Abstract: A sensor element with a thin-film structure is made of platinum or a platinum alloy. The structure being applied to a ceramic substrate, in particular an Al2O3 substrate and being covered by a glass-ceramic coating. The glass-ceramic coating has an outer surface with surface profiling. A sensor module, a measuring assembly, and an exhaust-gas re-circulation system include the sensor element.

Abstract: A fuel injection control apparatus is provided. An injection unit injects fuel in an internal combustion engine. A carbon monoxide concentration sensor is provided in an exhaust path of the internal combustion engine and detects a carbon monoxide concentration in an exhaust gas. A control unit controls the injection unit based on the carbon monoxide concentration detected by the carbon monoxide concentration sensor such that an air fuel ratio in the internal combustion engine becomes close to a target air fuel ratio.

Abstract: A sensor element drive circuit is a circuit including a plurality of semiconductor elements formed on a semiconductor substrate for realizing a current control function and a switching function. The current control function is a function of controlling the current flowing between electrodes such that the potential difference between electrodes becomes constant. The switching function is a function for switching between a connected state in which the electrodes are electrically connected to a sensor control apparatus and a cut-off state in which electrical continuity therebetween is broken. When one of an Ip+ terminal, a COM terminal, and a Vs+ terminal is determined to have an anomalous potential, the sensor control apparatus causes the sensor element drive circuit to perform switching from the connected state to the cut-off state, and connects the semiconductor substrate to a negative voltage lower than a ground potential applied to the sensor element drive circuit.

Abstract: A method is disclosed for detecting a malfunction of an oxygen sensor in the exhaust gas system of an internal combustion engine having several cylinders. The cylinders are operated at the same air-fuel ratio and the resultant first output signal of the oxygen sensor is monitored. The cylinders are operated at varying air-fuel ratios and the resultant second output signal of the oxygen sensor is monitored. The first and second output signals are compared to determine whether the oxygen sensor has malfunctioned.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine is provided. A controller is programmed to perform correction amount guard control allowing adjustment of a correction amount by setting a limit on the correction amount when an appearance frequency of a state where an output value from a downstream sensor is leaner than a predetermined value is equal to or higher than a predetermined value. When a state where the output value from the downstream sensor is leaner than the predetermined value lasts for a duration equal to or longer than a predetermined time, an incorporation speed at which, during learning control, the correction amount for sub feedback control is incorporated into a learning value is set to a larger value that when the duration is shorter than the predetermined time, and performance of the correction amount guard control is suppressed until the learning control is completed.

Abstract: A control facility is provided for a burner system having a burner, actuators with which the supply of fuel and air to the burner is set, and an ionization electrode arranged in the flame zone. The control facility is equipped with a flame amplifier at the ionization electrode to generate an ionization signal and a positioning facility which, in control operation, positions a first actuator and regulates a second actuator by using a corresponding target value for the ionization signal. The positioning facility carries out a control operation in a first test step, it shifts the actuators toward a supply ratio corresponding to an air coefficient above the stoichiometric value of ?=1 and in so doing captures the ionization signal in a second test step, and it calculates a target value from this and from stored data in a third test step. Correction of drift therefore takes place.

Abstract: Methods are provided for accurately learning part-to-part variability of an intake or exhaust oxygen sensor. A correction factor is learned based on a sensor reading in dry air conditions, the dry air reading learned by applying a higher reference voltage to the sensor. An ethanol transfer function is then adjusted based on the learned correction factor so as to improve the accuracy of combusted fuel ethanol content estimation.

Abstract: Methods are provided for accurately learning part-to-part variability of an intake or exhaust oxygen sensor. A correction factor is learned based on sensor readings at voltages above and below a voltage corresponding to dry air conditions. An ethanol transfer function is then adjusted based on the learned correction factor so as to improve the accuracy of combusted fuel ethanol content estimation.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine of the present invention determines whether or not a lean request has occurred, based on a comparison between a value correlating with an output value of the downstream air-fuel ratio sensor disposed downstream of the catalyst (downstream air-fuel ratio sensor output correlating value) and a predetermined lean request determining value, and determines whether or not a rich request has occurred, based on a comparison between the downstream air-fuel ratio sensor output correlating value and a predetermined rich request determining value. Further, the air-fuel ratio control apparatus calculates a total amount of oxygen (released oxygen amount) released from the catalyst in the rich request occurring period, and calculates an integrated value (present stored oxygen amount) of oxygen stored in the catalyst after a start of the lean request occurring period which follows the rich request occurring period.

