Abstract: An air-fuel ratio controlling apparatus includes an internal pressure detector for detecting an internal pressure of a combustion chamber of the engine. The apparatus estimates a motoring pressure of the engine and determines a start-of-combustion time, a time point when a difference between the internal pressure and the motoring pressure exceeds a predetermined value in a compression stroke and a combustion stroke of the engine. Firing delay for each cylinder is calculated from as a duration from sparking to the start-of-combustion time. Air-fuel ratio of each cylinder is estimated based on the firing delay and fuel injection amount for each cylinder is calculated to make the air-fuel ratio of plural cylinders uniform.

Abstract: An engine control system and an engine control method are disclosed wherein a combustible component quantity of intake air, reflecting combustible components in a crankcase of an engine, is calculated on the basis of a deviation between basic injection quantity for a target rotational speed to be attained and an actual injection quantity during operation to perform idling stabilizing control. A ratio of the combustible components mixed to engine oil is calculated on the basis of the combustible component quantity of intake air and a temperature of engine oil. During a status of the engine with a given temperature of engine oil and the mixing ratio of the combustible components in engine oil, a fuel injection affect eliminating operation is executed.

Abstract: A target air-fuel ratio setting part has a sub-feedback part, a target air-fuel ratio enriching part, and a target air-fuel ratio changeover part. The sub-feedback part variably sets a target air-fuel ratio upstream of a catalyst on the basis of a detection signal of an O2 sensor provided downstream of the catalyst. The target air-fuel ratio changeover part uses, as the target air-fuel ratio, a rich target air-fuel ratio which is set by the target air-fuel ratio enriching part on conditions such that the target air-fuel ratio set by the sub-feedback part is rich. A cylinder-by-cylinder air-fuel ratio estimation part calculates a cylinder-by-cylinder air-fuel ratio on the basis of a detection value of an air-fuel ratio sensor and the target air-fuel ratio.

Abstract: In a method and apparatus for the cylinder-specific determination and control of a fuel injection quantity for a multi-cylinder internal combustion engine, the exhaust gas pressures of the cylinders of the internal combustion engine is recorded on a time-resolved, i.e. crankshaft angle-resolved, basis, and an exhaust gas pressure is calculated therefrom individually for each cylinder and used to determine the fuel quantity injected into the corresponding cylinder. In a comparison with a desired value the cylinder-specific actual fuel injection quantity error is then determined and used to set a corrected quantity of fuel to be injected into the corresponding cylinder.

Abstract: An air-fuel ratio of each cylinder is estimated on the basis of a detection value of an air-fuel ratio sensor disposed in an exhaust confluent portion. An air-fuel ratio correction quantity is computed on the basis of the estimated air-fuel ratio of each cylinder. The air-fuel ratio of an air-fuel mixture to be supplied to each cylinder is corrected on the basis of the cylinder air-fuel ratio correction quantity to reduce a variation in the air-fuel ratio between the cylinders. When a state in which the cylinder air-fuel ratio correction quantity or its learning value of any cylinder is outside a specified range continues for a while during a period in which this cylinder air-fuel ratio control is performed, a combustion is stopped for the cylinder outside the specified range and the cylinder air-fuel ratio control is continuously performed only for other normal cylinders.

Abstract: In a method of controlling an internal combustion engine having a common rail fuel injection system including individual fuel storage chambers, wherein the pressure pattern of the fuel supplied to each injector can be determined and actual and virtual fuel injection ends and fuel injection begins are determined, the deviations from the desired fuel injection ends and from the fuel injection begins are calculated and the injectors are evaluated on the basis of the deviations and further control of the internal combustion engine is based on an evaluation of the fuel injectors.

Abstract: The present invention relates to an operating method for a piston engine (1), in particular in a motor vehicle. The piston engine comprises a plurality of cylinders (6) having intake valves (9), exhaust valves (10), combustion chambers (7), and pistons (8); a fresh gas system (2) that contains an extra valve (13) assigned to the cylinders (6), a fuel system (5) and an exhaust system (4). To improve the smooth running of the piston engine (1), a fuel/fresh gas ratio in the exhaust gas is measured selectively for each cylinder in the exhaust system (4). The fuel system (5) is operated in such a way that it supplies the same amount of fuel to all combustion chambers (7) in steady-state operation of the piston engine (1).

