Abstract: Various embodiments disclose an electronic circuit for an electrochemical gas sensor. The electronic circuit comprises a first switching element electrically coupled to a reference terminal of the electrochemical gas sensor and a ground voltage terminal. Further, the electronic circuit comprises a second switching element electrically coupled to a sensing terminal of the electrochemical gas sensor and the ground voltage terminal. In an instance in which the electrochemical gas sensor is powered OFF, the first switching element and the second switching element are configured to electrically couple the reference terminal and the sensing terminal to the ground voltage terminal such that current generated when the sensing electrode and the target gas react while the electrochemical gas sensor is powered OFF flows to the ground voltage terminal and the potential of the reference terminal and the sensing terminal remain the equal.

Abstract: It is to determine whether a temperature rise condition of a first cell or a second cell is satisfied based on whether a first parameter has exceeded a predetermined first threshold or a second parameter has exceeded a predetermined second threshold. After satisfaction of the temperature rise condition, it is to determine that an exhaust gas sensor is in an active state upon determination that a corresponding time condition is satisfied.

Abstract: The disclosure relates to a method for the measurement of relative air humidity in a fresh air induction tube of an internal combustion engine. Here a concentration of oxygen in the fresh air induction tube is measured by an oxygen sensor and a temperature in the fresh air induction tube is determined. The relative air humidity is determined depending on the measured concentration of oxygen and the determined temperature.

Abstract: A sensor for detecting oxygen concentration in exhaust gas or an air-fuel ratio provided with a solid electrolyte body, an exhaust gas side electrode being disposed on one side of the solid electrolyte body and being in contact with the exhaust gas, an atmosphere side electrode being disposed on the other side of the solid electrolyte body and being in contact with the atmosphere, and an electric circuit applying a reference voltage between these electrodes is arranged in an engine exhaust passage. The sensor for detecting the oxygen concentration in the exhaust gas or the air-fuel ratio has a characteristic in which an output current continues to increase without having a limiting current region when the voltage applied between the electrodes is increased while the air-fuel ratio is constant. The air-fuel ratio is controlled based on the output current of the sensor for detecting the oxygen concentration in the exhaust gas or the air-fuel ratio.

Abstract: A method for a two-point lambda sensor includes, changing a composition of an air/fuel mixture supplied to an internal combustion engine from a predefined lambda value to lambda=1, determining a delay time of the voltage value reaching a value corresponding to the lambda=1, again changing the composition of the air/fuel mixture from the predefined lambda value to lambda=1, determining a characteristic of the changing performed in the second regulation based on the delay time, determining an actual value of lambda on an actual voltage-lambda characteristic curve of the two-point lambda sensor that corresponds to the predefined lambda value which is in reference to a reference voltage-lambda characteristic curve based on the determined characteristic, and identifying a voltage offset between the characteristic curves based on a deviation of the actual value from the predefined value.

Abstract: Method for the operation of an internal combustion engine having a plurality of cylinders (11 to detect misfires. An exhaust gas sensor at the exhaust gas of every cylinder of the internal combustion engine measures at least one actual exhaust gas value individually for the respective cylinder, and the respective measured actual exhaust gas value is compared with a reference exhaust gas value to determine at least one cylinder-specific deviation between the reference exhaust gas value and the actual exhaust gas value for each of the cylinders. It is determined for every cylinder based on the cylinder-specific deviation or based on every cylinder-specific deviation whether or not misfires are occurring at the respective cylinder.

Abstract: A control device for an internal combustion engine, equipped with: an exhaust purification catalyst provided in the exhaust passage of the internal combustion engine and capable of absorbing oxygen; a downstream air-fuel ratio sensor provided downstream from the exhaust purification catalyst in the direction of the exhaust flow; and an engine control device that controls the internal combustion engine in response to the output from the downstream air-fuel ratio sensor. The downstream air-fuel ratio sensor is configured such that the applied voltage for which the output current is zero changes in response to the exhaust air-fuel ratio, and such that when the exhaust air-fuel ratio equals the theoretical air-fuel ratio and the applied voltage in the downstream air-fuel ratio sensor is increased, the output current increases in conjunction therewith.

Abstract: A signal from a linear lambda probe, which signal is meant to represent an air/fuel ratio for the gas flowing in the exhaust section, specifically prior to combustion of said gas, is determined based on a pump current. A difference signal is formed based on a difference between a pump voltage signal and a Nernst voltage signal. An offset error in the measured signal is determined based on the difference signal for an approximately stoichiometrically prescribed raw setpoint value for the air/fuel ratio, with a setpoint value for the air/fuel ratio being determined based on the raw setpoint value and a forced excitation signal.

