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: There is provided a fuel injection control apparatus for an internal combustion engine, which includes an O2 sensor and a feedback controller that performs a feedback control of the injection quantity of fuel to the internal combustion engine. The feedback controller performs the feedback control such that the feedback gain set at the time of starting the feedback and which gives operation constant for performing feedback until the air/fuel ratio becomes optimum, is set larger than the feedback gain set for the normal operation period and which gives operation constant for performing feedback in a stable state, and the feedback gain is changed between the control start time and the normal operation period, thereby reducing the time required to attain a stable feedback state and therefore quick transition to the stable state upon starting the control and thus enabling effective reduction of harmful components in exhaust gas.

Abstract: A fuel injection apparatus for an engine includes various sensors (10), a control unit (20) and an injector (30). The control unit (20) includes a basic fuel injection quantity arithmetic means for determining a basic injection quantity conforming to the operation state, a data map (21) holding data for determining a regulating correction quantity in accordance with specific engine parameters (Th, Ne), and a correcting arithmetic means for determining the injection quantity by correcting the basic injection quantity with the data. The data map (21) includes plural areas for holding the data. Intermediate areas holding no data are provided between two adjacent data holding areas. The correcting arithmetic means includes a search means for determining interpolation data corresponding to the intermediate area through interpolation based on the data stored in two adjacent areas. The injection quantity for the intermediate area is determined by correcting the basic injection quantity with the interpolation data.

Abstract: A control system for a throttle valve actuating device is disclosed. The throttle valve actuating device includes a throttle valve of an internal combustion engine and an actuator for actuating the throttle valve. The control system includes a predictor for predicting a future throttle valve opening and controls the throttle actuating device according to the throttle valve opening predicted by the predictor so that the throttle valve opening coincides with a target opening.

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 described a method of controlling injection in a vehicle internal combustion engine, wherein the intake air flow and exhaust lambda are measured to estimate the fuel quantity actually injected into the engine and perform a closed-loop control whereby the estimated fuel quantity is made to substantially equal the nominal fuel quantity calculated to meet vehicle user requirements. More specifically, the difference between the nominal fuel quantity and the estimated fuel quantity is used to calculate a correction factor by which to correct the nominal fuel quantity.

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: A generic technique for the detection of air-fuel ratio or torque imbalances in a three-cylinder engine equipped with either a current production oxygen sensor or a wide-range A/F sensor, or a crankshaft torque sensor, is disclosed. The method is based on a frequency-domain characterization of pattern of imbalances and its geometric decomposition into two basic templates. Once the contribution of each basic template to the overall imbalances is computed, templates of same magnitude of imbalances but 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: A control system for controlling an engine (10) of an automotive vehicle has an air charge sensor (47) generating a first signal indicative of an air charge, a purge flow valve (74) generating a second signal indicative of purge flow. A controller (42) is coupled to the air charge sensor and the purge flow valve. The controller (42) is configured to determine a first amount of fuel to deliver to the cylinder based on the first signal and a desired air-fuel ratio. The controller is configured to calculate a first air-fuel ratio change value based on the first signal and is configured to calculate a second air-fuel ratio change value based on the second signal. The controller is configured to deliver a second amount of fuel to the cylinder based on the first amount of fuel and the first and second air-fuel ratio change values.

Abstract: A control system for controlling an engine (10) of an automotive vehicle has an air charge sensor (47) generating a first signal indicative of an air charge, a purge flow valve (74) generating a second signal indicative of purge flow. A controller (42) is coupled to the air charge sensor and the purge flow valve. The controller (42) is configured to determine a first amount of fuel to deliver to the cylinder based on the first signal and a desired air-fuel ratio. The controller is configured to calculate a first air-fuel ratio change value based on the first signal and is configured to calculate a second air-fuel ratio change value based on the second signal. The controller is configured to deliver a second amount of fuel to the cylinder based on the first amount of fuel and the first and second air-fuel ratio change values.

Abstract: A fuel injection is carried out as n split injections. Each of injection quantities is defined by dividing an injection quantity into n fuel injections. A FCCB correction and an ISC correction are carried out while n split injection cycles are performed. A value obtained by adding up an FCCB correction for each injection cycle and an ISC correction for each injection cycle is updated and stored as a learned injection quantity. The learned injection quantity is calculated as an injection quantity correction for each cylinder to be added to a command injection quantity for each injection cycle.

