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.

Abstract: An air-fuel ratio control system for a multi-cylinder engine is provided. An air-fuel ratio sensor is arranged in an exhaust system of the engine for detecting an air-fuel ratio of a mixture supplied to the engine and for generating an output indicative of the air-fuel ratio of the mixture. An adaptive controller determines an amount of fuel to be supplied to the engine with a first predetermined repetition period in a manner such that the output from the air-fuel ratio sensor becomes equal to a desired value. An adaptive parameter-adjusting mechanism adjusts adaptive parameters used by the adaptive controller. In the adaptive parameter-adjusting mechanism, the adaptive parameters are calculated with a second predetermined repetition period longer than the first predetermined repetition period, and output data indicative of results of the calculation is generated.

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-adjusting device for adjusting adaptive parameters used by the adaptive controller. The adaptive controller is configured in a manner adapted to a predetermined dead time shorter than an actual dead time which the plant and the detection means possess. Sampling timing of an input vector input to the adaptive parameter-adjusting device corresponds to the actual dead time.

Abstract: A system for purifying exhaust gas generated by an internal combustion engine including a bypass branching out from the exhaust pipe downstream of a catalyst and merging to the exhaust pipe, an adsorber installed in the bypass, a bypass valve member which closes the bypass, and an EGR conduit connected to the bypass at one end and connected to the air intake system for recirculating the exhaust gas to the air intake system. The bypass valve member is opened for a period after engine startup to introduce the exhaust gas such that the adsorber installed in the bypass adsorbs the unburnt HC component in the exhaust gas. The adsorber adsorbs the HC component when the exhaust temperature rises and the adsorbed component is recirculated to the air intake system through the EGR conduit. In the system, the bypass valve is provided at or close to the branching point in the exhaust pipe and a chamber is provided close to the branching point such that the conduit is connected to the bypass at the one end in the chamber.

Abstract: A deterioration of a catalytic converter for purifying an exhaust gas produced by burning a mixture of a fuel and air in an internal combustion engine, for example, is judged by supplying the exhaust gas to the catalytic converter, detecting the amount of a predetermined component of the exhaust gas which has passed through the catalytic converter with an exhaust gas sensor disposed downstream of the catalytic converter, calculating a target air-fuel ratio for the exhaust gas to be supplied to the catalytic converter for achieving a predetermined emission purifying capability of the catalytic converter based on a detected output signal from the exhaust gas sensor, and judging a deteriorated state of the catalytic converter based on the calculated target air-fuel ratio.

Abstract: An air-fuel control system for use with an internal combustion engine has a catalytic converter disposed in an exhaust system of the engine, for purifying an exhaust gas emitted from the engine, a first exhaust gas sensor in the exhaust system for detecting an air-fuel ratio of the exhaust gas upstream of the catalytic converter, a second exhaust gas sensor in the exhaust system for detecting the concentration of a component of the exhaust gas which has passed through the catalytic converter, downstream of the catalytic converter, and a correction quantity calculator for determining a correction quantity to correct an air-fuel ratio of the engine based on an output from the second exhaust gas sensor so as to equalize the concentration of the component of the exhaust gas downstream of the catalytic converter to a predetermined appropriate value.

Abstract: A fuel metering control system for an internal combustion engine having a plurality of cylinders. The system includes an air/fuel ratio sensor and engine operating condition detecting means for detecting engine operating conditions such as engine speed and engine load. The basic quantity of fuel injection is determined by retrieving mapped data according to the detected parameters. A plurality of controllers are provided all using outputs of the air/fuel ratio sensor. The controllers are configured to receive the sensor outputs through filters having different cutout frequency so as to avoid control interference therebetween.

Abstract: According to a sliding mode control method, a hyperplane for a sliding mode control process is established with a linear function having as variables a plurality of state quantities of an object to be controlled. The state quantities are converged onto the hyperplane, and also converged toward a balanced point on the hyperplane while the state quantities are being converged onto the hyperplane, thereby to control the state quantities at target state quantities represented by the balanced point. The hyperplane are variably established depending on the manner in which the state quantities are converged onto the hyperplane.

