Abstract: In an air-fuel ratio control system, a gain Kh is adaptively determined on the basis of a value z obtained by multiplying a target fuel amount difference value ?ym (derivative value of a target fuel amount) by an error e between a target excess fuel ratio (target ?) and an actual excess fuel ratio (actual ?) detected by an air-fuel ratio sensor. A value obtained by multiplying the target fuel amount difference value ?ym by the gain Kh is determined as an F/F corrected value ucmp. In this case, when the error e between the target ? and the actual ? is determined in consideration of the fact that a controlled system has dead time d, a target ?d at the point in time going back in the past by the amount of the dead time d is used to obtain error e=target ?d?actual ?.

Abstract: In an air-fuel ratio control system, a gain Kh is adaptively determined on the basis of a value z obtained by multiplying a target fuel amount difference value &Dgr;ym (derivative value of a target fuel amount) by an error e between a target excess fuel ratio (target &phgr;) and an actual excess fuel ratio (actual &phgr;) detected by an air-fuel ratio sensor. A value obtained by multiplying the target fuel amount difference value &Dgr;ym by the gain Kh is determined as an F/F corrected value ucmp. In this case, when the error e between the target &phgr; and the actual &phgr; is determined in consideration of the fact that a controlled system has dead time d, a target &phgr;d at the point in time going back in the past by the amount of the dead time d is used to obtain error e=target &phgr;d−actual &phgr;.

Abstract: Calculation of a present air-fuel ratio correction coefficient correction value &Dgr;FAF (i) is based on a control parameter calculated by an ECU, a change in air-fuel ratio detected by an air-fuel ratio sensor, a deviation of an actual air-fuel ratio from a target air-fuel ratio and an immediately preceding air-fuel ratio correction coefficient correction value &Dgr;FAF (i−1) Then, a present air-fuel ratio correction coefficient FAF (i) is found by adding the present air-fuel ratio correction coefficient correction value &Dgr;FAF (i) to an immediately preceding air-fuel ratio correction coefficient FAF (i−1). As a result, the air-fuel ratio correction coefficients is not be thrown into confusion and no phenomenon of the air-fuel ratio being thrown into confusion occurs even if the control parameter is changed in accordance with operating conditions of the engine.

Abstract: An intermediate target value calculating unit calculates an intermediate target value &phgr;midtg(i) on the basis of an output &phgr;(i−1) of an A/F ratio sensor in computation of last time and a final target value &phgr;tg(i). By the computation, the intermediate target value &phgr;midtg(i) is set between the output &phgr;(i−1) of the A/F ratio sensor in computation of last time and the final target value &phgr;tg(i). A correction amount calculating unit calculates a correction amount AFcomp(i) of the target A/F ratio on the basis of a deviation &Dgr;&phgr;(i) between the intermediate target value &phgr;midtg(i) and the output &phgr;(i) of the A/F ratio sensor. Consequently, the control is hard to be influenced by variations in waste time of the subject to be controlled and an error in modeling. While maintaining the stability of the A/F ratio feedback control, higher gain can be achieved and robustness can be also increased.

Abstract: The following conditions are used as requirements for executing a fuel property detection: an intake air temperature is lower than a restart judging value; a water temperature is in a predetermined range; and it is in an idle operation. In a case that the requirements are established, an injection amount of fuel and a combustion amount of fuel are calculated. After that, the injection amount is corrected by using a learned value for correcting an error of system, and the combustion amount is corrected according an intake pressure. A fuel property parameter for evaluating the fuel property is calculated based on a ratio of an accumulated value of the combustion amount relative to an accumulated value of the injection amount during a predetermined time. A command value of the injection amount for a fuel injection valve is corrected according to the fuel property parameter calculated above. As a result, the fuel property is reflected in the command value of the injection amount.

Abstract: Calculation of a present air-fuel ratio correction coefficient correction value &Dgr;FAF (i) is based on a control parameter calculated by an ECU, a change in air-fuel ratio detected by an air-fuel ratio sensor, a deviation of an actual air-fuel ratio from a target air-fuel ratio and an immediately preceding air-fuel ratio correction coefficient correction value &Dgr;FAF (i−1) Then, a present air-fuel ratio correction coefficient FAF (i) is found by adding the present air-fuel ratio correction coefficient correction value &Dgr;FAF (i) to an immediately preceding air-fuel ratio correction coefficient FAF (i−1). As a result, the air-fuel ratio correction coefficients is not be thrown into confusion and no phenomenon of the air-fuel ratio being thrown into confusion occurs even if the control parameter is changed in accordance with operating conditions of the engine.

