Abstract: An engine controller comprises a combustion state detection or estimation means for detecting or estimating a combustion state in the combustion chamber, a combustion air-fuel ratio estimation means for estimating a combustion air-fuel ratio in the combustion chamber according to an exhaust air-fuel ratio and the detected or estimated combustion state, and a means for calculating engine control parameters according to the estimated combustion air-fuel ratio.

Abstract: An air-fuel ratio control system for an internal combustion engine, which is capable of accurately estimating an exhaust gas state parameter according to the properties of fuel, thereby making it possible to properly control the air-fuel ratio of a mixture.

Abstract: Engine systems and methods for accomplishing regeneration of a NOx adsorber (28) using in-cylinder post-injection in a way that creates a lean-rich transition (FIG. 3) for regenerating the NOx adsorber while attenuating engine torque output fluctuations during the transition without the necessity of using torque sensing to attenuate the fluctuations.

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: The invention relates to a device for controlling an internal combustion engine, comprising a first regulator, whose regulating difference is the difference of an actual value and an estimated value of individual cylinder deviation of the air/fuel ratio from a preset air/fuel ratio. The first regulator also has an integral regulating parameter, its manipulated variable being a first estimated value. A second regulator is also provided, the regulating difference of which is the first estimated value. Said regulator has a proportional regulating parameter whose manipulated variable is an individual cylinder lambda regulating factor. A PT1 filter is additionally provided, by means of which a second estimated value is determined through PT1 filtering of the individual cylinder lambda regulating factor.

Abstract: A feedback control of an air-fuel ratio of an internal combustion engine is performed in such a manner that when fuel injection is resumed from a condition where fuel injection is stopped due to deceleration running, air-fuel ratio feedback control is resumed once the output from an air-fuel ratio sensor indicates an air-fuel ratio less than or equal to a threshold value SL.

Abstract: A method for detecting combustion misfires of an internal combustion engine and a device for carrying out the method, in which an evaluation of a lambda signal made available by at least one broadband lambda sensor is provided. The lambda signal is compared to a lambda signal threshold value. A warning signal is made available in response to the exceeding of a threshold in the direction of lean combustion. The procedure especially makes possible the detection of continual misfires which occur, for example, in response to an error in the air supply to the internal combustion engine and/or because of a lack of fuel. The procedure makes possible the detection of dangerous situations for at least one exhaust gas treatment device that is present, which may be removed by introducing protective measures, error warnings and error memory entries.

Abstract: This invention is a method and system for controlling engine-out exhaust species of a combustion engine having a plurality of cylinders by providing a means for controlling combustion parameters in individual cylinders, grouping the individual cylinders into a lean set and a rich set of one or more cylinders, combusting the lean set in a lean combustion parameter condition having a lean air:fuel equivalence ratio, combusting the rich set in a rich combustion parameter condition having a rich air:fuel equivalence ratio, and providing a means for adjusting the lean set and the rich set of one or more cylinders to generate net-lean combustion. The exhaust species have elevated concentrations of hydrogen and oxygen.

Abstract: A technique of controlling an air-fuel ration for an engine, in which an air-fuel ratio feedback correction coefficient ? to correct an amount of fuel injection into the engine is computed based on an output from an air-fuel ratio sensor disposed on an upstream side of a catalytic converter. A gain of the air-fuel ratio feedback correction coefficient ? in respect to a detection result of the air-fuel ratio sensor is decreased as a delay in a transient response of the air-fuel ratio sensor occurs. Thus, an excessive increase in the amount of fuel injection immediately after fuel cuts is prevented.

