Abstract: In a control method, the setting for a setting device (5), comprising a device (9) for reporting the setting, is regulated in a range between two end positions by using a measured parameter, given by the device (9) for reporting the setting, depending on the setting of the setting device and a characteristic curve, whereby, during the regulation a set value or an actual value for the setting is monitored. The characteristic curve is adapted when the set value or the actual value for the setting lies within a given separation from a given value for an adaptation setting.

Abstract: When in controlling an air-fuel ratio by a feedback control, a target air-fuel ratio is changed between normal time and at rich control time, a difference between a change amount of the target air-fuel ratio and a change amount of an air-fuel ratio feedback correction coefficient is learned as a sensor error in the rich control. A final detected air-fuel ratio is calculated by correcting a detected air-fuel ratio of an air-fuel ratio sensor in rich control based on the sensor error. Alternatively, the target air-fuel ratio or the air-fuel ratio feedback correction coefficient in the rich control may be corrected based on the sensor error.

Abstract: An electronic control unit (an ECU) of a fuel injection system performs a learning injection based on a learning injection quantity and obtains multiple influence values of an operating state of an engine generated through the learning injection. The ECU calculates a learning value for correcting the injection quantity in a normal operation based on the multiple influence values. The ECU determines whether the influence value obtained during the learning injection is within a predetermined range of the influence value. The ECU calculates a provisional learning injection quantity for bringing a subsequent influence value into the predetermined range if the influence value obtained in an early stage of the obtainment is out of the predetermined range. Then, the ECU calculates the other influence values by performing the other learning injections based on the provisional learning injection quantity.

Abstract: A fuel supply control system for an internal combustion engine wherein a basic fuel amount supplied to said engine can be calculated according to the intake air flow rate detected by said intake air flow rate sensor. An air-fuel ratio correction coefficient can be calculated for correcting an amount of fuel to be supplied to the engine so that the detected air-fuel ratio coincides with a target air-fuel ratio. At least one correlation parameter vector which defines a correlation between the air-fuel ratio correction coefficient and the intake air flow rate detected by the intake air flow sensor, can be calculated using a sequential statistical processing algorithm. A learning correction coefficient relating to a change in characteristics of the intake air flow rate sensor can be calculated using the correlation parameter. An amount fuel to be supplied to the engine can be controlled using the basic fuel amount, the air-fuel ratio correction coefficient, and the learning correction coefficient.

Abstract: An ECU calculates the air-fuel ratio of each cylinder based on a sensor signal from an A/F sensor arranged at the collecting portion of the exhaust manifold and feedback controls the fuel injection quantity for each cylinder by using the individual cylinder air-fuel ratio obtained. A collecting portion fuel quantity is calculated from the air-fuel ratio at the exhaust collecting portion based on from the A/F sensor signal, and the gas flow rate at the exhaust collecting portion is calculated using the gas flow rate history of each cylinder. An observer using the individual cylinder fuel quantity as a variable is constructed by a model in which the collecting portion fuel quantity is associated with the individual cylinder fuel quantity, so that the individual cylinder fuel quantity is estimated from the result of observation by the observer. Each cylinder's air-fuel ratio is calculated from the estimated individual cylinder fuel quantity.

Abstract: An engine control system that identifies fuel dynamical steady state (FDSS) includes a cylinder and a controller that determines a detection period. The controller monitors a mass of fuel ingested by the cylinder during the detection period. The controller identifies FDSS if the mass of fuel remains within a predetermined range during the detection period.

Abstract: An operating internal combustion engine with at least one cylinder (2), and a piston (12), which can move in an alternating manner therein, is used to compress a fuel mix in a combustion chamber (11). In order to determine the nitrogen oxide content in oxygen-containing exhaust gases, the quantity of fuel fed to the cylinder (2) and the air mass flowing in an induction pipe (15) are recorded and are fed to an electronic circuit (6). The center of gravity (S) of the combustion is determined from at least one current measured value for the engine operation, and the level of nitrogen oxide emissions is calculated from the value for the center of gravity (S) of the combustion, including the values for the recorded fuel quantity and air mass.