Abstract: An oxygen amount (an oxygen storage amount OSA) stored by metal cerium during a storage cycle is obtained based on an output value of an A/F sensor in a time period immediately before an exhaust air-fuel ratio (a downstream side A/F) detected by the A/F sensor shifts to a lean region, and degradation relating to OSC of the three-way catalyst is detected. In the storage cycle, a target air-fuel ratio is set so that an air-fuel ratio of exhaust emission flowing into an S/C changes from rich to lean. Therefore, the downstream side A/F shifts from stoichiometry to the lean region at a time after reaching stoichiometry. When the three-way catalyst degrades, the downstream side A/F shifts to the lean region from stoichiometry at a time. Therefore, the calculated oxygen storage amount OSA becomes extremely smaller as compared with that at a normal time.

Abstract: The present invention relates to a method for monitoring a pollutant conversion capacity of a catalytically coated, oxidizing exhaust gas aftertreatment component (29) in an exhaust gas system (13) of an internal combustion engine (15). A nitrogen oxide sensor (31, 32) is disposed in each case in the flow path of the exhaust gas upstream of and downstream of the oxidizing exhaust gas aftertreatment component (29), a capacity of said oxidizing exhaust gas aftertreatment component (29) for converting NO to NO2 being ascertained from a comparison of the two signals (Z?, Z?) of the nitrogen oxide sensors (31, 32). Additional independent claims relate to an open-loop and/or closed-loop control device (17), a computer program and a computer program product.

Abstract: A control apparatus for an internal combustion engine including a plurality of combustion chambers and a catalyst that cleans exhaust gases includes a controller configured to execute individual air-fuel ratio control in which an air-fuel ratio of an air-fuel mixture generated in at least one non-specific combustion chamber is controlled such that an average air-fuel ratio of the engine matches a target air-fuel ratio, based on an air-fuel ratio of an air-fuel mixture generated in at least one specific combustion chamber, the controller being configured to execute catalyst temperature increase control in which a temperature of the catalyst is increased, and the controller being configured to prohibit execution of the individual air-fuel ratio control when the catalyst temperature increase control is executed.

Abstract: Methods and systems are provided for adjusting cylinder valve timings to enable a group of cylinders to operate and combust while another group of cylinders on a second are selectively deactivated. Valve timing may be adjusted to allow flow of air through the inactive cylinders to be reduced, lowering catalyst regeneration requirements upon reactivation. The valve timing may alternatively be adjusted to enable exhaust gas to be recirculated to the active cylinders via the inactive cylinders, providing cooled EGR benefits.

Abstract: A control apparatus for an internal combustion engine is configured to execute an air-fuel ratio control based on an output of an air-fuel ratio detector provided in an exhaust passage through which exhaust gas from a plurality of cylinders flows. The control apparatus includes an abnormal lean deviation detection portion configured to detect whether an abnormal lean deviation is occurring in at least one specific cylinder among the plurality of cylinders, the exhaust gas from the at least one specific cylinder influencing the air-fuel ratio detector more strongly than the exhaust gas from each of a rest of the plurality of cylinders; and an enriching control portion configured to execute an enriching control for the at least one specific cylinder when the abnormal lean deviation detection portion detects that the abnormal lean deviation is occurring in the at least one specific cylinder.

Abstract: An internal combustion engine has an exhaust gas tract with a first and a second exhaust gas catalyst downstream of the first one, a first exhaust gas sensor, which is disposed upstream or in the first catalyst, and a second exhaust gas sensor, which is disposed downstream of the first catalyst and upstream of the second catalyst. During trailing throttle operation, the measurement signal of the second sensor is monitored for a signal characteristic that is typical of a maximum possible saturation state with oxygen that the first catalyst can achieve, upon which a characteristic variable is determined for a saturation state of the second catalyst with oxygen as a function of an engine operating variable. Outside the trailing throttle operation, an enrichment mode is controlled by enriching the air/fuel mixture, specifically as a function of the characteristic variable for the saturation state of the second catalyst with oxygen.

