Abstract: A control apparatus for an internal combustion engine provided with a fuel supply mechanism capable of adjusting a fuel supply amount includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change of the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a fuel supply mechanism control unit that controls the fuel supply mechanism. The fuel supply mechanism control unit controls the fuel supply mechanism such that the characteristic change in the internal combustion engine is compensated in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A control apparatus for an internal combustion engine provided with a fuel supply mechanism capable of adjusting a fuel supply amount includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change of the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a fuel supply mechanism control unit that controls the fuel supply mechanism. The fuel supply mechanism control unit controls the fuel supply mechanism such that the characteristic change in the internal combustion engine is compensated in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A control apparatus for an internal combustion engine provided with a fuel supply mechanism capable of adjusting a fuel supply amount includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change of the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a fuel supply mechanism control unit that controls the fuel supply mechanism. The fuel supply mechanism control unit controls the fuel supply mechanism such that the characteristic change in the internal combustion engine is compensated in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A control apparatus for an internal combustion engine provided with a fuel supply mechanism capable of adjusting a fuel supply amount includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change of the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a fuel supply mechanism control unit that controls the fuel supply mechanism. The fuel supply mechanism control unit controls the fuel supply mechanism such that the characteristic change in the internal combustion engine is compensated in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A control apparatus for controlling an internal combustion engine includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change in the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a control unit capable of correcting a control amount of the internal combustion engine so as to compensate the characteristic change thereof in accordance with an estimation performed by the characteristic change estimation unit.

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 control apparatus for an internal combustion engine provided with a fuel supply mechanism capable of adjusting a fuel supply amount includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change of the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a fuel supply mechanism control unit that controls the fuel supply mechanism. The fuel supply mechanism control unit controls the fuel supply mechanism such that the characteristic change in the internal combustion engine is compensated in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A control apparatus for controlling an internal combustion engine includes a flow rate sensor that detects an intake air flow rate that represents a flow rate of air admitted into a combustion chamber of the internal combustion engine, a pressure sensor that detects a pressure of the air admitted into the combustion chamber of the internal combustion engine, a characteristic change estimation unit that estimates a characteristic change in the internal combustion engine in accordance with the intake air flow rate detected by the flow rate sensor and the intake air pressure detected by the pressure sensor, and a control unit capable of correcting a control amount of the internal combustion engine so as to compensate the characteristic change thereof in accordance with an estimation performed by the characteristic change estimation unit.

Abstract: A response time constant of an A/F ratio control system is calculated in accordance with an engine operating condition. A control gain is calculated based on the response time constant. A degradation index of a response of an A/F sensor is calculated, so as to be used as a parameter representing a model error or aging degree of the A/F control system. The control gain is corrected with a correction coefficient corresponding to the model error. An A/F feedback correcting amount is calculated using the response time constant, the control gain and a deviation between a detected A/F and a target A/F, so as to decrease the deviation. Thus, the A/F control system is prevented from a degradation caused by aging.

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 fuel transportation lag model has a fuel transportation lag element A (FTLEA) due to adhesion of an injected fuel onto wall faces and a first-order lag element B (FOLEB) for compensating a model error of the (FTLEA). A fuel correction amount has a (FTLEA) compensation term and a (FOLEB) compensation term. By a compensation term for the (FTLEA), a first wall adhesion correction amount is obtained by multiplying a deviation between the wall face adhesion fuel amount (WFAFA) in a steady driving mode and a (WFAFA) at a present time with a first reference adaptation parameter and a first correction factor. By a compensation term for the (FOLEB), a second wall adhesion correction amount is obtained by multiplying a deviation between a required fuel amount of a present time and a required fuel amount of last time with a second reference adaptation parameter and a second correction factor.

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: Flow amount calculation controller controls a certain subject based on a flow amount of fluid, passing through a variable throttle portion provided in an air passage, calculated from an upstream pressure Pu, an upstream density &rgr;u, a downstream pressure Pd, an opening area Ad and a specific heat ratio k by the following formula.

Abstract: A fuel transportation lag model has a fuel transportation lag element A (FTLEA) due to adhesion of an injected fuel onto wall faces and a first-order lag element B (FOLEB) for compensating a model error of the (FTLEA). A fuel correction amount has a (FTLEA) compensation term and a (FOLEB) compensation term. By a compensation term for the (FTLEA), a first wall adhesion correction amount is obtained by multiplying a deviation between the wall face adhesion fuel amount (WFAFA) in a steady driving mode and a (WFAFA) at a present time with a first reference adaptation parameter and a first correction factor. By a compensation term for the (FOLEB), a second wall adhesion correction amount is obtained by multiplying a deviation between a required fuel amount of a present time and a required fuel amount of last time with a second reference adaptation parameter and a second correction factor.

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: Flow amount calculation controller controls a certain subject based on a flow amount of fluid, passing through a variable throttle portion provided in an air passage, calculated from an upstream pressure Pu, an upstream density &rgr;u, a downstream pressure Pd, an opening area Ad and a specific heat ratio k by the following formula.

Abstract: An air-fuel ratio control system has a catalyst and controls the air-fuel ratio properly in accordance with the in-catalyst state. The in-catalyst state amount variation is calculated based on the deviation between the actual excess fuel factor detected by means of an air-fuel ratio sensor on the upstream side of the catalyst and the target excess fuel factor, and then accumulated to obtain the current in-catalyst state amount. At that time, the previous air flow derived earlier by a lag time corresponding to the time period from the time of fuel injection to the time of detection of the excess fuel factor of exhaust gas is used as the air flow. The calculated in-catalyst state amount value is subjected to guard processing, and thereafter the target excess fuel factor on the upstream side of the catalyst is calculated by use of various gains and control parameters.

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: When a diagnosis execution condition is established, a canister closure valve is closed, thereafter, a purge control valve is opened, a purge control valve is closed in a state where negative pressure is introduced into an evaporated gas system to thereby maintain the evaporated gas system in a hermetically-sealed state and the hermetically-sealed state is continued until abnormality diagnosis is finished. Time period for maintaining the evaporated gas system in the hermetically-sealed state is divided into three time periods of a pressure change determining time period at a first time, an awaiting time period and a pressure change determining time period at a second time.

Abstract: An inflow quantity of an exhaust gas component flowing into a catalyst is calculated based upon air fuel ratio detected by an upstream air fuel ratio sensor which is provided on the upstream side of the catalyst. In addition, an outflow quantity of an exhaust gas component flowing out of the catalyst is calculated based upon air fuel ratio detected by a downstream air fuel ratio sensor which is provided on the downstream side of the catalyst. The quantity of an exhaust gas component absorbed by the catalyst can be detected in real time based upon a difference between the inflow quantity and outflow quantity. Thus, a state of the catalyst can be precisely detected in real time.