Abstract: A system controls the air-fuel ratio in an exhaust gas supplied from an internal combustion engine to a catalytic converter in order to keep an output voltage Vout of an O2 sensor disposed downstream of the catalytic converter at a predetermined target value Vop. In the system, the temperature of an active element of the O2 sensor is controlled at a predetermined temperature such that the output voltage of the O2 sensor at an inflection point of output characteristics thereof is substantially the same as the target value Vop.

Abstract: A control system for a plant, having an identifier and a controller. The identifier identifies model parameters of a controlled object model which is obtained by modeling the plant. The controller calculates a control input to the plant so that an output from the plant coincides with a control target value, using the identified model parameters. The controller calculates a self-tuning control input, using the model parameters identified by the identifier. The controller further calculates a damping control input according to the rate of change in the output from the plant or the rate of change in a deviation between the output from the plant and the control target value. The controller calculates the control input to the plant as a sum of the self-tuning control input and the damping control input.

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: 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&thgr;(k)) by multiplying an updating component d&thgr; of a model parameter vector by a correction coefficient KID, and adds the corrected updating vector to a preceding value &thgr;(k−1) of the model parameter vector, to thereby calculate a present value &thgr;(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: An apparatus for controlling the air-fuel ratio of an internal combustion engine to compensate for the effect of the dead times of an exhaust system including a catalytic converter, etc. 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 a dead time of an air-fuel ratio manipulating system comprising an internal combustion engine 1 and an engine-side control unit 7b, and sequentially estimates an output of an O2 sensor 6 after a total set dead time which is the sum of the above set dead times. The exhaust-side control unit 7a sequentially generates a target air-fuel ratio KCMD to converge the output of the O2 sensor 6 to a target value using the estimated value, and manipulates the air-fuel ratio of the internal combustion engine 1.

Abstract: An exhaust gas treatment system for an internal combustion engine includes a three-way catalyst and a NOx device located downstream of the three-way catalyst. The device is preconditioned for emissions reduction at engine operating conditions about stoichiometry by substantially filling the device with oxygen and NOx; and purging stored oxygen and stored NOx from only an upstream portion of the device, whereupon the upstream portion of the device operates to store oxygen and NOx during subsequent lean transients while the downstream portion of the device operates to reduce excess HC and CO during subsequent rich transients.

Abstract: An arrangement for correcting a signal (S) is suggested which contains a signal evaluation (28), which determines a characteristic variable of the input signal (US) of a controller (26) and/or the actuating variable (fr) of the controller (26) and/or at least one determined corrective signal (ora, fra) and/or at least one of their mean values (form) and compares the characteristic variable to at least one threshold value (SC1, SC2, SC3) and, when reaching or passing through at least one threshold value (SC1, SC2, SC3), an output signal (A) is made available at the end of the determination of the corrective signal (ora, fra).

Abstract: A system for controlling exhaust emissions produced by an internal combustion engine includes an engine controller having an emission manager configured to produce a base emission level cap command, corresponding to a maximum allowable emission level of the engine, as a function of at least altitude and ambient temperature. The emission manager may also include one or more auxiliary emission control devices (AECDs), and the emission manager is further operable in such cases to determine a maximum allowable emission level associated with each active AECD. A final emission level cap command is determined as a function of the base emission level cap command and the maximum allowable emission level associated with each active AECD. The emission manager is further operable to produce a protection state data structure that includes information relating to the operational status of each AECD.

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 fuel injection control apparatus of an internal combustion engine calculates a basic fuel injection amount according to a predicted in-cylinder intake air amount based on a predicted operating state quantity of the engine, calculates an actual in-cylinder intake air amount from the actual engine operating state quantity, and calculates a feedforward fuel injection amount by correcting an excess or shortage of fuel due to an error in the predicted in-cylinder intake air amount by using a feedforward correction amount. The control apparatus also calculates a feedback correction amount based on a detected air/fuel ratio and an air/fuel ratio of an air-fuel mixture determined by the feedforward fuel injection amount, and obtains a final fuel injection amount by correcting the feedforward fuel injection amount with the feedback correction amount.