Abstract: There is provided a fuel injection control apparatus for an internal combustion engine, which includes an O2 sensor and a feedback controller that performs a feedback control of the injection quantity of fuel to the internal combustion engine. The feedback controller performs the feedback control such that the feedback gain set at the time of starting the feedback and which gives operation constant for performing feedback until the air/fuel ratio becomes optimum, is set larger than the feedback gain set for the normal operation period and which gives operation constant for performing feedback in a stable state, and the feedback gain is changed between the control start time and the normal operation period, thereby reducing the time required to attain a stable feedback state and therefore quick transition to the stable state upon starting the control and thus enabling effective reduction of harmful components in exhaust gas.

Abstract: An engine control system includes an adaptive bias sub-system (100) that generates bias values for controlling the air-fuel ratio. The sub-system (100) includes an integral controller (118) that reads an error signal from a post-catalyst switching EGO sensor (112). A plurality of noise isolation integrators (122) filter any noise resulting from a particular engine operating condition (e.g. acceleration, deceleration, idling) from the integrated error signal and stores the signal in a corresponding keep-alive memory (124) as a bias value for that engine operating condition. In a preferred embodiment, the post-catalyst feedback loop includes a gated proportional controller 116 that turns on for a limited period of time after the post-catalyst switching EGO sensor (112) switches states.

Abstract: An O2 amount in the intake air is determined based on a fresh air and an EGR gas. A consumed O2 amount is determined with a command injection amount Qr. Then, the consumed O2 amount is subtracted from the O2 amount in the intake air to obtain an exhaust O2 amount. An exhaust O2 concentration is estimated based on the exhaust O2 amount. According to the invention, the system is not affected by a delay for the exhaust gas to reach an O2 sensor and a delay of the chemical reaction in the O2 sensor. Therefore, the exhaust O2 concentration can be highly precisely estimated compare to the case in which the exhaust O2 concentration is detected by the O2 sensor.

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: The present invention is constituted so that an actual air-fuel ratio is detected by an exhaust state by an air-fuel ratio sensor, parameters of transfer functions are calculated while sequentially identifying a plant model representing a plant between a fuel injection valve and the air-fuel ratio sensor by the transfer functions, a feedback control amount of said air-fuel ratio control signal is set using the parameters of the identified pant model, an offset correction amount of the air-fuel ratio control signal is set, and the plant model is identified using a valve obtained by adding the offset correction amount to the feedback control amount, and the actual air-fuel ratio.

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: A control system for an internal combustion engine having at least one control device that affects an air-fuel ratio of an air-fuel mixture to be supplied to the engine, is disclosed. An air-fuel ratio correction coefficient is 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. An air-fuel ratio affecting parameter indicative of a degree of influence that an operation of the control device exercises upon the air-fuel ratio, is calculated. A correlation parameter which defines a correlation between the air-fuel ratio correction coefficient and the air-fuel ratio affecting parameter is calculated using a sequential statistical processing algorithm. A learning correction coefficient relating to a change in characteristics of the control device is calculated using the correlation parameter. The air-fuel ratio is controlled using the air-fuel ratio correction coefficient and the learning correction coefficient.

Abstract: The invention relates to a method for limitation of at least one controllable operating parameter that can cause ageing of at least one component or one material in connection with an engine. The method includes the steps of determination of a maximum limit value allowed regarding the operating parameter and control of the engine so that the limit value is not exceeded, thereby limiting ageing of the component or material. The invention includes continuous determination of a measure that corresponds to the degree of impairment of the component that depends on ageing, wherein said determination of the limit value is made depending on the measure. The invention also relates to an arrangement for accomplishing this method.

Abstract: An internal combustion engine that utilizes a control system for improving operation of the engine under a variety of conditions. The control system includes a sensor that directly senses a combustion condition. The output of the sensor is utilized in adjusting the air-fuel mixture delivered to each cylinder to optimize engine operation.

Abstract: An engine for a marine vehicle includes a controller having a predetermined map defining a relationship between a fuel injection parameter and an engine operation characteristic. Additionally, the controller includes at least one compensation factor for adjusting the fuel injection parameter. The compensation value is derived from data recorded during a test of the engine. The compensation factor is used during the normal operation of the engine to achieve a predetermined air/fuel ratio.