Abstract: An air-fuel control system for use with an internal combustion engine has a catalytic converter disposed in an exhaust system of the engine, for purifying an exhaust gas emitted from the engine, a first exhaust gas sensor disposed in the exhaust system for detecting an air-fuel ratio of the exhaust gas upstream of the catalytic converter, a second exhaust gas sensor disposed in the exhaust system for detecting the concentration of a component of the exhaust gas which has passed through the catalytic converter, downstream of the catalytic converter, and a control unit for controlling an air-fuel ratio of the engine based on outputs from the first exhaust gas sensor and the second exhaust gas sensor.

Abstract: An air-fuel control system for use with an internal combustion engine has a catalytic converter in an exhaust system of the engine, for purifying an exhaust gas emitted from the engine, a first exhaust gas sensor in the exhaust system for detecting an air-fuel ratio of the exhaust gas upstream of the catalytic converter, and a second exhaust gas sensor in the exhaust system for detecting the concentration of a component of the exhaust gas which has passed through the catalytic converter, downstream of the catalytic converter. A sliding mode controller determines a correction quantity at a first period to correct the air-fuel ratio of the engine so as to equalize the concentration of the component downstream of the catalytic converter to a predetermined appropriate value, according to a sliding mode control process based on the output from the second exhaust gas sensor.

Abstract: An air-fuel control system for use with an internal combustion engine has a catalytic converter, a first exhaust gas sensor, and a second exhaust gas sensor. A sliding mode controller determines a correction quantity to equalize the concentration of the component downstream of the catalytic converter to a predetermined appropriate value based on the output from the second exhaust gas sensor. A feedback controller determines a correction quantity to converge the concentration of the component downstream of the catalytic converter toward the predetermined appropriate value, and feed-back controls the rate at which fuel is supplied to the engine with the determined correction quantity.

Abstract: There is provided an air-fuel ratio control system for an internal combustion engine installed on an automotive vehicle. The control system controls the air-fuel ratio of a mixture supplied to the engine to a value leaner than a stoichiometric air-fuel ratio immediately after the start of the engine. Operating conditions of the engine and/or operating conditions of the automotive vehicle is detected. Starting of the vehicle is predicted based on the detected operating conditions of the engine and/or the detected operating conditions of the automotive vehicle. The air-fuel ratio of the mixture supplied to the engine is changed to a richer value than the leaner value when the starting of the vehicle is predicted.

Abstract: A fuel metering control system for an internal combustion engine having a plurality of cylinders. The system includes an air/fuel ratio sensor and engine operating condition detecting means for detecting engine operating conditions at least including engine speed and engine load. The basic quantity of fuel injection is determined by retrieving mapped data according to the engine speed and engine load. An adaptive controller is provided to calculate a first feedback correction coefficient to correct the quantity of basic fuel injection such that the detected air/fuel ratio is brought to a desired value, and second feedback loop is provided for calculating feedback correction coefficients to correct the quantity of fuel injection. The desired air/fuel ratio is corrected by a second air/fuel ratio installed downstream of a catalytic converter.

Abstract: There is provided an air-fuel ratio control system for an internal combustion engine installed on an automotive vehicle. The control system controls the air-fuel ratio of a mixture supplied to the engine to a value leaner than a stoichiometric air-fuel ratio immediately after the start of the engine. Operating conditions of the engine and/or operating conditions of the automotive vehicle is detected. Starting of the vehicle is predicted based on the detected operating conditions of the engine and/or the detected operating conditions of the automotive vehicle. The air-fuel ratio of the mixture supplied to the engine is changed to a richer value than the leaner value when the starting of the vehicle is predicted.