Abstract: An analysis tool which extracts all the available parameter identifications (i.e. PIDS) from a vehicle's power train control module for diagnostic decisions. This is done by checking these PIDS and other information (e.g., calculated PIDS, Break Points, charts and algorithms) in three states; key on engine off, key on engine cranking, key on engine running In all three modes the tool is comparing the live data from PIDS and voltage to the other information (e.g., Break Points). If any of this data are outside the programmed values a flag is assigned to the failure or control problem. The relationship between a particular PID and its associated preprogrammed value(s) may be indicated by a light. The depth of the problem (if any) is conveyed by the color of the light. Also included are tests/charts for fuel trim, engine volumetric efficiency, simulated injector, power, catalyst efficiency, and engine coolant range.

Abstract: An internal combustion engine has an exhaust gas tract with a first and a second exhaust gas catalyst downstream of the first one, a first exhaust gas sensor, which is disposed upstream or in the first catalyst, and a second exhaust gas sensor, which is disposed downstream of the first catalyst and upstream of the second catalyst. During trailing throttle operation, the measurement signal of the second sensor is monitored for a signal characteristic that is typical of a maximum possible saturation state with oxygen that the first catalyst can achieve, upon which a characteristic variable is determined for a saturation state of the second catalyst with oxygen as a function of an engine operating variable. Outside the trailing throttle operation, an enrichment mode is controlled by enriching the air/fuel mixture, specifically as a function of the characteristic variable for the saturation state of the second catalyst with oxygen.

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 engine control system includes an fuel injector for each cylinder of the engine, an air-fuel ratio sensor disposed in an exhaust manifold and an electronic control unit to which signals from various sensors are fed. Operation of the engine is controlled by the electronic control unit. An air-fuel ratio deviation among cylinders is calculated based on output signals of the air-fuel ratio sensor, and injection amount errors of each injector are calculated from the deviation of air-fuel ratio among cylinders. An injection characteristic of each injector is learned from the injection amount errors, and a right amount of fuel is supplied to each cylinder based on the learned injection characteristic. In this manner, the injection amount errors are effectively adjusted, and the air-fuel ratio deviation among cylinders due to external disturbances is surely adjusted.

Abstract: An electronic control device according to the invention is disclosed for controlling the internal combustion engine in a motor vehicle, for fault recognition with an irregular running determination unit and with an injection quantity correction unit, a defined group of cylinders being associated with a lambda probe, the injection quantity of a cylinder to be investigated of the defined group is adjusted in the direction of lean by a differential adjustment value associated with an irregular running differential value, and the injection value of at least one of the remaining cylinders, which are associated with the same lambda probe, is correspondingly adjusted in the direction of rich, so that in total a predetermined lambda value of this group of at least approximately 1 is reached. Homogeneous operation is thus ensured. The differential adjustment values may, for example, relate to the injection quantity itself, the injector stroke or the injection time.

Abstract: Methods and systems are provided for monitoring cylinder valve deactivation in an engine operating with a plurality of cylinder valves. One example method comprises, sensing a plurality of cylinder valve positions of a plurality of cylinder valves; and combining the plurality of sensed positions to form a combined cylinder valve signal. The method may further include identifying valve degradation and differentiating valve degradation among the plurality of cylinder valves based on the combined cylinder valve signal and an expected value of the signal, and further based on a crank angle at which the expected value differs from the combined signal.

Abstract: A common fuel injection amount is calculated for the cylinders of a first cylinder group, which performs a rich burn process, and the cylinders of a second cylinder group, which performs a lean burn process. The calculated fuel injection amount is corrected with an air-fuel ratio learning value that is acquired beforehand during a stoichiometric operation. Intake valve lift amounts for the cylinders of the first and second cylinder groups are calculated in accordance with an engine speed and engine load. In compliance with the calculated values, a variable valve mechanism is driven, and fuel is ignited. When performing sulfur poisoning recovery of the Ox catalyst, the exhaust air fuel ratio control means change the intake air amount for each cylinder while providing substantially the same fuel injection amount for all cylinders.