Abstract: A device for controlling the air-fuel ratio of an internal combustion engine, which is capable of highly precisely finding learning correction values in an open-loop operation region by using an ordinary air-fuel ratio sensor. The device comprises means 22 for correcting the amount of fuel depending upon a target air-fuel ratio AFo, means 23 for determining the conditions CF for controlling the air-fuel ratio feedback of the internal combustion engine depending upon the operation conditions, means 24 for controlling the air-fuel ratio feedback in the feedback operation region, and means 25 for finding learning correction values Zs for every operation region based on the control quantity AFc of the feedback control means, wherein the feedback control operation is executed in the open-loop operation region, and the learning correction values in the open-loop operation region are found during the feedback control operation that lasts only temporarily.

Abstract: Gas containing fuel vapor is purged as purge gas from a canister to an intake passage through a purge line. An ECU computes purge flow rate, which is the flow rate of the purge gas, and computes vapor concentration, which is the concentration of the fuel vapor contained in the purge gas. The ECU obtains a concentration correction value in accordance with the rate of change of the computed purge flow rate. The ECU correct the computed vapor concentration by using the concentration correction value and by taking into consideration of the time at which the purge flow rate is computed and the time at which purge gas having the computed flow rate is drawn into the combustion chamber. The ECU sets the fuel supply amount in accordance with the computed purge flow rate and the corrected vapor concentration. As a result, the accuracy of the air-fuel ratio control during purging is improved.

Abstract: A method and apparatus for automatic tuning of fuel injected engines includes an air-fuel ratio sensor, a load device for controlling engine RPM, a digital computer and a display device. The digital computer displays a plurality of throttle positions to an operator who sets the throttle of said engine to correspond to said display of throttle position. The digital computer varies the engine RPM over the operating range of the engine to determine corresponding map values for storage in an injector signal modifier.

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: Even when a reaction delay time of an A/F ratio detection device changes, an A/F ratio controller prevents an A/F ratio feedback control from being disturbed. The controller is programmed to calculate an A/F ratio feedback coefficient by proportional term control and integration term control, and to set length of time for said integration term to be carried out in accordance with an operating state of the engine. It is programmed to calculate the integration term based on the set time and to set a proportional term for shifting said A/F ratio feedback coefficient. It is further programmed to detect a deviation between a first A/F ratio feedback coefficient before the integration term is carried out and a second A/F ratio feedback coefficient after the integration term is carried out and the coefficient is shifted by the proportional term set by said means for setting the proportional term. Based on the detected deviation, the length of time for the integration term to be carried out is corrected.

Abstract: An exemplary embodiment of the invention is directed to a control system for controlling an engine. The control system includes a schedule memory for storing a schedule representing target values for a controlled variable. The control system also includes a processor coupled to the schedule memory. The processor receives a reference input and generates a control signal in response to the reference input and the schedule. The schedule in the schedule memory may be updated to account for engine deterioration so that accurate control is performed. Another exemplary embodiment of the invention is a method for controlling an engine. The method includes updating a schedule to account for deterioration of the engine.

Abstract: This invention is a method and system for a hybrid electric vehicle adaptive fuel strategy to quickly mature an adaptive fuel table. The strategy adaptively alters the amount of fuel delivered to an internal combustion engine to optimize engine efficiency and emissions using engine sensors. Before the adaptive fuel strategy is permitted, an engine “on” idle arbitration logic requires the HEV to be in idle conditions, with normal battery state of charge, normal vacuum in the climate control and brake system reservoir; and, the vapor canister not needing purging. The strategy orders the engine throttle to sweep different airflow regions of the engine to adapt cells within the adaptive fuel table. In the preferred configuration, a generator attached to the vehicle drive train, adds and subtracts torque to maintain constant engine speed during the throttle sweeps.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine has an oxygen sensor, a first operational means, a second operational means, a maximum and minimum setting means, an air-fuel ratio correcting means, a maximum and minimum magnifying means, and a maximum and a minimum returning means. When an air-fuel ratio learning value calculated by the second operational means reaches a maximum or minimum limit set by the maximum and minimum setting means, an air-fuel ratio feedback correction value is measured for a predetermined time. The maximum and minimum magnifying means increases the maximum or decreases the minimum limit of the air-fuel learning value in response to a deviation of fuel injection amount from a fuel injection amount requested for maintaining a target air-fuel ratio.

Abstract: A method is presented for controlling fuel tank pressure in an internal combustion engine. The engine, the fuel tank and the carbon canister are connected in a three-way connection. The engine can be selectively isolated by a purge control valve, and the fuel tank can be selectively isolated by a fuel tank control valve. The operation of both valves is coordinated by an electronic engine controller. By isolating the fuel tank during the carbon canister purge, better estimate of the fuel fraction flowing into the engine can be achieved, thereby improving fuel economy.