Abstract: The amount of fuel to be injected in each cylinder of a multi-cylinder spark ignition internal combustion engine may be determined with enhanced precision if the fuel injection durations are determined as a function of the sensed mass air flow in all the cylinders of the engine, instead of considering only the air flow in the same cylinder. This finding has led to the realization of a more efficient approach of controlling a multi-cylinder spark ignition internal combustion engine and a feedforward control system.

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: In a multi-cylinder engine, to compute the air-fuel ratio of each cylinder by an air-fuel ratio sensor disposed in an exhaust pipe, a cylinder is determined by a crank angle detected by a crank angle sensor. A deviation in the air-fuel ratio of each cylinder is detected on the basis of the output signal of the air-fuel ratio sensor disposed in the exhaust pipe and the forcibly changed quantity of the air-fuel ratio.

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: 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: A control apparatus for an internal combustion engine including a plurality of cylinders and a changing mechanism the changes a timing at which an intake valve provided for each of the cylinders closes, comprising: a control portion that controls the changing mechanism so that the intake valve closes at a timing within a predetermined range from a bottom dead center; and a detection portion that detects at least one of an air-fuel ratio of each of the cylinders and a value corresponding to the air-fuel ratio when the changing mechanism is controlled so that the intake valve closes at the timing within the predetermined range from the bottom dead center.

Abstract: The invention provides an engine controller, which can determine a deterioration mode (gain deterioration or response deterioration) of an air/fuel (A/F) ratio sensor, can detect a degree of the deterioration with high accuracy, and can optimize A/F ratio feedback control in accordance with the diagnosis result. The controller includes a unit for computing frequency response characteristics in a range from an A/F ratio adjusting unit to the A/F ratio sensor, and it diagnoses the A/F ratio sensor based on a gain characteristic and a response characteristic given by the computed frequency response characteristics. In accordance with the diagnosis result, parameters (P- and I-component gains) used in A/F ratio feedback control (PI control) are optimized.

Abstract: A method for calculating transient fuel wall wetting characteristics of an operating engine is described. The method accounts for cylinder valve deactivation of cylinders in the engine in calculating the dynamic fueling compensation. In one example, fuel vaporization effects from fuel puddles in deactivated cylinders are considered when calculating the fueling compensation for active cylinders.

Abstract: A method for operating a marine engine uses four valves to control the flow of secondary air that is inducted into each of the cylinders of an engine. An oxygen sensor is disposed in an exhaust passage downstream from the cylinders and upstream from a catalytic converter. A carburetor is calibrated to provide a richer than stoichiometric air/fuel ratio so that inducted secondary air through the valves associated with each cylinder can result in a stoichiometric ratio of air flowing into each cylinder. The cylinders are each provided with their own valve in order to allow the air/fuel ratios to be equalized for each cylinder regardless of the configuration and geometry of the intake manifold and its associated conduits.

Abstract: An internal combustion engine (1) generates power by burning a mixture of fuel and air in each combustion chamber 3. The internal combustion engine 1 is provided with an in-cylinder pressure sensor (15) disposed in each combustion chamber (3) and an ECU (20). The ECU (20) calculates control parameters at two predetermined points, each of which is a product of an in-cylinder pressure detected by the in-cylinder pressure sensor (15) and a value obtained by exponentiating an in-cylinder volume at the timing of detecting the in-cylinder pressure with predetermined index, as well as calculates a correction value of a fuel injection quantity based upon a difference in the control parameter between the two predetermined points. One of the two predetermined points is set after an intake valve (Vi) opens and before an ignition plug (7) ignites, and the other is set after the ignition plug (7) ignites and before an exhaust valve (Ve) opens.