Abstract: A valve timing correction control apparatus for an internal combustion engine is provided. The engine includes a plurality of banks and variable valve operating mechanisms disposed at the respective banks for variably controlling valve timings of intake valves separately at the respective banks. The valve timing correction control apparatus comprises air/fuel ratio sensors provided to exhaust systems of the respective banks, and a control unit that corrects the valve timings of the intake valves at the respective banks in accordance with deviations of air/fuel ratios detected by the respective air/fuel ratio sensors. A valve timing correction control method is also provided.

Abstract: An interface module is proposed, to which sensors are connected and which is positioned in a control device, it being indicated via an identification input how the sensor data are to be classified by the interface module. In particular, this can be used to distinguish between safety-relevant and safety-irrelevant data. Furthermore, the nature of the data can be identified therewith. This identification input is advantageously designed as a voltage input, the voltage levels being then converted into a bit sequence. The identification input is connected to ground via a resistor, so that, in the case of an unspecified input potential, the voltage level is connected to ground. The interface module has a logic circuit to which voltage comparators are connected, which compare the voltages to reference potentials, and then the logic circuit performs a coding using the bit sequences, as a function of the output signals of the voltage comparators.

Abstract: A control apparatus calculates a exhaust gas air-fuel ratio of a plurality of cylinders, in which the operation angle of an intake valve is set to a predetermined operation angle, e.g., a maximum operation angle, based on a value output from an air-fuel ratio sensor so as to minimize a variation in an fuel injection quantity between the plurality of cylinders by that exhaust gas air-fuel ratio. That is, the exhaust gas air-fuel ratio of the plurality of cylinders, in which the valve opening characteristics of the intake valve and an exhaust valve are set such that the intake air amount to be introduced into the plurality of cylinders is limited by the opening amount of a throttle valve, for example, and not limited by the valve opening characteristics of the intake valve or the exhaust valve is calculated, and the variation in the fuel injection quantity among the plurality of cylinders is then reduced by that exhaust gas air-fuel ratio.

Abstract: When the output of the AFR ratio sensor is stable in a steady operating state, the amount of fuel is increased by step inputting to detect a point where the gradient of change in the sensor output exceeds a threshold value as a point of start of change. The time from the timing of increasing the fuel until the point of start of change is detected as a dead time. A response time is calculated until the amount of change in the sensor output reaches a predetermined ratio of the amount of change (AA?BA) of up to the steady value AA of the sensor output after the amount of the fuel is increased from the steady value BA of the sensor output before the amount of the fuel is increased. The fail condition in the AFR ratio sensor is determined based on the dead time TA and the response time TB.

Abstract: Various systems and methods are disclosed for carrying out combustion in a fuel-cut operation in some or all of the engine cylinders of a vehicle. Further, various subsystems are considered, such as fuel vapor purging, air-fuel ratio control, engine torque control, catalyst design, and exhaust system design.

Abstract: A method of resetting an active emissions system error indictor associated with a vehicle. The method comprises performing a first requesting step and a second requesting step until the active emissions system error indicator resets in response to the first or second requesting steps. In one embodiment, the first requesting step comprises requesting a first type of information (e.g., information from a first vehicle oxygen sensor) from a vehicle computer associated with the vehicle, and the second requesting step comprises requesting a second type of information (e.g., information from a second vehicle oxygen sensor) from the vehicle computer. In a particular embodiment of the invention, an electronic tool, such as a bi-directional scan tool, is used to perform the first and second requesting steps.

Abstract: A system and method for controlling an internal combustion engine having a plurality of cylinders, at least some of which may be selectively deactivated to provide variable displacement operation, including temperature management of at least one engine/vehicle component by monitoring the temperature of the component and controlling activation of at least one cylinder to control the temperature of the component. In one embodiment, the engine/vehicle component is an emission control device, such as a catalytic converter.

