Abstract: An engine ECU calculates a rotational variation based on a required rotation time when a complete misfire occurs in a cylinder, a required rotation time when complete combustion occurs in the cylinder, and a required rotation time during the current combustion stroke, and integrates the calculated rotational variation. If it is determined that the number of times the rotational variation has been integrated has reached a predetermined number, the engine ECU calculates an amount of learning value deviation from the integrated rotational variation. If the amount of learning value deviation is equal to or greater than a certain amount, the engine ECU corrects a learning value of a sub-feedback control with respect to the air-fuel ratio.

Abstract: A control apparatus of an internal combustion engine capable of appropriately reflecting various requests relating to the performance of the internal combustion engine. Specifically, the control device of the internal combustion engine acquires various requests relating to the performance of the internal combustion engine, and sets restricted ranges of the value of the control variable in accordance with the details of the requests. At this moment, the control device temporally changes the set restricted ranges for specific requests associated with the time integral value of the control variable rather than the instantaneous value of the control variable. Subsequently, the control device determines a final restricted range on the basis of the overlap between the restricted ranges set for each request, and determines the target value of the control variable in the final restricted range.

Abstract: Provided is an internal combustion engine system controller, including a sub-feedback learning section, a state determining section, and a learning update-speed setting section. The state determining section determines, to which of at least three states including: (a) a stable state in which a fluctuating state of a sub-feedback learning value is stable; (b) an unstable state in which the fluctuating state greatly fluctuates; and (c) an intermediate state between the stable state and the instable state (may be referred to as sub-stable state), the fluctuating state corresponds. The learning update-speed setting section sets an update speed of the sub-feedback learning value in accordance with the result of determination by the state determining section. Further, the learning update-speed setting section suppresses the occurrence of hunting of the sub-feedback learning value.

Abstract: A catalyst degradation determining method includes the steps of: controlling an upstream-of-catalyst air-fuel ratio occurring upstream of a first catalyst to an air-fuel ratio that is rich of a stoichiometric air-fuel ratio so that first and second catalysts store oxygen up to a maximum storage amount of oxygen. The method then includes the steps of controlling the upstream-of-catalyst air-fuel ratio to a first lean air-fuel ratio until an output of a downstream-of-first-catalyst sensor indicates a lean air-fuel ratio, and then to a second lean air-fuel ratio and that has a value that is determined in accordance with an oxidizing-reducing capability index value, until a time point when an output of a downstream-of-second-catalyst air-fuel ratio sensor indicates an air-fuel ratio that is lean.

Abstract: The present invention relates to an air-fuel ratio control device for an internal combustion engine, and makes it possible to maintain high purification performance by suppressing a decrease in the oxygen occlusion capability of a catalyst. When an O2 sensor output oxs is greater than a reference value oxsref, which corresponds to a stoichiometric air-fuel ratio, and smaller than an upper threshold value oxsrefR, a sub-FB reflection coefficient is fixed at a predetermined value vdox2 for providing a lean air-fuel ratio. When, on the other hand, the O2 sensor output oxs is smaller than the reference value oxsref and greater than a lower threshold value oxsrefL, the sub-FB reflection coefficient is fixed at a predetermined value vdox2 for providing a rich air-fuel ratio. The sub-FB reflection coefficient reflects the O2 sensor output oxs in the calculation of a fuel injection amount and increases or decreases to have a consequence on the air-fuel ratio of an exhaust gas.

Abstract: Disclosed is a control device that is used for an internal combustion engine and capable of making various requests concerning the performance of the internal combustion engine be reflected in a target control amount value while the requests need not be expressed in the form of a requested control amount value. The control device acquires various requests concerning the performance of the internal combustion engine and sets a request-specific constraint on a control amount value. More specifically, the control device expresses constraints to be set for control amount values as a set of constraint index values assigned to individual control amount values, and varies the distribution of the constraint index values assigned to the control amount values in accordance with the type of a request. Next, the control device integrates, for each control amount value, the constraint index values assigned to individual requests with respect to each control amount value.

Abstract: A control device for an internal combustion engine provided by the present invention is a control device which can satisfy both a requirement relating to exhaust gas performance of the internal combustion engine and a requirement relating to operation performance by properly regulating a change speed of a required air-fuel ratio, in the internal combustion engine which uses torque and an air-fuel ratio as control variables. The control device receives the requirement relating to the exhaust gas performance of the internal combustion engine, and calculates an air-fuel ratio which satisfies the requirement as a required air-fuel ratio. When a predetermined reduction condition is not satisfied, an original required air-fuel ratio is directly determined as a final required air-fuel ratio.

Abstract: A fuel injection amount control apparatus calculates as a proportional term a value obtained by multiplying by a proportional gain Kp a deviation DVoxslow between a downstream side target value Voxsref and an output value Voxs of a downstream side air-fuel ratio sensor disposed downstream of a catalyst. The control apparatus calculates a time integrated value SDVoxslow by integrating a value obtained by multiplying by a predetermined adjustment gain K the deviation DVoxslow, calculates a value that is commensurate with the time integrated value SDVoxslow as an integral term Ki×SDVoxslow, and obtains the integral term Ki×SDVoxslow as a sub-FB learned value KSFBg. The control apparatus sets the proportional gain Kp at a small value after the sub-FB learned value KSFBg is determined to have converged, and sets the adjustment gain K at a small value after the sub-FB learned value KSFBg is determined to have converged.

