and which is provided with a metallic washer (10), soldered to said tube (9), which is separated from second body (8) by an electrically insulating washer (12).

Abstract: A system for generating electricity includes a generator and an interface. The generator is coupled to the interface and provides data to the interface regarding electricity generation. The interface is coupled to a control node for monitoring and controlling the generator. The control node may be coupled to the generator through a medium such as the internet. In some aspects of the invention, a continuous emissions monitoring system is provided for fossil-fuel based generators to enhance operation and reduce emissions of such generators.

Abstract: An air/fuel ratio sensor (4) and a three-way catalytic converter (3A) having an oxygen storage function are provided in an exhaust passage (2) of an internal combustion engine (1). A controller (6) runs the engine (1) under the alternating application of a stoichiometric air/fuel ratio and a rich air/fuel ratio, and a diagnosis of deterioration in the air/fuel ratio sensor (4) is performed on the basis of the amplitude of variation in the air/fuel ratio detected by the air/fuel ratio sensor (4). By executing the diagnosis only immediately after a fuel cut, the amount of oxygen stored in the three-way catalytic converter (3A) at the start point of the diagnosis is equal to the maximum amount. When the rich air/fuel ratio is applied, the converter (3A) releases the stored oxygen to maintain the exhaust gas purification performance of the converter (13).

Abstract: The invention relates to a method for operating a nitrogen oxide (NOx) storage catalytic converter (12?). During a first operating phase of the storage catalytic converter (12?), nitrogen oxides are stored and, during a second operating phase, stored nitrogen oxides are discharged from the converter (12?). The stored quantity of nitrogen oxides is determined during the first operating phase. In order to be able to determine start and end of the second operating phase as accurately as possible, a quantity, which characterizes the discharge quantity of nitrogen oxides, is determined during the second operating phase and compared to the stored quantity of nitrogen oxides determined during the first operating phase. With the comparison, a plausibility check and a calibration of the output signal of a nitrogen oxide (NOx) sensor (14?) can take place. The nitrogen oxide (NOx) sensor (14?) is disposed downstream of the storage catalytic converter (12?).

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.