Abstract: An air-fuel ratio feedback control range is enlarged to improve exhaust purification performance and output stability. In one aspect, an air-fuel ratio control apparatus of an internal combustion engine comprises an air-fuel ratio sensor capable of detecting an air-fuel ratio across both lean and rich ranges with a theoretical air-fuel ratio interposed therebetween. Feedback control is performed so as to bring an actual air-fuel into a target air-fuel ratio at least in a predetermined operational range on the basis of a detected value of the air-fuel ratio sensor. Even in a range where the air-fuel ratio is made richer than the theoretical air-fuel ratio, the target air-fuel ratio is set to be richer, and the air-fuel ratio feedback control may still be executed.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine, implementing integral correction of the air-fuel ratio by an integral term edfii obtained by multiplying an integrated difference between a target air fuel ratio and the actual air-fuel ratio by an integral gain, wherein the upper and lower limit values of the integral term are set based on the actual intake air amount and the actual air-fuel ratio. This limits the range of the integral term edfii to prevent it from being set at an excessively high or low level removed from the realities of the intake air amount and the air-fuel ratio, and thereby to prevent erroneous air-fuel ratio correction by the integral term.

Abstract: A method and a device for controlling the exhaust gas recirculation in an internal-combustion engine are described herein. The engine is provided with an air-intake system, a gas-exhaust system, and an exhaust-gas-recirculation system. A linear oxygen sensor is arranged along the air-intake system in a section traversed, in use, by the air/recirculated-exhaust-gas mixture, for measuring the oxygen concentration in the mixture itself An electronic control unit is connected to the oxygen sensor and to the exhaust-gas-recirculation system for controlling the flow rate of recirculated exhaust gases on the basis of the oxygen concentration in the mixture taken in by the engine. In particular, the oxygen sensor is a UHEGO probe.

Abstract: An simplified structure of an air-fuel ratio control system for an internal combustion engine includes an upstream and a downstream catalytic device installed in an exhaust pipe of the engine and a first, a second, and a third air-fuel ratio sensor installed in upstream or downstream side of the exhaust pipe. The system also includes a first feedback controller working to bring a value of the air-fuel ratio, as measured by the first air-fuel ratio sensor, into agreement with a target one and a second feedback controller working to sample values of the air-fuel ratios, as measured by the second and third air-fuel ratio sensors, to correct a predetermined controlled parameter in the feedback control of the first feedback controller.

Abstract: In a diagnosis apparatus for an internal combustion engine which determines the abnormality of a linear A/F sensor which is disposed on the upstream side of a catalyst of the engine and detects the A/F of exhaust gas, the apparatus includes a response/gain deterioration detection unit that separately detects the response deterioration in which the response of the linear A/F sensor is delayed and the gain deterioration in which the detection sensitivity of the linear A/F sensor is abnormal.

Abstract: An individual-cylinder air-fuel ratio estimation model is designed so as to consider the mixing of gases exhausted from adjacent combustion cylinders, and a movement by which a mixed gas arrives at the position of an air-fuel ratio sensor, in order that influences ascribable to the intervals (combustion intervals) of the adjacent combustion cylinders may be reflected on the estimation values of individual-cylinder air-fuel ratios. In evaluating the mixing of the gases which are exhausted from the adjacent combustion cylinders, there are considered the lengths and shapes of the exhaust manifolds of the respective combustion cylinders. In evaluating the movement by which the mixed gas arrives at the position of the air-fuel ratio sensor, there are considered a distance or volume from the confluence to the position of the air-fuel ratio sensor, and the exhaust gas quantities of the respective combustion cylinders.

Abstract: To prevent RPM decrease, misfire, and engine stall by refraining from correcting, the amount of fuel to shift an air-fuel ratio toward a lean side to the extent of exceeding a combustion limit when the internal combustion engine operates at a low load, a control apparatus is provided for controlling operation of an internal combustion engine. The apparatus includes an air-fuel ratio state determiner, a characteristic retainer and a fuel correction amount calculator, in which a coolant temperature coefficient of a coolant temperature coefficient characteristic is set to be smaller than a constant value in a region where a coolant temperature is lower than a constant temperature.

Abstract: A method is provided for controlling an internal combustion engine operating in a homogenous mode. The internal combustion engine exhibits a control unit for setting the air supply, the fuel supply and the ignition angle. The method reduces the fuel consumption and increases a torque reserve that is to be made available for use. Starting from a specific distribution of air and fuel in the mixture, the air mass to be supplied is increased, which leans the air-fuel mixture such that a first torque reserve is generated. In the event of a positive torque request, the fuel mass to be supplied is increased in order to enrich the air-fuel mixture.