Abstract: In a method for suppressing interference in a controlled variable in a control circuit, in which the actuating variable is the useful signal, the controlled variable is detected continuously, at two successive sampling instants in each case, the values of the controlled variable are subtracted, and if the absolute amount of the difference deviates by a predefinable setpoint value, at least one control parameter is modified, in such a way that the response of the actuating variable to the interference is minimized.

Abstract: Fuel reforming catalysts 28 generate a hydrogen-containing reformed gas when they come into contact with exhaust gas that contains a reforming fuel. Upstream and downstream air-fuel ratio sensors 58, 60 are respectively installed upstream and downstream of the fuel reforming catalysts 28. The upstream air-fuel ratio sensor 58 outputs a upstream sensor signal in accordance with oxygen concentration. The downstream air-fuel ratio sensor 60 outputs a downstream sensor signal in accordance with oxygen concentration and hydrogen concentration by using zirconia's oxygen detection capability and a change of a diffusion layer's hydrogen-concentration-dependent oxygen detection capability. An ECU 50 detects the hydrogen concentration without being affected by the oxygen concentration through the use of the upstream sensor signal in which only the oxygen concentration is reflected and the downstream sensor signal in which the oxygen concentration and hydrogen concentration are reflected.

Abstract: The present invention relates to an air-fuel ratio control device for an internal combustion engine, and makes it possible to maintain high purification performance by suppressing a decrease in the oxygen occlusion capability of a catalyst. When an O2 sensor output oxs is greater than a reference value oxsref, which corresponds to a stoichiometric air-fuel ratio, and smaller than an upper threshold value oxsrefR, a sub-FB reflection coefficient is fixed at a predetermined value vdox2 for providing a lean air-fuel ratio. When, on the other hand, the O2 sensor output oxs is smaller than the reference value oxsref and greater than a lower threshold value oxsrefL, the sub-FB reflection coefficient is fixed at a predetermined value vdox2 for providing a rich air-fuel ratio. The sub-FB reflection coefficient reflects the O2 sensor output oxs in the calculation of a fuel injection amount and increases or decreases to have a consequence on the air-fuel ratio of an exhaust gas.

Abstract: In the calibration of a lambda sensor (26), inaccuracies occur during a fuel cut-off overrun phase depending on the temperature. A method is proposed for correcting an output signal of a lambda sensor (16) of an internal combustion engine (1), having the following steps: detection of a fuel cut-off overrun phase of the internal combustion engine (1), sensing of an exhaust-gas composition by the lambda sensor (16) during the fuel cut-off overrun phase, sensing of a temperature which represents a measure of the intake air of the internal combustion engine (1), calibration of the lambda sensor (16) based on the second temperature.

Abstract: A heating module for an oxygen sensor comprises an estimated mass module, a cumulative mass module, and a temperature control module. The estimated mass module determines an estimated mass of intake air to remove condensation from an exhaust system after startup of an engine. The cumulative mass module determines a cumulative mass of intake air after the engine startup. The temperature control module adjusts a temperature of an oxygen sensor measuring oxygen in the exhaust system to a first predetermined temperature after the engine startup and adjusts the temperature to a second predetermined temperature when the cumulative air mass is greater than the estimated air mass, wherein the second predetermined temperature is greater than the first predetermined temperature.

Abstract: A system for calibrating a response to an exhaust-stream NOx level in a motor vehicle is provided. The system comprises a NOx sensor that includes an electrode, a current from the electrode responsive to the exhaust-stream NOx level while a bias voltage is applied to the electrode. The system further comprises a controller configured to interrupt the bias voltage and to adjust a motor-vehicle response to the current based at least partly on an attained voltage of the electrode while the bias voltage is interrupted. Other embodiments provide a method of calibrating a NOx sensor response in terms of gain and offset parameters.

Abstract: An oxygen sensor generating an accurate output concerning low-concentration exhaust gas positioned downstream of a three-way catalyst. The oxygen sensor includes an exhaust gas side electrode exposed to an exhaust gas; a reference gas side electrode exposed to a reference gas serving as a reference for oxygen concentration; and an electrolyte positioned between the exhaust gas side electrode and the reference gas side electrode. Further, a reduction mechanism positioned toward a front surface of the exhaust gas side electrode ensures the ratio of the amount of exhaust gas introduced to the exhaust gas side electrode to the amount of an exhaust gas flow to the outside of the oxygen sensor is smaller than the ratio of the amount of exhaust gas introduced to an electrode for the air-fuel ratio sensor to the amount of an exhaust gas flow to the outside of the air-fuel ratio sensor.