Abstract: The invention concerns a method for automatic adaptation of an injection engine by a computer connected to sensors. The sensors supply an engine filling parameter. An oxygen probe in the exhaust gases, defines, at each adapting cycle, a new line of control magnitude based on the filling parameter and using new coefficients computed from coordinates of two points. Corresponding corrected values of the control magnitude from a working line are filtered and stored during a preceding cycle. One of the two points is acquired previously, and then in adopting a new working line, an intermediate line between the new line and the previous working line is used. The invention is applicable to injection engine control.

Abstract: A fuel injection control system for a direct injection-spark ignition type of engine forcibly turns off appliances as an external engine load while the engine operates in a stratified charge combustion mode after warming-up so as thereby to fix a quantity of intake air approximately constant and concurrently feedback controls a quantity of fuel injection according to an engine speed so as to bring the engine speed into a specified idling speed. An actual quantitative variation of fuel injection is learned on the basis of a feedback correction value of the quantity of fuel injection for each of predetermined fuel injection timings which are changed from a timing for minimum advance for best torque (MBT) so as to correspond to injection pulse widths within a region adopted for a micro-flow characteristic of the fuel injector.

Abstract: A purge control system of an engine has a purge valve which is opened and closed in accordance with the state of operation of the engine so as to establish a purge-on mode and a purge-off mode, thereby controlling purge rate which is the flow rate of the purge gas supplied to said engine. An air-fuel ratio feedback controller performs feedback control of the air-fuel ratio based on an output signal from an air-fuel ratio sensor and a purge density which is computed as the concentration of the evaporated fuel in the purge gas supplied to said engine. An air-fuel ratio correcting device performs, in the purge-on mode, a purge learning control having a plurality of cycles for learning the results of computations of the purge density and for effecting correction of the air-fuel ratio based on purge learned values obtained through the learning. The air-fuel ratio correcting device effects, in the purge-off mode, correction of the air-fuel ratio based on normal learned values learned in the purge-off mode.

Abstract: An internal combustion engine is simulated as a control model that covers from a fuel injection point to an air-fuel ratio detection point. A response time constant of the control model is calculated as a continuous function of the amount of intake air, and a control gain of the control model is calculated as a continuous function of the response time constant. Control parameters of the control model are calculated using a calculation interval, the response time constant, an attenuation coefficient and the control gain. Thus, the control parameters are varied continuously in response to changes in the intake air amount. The air-fuel correction coefficient is calculated using the control parameters a0, a1, a2, b1 and b2 as well as a deviation of an actual air-fuel ratio from a target air-fuel ratio. The amount of fuel supplied to the engine is calculated using the air-fuel ratio correction coefficient.

Abstract: An improved internal combustion engine fuel control wherein a single oxygen sensor responsive to the combined exhaust gas flow of several engine cylinders is used both to control the overall or average air/fuel ratio, and to trim the air/fuel ratio in the individual engine cylinders. The oxygen sensor output is sampled in synchronism with the engine firing events, but at twice (or higher) the frequency, and filtered by an engine speed dependent high-pass filter to form a measure of the air/fuel ratio imbalance with respect to time. The imbalance signal, in turn, is parsed into an array of imbalance values that are associated with individual engine cylinders based on engine operating conditions, and the imbalance values are then used to develop correction factors for the respective engine cylinders that reduce the imbalance while preserving the overall or average air/fuel ratio of the engine.

Abstract: A self-adapting method of controlling the mixture ratio of an injection system, of an internal combustion engine. In each operating state of the engine and for each injector, the method determines a nominal quantity of fuel to be injected as a function of a number of engine parameters and operating conditions, an operating parameter as a function of a signal representing exhaust gas composition and of a proportional-integral regulating function and hot and cold correction coefficients indicating a correction to be made to the nominal quantity of fuel to take into account the effect on injection of different engines and different injection systems during hot and cold engine operation.

Abstract: A system and method is provided for controlling noxious emissions, such as NOx, from an internal combustion engine. The invention utilizes a closed loop and an open loop control algorithm to control one or more compensating levers, each compensating lever corresponding to a controllable engine operating parameter that when changed yields a change in the NOx emissions. In the closed loop control approach, the mass flow rate of the NOx is compared to a predetermined threshold to obtain a delta value. This delta value is applied through a PID controller to generate a corresponding change in one or more compensating levers. In the open loop portion, predetermined relationships are generated between one or more compensating levers and changes in a measure of the noxious emissions. Current values for one or more of the levers are compared against nominal values, and the change in these values are evaluated using predetermined relationships to produce a number of NOx delta values.

