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 in-cylinder pressure detection device for an internal combustion engine, which is capable of detecting an in-cylinder pressure accurately without being adversely affected by changes in the atmospheric pressure even when the atmospheric pressure changes. An in-cylinder pressure sensor detects pressure within a cylinder as a detected in-cylinder pressure. An ECU estimates pressure generated in the cylinder during a non-combustion period as a motoring pressure. An atmospheric pressure sensor detects an atmospheric pressure (PA). The ECU corrects the motoring pressure according to the atmospheric pressure and identifies correction parameters such that the difference between the detected in-cylinder pressure detected during a compression stroke of the engine and the corrected motoring pressure becomes minimum, and corrects the detected in-cylinder pressure by the identified correction parameters, to thereby calculate an in-cylinder pressure.

Abstract: An ignition timing control system for an internal combustion engine, which is capable of ensuring both stability of control in a steady operating condition of the engine, and an excellent follow-up property of a controlled variable to a target value in a transient operating condition of the engine, even when the controlled variable contains a lot of high-frequency noise components. In the ignition timing control system, a maximum pressure angle-calculating section calculates a maximum pressure angle based on an in-cylinder pressure and a crank angle position. A target angle-calculating section calculates a target angle. A maximum pressure angle controller calculates a maximum pressure angle correction term with a control algorithm to which is applied a sliding mode control algorithm, using a value obtained by performing ?-filtering on a switching function, such that the maximum pressure angle converges to the target angle. The ignition timing is calculated by adding corrected ignition timing to the value.

Abstract: An ignition timing control apparatus and method for an internal combustion engine, and an engine control unit are provided for more rapidly and effectively restraining knocking as the entire internal combustion engine, and extending the lifetime of the internal combustion engine. The ignition timing control apparatus comprising an ECU. The ECU determines a basic ignition timing on a cylinder-by-cylinder basis, calculates a knock intensity on a cylinder-by-cylinder bases based on a detected signal of a cylinder inner pressure sensor, and updates a correction coefficient learning value for a corresponding cylinder when the knock intensity is larger than a predetermined first determination value and is smaller than a predetermined second determination value larger than the predetermined first determination value, and updates the knock intensities for all the cylinders when the one knock intensity parameter is equal to or larger than the predetermined second determination value.

Abstract: An in-cylinder pressure detection device for an internal combustion engine, which is capable of calculating a hysteresis amount properly to thereby detect in-cylinder pressure with high accuracy. The in-cylinder pressure detection device comprises an in-cylinder pressure sensor that detects in-cylinder pressure as a detected in-cylinder pressure. The in-cylinder pressure detection device estimates an in-cylinder pressure generated when combustion is not performed in the cylinder, as a motoring pressure, calculates a hysteresis amount indicative of a difference between the detected in-cylinder pressure and an actual in-cylinder pressure, based on the detected in-cylinder pressure and the motoring pressure obtained during the exhaust stroke of the engine, and corrects the detected in-cylinder pressure based on the calculated hysteresis amount.

Abstract: An air-fuel ratio control system for an internal combustion engine, which is capable of accurately estimating an exhaust gas state parameter according to the properties of fuel, thereby making it possible to properly control the air-fuel ratio of a mixture.

Abstract: An engine control unit includes pressure detector provided in a combustion chamber of the engine. A motoring pressure of the engine is estimated. A combustion starting time is detected when the difference between an internal pressure detected by the pressure detector and the pressure estimated by the ECU exceeds a predetermined value. When the internal pressure detected by the pressure detector reaches its peak after the combustion starting time has been detected, the crank angle at this time point is determined to correspond to the maximum internal cylinder pressure that is generated by combustion.

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: A control system for a plant is disclosed. The control system includes a controller for controlling the plant based on a controlled object model which is obtained by modeling the plant. The controlled object model is modeled using an input and an output of the plant which are sampled at intervals of a sampling period which is longer than a control period of the controller. The sampled input of the plant is a filtered control output which is obtained by filtering an output of the controller. The controller carries out a control process of the plant at intervals of the control period.

Abstract: A combustion state detecting apparatus is provided for an engine having internal pressure sensor for detecting an internal pressure of a combustion chamber of the engine and crank angle detector for detecting a crank angle of the engine. The apparatus calculates a volume of the combustion chamber based on the crank angle detected by the crank angle detector and estimator for estimating a motoring pressure of the engine in accordance with a calculation equation using the calculated volume. The apparatus adjusts either of the pressure detected by the internal pressure sensor and the pressure estimated by the estimator during a compression stroke of the engine to minimize the error between the detected pressure and the estimated pressure. The apparatus determines a combustion state during a combustion stroke of the engine based on a relation between the pressure adjusted and the other pressure.

Abstract: A combustion state detecting apparatus is provided for an engine having internal pressure sensor for detecting an internal pressure of a combustion chamber of the engine and crank angle detector for detecting a crank angle of the engine. The apparatus calculates a volume of the combustion chamber based on the crank angle detected by the crank angle detector and estimator for estimating a motoring pressure of the engine in accordance with a calculation equation using the calculated volume. The apparatus adjusts either of the pressure detected by the internal pressure sensor and the pressure estimated by the estimator during a compression stroke of the engine to minimize the error between the detected pressure and the estimated pressure. The apparatus determines a combustion state during a combustion stroke of the engine based on a relation between the pressure adjusted and the other pressure.