Abstract: An exhaust probe is arranged on an internal combustion engine with multiple cylinders and the injection valves provided for the cylinders measure the fuel. The exhaust probe is arranged on an exhaust manifold, and the measured signal is characteristic of the air/fuel ratio in the corresponding cylinder. The measured signal is recorded at a given crankshaft angle with relation to a reference position for the piston and allocated to the corresponding cylinder. A set parameter for adjustment of the air/fuel ratio in the corresponding cylinder is generated depending on the measured signal recorded for each cylinder. The given crankshaft angle is adjusted depending on a value criterion which depends on a uneven running of an output shaft from the internal combustion engine.

Abstract: An oxygen sensor is mounted in an exhaust path of an internal combustion engine. The status of an exhaust gas is detected in accordance with the output of the oxygen sensor. The oxygen sensor incorporates a heater for heating an element of the sensor. In a region in which the temperature of the sensor element is below 300° C., an adsorbable species becomes adsorbed. In a region in which the exhaust pipe temperature is above 80° C., the adsorbable species becomes adsorbed remarkably. Power supply control is continuously exercised over the heater so as to maintain the sensor element at a temperature of 300° C. or higher until the exhaust pipe temperature drops below 80° C. after an internal combustion engine stop. The power supply to the heater is shut off after the exhaust pipe temperature drops below 80° C.

Abstract: An oxygen sensor is mounted in an exhaust path of an internal combustion engine. The status of an exhaust gas is detected in accordance with the output of the oxygen sensor. The oxygen sensor incorporates a heater for heating an element of the sensor. In a region in which the temperature of the sensor element is below 300° C., an adsorbable species becomes adsorbed. In a region in which the exhaust pipe temperature is above 80° C., the adsorbable species becomes adsorbed remarkably. Power supply control is continuously exercised over the heater so as to maintain the sensor element at a temperature of 300° C. or higher until the exhaust pipe temperature drops below 80° C. after an internal combustion engine stop. The power supply to the heater is shut off after the exhaust pipe temperature drops below 80° C.

Abstract: An oxygen sensor is mounted in an exhaust path of an internal combustion engine. The status of an exhaust gas is detected in accordance with the output of the oxygen sensor. The oxygen sensor incorporates a heater for heating an element of the sensor. In a region in which the temperature of the sensor element is below 300° C., an adsorbable species becomes adsorbed. In a region in which the exhaust pipe temperature is above 80° C., the adsorbable species becomes adsorbed remarkably. Power supply control is continuously exercised over the heater so as to maintain the sensor element at a temperature of 300° C. or higher until the exhaust pipe temperature drops below 80° C. after an internal combustion engine stop. The power supply to the heater is shut off after the exhaust pipe temperature drops below 80° C.

Abstract: An oxygen sensor is mounted in an exhaust path of an internal combustion engine. The status of an exhaust gas is detected in accordance with the output of the oxygen sensor. The oxygen sensor incorporates a heater for heating an element of the sensor. In a region in which the temperature of the sensor element is below 300° C., an adsorbable species becomes adsorbed. In a region in which the exhaust pipe temperature is above 80° C., the adsorbable species becomes adsorbed remarkably. Power supply control is continuously exercised over the heater so as to maintain the sensor element at a temperature of 300° C. or higher until the exhaust pipe temperature drops below 80° C. after an internal combustion engine stop. The power supply to the heater is shut off after the exhaust pipe temperature drops below 80° C.

Abstract: An exhaust probe is arranged on an internal combustion engine with multiple cylinders and the injection valves provided for the cylinders measure the fuel. The exhaust probe is arranged on an exhaust manifold, and the measured signal is characteristic of the air/fuel ratio in the corresponding cylinder. The measured signal is recorded at a given crankshaft angle with relation to a reference position for the piston and allocated to the corresponding cylinder. A set parameter for adjustment of the air/fuel ratio in the corresponding cylinder is generated depending on the measured signal recorded for each cylinder. The given crankshaft angle is adjusted depending on a value criterion which depends on a uneven running of an output shaft from the internal combustion engine.

Abstract: A method for compensating for mismatches of the precontrol of a fuel metering for an internal combustion engine. A regulation being superimposed on the precontrol. At least one correction quantity being formed, from the behavior of the regulation at high temperatures of the internal combustion engine, which influences the fuel metering even at low temperatures of the internal combustion engine in a supplementing manner to the superimposed regulation for compensating for the mismatches. At low temperatures a further correction quantity is formed which acts upon the fuel metering, whose effect at low temperatures of the internal combustion engine is greater than at high temperatures.