Abstract: Disclosed herein is a method and apparatus for controlling a process, such as a chemical reaction, that emits a multi-component mixture of gases; and for controlling a device to which is transmitted a product of a chemical reaction that emits a multi-component mixture of gases.

Abstract: When carrying out abnormality determination for an air-fuel ratio sensor 33 by comparison of an average value tave of all diagnostic values t(n) and an abnormality determination value C, the abnormality determination value C is corrected using an average value ?tave for the disturbance correction values ?t(n). A disturbance correction value ?t(n) is derived by subtracting a correction reference value A, which is a diagnostic value with a normal air-fuel ratio sensor 33 when there is no disturbance, from the diagnostic value t(n). The present invention provides the abnormality diagnosis device for the air-fuel ratio sensor that can acquire highly precise diagnosis results without lowering frequency of diagnosis accurately taking into consideration the influence of disturbance.

Abstract: The invention relates to a method of estimating a nitrogen oxide mass stored in a catalytic nitrogen oxide trapping device (1) which comprises a catalytic phase and which is traversed by the exhaust gases (2) from the internal combustion engine (3) of a motor vehicle (4) comprising an electronic control unit (5). The inventive method consists in: discretising the geometry of the catalytic trapping device (1) into several (n) perfectly-stirred, successive individual reactors (6, 7); and combining a thermal model, which can be used to calculate the temperature variation of the catalytic phase of the catalytic trapping device (1) during the traversing movement of the exhaust gases, and an absorption model, which can be used at any moment to calculate the nitrogen oxide mass stored in the catalytic trapping device (1) on the basis of the characteristics of said device (1), the temperatures from the thermal model for each individual reactor and the exhaust gas mass flow from the engine (3).

Abstract: A method for regulating an internal combustion engine where engine measurement and engine adjustment values is provided, and adaptation values modify the engine parameters, comprising measuring a first engine measurement parameter representative of a first physical engine parameter, measuring a second engine measurement parameter representative of a second physical engine parameter, calculating a first estimation parameter via a first engine parameter, calculating a second estimation parameter via a second engine parameter, determining a first operating mode of the engine regulation method, the first operating mode determined by generating a first adaptation value based on the first engine parameter, generating a second adaptation value based on the second measurement parameter, and comparing the percent difference of the first and second adaptation values to a neutral value of the respective engine parameter, and determining a second operating mode of the engine regulation method.

Abstract: Fuel properties estimating apparatus for an internal combustion engine includes a controller to determine an estimated component concentration of a component in a fuel. The controller calculates an air-fuel correction quantity in accordance with an actual air fuel ratio of the engine; and calculates an air-fuel ratio sensitivity correction quantity from the air-fuel ratio correction quantity and a fuel properties correction quantity calculated from a most recent value of the component concentration. The controller then determines a new value of the estimated component concentration in accordance with the air-fuel ratio sensitivity correction quantity.

Abstract: A first integration value is obtained by performing time integration on a feedback control signal during the time interval between the instant at which the deviation between a reference signal and the output signal of an oxygen sensor reverses from a negative value to a positive value and the instant at which the deviation reverses back to the negative value. A second integration value is obtained by performing time integration on a feedback control signal during the time interval between the instant at which the deviation between a reference signal and the output signal of the oxygen sensor reverses from a positive value to a negative value and the instant at which the deviation reverses back to the positive value. When the deviation between the absolute values of the first and second integration values is smaller than a predetermined threshold value, it is concluded that a feedback learning value is completely learned.

Abstract: A method for controlling an internal combustion engine in which each cylinder of the internal combustion engine is assigned at least one system deviation and at least one controller, each controller predefining a cylinder-specific control signal on the basis of the assigned system deviation, is characterized in that at least one first controller which predefines the control signal as a function of at least one signal characterizing the rotational speed of the internal combustion engine is provided, and at least one second controller which predefines the control signal as a function of at least one signal characterizing the exhaust-gas composition is provided; and, as a function of at least one operating parameter characterizing the operating state of the internal combustion engine, the control signal is predefined either by the at least one first or the at least one second controller or by a combination of a control signal generated by the at least one first controller and a control signal generated by the at

Abstract: An intake-air quantity estimation apparatus for an internal combustion engine, including an intake-air quantity estimation device that includes a cylinder pressure estimation device that estimates pressure within a cylinder through calculation using a model of the cylinder obtained based on a law of conservation of energy, the intake-air quantity estimation device estimates a cylinder intake-air quantity based on the estimated pressure within the cylinder, the cylinder intake-air quantity representing the amount of air flowing into the cylinder.

