摘要:
A first exhaust gas sensor 5 (air-fuel ratio sensor) and a second exhaust gas sensor 6 (O2 sensor) are disposed respectively upstream and downstream of a catalytic converter. An exhaust system E which ranges from the exhaust gas sensor 5 to the exhaust gas sensor 6 and includes the catalytic converter 3 is regarded as an object exhaust system E, and a behavior of the object exhaust system E is modeled. When an internal combustion engine 1 is in operation, parameters to be set of the model of the object exhaust system E are sequentially identified based on the data of outputs of the exhaust gas sensors 5, 6. A deteriorated state of the catalytic converter 3 is determined based on the data of the identified values. Concurrent with the determination of the deteriorated state, a target air-fuel ratio for the internal combustion engine 1 is sequentially determined in order to converge the output of the exhaust gas sensor 5 to a given target value, and the air-fuel ratio of the internal combustion engine 1 is controlled to converge the output (the detected value of the air-fuel ratio) of the first exhaust gas sensor 5 to the target air-fuel ratio, for thereby allowing the catalytic converter 3 to achieve an optimum purifying capability. In this manner, the deteriorated state of the catalytic converter 3 can be determined in various operation states of the internal combustion engine 1 while keeping the purifying capability of the catalytic converter 3.
摘要:
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.
摘要:
An exhaust system is regarded as being equivalent to a system for generating an output of an O2 sensor or exhaust gas sensor from a combined air-fuel ratio that is produced by combining outputs of air-fuel ratio sensors associated with respective cylinder groups according to a filtering process of the mixed model type. With the equivalent system as an object to be controlled, an exhaust system controller determines a target value for the combined air-fuel ratio, and determines a target air-fuel ratio for the cylinder groups from the target combined air-fuel ratio. The outputs of the air-fuel ratio sensors are converted to the target combined air-fuel ratio under feedback control.
摘要:
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.
摘要:
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.
摘要:
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. Calculation of the learned value of the desired air-fuel ratio correction amount is permitted depending on a ratio between a time period over which the output from the second air-fuel ratio sensor is on a richer side with respect to a predetermined reference value and a time period over which the output from the second air-fuel ratio sensor is on a leaner side with respect to the predetermined reference value.
摘要:
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.
摘要:
A system for estimating an exhaust gas recirculation rate for an internal combustion engine. In the system, the EGR rate when its operation is steady is first determined to a desired value with respect to the engine operating conditions at least including the engine speed and the engine load, then the EGR rate is estimated as;EGR rate=(steady-state EGR rate).times.{(gas flow rate QACT determined by the actual valve lifting amount and the ratio between the upstream pressure and the downstream pressure of valve)/(gas flow rate QCMD determined by a command value and the ratio between the upstream pressure and the downstream pressure of valve)} A delay time until the recycled gas enters the combustion chamber is determined and one from among the EGR rates or a fuel injection correction coefficients calculated therefrom consecutively is selected.
摘要:
An ignition timing control system controls ignition timing of spark plugs of an internal combustion engine associated with a plurality of changeover devices, changeover of an operative state of each of which has influence upon output torque of the engine. Operating conditions of the engine are detected. A basic ignition timing advance value is calculated based on results of detection of the operating conditions of the engine. A changeover of the operative state of each of the changeover devices is detected. A correction value for correcting the basic ignition timing advance value for suppressing the engine torque is calculated, in response to results of detection of the changeover of the operative state of each of the changeover devices. The largest one of a plurality of the correction values calculated is selected to a final correction value to be used for correcting the basic ignition timing advance value, when changeovers of the operative states of at least two of the changeover devices are detected substantially at the same time.
摘要:
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.