Abstract: An engine control system includes an adaptive bias sub-system (100) that generates bias values for controlling the air-fuel ratio. The sub-system (100) includes an integral controller (118) that reads an error signal from a post-catalyst switching EGO sensor (112). A plurality of noise isolation integrators (122) filter any noise resulting from a particular engine operating condition (e.g. acceleration, deceleration, idling) from the integrated error signal and stores the signal in a corresponding keep-alive memory (124) as a bias value for that engine operating condition. In a preferred embodiment, the post-catalyst feedback loop includes a gated proportional controller 116 that turns on for a limited period of time after the post-catalyst switching EGO sensor (112) switches states.

Abstract: For a control model which simulates a control object ranging from the fuel injection valve up to the air-fuel ratio sensor, coefficients of a characteristic polynomial of the control model are calculated based on the pole arrangement scheme, with roots equal in number to the dead time of the control model being made 0, control parameters are calculated from the coefficients of the characteristic polynomial and from model parameters, and the air-fuel ratio correction factor is calculated from the control parameters. The control model is expressed in terms of a dead time plus first-order lag system, with the total number of roots being set greater by two than the number n of roots which are derived from the time lag, and unknown roots other than those of the dead time are solved based on formulas which are expressed in terms of a second-order lag system.

Abstract: A method and apparatus for controlling the air-fuel ratio of an internal combustion engine that prevents erroneous learning while properly setting a learning frequency to thereby execute highly accurate air-fuel ratio control. Fuel vapor generated in a fuel tank is temporarily adsorbed in a canister via a tank inner pressure-regulating valve, and the adsorbed vapor is discharged to an engine intake system via a purge solenoid valve. A sensor for detecting tank inner pressure is arranged in the fuel tank, and an ECU calculates a feedback correction amount based on an oxygen concentration in exhaust gas and executes air-fuel ratio feedback control by using the feedback correction amount. The ECU prohibits the air-fuel ratio learning value from being updated when the tank inner pressure exceeds a predetermined criterion value based on the tank inner pressure detected by the tank inner pressure sensor.

Abstract: An apparatus for detecting a concentration of a vapor fuel in a lean-burn internal combustion engine includes a module for performing purge concentration learning when in a lean-burn where an air/fuel ratio sensor does not sufficiently work. When detecting the concentration of the vapor fuel during a lean-burn operation of the internal combustion engine, the internal combustion engine is switched over to a homogeneous combustion operation from a lean-burn operation, and the concentration of the vapor fuel is detected under the homogeneous combustion operation. Alternatively, the combustion is switched over to the homogeneous combustion when in a rich spike and when ensuring a brake negative pressure, and hence the concentration of the vapor fuel is detected by utilizing this timing. The thus detected and learned concentration of the vapor fuel is utilized for the purge control when in the lean-burn.

Abstract: An apparatus for detecting a concentration of a vapor fuel in a lean-burn internal combustion engine includes a module for performing purge concentration learning when in a lean-burn where an air/fuel ratio sensor does not sufficiently work. When detecting the concentration of the vapor fuel during a lean-burn operation of the internal combustion engine, the internal combustion engine is switched over to a homogeneous combustion operation from a lean-burn operation, and the concentration of the vapor fuel is detected under the homogeneous combustion operation. Alternatively, the combustion is switched over to the homogeneous combustion when in a rich spike and when ensuring a brake negative pressure, and hence the concentration of the vapor fuel is detected by utilizing this timing. The thus detected and learned concentration of the vapor fuel is utilized for the purge control when in the lean-burn.

Abstract: A fuel control system that estimates the fuel quantity received from purging of an evaporative emission control system and then accounts for the purge fuel in determining the amount of fuel to be injected into a cylinder of an internal combustion engine. Purge fuel quantity is represented by a purge equivalence ratio which is computed based upon an estimate of the hydrocarbon concentration in the purge gas. The hydrocarbon concentration is adaptively learned using an iterative routine that updates the estimate based on the integrated error between the actual and desired air/fuel ratios. Wall wetting and closed loop corrections are applied only to the non-purge fuel portion of the total fuel delivered to the engine cylinder. The closed loop control includes a block learn memory that provides a correction to the factory fuel calibration.