Abstract: During a learning mode period, the fuel correction coefficient is forcibly changed three times from a situation in which no correction is necessary, whereby the fuel injection quantity of each cylinder is forcibly changed three times. A cross-correlation between the estimated air-fuel ratio and the fuel correction coefficient, which are calculated based on the detected value of the air-fuel ratio sensor every 60° CA, is evaluated to learn a deviation of the air-fuel ratio detecting timing from the appropriate value.

Abstract: Method of regulating an internal combustion engine in order to reach presettable nitrogen oxide emission values of the internal combustion engine, wherein the internal combustion engine is supplied at least some of the time with a first fuel and at least some of the time with a second fuel, the quantity of the first fuel supplied to the internal combustion engine per unit of time being controlled according to a preset control actual value or kept constant and the quantity of the second fuel supplied to the internal combustion engine per unit of time to reach a presettable nitrogen oxide emission value being regulated according to at least one recorded engine parameter.

Abstract: An engine control strategy that ensures that NOx emissions from the engine will be maintained at an acceptable level. The control strategy is based on a two-dimensional fuel-air curve, in which air manifold pressure (AMP) is a function of fuel header pressure and engine speed. The control strategy provides for closed loop NOx adjustment to a base AMP value derived from the fuel-air curve.

Abstract: A control apparatus for an internal combustion engine can avoid overcorrection at a lean side of air fuel ratio learning correction by unburnt fuel in a blowby gas, and prevent rotational speed reduction and engine stall during air fuel ratio open-loop control after restarting of the engine. A temperature detecting section detects the temperature of the engine based on signals of various sensors, and an air fuel ratio learning correction value changing section updates an air fuel ratio learning correction value in accordance with the engine operating condition. When the engine is stopped with its temperature having not yet reached a predetermined value after started from a cold state thereof, an amount of update of the air fuel ratio learning correction value at a lean side is set in such a manner that the lower a temperature parameter immediately before engine starting, the smaller does the amount of update become.

Abstract: Automotive vehicles are increasingly being equipped with remote starting devices. If the vehicle is within a space which is very well sealed, it is possible that the concentration of the exhaust gases may exceed desirable levels. A method and system are disclosed in which a mass-based determination of air/fuel ratio is compared with the air/fuel ratio being maintained by the exhaust gas oxygen sensor. When the air/fuel ratio based on a mass measurement deviates from the air/fuel ratio based on the exhaust gas oxygen sensor by more than a threshold difference, the remotely started vehicle is turned off.

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: An apparatus for controlling the air-fuel ratio of an internal combustion engine to stably determine a highly reliable identified value of a parameter of a model of an exhaust system including a catalytic converter and to increase the purifying capability of the catalytic converter. An exhaust-side control unit 7a sequentially variably sets a dead time of an exhaust system E depending on the flow rate of an exhaust gas supplied to a catalytic converter 3, and sequentially identifies the value of a parameter of a model of the exhaust system E which has a dead time element of the set dead time. The exhaust-side control unit 7a sequentially calculates a target air-fuel ratio KCMD to converge the output of an O2 sensor 6 to a target value using the identified value of the parameter, and an engine-side control unit 7b manipulates the air-fuel ratio of the internal combustion engine 1 depending on the target air-fuel ratio KCMD.

Abstract: A method for detecting emissions from an internal combustion engine generally including determining a reference air/fuel mixture signal based on an engine speed and an airflow into the engine. The method includes determining an actual air/fuel mixture signal from an air/fuel mixture sensor and comparing the reference air/fuel mixture signal to the actual air/fuel mixture signal. The method also includes determining whether an air/fuel imbalance condition occurs based on the comparison and setting a service indicator based on the determination of whether the air/fuel imbalance condition occurred.

