Abstract: The values of parameters of a model of an object exhaust system including a catalytic converter are identified from the data of outputs from an air-fuel ratio sensor and an O2 sensor which are disposed respectively upstream and downstream of the catalytic converter while an internal combustion engine associated with the catalytic converter is in operation. A deterioration evaluating parameter representing the degree of variation of time-series data of the identified parameters is determined from the time-series data of the identified parameters. The deteriorated state of the catalytic converter is evaluated based on the deterioration evaluating parameter.

Abstract: A system for purifying exhaust gas generated by an internal combustion engine having an adsorbent, installed in an exhaust system of the engine, which adsorbs unburned components of the exhaust gas such as hydrocarbons generated by the engine. The system has a first temperature sensor for detecting a temperature of the adsorbent and timer for measuring a time until the detected temperature becomes greater or equal to a predetermined value, when the measured time is less than a threshold value, it is discriminated that the adsorbent deteriorates. With this, the deterioration of the adsorbent can be discriminated accurately.

Abstract: An object system is regarded as being equivalent to a system for generating an output of an O2 sensor or exhaust gas sensor from a target combined air-fuel ratio that is produced by combining target air-fuel ratios KCMD for respective cylinder groups according to a filtering process of the mixed model type. With the equivalent system as an object to be controlled, an air-fuel ratio processing controller determines a target combined air-fuel ratio, and determines a target air-fuel ratio KCMD for each of the cylinder groups from the target combined air-fuel ratio. The air-fuel ratios in the cylinder groups are manipulated into the target air-fuel ratio according to a feed-forward control process.

Abstract: A control system for an internal combustion engine having a catalyst arranged in the exhaust system is disclosed. In the control system, catalyst temperature rise accelerating control is executed by increasing the intake air amount immediately after starting of the engine and retarding the ignition timing to make the rotational speed of the engine coincide with a target rotational speed. The air-fuel ratio of an air-fuel mixture supplied to the engine is controlled to a lean region with respect to the stoichiometric ratio immediately after starting of the engine. The degree of making the air-fuel ratio leaner is suppressed when the retard amount of the ignition timing during the execution of the catalyst temperature rise accelerating control is less than a predetermined retard amount.

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: An allowable range (adaptive allowable range) for limiting a manipulated variable generated in order to converge the difference between an output from an O2 sensor disposed downstream of a catalytic converter and a target value thereof to “0” is sequentially updated depending on how the manipulated variable deviates from the allowable range.

Abstract: A system for purifying exhaust gas generated by an internal combustion engine having a bypass exhaust gas passage branching from an exhaust pipe which is opened or closed by a switch-over valve, and an adsorbent which adsorbs unburneds component in the exhaust gas installed at the bypass exhaust passage. In the system, when the engine operation is within a high engine speed and high load region, the switch-over valve is operated to open the bypass exhaust gas passage to reduce noise due to switch-over valve chattering, etc. Similarly, the bypass exhaust gas passage is opened at that range, when the exhaust gas temperature is greater or equal to a predetermined value, to introduce high temperature exhaust gas to burn away cloggy material adhered to the adsorbent which would otherwise deteriorate or degrade the adsorbent.

Abstract: While the amount of intake air introduced into an internal combustion engine is being increased by an intake air quantity control unit, an ignition timing control unit manipulates the ignition timing of the internal combustion engine to converge the rotational speed of the internal combustion engine to a target rotational speed according to a feedback control process (PI control process). The ignition timing control unit has a function to vary the feedback gain of the feedback control process depending on the ignition timing, such that the feedback gain is smaller as the ignition timing being manipulated is more retarded.

Abstract: A plant control system has a reference value setting unit for variably setting a reference value for an air-fuel ratio to be given to an exhaust system including a catalytic converter, depending on a component based on an adaptive control law of a manipulated variable of the air-fuel ratio generated by a controller according to an adaptive sliding mode control process in order to converge an output of an O2 sensor disposed downstream of the catalytic converter to a target value. The plant control system also has an estimator for estimating the difference between an output of the O2 sensor after the dead time of the exhaust system and a target value therefor, using the difference between the set reference value and a detected value of the air-fuel ratio, and giving the estimated difference to the controller.

Abstract: A plant control system has a reference value setting unit for variably setting a reference value for an air-fuel ratio to be given to an exhaust system including a catalytic converter, depending on a component based on an adaptive control law of a manipulated variable of the air-fuel ratio generated by a controller according to an adaptive sliding mode control process in order to converge an output of an O2 sensor disposed downstream of the catalytic converter to a target value. The manipulated variable generated by the controller represents the difference between the air-fuel ratio and the reference value, required to converge the output of the O2 sensor to the target value.

Abstract: An object system for generating an output signal of an O2 sensor from a target air-fuel ratio is expressed as a model including a response delay element and a dead time element. Data of identified values of parameters of the model are sequentially generated by an identifier. Data of an estimated value of the output signal of the O2 sensor after a dead time of the object system is sequentially generated by an estimator. The target air-fuel ratio is generated according to an adaptive sliding mode control process performed by a sliding mode controller using the data of the identified and estimated values. The air-fuel ratio of an internal combustion engine is manipulated on the basis of the target air-fuel ratio according to a feed-forward control process.