Abstract: Methods and apparatus are provided for diagnosing emissions in a multi-banked catalyst emissions system for a motor vehicle. A method of diagnosing emissions in a multi-banked emissions system suitably includes obtaining an emissions measurement for each bank in the multi-banked emissions system, converting the emissions measurements to scaled values, adding the scaled values to obtain a total emission value, and triggering an indication if the total emission value exceeds a pre-determined maximum. A system for processing emissions from an engine in a motor vehicle typically includes multiple exhaust banks and a processor. Each of the exhaust banks includes a catalytic converter and at least one oxygen sensor. The processor receives measurements from the oxygen sensors, converts the measurements to scaled values as a percentage of a threshold value, computes a total emission value from the scaled values, and triggers an indication if the total emission value exceeds the threshold value.

Abstract: A method of initializing the catalyst converter for monitoring the conversion efficiencies of a catalytic converter by measuring the oxygen storage capacity (OSC) of the converter. The measurement of the OSC indicates the degree of health of the converter. Under the same engine running conditions, the greater the OSC measurement, the healthier the converter. The catalyst needs to be set to either a rich state or a lean state prior to the measurement of its OSC time. This process is called catalyst state initialization. The catalyst has to be fully saturated from test to test in order to make consistent OSC measurements. This is through open loop fuel control by commanding a lean air to fuel ratio and then monitoring thepost-O2 sensor voltage until it falls below a calibrated value (e.g. 80 mV) indicating a lean state. The system continues to command a lean air to fuel ratio (e.g. 6%) for a calibrated duration of time (e.g.

Abstract: The invention relates to a method and an arrangement for operating an internal combustion engine wherein at least one control quantity of the engine is influenced in dependence upon a signal representing the fresh air charge. The throttle flap angle and the intake manifold pressure are determined and a respective signal is formed on the basis of the throttle flap angle and on the basis of the intake manifold pressure. The charge signal, which is formed on the basis of the throttle flap angle, is adapted to the signal, which is formed on the basis of the intake manifold pressure sensor, with the aid of at least one corrective factor.

Abstract: A method for controlling air-fuel ratio of an engine coupled to an emission control device uses an upstream linear exhaust gas sensor and a switching downstream exhaust gas sensor. During stoichiometric operation, both sensors are used for feedback control. During operation away from stoichiometry, the downstream sensor feedback is disabled.

Abstract: A method for controlling first and second air/fuel ratio oscillations in first and second cylinder groups, respectively, of an internal combustion engine is provided. The method includes determining a first frequency of the first air/fuel ratio oscillations in the first cylinder group. The method further includes determining a second frequency of the second air/fuel ratio oscillations in the second cylinder group. Finally, the method includes adjusting the first frequency towards the second frequency responsive to a frequency difference between the first and second frequencies.

Abstract: In a multi cylinder internal combustion engine comprising a cylinder head internally defining exhaust passages extending from a plurality of combustion chambers defined in part by the cylinder head, the exhaust passages converging into a converging area also internally defined in the cylinder head, an oxygen sensor for detecting an oxygen concentration in exhaust gas is passed into the converging area substantially in parallel with a cylinder axial line. Thus, the oxygen sensor can be mounted relatively close to the combustion chamber while permitting the sensor to be uniformly exposed to the exhaust gas from the combustion chambers of an entire cylinder bank. Therefore, the oxygen sensor can be activated relatively quickly substantially without any warm-up, and can measure the oxygen concentration of the overall exhaust gas.

Abstract: A method and apparatus for controlling universal exhaust gas oxygen (UEGO) sensors comprises an application specific integrated circuit (ASIC) that includes a sensor control utilizing proportional-integral-derivative control loop, sensor drivers for generating pumping currents that reflect the changes of voltages representative of oxygen levels in the reference and test chambers of the UEGO sensor, a communication circuit for communicating with an engine control module, and output buffers for conditioning replications of the pumping current for delivery to an output circuit. In addition to the ASIC, a sensor interface conditions the sensor signals and an output circuit transforms the pumping circuit replications to compatible inputs for the engine control module. Preferably, all of the circuits are formed on a portion of a circuit board in the engine control module. A trim compensation circuit compensates for sensor deviation from an ideal performance standard.