Abstract: A control apparatus for an exhaust gas recirculation valve is disclosed. The exhaust gas recirculation valve is provided in an exhaust gas recirculation pipe for recirculating exhaust gases from an internal combustion engine to an intake system of the engine. The exhaust gas recirculation valve controls an exhaust gas recirculation amount. An opening of the exhaust gas recirculation valve is controlled to a target opening, based on a controlled object model which is obtained by modeling the exhaust gas recirculation valve.

Abstract: A control system for a throttle valve actuating device is disclosed. The throttle valve actuating device has a throttle valve of an internal combustion engine and an actuator for actuating the throttle valve. Model parameters of a controlled object model obtained by modeling the throttle valve actuating device is identified by an identifier. The model parameters includes a specific model parameter irrelevant to an input and an output of the controlled object model. An opening of the throttle valve is controlled to a target opening using the identified model parameters. It is determined that the throttle valve actuating device is abnormal when the value of the specific model parameter becomes greater than a predetermined value.

Abstract: A failure diagnosis apparatus for a throttle valve actuating device is disclosed. The throttle valve actuating device has an actuator for actuating a throttle valve provided in an intake system of an internal combustion engine and biasing elements for biasing the throttle valve to a predetermined retention opening. A feedback control of the throttle valve is performed so that an opening of the throttle valve coincides with a first predetermined opening. After the throttle valve is controlled to the first predetermined opening, a feedback control of the throttle valve is performed so that an opening of the throttle valve coincides with a second predetermined opening. It is determined that the throttle valve actuating device has failed when the time period during which the opening of the throttle valve remains in a predetermined determination range including the second predetermined opening, is shorter than a predetermined time period when performing the feedback control to the second predetermined opening.

Abstract: A control apparatus for an exhaust gas recirculation valve is disclosed. The exhaust gas recirculation valve is provided in an exhaust gas recirculation pipe for recirculating exhaust gases from an internal combustion engine to an intake system of the engine. The exhaust gas recirculation valve controls an exhaust gas recirculation amount. An opening of the exhaust gas recirculation valve is controlled to a target opening, based on a controlled object model which is obtained by modeling the exhaust gas recirculation valve.

Abstract: A catalyst state detector for detecting a state of an exhaust gas purifying catalyst which is capable of accurately detecting the state, including deterioration, of an HC adsorbent contained in the exhaust gas purifying catalyst for adsorbing hydrocarbons in exhaust gases of an internal combustion engine, and can be manufactured at a low cost. The exhaust gas purifying catalyst is arranged at an intermediate portion of an exhaust pipe, and the HC adsorbent is capable of adsorbing hydrocarbons and moisture in exhaust gases. The catalyst state detector comprises a downstream humidity sensor arranged at a location downstream of the HC adsorbent in the exhaust pipe for detecting a humidity of the exhaust gases, and an adsorbent state detecting unit (ECU) for detecting the state of the HC adsorbent in accordance with the result of detection made by the downstream humidity sensor.

Abstract: A control system for a plant is disclosed. The control system includes a controller for controlling the plant based on a controlled object model which is obtained by modeling the plant. The controlled object model is modeled using an input and an output of the plant which are sampled at intervals of a sampling period which is longer than a control period of the controller. The sampled input of the plant is a filtered control output which is obtained by filtering an output of the controller. The controller carries out a control process of the plant at intervals of the control period.

Abstract: A target air-fuel ratio KCMD for an exhaust gas upstream of a catalytic converter is sequentially determined to converge the output VO2/OUT of an O2 sensor downstream of the catalytic converter to a target value VO2/TARGET, and the amount of fuel supplied to an internal combustion engine is controlled to converge the output KACT of an air-fuel ratio sensor to the target air-fuel ratio KCMD. While the amount of fuel supplied to the internal combustion engine is being thus controlled, the value of a deterioration linear function &sgr; whose variable components are represented by time-series data of the output VO2/OUT of the O2 sensor is determined. A central value of the square &sgr;2 of the value of the deterioration linear function &sgr; is determined as a deterioration evaluating parameter. A deteriorated state of the catalytic converter is evaluated on the basis of the value of the deterioration evaluating parameter.

Abstract: A control system for a throttle valve actuating device is disclosed. The throttle valve actuating device has a throttle valve of an internal combustion engine and an actuator for actuating the throttle valve. Model parameters of a controlled object model obtained by modeling the throttle valve actuating device is identified by an identifier. The model parameters includes a specific model parameter irrelevant to an input and an output of the controlled object model. An opening of the throttle valve is controlled to a target opening using the identified model parameters. It is determined that the throttle valve actuating device is abnormal when the value of the specific model parameter becomes greater than a predetermined value.

Abstract: A control system for an internal combustion engine having an exhaust system, an intake system, and an exhaust gas recirculation mechanism for recirculating exhaust gases from the exhaust system to the intake system is disclosed. The exhaust system is provided with an adsorbent for adsorbing hydrocarbon. When the adsorbent has adsorbed the hydrocarbon and the engine is operating in an idling condition, an intake air amount of the engine is increased and an ignition timing of said engine is retarded, and at the same time, the exhaust gas recirculation is performed to recirculate the hydrocarbon desorbed from the adsorbent to the intake system.