Abstract: There is provided a degradation determining system for an exhaust gas sensor, which, even when unexpected changes occur in the air-fuel ratio during execution of air-fuel ratio control, can determine degradation of the sensor by suppressing adverse influence of noise caused by the changes on the output from the sensor, to thereby enhance the accuracy of the degradation determination. In the degradation determining system, a determining input signal IDSIN for determining the degradation of the sensor is generated, and a modulation output (u(k), DSMSGNS(k), us(k), or ud(k)) is generated by modulating the determining input signal IDSIN by using any one of the &Dgr;&Sgr; modulation algorithm, the &Sgr;&Dgr; modulation algorithm, and the &Dgr; modulation algorithm. Degradation of the sensor is determined based on the output KACT delivered from the sensor when the fuel injection amount is controlled based on the generated modulation output.

Abstract: A voltage sensing system that has a pair of input leads having a first input lead, and a second input lead each sensing a non-grounded voltage, and an amplifier coupled to the pair of input leads, the amplifier generating an amplifier output voltage in response to a voltage on the first input lead, a voltage on the second input lead and an offset voltage. The system further includes a controller for receiving the amplifier output voltage and determining an operating range, and an offset voltage generator for generating the offset voltage, the offset voltage generator altering the offset voltage in response to the operating range determined by the controller. An oxygen sensing system using a sample resistance for sensing a bi-directional current may be coupled to the voltage sensing system. A method for sensing air-to-fuel ratio includes sampling an input voltage drop derived from a pumping current across a sampling resistance. The input voltage is indicative of air-to-fuel ratio.

Abstract: An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.

Abstract: A connector 2b for an NOx sensor is connected via a cable C to an end of a sensor body 2a through which a first pump current and a second pump current flow according to the concentration of oxygen and that of NOx, respectively, contained in a gas to be measured. The connector 2b is provided with not only terminals for inputting a signal to and outputting a signal from the sensor body 2a but also a label resistor RL having resistance corresponding to characteristics (relationship between oxygen concentration and first pump current and that between NOx concentration and second pump current) of the sensor body 2a and label signal output terminals T01 and T02 connected to opposite ends of the label resistor RL.

Abstract: An A/F signal proportional to an oxygen concentration in the exhaust gas from an internal combustion engine is output upon application of a voltage based on an instruction from a microcomputer. At the time an element resistance is detected, a bias instruction signal Vr from the microcomputer is converted by a D/A converter 21 to an analog signal Vb. An output voltage Vc obtained by removing high frequency components from the analog signal Vb through an LPF 22 is input to a bias control circuit 40. During this time period in which the element resistance is detected, an accurate A/F signal is not output. Therefore, the A/F signal that has theretofore prevailed is held by a Sample/Hold circuit 70 to thereby prevent the use of an erroneous A/F signal. Namely, at the time of detecting the element resistance, the detected value of the oxygen concentration is prevented from becoming abnormal. As a result, an accurate A/F control can be executed using the detected element resistance.

Abstract: The control arrangement comprises an oxygen linear test sensor located along the exhaust duct of an internal combustion engine, the sensor having a chamber able to receive part of the exhaust gas and two electrolytic cells of which one is electrically piloted; the arrangement having a retro-operation test circuit able to adjust the current piloted to the cell to give rise to an oxygen ions draining mechanism from and/or towards the chamber which induces the stoichiometric condition within the chamber itself, and an outlet circuit able to convert the piloted current into a first signal representative of nature of the mixture fed to the engine; the arrangement being provided with a memory circuit which memorises the value of a compensation resistance of the eventual spreads of the piloted current of a correcting circuit receiving the stored value of the compensation resistance and able to ensure a correction for the first signal to recover the spreads of piloted current to the cell; the correcting circuit provi

Abstract: The apparatus includes a sensor capable of delivering a voltage representative of the ratio between a reference oxygen pressure and the oxygen pressure in a volume of the sensor and provided with electrodes (12, 14) via which it is possible to pass a pumping current that controls said oxygen pressure in the volume, and monitoring and control means including a digital controller (26) receiving said representative voltage on an input and suitable for delivering the pumping current. The monitoring and control means deliver the pumping current in the form of a current that varies continuously and progressively, without interruptions, governed by the digital controller in such a manner as to servo-control the input voltage to a determined value.