Abstract: A control system for an internal combustion engine, which is capable of optimally controlling fuel injection by an injector even in a transient state of the engine. An ECU 2 of the engine provided with an EGR system (14) controls the amount (Fa) of air drawn into cylinders (3a) via an intake system (4). An air flow sensor (27) detects the intake air amount (Fa). The ECU 2 estimates a flow rate (Fe_hat) of EGR gases according to response delay of recirculation of the EGR gases by the EGR system (14), estimates the amount (mo2) of oxygen existing in the cylinder (3a), based on the detected intake air amount (Fa) and the estimated flow rate (Fe_hat) of the EGR gases, determines a fuel injection parameter (Q*) based on the engine speed (Ne) and the estimated in-cylinder oxygen amount (mo2), and controls an injector (6) based on the determined fuel injection parameter (Q*).

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: 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 method for calculating transient fuel wall wetting characteristics of an operating engine is described. The method accounts for cylinder valve deactivation of cylinders in the engine in calculating the dynamic fueling compensation. In one example, fuel vaporization effects from fuel puddles in deactivated cylinders is considered when calculating the fueling compensation for active cylinders.

Abstract: An apparatus, system, and method are disclosed for minimizing NOx in exhaust gasses. The apparatus includes an ionization module configured to at least partially ionize an exhaust gas of an engine. A characterization module is configured to identify NOx ions present in the ionized exhaust gas, and an engine control module is configured to communicate with the characterization module and modify engine parameters in response to identified NOx levels. The system includes an internal combustion engine having an intake manifold configured to deliver an air-fuel mixture to at least one combustion chamber, an exhaust manifold configured to receive exhaust gasses from the combustion chamber, and the apparatus. The method includes controlling an ionization module configured to at least partially ionize an exhaust gas of an engine, identifying NOx ions present in the ionized exhaust gas, and modifying one or more selected engine parameters in response to identified NOx levels.

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

Abstract: 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 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: An air-fuel ratio deviation calculated by an air-fuel ratio deviation calculation part is inputted to a cylinder-by-cylinder air-fuel ratio estimation part. A cylinder-by-cylinder air-fuel ratio is estimated in the cylinder-by-cylinder air-fuel ratio estimation part. In the cylinder-by-cylinder air-fuel ratio estimation part, attention is paid to gas exchange in an exhaust collective part of an exhaust manifold, and a model is created. In this model, a detection value of an A/F sensor is obtained by multiplying histories of the cylinder-by-cylinder air-fuel ratio of an inflow gas in the exhaust collective part and histories of the detection value of the A/F sensor by specified weights respectively and by adding them. The cylinder-by-cylinder air-fuel ratio is estimated on the basis of the model.

Abstract: A method and system for monitoring performance of an internal combustion engine equipped with individually actuated valve control mechanisms, such as a two-step finger-follower rocker-arm assembly, using a strategy that identifies cylinder-to-cylinder variations, is disclosed. The method and system preferably include monitoring engine operating conditions, based upon input from an exhaust gas sensor and engine sensors, and determining an engine operating point. Individual cylinder fueling modifiers are determined, each corresponding to one of the cylinders at the determined engine operating point, based upon input from the exhaust gas sensor. It is determined that the each individually actuated valve control mechanism is operating properly when a difference between the individual cylinder fueling modifier and a predetermined individual cylinder fueling modifier, each said modifier determined for the corresponding cylinder at the determined engine operating point, is less than a predetermined difference.

Abstract: A system and method to control engine valve timing to improve air-fuel control in an engine with valves that may be deactivated. Valves that may be deactivated are controlled in a manner to improve detection of individual cylinder air-fuel ratios.

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

Abstract: An engine misfire detection system includes a database of engine fingerprints, each fingerprint corresponding to a known misfire condition. A technician uses software to compare the fingerprints in the database to an engine with a combustion inefficiency to determine which cylinder in the engine has the combustion inefficiency. The fingerprints are generated by evaluating an output from a lambda sensor and a timing reference. An alternate embodiment associates oxygen sensors with each of the cylinders in the engine and infers combustion inefficiency when a given sensor detects a peak in the amount of oxygen.