Abstract: An exhaust gas analysis is to be performed, in a manner that is largely automatic, on motor vehicles having an on-board engine control and diagnostic system (OBD 2) and equipped with a diagnostic interface (3). To this end, control commands (15) are generated, preferably in an exhaust gas tester (12), and are transmitted via the diagnostic interface (3) to the engine control and diagnostic system (2). The engine control and diagnostic system (2), in accordance with the control commands (15), adjusts the operating states of the motor vehicle (1) that are prescribed for the exhaust gas analysis.

Abstract: The present invention is constituted so that an actual air-fuel ratio is detected by an air-fuel ratio sensor, a plant model representing a plant between a fuel injection valve and the air-fuel ratio sensor is sequentially identified to calculate parameters of the plant model, a control gain for calculating a feedback control amount is calculated using the calculated parameters, and the feedback control amount is calculated using the calculated control gain, wherein an absolute value of an input side parameter set on an input side of the plant model is limited to be a predetermined limit value or above, among the calculated parameters.

Abstract: A method is described for controlling fuel vapor purging and adaptive learning in a lean burn engine system. Fuel vapor purging is carried out during lean operating conditions to minimize impact on vehicle emissions, while adaptive learning is carried out during near stoichiometric conditions (oscillations around stoichiometry). This allows faster fuel vapor purging and additional adaptive learning opportunity.

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 method is described for controlling fuel vapor purging and adaptive learning in a lean burn engine system. Fuel vapor purging is carried out during lean operating conditions to minimize impact on vehicle emissions, while adaptive learning is carried out during near stoichiometric conditions (oscillations around stoichiometry). This allows faster fuel vapor purging and additional adaptive learning opportunity.

Abstract: There is provided a control system capable of realizing a highly robust control having a large margin of stability. The ECU of the control system controls the air-fuel ratio of exhaust gases emitted from the first to fourth cylinders. The ECU 2 estimates an estimation value of a detected air-fuel ratio, from a model defining a relation between the estimation value and a plurality of simulation values, and identifies an intake air amount variation coefficient such the estimation value becomes equal to a detected air-fuel ratio.

Abstract: A controller for controlling an air-fuel ratio of an engine is provided. An exhaust gas sensor is provided between an upstream catalyst disposed upstream of an exhaust pipe and a downstream catalyst disposed downstream of the exhaust pipe. A virtual exhaust gas sensor is configured downstream of the downstream catalyst. After an operating state in which the air-fuel is lean is cancelled, or after a fuel cut is cancelled, an estimated output of the virtual exhaust gas sensor is estimated based on a gas amount that contributes to reduction of the upstream and downstream catalysts and a detected output of the exhaust gas sensor provided between the upstream and downstream catalysts. The air-fuel ratio of the engine is controlled in accordance with the estimated output of the virtual exhaust gas sensor. Thus, the catalyst converter is appropriately reduced in accordance with a load of the engine and a state of the catalyst.

Abstract: When an output signal from an oxygen sensor is within a predetermined range including a value equivalent to a stoichiometric air-fuel ratio, the output signal is converted into air-fuel ratio data, to compute an air-fuel ratio control signal based on a deviation between the air-fuel ratio data and a target air-fuel ratio. When the output signal from the oxygen sensor is outside the predetermined range, it is judged based on the output signal whether an actual air-fuel ratio is richer or leaner than the target air-fuel ratio, to compute the air-fuel ratio control signal based on the judgment result.