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: Noxious emissions present in the exhaust gases of an internal-combustion engine of a motor vehicle are controlled by making use of an IR spectrophotometer provided on board the motor vehicle, for the purpose of obtaining an analysis of all the main components of the exhaust gases of the engine. The IR spectrophotometer is of the type with electrostatic micro-shutters so as to present overall dimensions designed to enable its use on board the motor vehicle.

Abstract: In an air/fuel ratio control system for an outboard motor engine, a learned correction coefficient KTIMn used in open-loop control for correcting a basic fuel injection amount to be supplied to the engine, is updated only when the manifold absolute pressure PBA (indicative of engine load) is within a predetermined range relative to the engine speed NE concerned. As a result, the air/fuel ratio can be accurately controlled to one other than the stoichiometric air/fuel ratio, even when an O2 sensor that produces an output whose property only changes near the stoichiometeic air/fuel ratio is used.

Abstract: An abnormality diagnosis method for a gas concentration measuring device, includes electrically shutting off measurement means from an oxygen concentration detecting cell and an oxygen pump cell of a gas sensor when a voltage at one of electrical connection points through which the measurement means is electrically connected to the oxygen concentration detecting cell and the oxygen pump cell becomes equal to a predetermined abnormal voltage value, and thereafter, electrically connecting the measurement means to the oxygen concentration detecting cell and the oxygen pump cell of the gas sensor to perform an abnormality diagnosis of the gas sensor. An abnormality diagnosis apparatus for a gas concentration measuring device is also provided.

Abstract: In order to average the continuously sampled individual values of the measuring signal through totaling over a summation period (TP1, TP2), said period corresponding to the period, dependent on engine speed, of pressure pulsations of the exhaust, while at the same time sparing the memory resources, it is proposed for totaling to be carried out across the N1 individual values block-by-block and already to start before signal updating so that the block values already formed continuously block-by-block up to the update time (tn) and buffered instead of the respective individual values are used for calculating an average.

Abstract: The invention provides a control apparatus comprising a controller for determining a manipulated variable for manipulating a controlled object so that an output of the controlled object converges to a desired value and a modulator for modulating the manipulated variable by using one of a delta-sigma modulation algorithm, a sigma-delta modulation algorithm and a delta modulation algorithm to generate a modulated signal to be applied to the controlled object. The modulator generates the modulated signal so that a center value of an amplitude of the modulated signal follows a change of the manipulated variable. Thus, the modulated signal in which the manipulated variable is reflected without any loss can be generated even when the manipulated variable changes.

Abstract: The present invention provides a control apparatus for a plant, which can suppress excessive correction for a spiky disturbance being applied and maintain a good controllability, when controlling the plant, which is a controlled object, with the self-tuning regulator. A detected equivalent ratio KACT is input to a high-pass filter 33, and a high-pass filter output KACTHP is input to a parameter adjusting mechanism 42. The parameter adjusting mechanism 42 calculates a corrected updating vector (KID·d?(k)) by multiplying an updating component d? of a model parameter vector by a correction coefficient KID, and adds the corrected updating vector to a preceding value ?(k?1) of the model parameter vector, to thereby calculate a present value ?(k). The correction coefficient KID is changed from “1.0” to a value near “0” upon detection of the spiky response where an absolute value of the high-pass filter output KACTHP increases.

Abstract: In a lean-burn engine equipped, in the exhaust pipe, with NOx trap catalyst that collects NOx by absorption or occlusion, the rich spike start timing and rich spike volume are optimized. The above subject is achieved by an engine control system equipped, in the downstream side of the NOx trap catalyst, with a NOx sensor that detects the NOx component in the exhaust, NOx trap catalyst model, and a device that controls the engine operating condition based on the outputs of the NOx trap catalyst model and NOx sensor.

Abstract: A method for controlling an internal combustion engine in which in each case the lambda value is ascertained by evaluating a measuring signal of a lambda probe. In this context, two combustion periods of the internal combustion engine are compared to each other. In the two combustion periods, in a single cylinder the lambda value is induced once in the direction of a lambda increase and once in the direction of a lambda decrease.