Abstract: A generic technique for the detection of air-fuel ratio (or torque) imbalances in a 4-cylinder engine equipped with either a production oxygen sensor or a wide-range A/F sensor (or a crankshaft torque sensor) is developed. The method is based on a novel frequency-domain characterization of pattern of imbalances and its geometric decomposition into four basic templates. Once the contribution of each basic template to the overall imbalances is computed, templates of opposite direction are imposed to restore air-fuel ratio (or torque) balance among cylinders. At any desired operating condition, elimination of imbalances is achieved within few engine cycles. The method is applicable to current and future engine technologies with variable valve actuation, fuel injectors and/or individual spark control.

Abstract: The individual cylinder air to fuel ratio of an internal combustion engine varies due to the fact that the intake manifold cannot distribute airflow into the individual cylinders evenly. This feature of the present invention utilizes minimum timing for best torque MBT timing criterion provided by the ionization signals or by the in-cylinder pressure signals to balance the air to fuel ratios of the individual cylinders. The control method of the present invention comprises: calculating a mean timing coefficient, calculating a timing coefficient error, integrating the minimum timing for best torque timing coefficient error, calculating a raw fuel trim coefficient, resealing the raw fuel trim coefficient, updating a feedforward look-up table based upon the current engine operating conditions, and calculating a final fueling command.

Abstract: The invention concerns a method for operating an internal combustion engine (1, 18) having a plurality of combustion chambers (4), in the case of which the combustion chambers (4) are charged with fuel and air or with a fuel/air mixture. In order to prevent torque jumps from occurring when cylinders (3) of the internal combustion engine (1, 18) are shut down and when switching the operating mode of direct-injection internal combustion engines (18), it is proposed that the charging of the combustion chambers (4) with fuel and air or with a fuel/air mixture be controlled individually via open-loop or closed-loop control for each combustion chamber (4). In the case of a direct-injection internal combustion engine (18), a certain number of combustion chambers (4) can be operated with homogenous-charge operation, and the remaining combustion chambers (4) can be operated with stratified-charge operation in accordance with the level of torque required.

Abstract: An air-fuel ratio control apparatus for a multiple cylinder engine, having catalytic converters and air-fuel ratio sensors in an exhaust manifold, comprises exhaust air-fuel ratio variation determining means which determines a variation in exhaust air-fuel ratio between one cylinder and other cylinders in one cylinder group when an exhaust air-fuel ratio on one of the rich side and the lean side with respect to a predetermined value is detected as to the one cylinder twice in succession, an exhaust air-fuel ratio on the other one of the rich side and the lean side from the exhaust air-fuel ratio of the one cylinder, and combustion air-fuel ratio control means which feedback-compensates the quantity of fuel injected into the one cylinder, and feedback-compensated the quantity of fuel injected into the other cylinder in a direction opposite to the direction in which the quantity of fuel injected into the one cylinder is compensated.

Abstract: A system for controlling fuel injection in an engine. The engine includes an intake passage, an intake passage injector, a cylinder having a combustion chamber, and a cylinder injector for injecting a target amount of fuel into the combustion chamber. The system includes a controller for controlling the intake passage and cylinder injectors to permit fuel injection, each with an injection ratio, while said engine operates in a condition in which said engine permits fuel injection from said cylinder injector, a sensor for sensing the amount of fuel injected from the cylinder injector, a detector for detecting the difference between the target injection amount and the amount of fuel injected and an adjuster for adjusting the injection ratio based on the result of the detection by the detector so that the intake passage injector performs fuel injection together with the fuel injection performed by the cylinder injector.

Abstract: A method for cylinder-specific adjustment of the injection quantity in internal combustion engines is provided, as well as an internal combustion engine with which the method may be implemented. The injection quantity per cylinder selected by the engine management is changed in a controlled manner following an orthogonal experimental plan. The effect of this change on the excess-air factor “lambda” is analyzed, allowing the formulation of a regression polynomial to determine necessary corrections of the injection quantity, which injection quantity is adjustable individually for each cylinder with a view to optimum combustion.