Abstract: An air-fuel ratio control apparatus of an internal combustion engine is provided which enables highly accurate calibration of an air-fuel feedback correction value to be completed in a short time, thus avoiding adverse influences on the emissions. The engine load is fixed when the air-fuel ratio or purge concentration is calibrated from the behavior of the air-fuel ratio feedback correction value. Thus, no change is observed in the engine load even if the driver operates the accelerator pedal to adjust the accelerator pedal position so as to change the required torque, and the air-fuel ratio of the air-fuel mixture is stabilized. Accordingly, air-fuel ratio calibration or purge concentration calibration can be promptly accomplished with high accuracy. Furthermore, while the engine load is being adjusted, the output torque is controlled in accordance with the required torque by adjusting the ignition timing.

Abstract: An improved individual cylinder fuel control method based on sampled readings of a single oxygen sensor responsive to the combined exhaust gas flow of several engine cylinders. A model-based observer is used to reproduce the imbalances of the different cylinders and a proportional-plus-integral controller is used for their elimination. Both the observer and the controller are formulated in terms of a periodic system. The observer input signal is preprocessed such that it reflects at each point of time the deviation from the current A/F-ratio mean value calculated over two engine cycles. Therefore, transient engine operating conditions do not harm the reconstruction of the cylinder imbalances dramatically. The control algorithm features process/controller synchronization based on table lookup and a mechanism to automatically adjust the mapping between the observer estimates and the corresponding cylinders if unstable control operation is detected.

Abstract: An engine control system includes an adaptive bias sub-system (100) that generates bias values for controlling the air-fuel ratio. The sub-system (100) includes an integral controller (118) that reads an error signal from a post-catalyst switching EGO sensor (112). A plurality of noise isolation integrators (122) filter any noise resulting from a particular engine operating condition (e.g. acceleration, deceleration, idling) from the integrated error signal and stores the signal in a corresponding keep-alive memory (124) as a bias value for that engine operating condition. In a preferred embodiment, the post-catalyst feedback loop includes a gated proportional controller 116 that turns on for a limited period of time after the post-catalyst switching EGO sensor (112) switches states.

Abstract: A fuel control system that estimates the fuel quantity received from purging of an evaporative emission control system and then accounts for the purge fuel in determining the amount of fuel to be injected into a cylinder of an internal combustion engine. Purge fuel quantity is represented by a purge equivalence ratio which is computed based upon an estimate of the hydrocarbon concentration in the purge gas. The hydrocarbon concentration is adaptively learned using an iterative routine that updates the estimate based on the integrated error between the actual and desired air/fuel ratios. Wall wetting and closed loop corrections are applied only to the non-purge fuel portion of the total fuel delivered to the engine cylinder. The closed loop control includes a block learn memory that provides a correction to the factory fuel calibration.

Abstract: A method and system is provided for improving the adjustment of fuel levels delivered to an internal combustion engine. A controller 15 calculates commanded air-fuel levels to deliver to the engine 13 based on a plurality of control signals, including air-fuel ratio signals measured by an air-fuel sensor 54 in the exhaust stream downstream of the engine 13. Systematic errors that reduce the accuracy of the commanded air-fuel level, including systematic errors associated with air-fuel ratio measurements, are identified and compensated for according to the present invention. Statistical methods and known operational characteristics of the air-fuel sensor are used to attribute a portion of the total system fuel error to air-fuel ratio measurement errors and such errors are compensated for to permit the calculation of a more accurate commanded air-fuel level.

Abstract: A method according to the present invention controls engine roughness by varying the ethanol content in a fuel mixture of a flexible fuel vehicle. Initially, a trigger threshold and fix threshold are established based on engine speed and manifold pressure. The fix threshold is less than the trigger threshold. A first ethanol amount is delivered to the fuel mixture if a first measured roughness is greater than the trigger threshold. A second measured engine roughness is determined after delivering the first ethanol amount. The delivery of the first ethanol amount is stopped if the second measured roughness is greater than the trigger threshold. A second ethanol amount is delivered if the second measured roughness is less than the trigger threshold but greater than the fix threshold. A third measured roughness is then determined. Delivery of the second ethanol amount is stopped if the third measured roughness is greater than the trigger threshold.

Abstract: An air/fuel ratio controller/method learns the deviation from a target air/fuel ratio and stores that learned value in a backup memory except when engine compartment temperature is ecessive.