Abstract: A system and method for utilizing a humidity sensor with an internal combustion engine of a vehicle is described. Specifically, information from the humidity sensor is used to adjust a desired air-fuel ratio to reduce engine misfire while improving vehicle fuel economy. Further, such information is also used to adjust timing and/or lift of the valve in the engine cylinder. Finally, diagnostic routines are also described.

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: An air-fuel ratio sensor detects an air-fuel ratio of an exhaust gas at a confluent portion of an exhaust gas. An air-fuel ratios in each cylinder are estimated to be controlled based on an output of the air-fuel ratio sensor. A computer determines whether an air-fuel detecting timing deviates according to a dispersion of the estimated air-fuel ratio among cylinders. When the deviation is detected, the air-fuel ratio detecting timing is varied to estimate an air-fuel ratio before and after correcting amount of fuel. The air-fuel ratio detecting timing is adapted as a proper timing when the variation amount of the estimated air-fuel ratio before and after the correction of fuel amount corresponds to the correct amount of fuel.

Abstract: A deterioration determining apparatus and a deterioration determining method are applied to an engine in which a feedback control of an air-fuel ratio is performed by calculating an air-fuel ratio correction coefficient based on an output of an oxygen sensor, and response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor is set so as to be variable. In the deterioration determining apparatus and the deterioration determining method, a deterioration determining value concerning a determination as to whether the oxygen sensor has deteriorated is set so as to be variable according to the set response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor, and the determination as to whether the oxygen sensor has deteriorated is made based on an inversion cycle of the output of the oxygen sensor and the deterioration determining value.

Abstract: A method and system for providing location specific fuel emissions compliance for a mobile vehicle including determining a mobile vehicle location, determining a current emissions zone based on the mobile vehicle location, determining at least one location specific emissions parameter based on the current emissions zone, and modifying at least one mobile vehicle function based on the location specific emissions parameter.

Abstract: An air/fuel ratio control apparatus an internal combustion engine, and an engine control unit are provided for conducting perturbation control to maintain a satisfactory exhaust gas purification percentage irrespective of whether or not a catalyst is deteriorated. The air/fuel ratio control apparatus for an internal combustion engine includes an ECU, and a LAF sensor and an O2 sensor disposed at locations upstream and downstream of a first catalyst, respectively, in an exhaust pipe. The ECU sets a target air/fuel ratio for converging the output of the O2 sensor to a predetermined target value such that it fluctuates over a predetermined amplitude at a predetermined frequency higher when the output of the O2 sensor remains near a predetermined target value than when it is not near the predetermined target value. The ECU also controls an air/fuel ratio to match the output of the LAF sensor with the target air/fuel ratio KCMD.

Abstract: A control apparatus for controlling an object that is modeled using at least one model parameter is provided. The control apparatus comprises an identifier, a controller and a modulator. The identifier identifies the model parameter. The controller is coupled to the identifier and uses the model parameter to determine a reference input so that an output of the object converges to a desired value. The modulator is coupled to the controller and applies any one of a delta-sigma modulation algorithm, a sigma-delta modulation algorithm and a delta modulation algorithm to the reference input to determine an input into the object. The model parameter is identified based on the output of the object and the reference input. Since the identifier determines the model parameter based on the reference input, the model parameters is prevented from vibrating.

Abstract: A high precision deterioration determination device for an exhaust gas purifier of an engine is provided. The engine includes an exhaust gas purifier disposed in an exhaust pipe of the engine, and a downstream exhaust gas sensor disposed in the exhaust pipe on the downstream of the purifier for generating outputs corresponding to components of an exhaust gas. The electronic control unit controls an air/fuel ratio of the engine to a predetermined value based on the outputs of the downstream exhaust gas sensor. The control unit is programmed to perform a non-linear filtering to extract rectangle-shaped waveform components from the outputs of the downstream exhaust gas sensor. The control unit subtracts the rectangle-shaped waveform components from the sensor outputs to extract noise components representing a degree of the catalyst deterioration.