Abstract: A control method for an internal combustion engine has multiple cylinder groups with at least one control device positioned between an intake manifold and a cylinder group. The engine operates the cylinder groups at different air/fuel ratios and uses the control device to balance torque produced by the different cylinder groups. In one aspect of the invention, one cylinder group is operated rich and another cylinder group is operated lean thereby providing heat to an exhaust system located downstream of the engine.

Abstract: A separate irregular-running determination is carried out for each cylinder bank. Each ascertained irregular-running value is compared to a lower and an upper threshold value, the upper threshold value being set in such a way that all irregular-running values below it are not caused by combustion misses. A defect is signaled in one of the exhaust trains when, for at least one of the two cylinder banks, an irregular-running value is ascertained lying between the lower and the upper threshold value, and the difference between the irregular-running values of the two cylinder banks exceeds a threshold. This method makes it possible to ascertain a defect in one of the two cylinder banks very early.

Abstract: An oxygen sensor is disposed behind an exhaust gas purifying catalyst for an internal combustion engine and which suppresses the influence of unburnt hydrocarbon on the output voltage. A sensor element 1 is provided with a detection electrode 4 on the outer face of a zirconia ceramic body 2, a reference electrode 3 on the inner face of the ceramic body 2 and a spinel protective layer 5 on the outer surface of the detection electrode 4. The tip end of the sensor element 1 is covered with a protective cover 10 which is provided with an outer partition wall 11 having through holes 11a and an inner partition wall 12 having through holes 12a. In a case where the pressure difference between the inside and outside of the protective cover 10 is &Dgr;P(atm) when the atmospheric air with a volume flow rate Q(L/min) is passed into the protective cover 10 from the outside, the ratio &Dgr;P/Q2 is 3.2×10−5 (atm·min2·L−2).

Abstract: A method and system for controlling fuel injected into an internal combustion engine fitted with a catalytic converter. A signal outputted by a first feedback loop and derived from the output of a first probe upstream from the catalytic converter is corrected in a corrector circuit by a value determined by another circuit on the basis of the output of a second probe downstream from the catalytic converter. The second circuit includes a comparator.

Abstract: A control system for an outboard motor is disclosed. The control system includes a feedback control which obtains feedback data from a combustion condition sensor. The motor includes an engine positioned in a cowling and having a vertically extending output shaft in driving relation with a water propulsion device of the motor. The engine has at least one combustion chamber and an air/fuel charging system for delivering air and fuel into the combustion chamber for combustion therein. The motor includes an exhaust system for routing exhaust from the engine to a point external to the motor. The exhaust system includes an exhaust passage leading from the chamber to a main exhaust passage which extends vertically downward to an exhaust guide positioned below the engine. A passage leads from the exhaust guide into an expansion chamber and thereon to an exhaust discharge.

Abstract: An air-fuel ratio control device for an engine comprises a three way catalyst arranged in the exhaust passage, an upstream-side air-fuel ratio sensor arranged in the exhaust passage upstream of the three way catalyst, and an downstream-side air-fuel ratio sensor arranged in the exhaust passage downstream of the three way catalyst. A first feedback correction coefficient is calculated on the basis of an output of the upstream-side sensor to make the air-fuel ratio equal to the stoichiometric air-fuel ratio. A smoothed value is calculated on the basis of an output of the downstream-side sensor, the absolute value of a changing rate of the smoothed value being smaller than the absolute value of the changing rate of the output of the downstream-side sensor. A second feedback correction coefficient is calculated on the basis of a deviation of the output of the downstream-side sensor from the smoothed value. The first feedback correction coefficient is corrected using the second feedback correction coefficient.

Abstract: A system for monitoring the operatibility of catalytic converters and/or lambda probes in exhaust gas detoxification systems. It is characterised in that a pollutant sensor is placed downstream of (in relation to the exhaust gas stream) or in the catalytic converter, in that the lambda value and/or oxygen content of the exhaust gas are altered by a specific amount either by the engine or by a device, and in that the electrical output signal from the pollutant sensor is compared in a comparator circuit to a value curve stored in a storage unit and corresponding to the defined alteration of the lambda value.