Abstract: An air-fuel ratio detecting device and a method capable of correctly and very precisely detecting the air-fuel ratio of an internal combustion engine. The air-fuel ratio detecting device comprises an air-fuel ratio sensor disposed in the exhaust system of an internal combustion engine, an air-fuel ratio sensor circuit which applies a voltage to the air-fuel ratio sensor, detects the current through the air-fuel ratio sensor and produces an output that varies in proportion to the magnitude of the current that is detected, and a storage means for storing the data of a conversion map which is used for calculating the air-fuel ratio of the internal combustion engine in response to the output of the air-fuel ratio sensor circuit.

Abstract: An arrangement for determining the concentration of a component in a gas mixture includes a first volume in which the concentration of the component is maintained constant with respect to the influence of the coupling to the concentration in the gas mixture. The coupling acts via a diffusion resistance. The above-mentioned influence of the coupling is compensated via a controllable flow of ions of the component through a solid electrolyte between the first volume and the gas mixture. The solid electrolyte serves as the pump device. The intensity of the pump current defines a measure for the wanted concentration in the gas mixture. The above-mentioned flow is controlled as a function of the deviation of the output voltage of a Nernst cell from a desired value. The Nernst cell is between a first volume and a reference gas volume.

Abstract: The invention relates to a combination of a heated lambda sensor with a stepped or binary sensor characteristic and another heated lambda sensor to determine the lambda value in a gas mixture, e.g. in the exhaust gas preferably of internal combustion engines, the output signal from one lambda sensor being used to calibrate the other one, and the two lambda sensors are arranged closely beside each other, the other lambda sensor having a wide-baud sensor characteristic.

Abstract: A method and apparatus are disclosed for measuring atmospheric pressure in conjunction with an air-fuel ratio sensor of the type comprising a concentration cell with atmospheric air and exhaust electrodes on opposite sides of a solid-state electrolyte having oxygen ion conductivity. During an atmospheric pressure measuring cycle, oxygen ions are pumped from the atmospheric air electrode to the exhaust electrode, in a quantity which is either predetermined at a fixed value, or is sufficient to bring the cell to an equilibrium state. Atmospheric pressure is then calculated from measured emf of the cell, using an experimentally derived functional relationship. In a second embodiment, ions are pumped until a predetermined change of the concentration cell emf is achieved, and atmospheric pressure is determined based on the amount of time required to achieve such change. The atmospheric pressure measuring mode is operated on a time shared basis with the air-fuel ration detection mode.

Abstract: A method and circuit for generating an output signal representative of the pumping current required to equalize the oxygen diffusion between the sensing cell and the pumping cell of an oxygen-ion concentration proportional sensor located in the exhaust system of an internal combustion engine. A replication current, which is isolated from but representative of the pumping current, is generated. The replication current is then passed through a load resistance for generating the output signal. The replication current is generated simultaneously with but isolated from the pumping current, thereby eliminating the need for separate amplification of a sensed version of the pumping current.

Abstract: An air/fuel ratio feedback control system for an internal combustion engine sets an air/fuel ratio feedback correction coefficient on the basis of an air/fuel ratio for an air/fuel mixture introduced into a combustion chamber of the engine, to cause the air/fuel ratio to approach a set point thereof. The correction coefficient consists of a rich control proportional component P.sub.R, a lean control proportional component P.sub.L and an integral component I. When the air/fuel ratio set by the feedback control system deviates from an initial set point (the stoichiometric value) due to deterioration of an oxygen sensor for detecting the air/fuel ratio, the feedback control system compensates for the deviation to cause the air/fuel ratio to approach the initial set point, by varying a ratio of the rich control proportional component P.sub.R to the lean control proportional component P.sub.

Abstract: This invention provides an self-calibrating buffer amplifier for a Universal Exhaust Gas Oxygen sensor interface circuit which couples and processes a voltage signal proportional to pumping cell current to a level and reference voltage suitable for input to an A-to-D convertor. The goal of this invention is to increase the accuracy of air-to-fuel ratio control by continually correcting for the effects of offset quantities in the amplifier stage necessary to the interface circuitry. This goal is accomplished by an approach which effectively generates and subtracts these offset quantities from the processed signal.

Abstract: A system which monitors the performance of at least one HC sensor arranged in an exhaust passage of and internal combustion engine. According to a first aspect of the invention, a value of output from the at least one HC sensor is stored, which is assumed when the fuel supply to the engine is cut off, and a value of output from the at least one HC sensor is corrected by the stored value. According to a second aspect of the invention, the value of output from the at least one HC sensor assumed when the fuel supply to the engine is cut off is compared with a predetermined value, and if the former exceeds the latter, it is judged that there is abnormality in the at least one HC sensor.