Abstract: An arrangement for determining purge valve flow tolerance for use with evaporative emissions control systems includes developing an equation based on data relating purge valve duty cycle to flow, wherein the equation describes a flow curve with reference to a first axis and a second axis. The arrangement further includes using the equation as a base equation for flow, and adapting the equation for part-to-part tolerance as a function of an intercept point of the equation with respect to the first axis, wherein the first axis relates to duty cycle.

Abstract: A fuel injector (5) injects fuel to generate an air-fuel mixture that is burnt in the engine (1), and a sensor (16) detects an air-fuel ratio of the air-fuel mixture from an exhaust gas composition of the engine (1). A controller (11) calculates a dead time representing a lag between the air-fuel ratio variation of the air-fuel mixture and the air-fuel ratio variation detected by the sensor (16), and calculates an estimated state quantity by applying a dead time compensation according to Smith method and a disturbance compensation to the air-fuel ratio detected by the sensor (16). By determining an air-fuel ratio feedback correction amount based on the estimated state quantity applying a sliding mode control process, the response and stability of air-fuel ratio control is improved.

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

Abstract: A control apparatus for a motor vehicle is provided in which each of a plurality of output values of the vehicle varies depending upon a plurality of input control parameters for controlling the vehicle. The control apparatus changes the input control parameter or parameters so that each of the output values becomes substantially equal to a corresponding target output value. The control apparatus then determines adapted values of the input control parameters, based on values of the input control parameters obtained when each of the output values becomes substantially equal to the corresponding target output value or falls within a permissible adaptation range of the target output value.

Abstract: A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

Abstract: An engine crankshaft torque observer (10) and method of operation. An engine combustion process (14) is modeled (26) to develop modeled pressure estimates of combustion chamber pressures in engine cylinders according to certain engine inputs, such as fuel (20), EGR (22), and timing (24), that influence combustion chamber pressures. Kinematics (16) relating reciprocal motion of pistons in the engine cylinders to an engine crankshaft and engine friction (18) relating running friction of the engine to engine crankshaft rotation are also modeled (28; 30). A processor processes the certain engine inputs through the combustion process model to develop modeled pressure estimates which are processed through the kinematics model to develop modeled positive torque contribution due to combustion processes and through the friction model to develop modeled torque loss due to running friction.

Abstract: An air-fuel ratio detected by an air-fuel ratio sensor is estimated based on an estimation value of air-fuel ratio of an air-fuel mixture formed inside a cylinder, and based on an air-fuel ratio estimated as being detected by this air-fuel ratio sensor and the air-fuel ratio detected based on an output signal of the air-fuel ratio sensor, the estimation value of the cylinder air-fuel ratio is corrected and a fuel injection quantity is corrected based on the corrected cylinder air-fuel ratio.

Abstract: A control apparatus is provided for eliminating a step in a control input before and after switching between control processing based on one modulation algorithm selected from a &Dgr; modulation algorithm, a &Dgr;&Sgr; modulation algorithm, and a &Sgr;&Dgr; modulation algorithm and control processing based on a response specified control algorithm to avoid a sudden change in the output of a controlled object in the event of the switching.

Abstract: The invention relates to the diagnosis of an exhaust gas recycling valve, whereby, on switching off the internal combustion engine, the throttle valve and the exhaust recycling valve are closed and a check is made of whether a compression is detectable in the cylinders of the internal combustion engine, by means of an engine speed check within a segment. Should an engine speed difference (Ndiff) be greater than a threshold value (Ndiff SW), then an incompletely closed exhaust gas recycling valve is recognized, assuming a complete closure of the throttle valve.

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: A vehicle controller for controlling the air-fuel ratio of an engine is provided. In one embodiment, the controller comprises a first exhaust gas sensor provided downstream of the catalyst for detecting oxygen concentration of exhaust gas, a first decimation filter connected to the first exhaust gas sensor, and a control unit connected to the first decimation filter. The control unit determines a manipulated variable for manipulating the air-fuel ratio. The first decimation filter oversamples, low-pass filters and then downsamples the output of the first exhaust gas sensor. The first decimation filter can remove chemical noise from the output of the exhaust gas sensor. In another embodiment, a second decimation filter is connected to a second exhaust gas sensor provided upstream of the catalyst for detecting the air-fuel ratio of the exhaust gas. The second decimation filter overasmples, low-pass filters and then downsamples the output of the second exhaust gas sensor.