Abstract: An air-fuel ratio control system for an internal combustion engine has a first air-fuel ratio sensor arranged in an exhaust passage at a location upstream of a catalyst and a second air-fuel ratio sensor arranged in the exhaust passage at a location downstream of the catalyst. In response to an output from the first air-fuel ratio sensor, an air-fuel ratio correction coefficient is calculated for correcting an amount of fuel supplied to the engine in a manner such that an air-fuel ratio of a mixture supplied to the engine is converged to a desired air-fuel ratio. In response to an output from the second air-fuel ratio sensor, a desired air-fuel ratio correction amount is calculated for correcting the desired air-fuel ratio. A learned value of the desired air-fuel ratio correction amount is calculated, and the desired air-fuel ratio is corrected.

Abstract: There is provided an air-fuel ratio control system for an internal combustion engine installed on an automotive vehicle. The control system controls the air-fuel ratio of a mixture supplied to the engine to a value leaner than a stoichiometric air-fuel ratio immediately after the start of the engine. Operating conditions of the engine and/or operating conditions of the automotive vehicle is detected. Starting of the vehicle is predicted based on the detected operating conditions of the engine and/or the detected operating conditions of the automotive vehicle. The air-fuel ratio of the mixture supplied to the engine is changed to a richer value than the leaner value when the starting of the vehicle is predicted.

Abstract: A fuel metering control system for an internal combustion engine including a feedback loop having an adaptive controller and an adaptation mechanism that estimates controller parameters .theta.. The adaptive controller corrects the quantity of fuel injection to bring a controlled variable obtained at least based on an output of said air/fuel ratio sensor, to a desired value. The adaptation mechanism is input with the controlled variable once per prescribed crank angle such as a TDC of a certain cylinder and estimates the controller parameters. Since, however, the input is limited to a specific cylinder's air/fuel ratio, the air/fuel ratio is averaged for all cylinders and used in the calculation. Similar averaging is made for the other parameters input to the mechanism or output from the controller.

Abstract: A system for controlling fuel metering for an internal combustion engine having a feedback system which has a controller for calculating a feedback correction coefficient, using an adaptive control law to correct a quantity of fuel injection such that a detected air/fuel ratio is brought to a desired air/fuel ratio. In the system, it is discriminated whether the feedback correction coefficient and the detected air/fuel ratio are in phase, and the feedback system is instable when they are discriminated to be in phase. Since the coefficient acts to correct the deviation of the detected air/fuel ratio from the desired air/fuel ratio, they are normally in antiphase. It is thus possible to find the system instable, by discriminating whether they are in phase or not.

Abstract: A system for controlling fuel metering for an internal combustion engine provided with a first feedback loop that calculates a first feedback correction coefficient using an adaptive control law to correct a quantity of fuel injection such that a detected air/fuel ratio is brought to a desired air/fuel ratio, a second feedback loop that calculates a second coefficient using a PID control law to similarly correct the quantity of fuel injection, and a third feedback loop that calculates a third coefficient using a PID controller to correct the quantity of fuel injection such that air/fuel ratio variance among the cylinders decreases. Either of the first or second coefficient is selected and based on the selected coefficient, the feedback gains of the third feedback loop are determined.

Abstract: A fuel metering control system for an internal combustion engine including a feedback loop having an adaptive controller and an adaptation mechanism that estimates a controller parameters .theta.. The adaptive controller corrects the quantity of fuel injection to bring a controlled variable obtained at least based on an output of said air/fuel ratio sensor, to a desired value. The air/fuel ratio sensor outputs are sampled and one of the sampled data is selected as the air/fuel ratio to be input to the adaptation mechanism. Similarly, the senor outputs are sampled and one of the sampled is selected in accordance with another characteristic to be used in the estimation of the air/fuel ratios of the individual cylinder. The air/fuel ratio is discriminated to be within a prescribed range, and set to a predetermined value when it is determined to be within the prescribed range.