Abstract: An apparatus for controlling an internal combustion engine has an amount-of-intake-air control unit for generating a command value for the opening of a flow control valve in an intake passage of the engine, which emits exhaust gases through a catalytic converter, so as to increase an amount of intake air introduced into a combustion chamber by a predetermined quantity greater when the engine operates in an idling mode after it has started to operate than when the engine operates in a normal idling mode, and controlling the opening of the flow control valve based on the generated command value, and an ignition timing control unit for controlling the ignition timing according to a feedback control process to correct the ignition timing so as to be retarded in order to converge the rotational speed of the engine to a predetermined target rotational speed while the amount of intake air is being increased.

Abstract: A plant control system has an actuator for generating an input to the plant, a first sensor for detecting an output from the plant, a manipulated variable determining unit for sequentially determining a manipulated variable which determines the input to the plant to equalize the output from the first sensor to a predetermined target value, an actuator controller for controlling operation of the actuator based on the manipulated variable determined by the manipulated variable determining unit, and an estimator for sequentially generating data representing an estimated value of the output from the first sensor after a total dead time which is the sum of a first dead time of the plant and a second dead time of a system which comprises the actuator and the actuator controller. The manipulated variable determining unit determines the manipulated variable based on the data generated by the estimator.

Abstract: A system for detecting malfunctions of an exhaust switch-over valve of an internal combustion engine, which opens/closes a bypass exhaust gas passage branched from an exhaust pipe of the engine and storing an adsorbent that adsorbs unburned components of the exhaust gas generated by the engine when the engine is started. In the system, the entrance temperature and the exit temperature in the bypass exhaust gas passage are detected and compared with each other in a first detection period when the passage is opened and in a second detection period when the passage is closed. Based on this comparison, it is determined whether the valve malfunctions. Alternatively, the valve malfunction is determined by comparing the valve opening/closing state with an instruction to operate the valve. With this, little time lag exists in the detection, thereby improving malfunction detection accuracy.

Abstract: A control system for a plant includes a sensor for detecting an output from the plant, an adaptive controller for controlling a manipulated variable applied to control of the plant in such a manner that an output from the sensor becomes equal to a desired value, and an adaptive parameter-adjusting device for adjusting adaptive parameters used by the adaptive controller. The adaptive parameter-adjusting device has an identification error-calculating device for calculating an identification error of the adaptive parameters and generating an identification error signal indicative of the calculated identification error, and an adjusting device for adjusting the adaptive parameters based on the calculated identification error. The adaptive parameter-adjusting device includes a non-linear filter for generating an output of 0 or approximately 0 in response to the identification error signal when the identification error is within a predetermined range.

Abstract: A control system for controlling an internal combustion engine which discharge exhaust gases through an emission purifier includes a controller which increases the quantity of intake air drawn into the internal combustion engine while the internal combustion engine is idling after the internal combustion engine has started to operate, to a level which is greater by a predetermined increase than the quantity of intake air drawn into the internal combustion engine while the internal combustion engine is idling normally. The controller also generates a command value for ignition timing of the internal combustion engine according to a feedback control process to converge the rotational speed of the internal combustion engine toward a predetermined target rotational speed, and controlling the ignition timing of the internal combustion engine based on the generated command value thereby to retard the ignition timing.

Abstract: A plant control system controls a plant modeled as a discrete-system model including an element relative to a response delay of the plant. The plant control system includes an actuator for generating an input to the plant, a first detector detecting an output from the plant, and a second detector for detecting the input to the plant which is generated by the actuator. An identifier identifies parameters to be established of the discrete-system model based on data representing an output of the first detector and data representing an output of the second detector. A manipulated variable determining unit determines a manipulated variable which determines the input to the plant to control operation of the actuator such that the output from the first detector will be equalized to a predetermined target value, according to a predetermining algorithm using the parameters of the discrete-system model which are identified by the identifier.

Abstract: A plant control system for controlling a plant includes an actuator for generating an input to the plant and a first detector for detecting an output from the plant. A manipulated variable determining unit determines a manipulated variable which determines the input to the plant according to a sliding mode control process such that an output from the first detector will be equalized to a predetermined target value. The manipulated variable determining unit determines the manipulated variable to converge a plurality of state quantities, which comprise differences between a plurality of present and previous time-series data of the output of the first detector and the target value, onto a balanced point on a hyperplane for the sliding mode control process, which is defined by a linear function having variables represented respectively by the state quantities.

Abstract: A plant control system controls a plant modeled as a discrete-system model including an element relative to a response delay of the plant and an element relative to a dead time of the plant. The plant control system includes an actuator for generating an input to the plant, a first detector for detecting an output from the plant, and a second detector for detecting the input to the plant. An estimator generates data representing an estimated value of an output of the first detector after the dead time, based on data representing the output of the first detector and data representing an output of the second detector. A manipulated variable determining unit determines a manipulated variable which determines the input to the plant, based on the estimated value, represented by the data generated by the estimator, of the output of the first detector after the dead time.

Abstract: A control system for a plant includes a sensor for detecting an output from the plant, an adaptive controller for controlling a manipulated variable applied to control of the plant in a manner such that an output from the sensor becomes equal to a desired value, and an adaptive parameter vector-adjusting mechanism for adjusting an adaptive parameter vector used by the adaptive controller. The adaptive parameter vector-adjusting mechanism is constructed such that an updating component for updating the adaptive parameter vector is added to an initial value of the adaptive parameter vector, and updates the adaptive parameter vector by multiplying at least part of preceding values of the updating component by a predetermined coefficient which is larger than 0 but smaller than 1.