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

Abstract: There is provided a failure determination system for a variable-cylinder internal combustion engine which is capable of promptly and accurately carrying out failure determination of the valve-actuating system for cylinders for being made idle during a partial-cylinder operation mode. The failure determination system is capable of switching a cylinder operation mode between an all-cylinder operation mode in which all the cylinders are operated, and a partial-cylinder operation mode in which part of the cylinders are made idle. The failure determination system includes an ECU which executes a failure-determining operation mode for causing a valve-actuating mechanism to resume actuation of intake valves and exhaust valves of the part of the cylinders in a state in which fuel supply to the part of the cylinders is stopped, when the cylinder operation mode is shifted from the partial-cylinder operation mode to the all-cylinder operation mode.

Abstract: In an engine capable of continuously controlling an intake air quantity by varying an intake valve operating characteristic, an intake valve lift is sensed as well as an engine speed. Then, an intake air quantity is calculated in accordance with the engine speed and intake valve lift when an engine operating point is in a very low lift state.

Abstract: A method is presented for determining the fuel/air ratio in the individual cylinders (single cylinder lambda) of an internal combustion engine having a plurality of cylinders, whose exhaust gases mix together in a common exhaust gas pipe system, from the signal of an exhaust gas probe, whose mounting location lies in the common exhaust gas pipe system, with the aid of an invertible model for the intermixing of the exhaust gases at the mounting location of the exhaust gas probe. The method is distinguished in that, in the determination of the single cylinder lambda from the signal of the one exhaust gas probe evaluated with the aid of the inverted model, the rotational angle position of the exhaust gas probe at its mounting position is taken into consideration.

Abstract: Optimization control of a control system by improving evolution efficiency while retaining the advantages of genetic optimization is described. An optimizer for evolving control parameters affecting the characteristics of a control system uses actual user fitness evaluations of various control parameters or control parameters arranged as chromosomes. Parameters or chromosomes for a next generation are pre-processed using an evaluation model that estimates the fitness of new chromosomes before the chromosomes are presented to the user. Chromosomes that have a low estimated fitness value are modified or deleted, thereby reducing the number of low-quality chromosomes evaluated by the user.

Abstract: A powertrain controller of a vehicle provides fuel injection pulses based on gasoline operation. The pulse widths of the fuel injection pulses are modified with reference to air temperature, engine speed, and exhaust gas oxygen (EGO) content to control fuel injectors for an alternative fuel such as natural gas. The EGO content, based on alternative fuel operation, is detected and compared to a desired air-fuel ratio or desired fuel trims to provide error information that is used to adjust the modification of the pulse widths. In response to the error information, a neural network (as an example) dynamically adjust the pulse widths of the alternative fuel injection based on the weights of measured, detected engine speed, EGO, universal exhaust gas oxygen, or air temperatures. The engine operating on alternative fuel is provided with the proper mixture of alternative fuel and air to respond to various engine loads and meet emission standards.

Abstract: A manipulation variable generating unit 7 for generating a target air-fuel ratio KCMD to converge the output of an oxygen concentration sensor 5 disposed downstream of a catalytic converter 3 in an exhaust system E as a plant to a given target value has a plurality of estimators for generating data indicating estimated values of the output of the oxygen concentration sensor after a dead time of the exhaust system E or a total dead time which is the sum of the dead time of the exhaust system E and a dead time of a system comprising an engine control unit 8 and an internal combustion engine 1, according to respective different algorithms. The manipulation variable generating unit 7 generates the target air-fuel ratio KCMD according to an adaptive sliding mode control process using a value selected from the estimated values or a combined value representing a combination of the estimated values.