Abstract: A system and method for monitoring efficiency of a catalytic converter count switches of at least one upstream sensor interposed the engine and the converter and count switches of a downstream sensor, interposed the converter and atmosphere, during a definite time period after a switch of the at least one upstream sensor to account for propagation delay of exhaust gases traveling between the at least one upstream and downstream sensor. Upstream sensor switches may optionally be counted only if predetermined entry conditions are satisfied while downstream switches occurring during respective definite time periods after an upstream switch are counted without regard to the entry conditions. A switch ratio based on the number of switches of the at least one upstream sensor and switches of the downstream sensor is used to monitor conversion efficiency of the catalyst.

Abstract: In an exhaust gas purification device for an internal combustion engine, a three-way catalyst and a NO.sub.X occluding and reducing catalyst (a NORC) are disposed in the exhaust gas passage of an engine in this order from the upstream side. A first air-fuel ratio sensor is disposed in the exhaust gas passage between the three-way catalyst and the NORC, and a second air-fuel ratio sensor is disposed in the exhaust gas passage downstream of the NORC. An engine electronic control unit (ECU) changes the operating air-fuel ratio of the engine from a lean air-fuel ratio to a rich air-fuel ratio and a rich air-fuel ratio to a lean air-fuel ratio in order to evaluate the abilities of the three-way catalyst and the NORC. The ECU evaluates the catalytic abilities based on the output of the first air-fuel ratio sensor when the engine air-fuel ratio is changed. Further, the ECU evaluates the catalytic ability and the NO.sub.

Abstract: An air/fuel control system (8) and method for an engine (28) having two engine banks coupled to a single catalytic converter (50) uses first and second exhaust gas oxygen sensors (44, 55) coupled to respective first and second exhaust manifolds (56, 57) and various engine operating parameters. During a first set of engine operating conditions, air/fuel control system (8) maintains the exhaust air/fuel ratio oscillations of the two bank in phase with one another. During a second set of engine operating conditions, air/fuel control system (8) maintains the exhaust air/fuel ratio oscillations of the two bank 180 degrees out of phase with one another. When transitioning, emission impacts are minimized.

Abstract: An exhaust gas sensor has first and second sensor elements. Exhaust gas surroundings of the first sensor element are catalytically activated, so that an oxygen partial pressure which is in equilibrium will always be measured by the first sensor element, regardless of the conversion capability of a catalytic converter. The exhaust gas surroundings of the second sensor element are separate from the exhaust gas surroundings of the first sensor element, so that the exhaust gas surroundings of the second sensor element are not catalytically active. As a function of the conversion capability of the catalytic converter, the second sensor element measures either an equilibrium oxygen partial pressure or a free oxygen partial pressure, which are of different magnitudes. A malfunction of the catalytic converter is detected by comparing measurement signals of the first and second sensor elements.

Abstract: In a device having air-fuel ratio sensors upstream and downstream of an exhaust gas purifying catalytic converter with learning carried out based on output values from the downstream air-fuel ratio sensor, independent learning is carried out depending on whether the catalytic converter is active or not. The air-fuel ratio is then controlled based on the output value of the first air-fuel ratio sensor, the output value of the second air-fuel ratio sensor and the learned value. As a result leaning accuracy is increased and air-fuel ratio control performance enhanced.

Abstract: An exhaust gas purifying apparatus mounted in an vehicular engine, which includes a detector for detecting the actuated condition of a catalyst. Injectors for fuel injection are disposed along an air intake passage of the engine and plurality of catalysts are provided along an exhaust gas passage. A catalyst incorporating an electrical heater is disposed at the most upper stream side thereof. A secondary air source can be supplied into the inlet port of the heatable catalyst by means of secondary air supply mechanism. To determine the activated condition of the catalyst, a temperature sensor is provided to the catalyst. An electronic control unit (ECU) controls the injectors, secondary air supply mechanism, and heatable catalyst when the engine is initiated in the cold state. The ECU computes a temperature change rate of the catalyst based upon a value detected by the temperature sensor while secondary air supply is provided into the inlet port of the heatable catalyst.

Abstract: A conversion efficiency of a catalyst is estimated by a correlation function concerning output signals of upper and down stream side air fuel ratio sensors. The conversion efficiency is measured by comparing the correlation function and a complementary value of the correlation function with a comparing standard value.