Abstract: An intermediate target value calculating unit calculates an intermediate target value &phgr;midtg(i) on the basis of an output &phgr;(i=1) of an A/F ratio sensor in computation of last time and a final target value &phgr;tg(i). By the computation, the intermediate target value &phgr;midtg(i) is set between the output &phgr;(i−1) of the A/F ratio sensor in computation of last time and the final target value &phgr;tg(i). A correction amount calculating unit calculates a correction amount AFcomp(i) of the target A/F ratio on the basis of a deviation &Dgr;&phgr;(i) between the intermediate target value &phgr;midtg(i) and the output &phgr;(i) of the A/F ratio sensor. Consequently, the control is hard to be influenced by variations in waste time of the subject to be controlled and an error in modeling. While maintaining the stability of the A/F ratio feedback control, higher gain can be achieved and robustness can be also increased.

Abstract: The following conditions are used as requirements for executing a fuel property detection: an intake air temperature is lower than a restart judging value; a water temperature is in a predetermined range; and it is in an idle operation. In a case that the requirements are established, an injection amount of fuel and a combustion amount of fuel are calculated. After that, the injection amount is corrected by using a learned value for correcting an error of system, and the combustion amount is corrected according an intake pressure. A fuel property parameter for evaluating the fuel property is calculated based on a ratio of an accumulated value of the combustion amount relative to an accumulated value of the injection amount during a predetermined time. A command value of the injection amount for a fuel injection valve is corrected according to the fuel property parameter calculated above. As a result, the fuel property is reflected in the command value of the injection amount.

Abstract: The following conditions are used as requirements for executing a fuel property detection: an intake air temperature is lower than a restart judging value; a water temperature is in a predetermined range; and it is in an idle operation. In a case that the requirements are established, an injection amount of fuel and a combustion amount of fuel are calculated. After that, the injection amount is corrected by using a learned value for correcting an error of system, and the combustion amount is corrected according an intake pressure. A fuel property parameter for evaluating the fuel property is calculated based on a ratio of an accumulated value of the combustion amount relative to an accumulated value of the injection amount during a predetermined time. A command value of the injection amount for a fuel injection valve is corrected according to the fuel property parameter calculated above. As a result, the fuel property is reflected in the command value of the injection amount.

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.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine is provided which includes an air-fuel ratio determining circuit which determines an air-fuel ratio of exhaust gases flowing upstream of a catalytic converter for controlling the air-fuel ratio of the exhaust gases so as to agree with a target air-fuel ratio under feedback control, a sorbed substance amount determining circuit for determining the amount of substances sorbed in the catalytic converter, and a target air-fuel ratio determining circuit for determining said target air-fuel ratio so that the amount of substances determined by said sorbed substance amount determining means falls within a given range.

Abstract: A fuel supply amount control apparatus improves controllability during engine acceleration and deceleration and immediately after starting the operation of the engine, by enabling the setting of suitable parameters. An evaporation time constant indicating chronological changes in the fuel amount introduced into a cylinder from an intake system of the engine is computed by a predetermined computation equation. During this computation, the computation load is reduced by using an Aquino operator .alpha. and a stroke interval Aquino operator A.alpha. and computation for computing the fuel injection amount is executed at an interval shorter than the interval of two successive fuel injections, e.g., a crank angle of 60.degree.. During computation of the evaporation time constant, the evaporation time constant after full warm-up is corrected based on an average temperature weighted according to an adherence rate of fuel to the intake manifold and intake valve.

Abstract: A temperature projecting system includes a temperature sensor for monitoring a temperature of an objective portion where the temperature changes depending on an engine operating condition. The temperature projecting system projects an actual temperature of the objective portion based on the monitored temperature but free of a first-order lag of the temperature sensor. A temperature control system includes the temperature projecting system. The temperature control system derives a correction amount for a basic control amount of an actuator based on a difference between the projected actual temperature and a target temperature. The basic control amount is corrected by the correction amount to derive a corrected control amount which controls the engine operating condition and thus the temperature of the objective portion.