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: In an air-fuel ratio feedback control for an engine, a cylinder-by-cylinder variation value is calculated for each cylinder based on changes of intake pipe pressure detected by an intake pipe pressure sensor, or the like, and a fuel injection amount or the like is corrected for each cylinder based on the variation value. When the variation is large during an engine operation, or until the variation correction is completed, it is determined that the output of an exhaust gas sensor will be disturbed by the variation and an air-fuel ratio feedback correction amount will be disturbed. Therefore, a control gain of the air-fuel ratio feedback control is changed to a value smaller than a normal value, or the feedback control is inhibited.

Abstract: A method and a device for controlling the drive unit of a vehicle. In this context, at least one correction variable of the drive unit is set as a function of a setpoint value for an output variable of the drive unit, and as a function of a setpoint correction time, which represents the time in which the setpoint value for the output variable must be attained.

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 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: 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 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 method for cylinder-specific adjustment of the injection quantity in internal combustion engines is provided, as well as an internal combustion engine with which the method may be implemented. The injection quantity per cylinder selected by the engine management is changed in a controlled manner following an orthogonal experimental plan. The effect of this change on the excess-air factor “lambda” is analyzed, allowing the formulation of a regression polynomial to determine necessary corrections of the injection quantity, which injection quantity is adjustable individually for each cylinder with a view to optimum combustion.

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: 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: A control system of an internal combustion engine is comprised of an operation angle adjustment mechanism which continuously varies an operation angle of intake valves of the engine, an air-fuel ratio detector which detects an exhaust parameter indicative of air-fuel ratio information, and a control unit which are coupled to the operation angle adjustment mechanism and the air-fuel ratio detector. The control unit feedback-controls an air-fuel ratio of the engine on the basis of the exhaust parameter and corrects the operation angle on the basis of the exhaust parameter.

Abstract: An air-fuel ratio control system for an internal combustion engine is provided which is capable of appropriately and promptly correcting variation in the air-fuel ratio of a mixture between cylinders and realizing a very robust air-fuel ratio control, even with a complicated exhaust system layout. The ECU of the system for control of the air-fuel ratio of a mixture supplied to first to fourth cylinders determines a feedback correction coefficient, calculates a cylinder-by-cylinder variation coefficient indicative of variation in air-fuel ratio between the cylinders, based on a model parameter of a model having the input of the feedback correction coefficient thereto and the output of the detected air-fuel ratio, identifies the model parameter, corrects a basic fuel injection amount such that the cylinder-by-cylinder variation parameter converges to a moving average value thereof, thereby calculating a cylinder-by-cylinder final fuel injection amount.

Abstract: The invention relates to an internal combustion engine comprising a fuel injector (2) for each cylinder; a fuel injection control unit (4) for controlling fuel injection quantity and a piston (5) in each cylinder whose compression action causes a mixture of air and fuel to be ignited. The engine is further provided with inlet and outlet valves (6, 7) and various sensors (12-16) for measuring various engine operating parameters. During compression ignition mode, the control unit (4) is arranged to select a &lgr;-value from a map stored in the control unit, which value is a function of engine load and engine speed, and to compare the actual &lgr;-value with the selected &lgr;-value; whereby the control unit is arranged to adjust the intake manifold pressure as a function of the difference between the said &lgr;-values in order to obtain the selected &lgr;-value. The invention further relates to a method for operating the engine and a computer readable storage device (4).

Abstract: In an air-fuel ratio feedback control for an engine, a cylinder-by-cylinder variation value is calculated for each cylinder based on changes of intake pipe pressure detected by an intake pipe pressure sensor, or the like, and a fuel injection amount or the like is corrected for each cylinder based on the variation value. When the variation is large during an engine operation, or until the variation correction is completed, it is determined that the output of an exhaust gas sensor will be disturbed by the variation and an air-fuel ratio feedback correction amount will be disturbed. Therefore, a control gain of the air-fuel ratio feedback control is changed to a value smaller than a normal value, or the feedback control is inhibited.