Abstract: A method of metering fuel with a fuel injector, in particular a fuel injector for fuel injection systems in internal combustion engines is described, having a piezoelectric or magnetostrictive actuator and a valve closing body which is operable by the actuator with a valve lift, cooperating with a valve seat face provided on a valve seat body to form a sealing seat. The valve lift may be adjusted variably as a function of a variable control signal triggering an actuator to produce a variable fuel flow at the sealing seat. To produce afitted curve, the fuel flow of the fuel jet sprayed by the fuel injector is measured as a function of the control signal to produce a fitted curve, and a predetermined fuel flow is set with the control signal by using the fitted curve.

Abstract: A device and a method are described for controlling an internal combustion engine, in which a control deviation and a governor are allocated to each cylinder of the internal combustion engine, each governor preselecting a cylinder-specific triggering signal on the basis of the allocated control deviation. Cylinder-specific actual values are ascertained on the basis of a signal from a sensor arranged in the exhaust train and are compared to a setpoint value. Triggering signals for the cylinder-individual control of the fuel quantity and/or air quantity are preselected on the basis of the comparison.

Abstract: An air-fuel ratio control apparatus for controlling an air-fuel ratio of an air-fuel mixture to be supplied to an internal combustion engine having a plurality of cylinders so that the air-fuel ratio coincides with a target air-fuel ratio. An air-fuel ratio is detected by an air-fuel ratio sensor provided at a position downstream of a joining portion of an exhaust manifold connected to the plurality of cylinders. Model parameters of a controlled object model defined by a relation between an air-fuel ratio detected by the air-fuel ratio sensor and a fuel supply amount parameter that specifies a fuel supply amount to each cylinder of the engine. A degree of differences between air-fuel ratios of air-fuel mixtures to be supplied to the plurality of cylinders is determined according to the identified model parameters.

Abstract: An air-fuel ratio control device for an internal combustion engine is provided with: an air-fuel ratio sensor; an O2 sensor; a device for setting a reference air-fuel ratio target value; a device for setting a target value of an output value of the O2 sensor; a device for obtaining an air-fuel ratio target value correction value; a device for obtaining a forcible air-fuel ratio oscillation width target value; a device for computing an air-fuel ration target value; a device for computing a correction value; a device for obtaining a forcible air-fuel ratio oscillating width injector driving time correction value; and a device for setting injector driving time.

Abstract: A canister includes an adsorbent, an air layer and an air hole. An ECU obtains a physical status quantity Mgair representing the vapor stored state of the air layer, a physical status quantity Mgcan representing the fuel vapor stored state of the adsorbent, and a physical status quantity Fvptnk representing the vapor generating state in the fuel tank. The ECU then estimates a total vapor flow rate Fvpall purged to an intake system of the engine by using a physical model related to the vapor behaviors. The physical model is based on the obtained physical status quantities. The ECU corrects the fuel supply amount to the engine according to the estimated flow rate Fvpall. As a result, the air-fuel ratio feedback control is readily prevented from being influenced by the fuel vapor purging.

Abstract: There is provided an exhaust emission control apparatus for an internal combustion engine, which includes a failure diagnostic device that fixes three parameters selected from the group consisting of the engine speed detected by an engine speed detecting device, the fuel quantity controlled by a fuel quantity control device, the ignition timing controlled by an ignition timing control device, and the intake air volume controlled by an intake air control device at respective predetermined values, and finds values of the remaining one parameter, and compares the values of the remaining one parameter with each other to determine whether an exhaust flow control apparatus has failed or not.

Abstract: An air mass is supplied to the combustion chambers by an intake manifold (12) in an internal combustion engine (10). An underpressure store (18) of a servo system (20) can be subjected to an underpressure via this intake manifold (12). The air mass flow in the inlet region (30) of the intake manifold (12) is determined by a sensor (32) and is supplied to an electronic control unit (26) for the fill computation. The actuation of the servo system (20) is detected and the determined air mass flow is corrected with or directly after a detected actuation of the servo system (20).