Abstract: In order to optimally suppress effects of error exerted upon control results by any modeling error which may arise from load fluctuations or the like of the internal combustion engine approximated as a dynamic model under an advanced control theory, present and past values of an operating quantity and control quantity which correspond respectively to a control input and control output of an internal combustion engine are utilized as state variable quantities representing the internal state of the dynamic model of an internal combustion engine. Furthermore, the target value and difference are accumulated for the foregoing control quantity. Modeling of the internal combustion engine is performed in realtime, and optimal feedback gain is calculated periodically or under certain specified conditions for a regulator constructed on the basis of these model constants calculated in realtime.

Abstract: An air-fuel ratio control system for an internal combustion engine uses a dynamic model which is set as an approximation to a controlled object. The controlled object covers an operation sequence from a fuel injection valve to an air-fuel ratio sensor which is provided downstream of a catalytic converter for detecting an actual air-fuel ratio based on the exhaust gas downstream of the catalytic converter. The system derives a fuel injection amount to be fed to the engine by performing a state-feedback control in such a manner as to control the actual air-fuel ratio to a target air-fuel ratio. The system performs the state-feedback control using, as state variables, current and past input and output data relative to the dynamic model. Accordingly, the actual air-fuel ratio monitored on the downstream-side of the catalytic converter is controlled to the target air-fuel ratio without delay by directly deriving the fuel injection amount using the state-feedback control.

Abstract: A valve operation timing regulation apparatus for changing the operation timing of the intake valve, etc., of internal combustion engine, in which the controllability is improved by avoiding operation variations of a value actuator. The rotational phase angle difference between the crankshaft and the camshaft is changed by driving a member interposed between the two shafts. A target value of the rotational phase angle difference is determined and an actual value measured by detecting operating conditions at various parts of the engine. The control deviation between the target and the actual value is calculated, so that a control unit decides a present control value of the actuator, by selecting on the basis of the error and past control values, one of a plurality of control values predetermined in a region free of unfavorable influences of actuator characteristic variations.

Abstract: The digital control unit of the present invention relates to improvements in what is called recent control, and more particularly relates to the idle rotating speed control unit of an internal combustion engine in which the idle rotating speed can be quickly converged to the target rotating speed in the case where a load given from the outside varies. Especially, when the value of the state variable is reversely calculated from the state in which open loop control is conducted, the initial value can be accurately determined.

Abstract: A speed control apparatus for an engine which is equipped with an air quantity control device for controlling an intake air quantity to the engine when being in an idling state and a speed control device for determining a control amount of the air quantity control device on the basis of the actual engine idle speed. For controlling the engine idle speed, the apparatus comprises a state variable outputting section for outputting the actual engine idle speed, the control amount of the air quantity control device and an ignition timing control amount of an igniter of the engine as state variables representing an internal state of a dynamic model of the engine, a speed deviation accumulating section for accumulating a deviation between the target speed and the actual engine idle speed, and an ignition timing deviation accumulating section for accumulating a deviation between a target ignition timing and the actual ignition timing.

Abstract: An engine control apparatus comprises: an actual control condition detector for detecting an actual control condition of an engine; an adjusting device for adjusting the actual control condition of the engine; and a controller for controlling the adjusting device such that the actual control condition of the engine is controlled to a target control condition using a state variable amount and a feedback constant determined on the basis of a dynamic model of the engine, wherein the controller has: a predicated control condition operation circuit for operating a predicted control condition on the basis of the dynamic model of the engine; a deviation operation circuit for operating a deviation of the predicated control condition from the target control condition; a changing circuit for changing control of the controller such that fluctuations of the control condition become small in accordance with a judgement made such that an error of the dynamic model exceeds a tolerance when the deviation exceeds a predetermi

Abstract: A state value related to operating state of a controlled object is detected. An actuator serves to adjust the operating state of the controlled object. A target control quantity of the actuator is determined on the basis of the detected state value. The actuator is controlled in accordance with the determined target control quantity. The detected state value and the determined target control quantity are stored. A new target control quantity of the actuator is calculated on the basis of a vector of predetermined optimal feedback gain and a vector of state variables. The optimal feedback gain depends on model constants in a dynamic model which is an approximation to the operating state of the controlled object. The state variables are composed directly of the stored state value and the stored control quantity.