Abstract: An air-fuel ratio control system of a multi-cylinder internal combustion engine provided with a throttle valve and opening characteristic control means, which system performs feedback control of an air-fuel ratio based on an output of a sensor detecting an air-fuel ratio of exhaust gas and is capable of performing more accurate air-fuel ratio control, is provided. In the feedback control, the relationship of the output of the sensor and a feedback value is corrected based on a feedback learning correction value learned and determined based on the output of the sensor during the feedback control, and, when newly learning the feedback learning correction value, the intake air amount is controlled by only the throttle valve.

Abstract: Detecting a combustion state of an internal combustion engine includes calculating a one-step difference value and a two-step difference value of a physical quantity that correlates with torque generated by the internal combustion engine; detecting that a misfire has occurred, when the calculated one-step difference value is greater than a first determining value, and the calculated two-step difference value is greater than a second determining value; and determining the first determining value and the second determining value according to a required torque of the internal combustion engine, sensitivity of a change in the one-step difference value with respect to a change in the required torque, and sensitivity of a change in the two-step difference value with respect to a change in the required torque.

Abstract: The control system of an internal combustion engine of the present invention comprises an S/V ratio changing mechanism able to change an S/V ratio of a combustion chamber and a detection device having an output value changing in accordance with a hydrogen concentration in exhaust gas, which increases along with an increase in the S/V ratio, the internal combustion engine being controlled by the output value of the detection device. Further, the output value of the detection device or a parameter relating to operation of the internal combustion engine is corrected in accordance with the S/V ratio of the above S/V ratio changing mechanism. Due to this, even if the hydrogen concentration in the exhaust gas increases along with an increase in the S/V ratio, the internal combustion engine can be suitably controlled.

Abstract: A monitoring apparatus including a catalytic converter, an upstream air-fuel ratio sensor, and a downstream air-fuel ratio sensor; calculates a sub feedback amount to have an air-fuel ratio represented based on an output value of the downstream air-fuel ratio sensor coincide with a stoichiometric air-fuel ratio; and controls an fuel injection amount based on an output value of the upstream air-fuel ratio sensor and the sub feedback amount, in such a manner that an air-fuel ratio of a mixture supplied to an engine coincides with the stoichiometric air-fuel ratio.

Abstract: An evaporated fuel gas concentration learning section A8 renews an evaporated fuel gas concentration learning value based on a feedback correction amount FAF. An estimated purge rate calculating section A9 estimates, a flow of an evaporated fuel gas introduced into a combustion chamber based on a flow KP of an evaporated fuel gas passing through a purge control valve in consideration of a transportation delay time duration and a behavior of the evaporated fuel gas. An instructed injection amount determining section A10 calculates a purge correction amount based on the evaporated fuel gas concentration learning value and the estimated purge flow.

Abstract: An engine ECU calculates a rotational variation based on a required rotation time when a complete misfire occurs in a cylinder, a required rotation time when complete combustion occurs in the cylinder, and a required rotation time during the current combustion stroke, and integrates the calculated rotational variation. If it is determined that the number of times the rotational variation has been integrated has reached a predetermined number, the engine ECU calculates an amount of learning value deviation from the integrated rotational variation. If the amount of learning value deviation is equal to or greater than a certain amount, the engine ECU corrects a learning value of a sub-feedback control with respect to the air-fuel ratio.

Abstract: An evaporated fuel gas concentration learning section A8 renews an evaporated fuel gas concentration learning value based on a feedback correction amount FAF. An estimated purge rate calculating section A9 estimates, a flow of an evaporated fuel gas introduced into a combustion chamber based on a flow KP of an evaporated fuel gas passing through a purge control valve in consideration of a transportation delay time duration and a behavior of the evaporated fuel gas. An instructed injection amount determining section A10 calculates a purge correction amount based on the evaporated fuel gas concentration learning value and the estimated purge flow.

Abstract: A fuel injection amount is controlled so that the air-fuel ratio of exhaust gas flowing into a catalyst (6) oscillates around a stoichiometric air-fuel ratio. When it is estimated that the level of oxygen storage capacity of the catalyst (6) is lower than a predetermined reference capacity, the amplitude of the air-fuel ratio of the exhaust gas which oscillates around the stoichiometric air-fuel ratio is reduced by controlling the fuel injection amount. The level of the oxygen storage capacity of the catalyst (6) is estimated based on the amplitude of the output signal from an oxygen sensor (14) disposed downstream of the catalyst (6).

Abstract: In an air-fuel ratio control apparatus for an internal combustion engine, a feedforward correction amount obtained in accordance with a deviation of a target air-fuel ratio from a stoichiometric air-fuel ratio and a feedback correction amount calculated on the basis of an output value of an air-fuel ratio sensor and subjected to a guard processing are added to a base fuel injection amount corresponding to the stoichiometric air-fuel ratio to decide a fuel injection amount. An upper limit (1) and a lower limit (1) of the feedback correction amount are set on the basis of an alcohol concentration and the feedforward correction amount.

Abstract: An air-fuel ratio control device includes an air-fuel ratio sensor provided upstream from a three-way catalyst, and an oxygen sensor provided downstream from the three-way catalyst. The air-fuel ratio control device controls the fuel supply amount based on the output from the air-fuel ratio sensor, and compensates for errors in the air-fuel ratio sensor by correcting the fuel supply amount based on the output from the oxygen sensor. The fuel supply correction amount is calculated based on an integral term that integrates the deviation between the output from the downstream air-fuel ratio sensor and the target air-fuel ratio. When a fuel supply adjustment control is executed, the value of the integral term in the sub-feedback control is not updated for a predetermined period after the fuel supply adjustment control ends. The actual air-fuel ratio is thus brought to the target air-fuel ratio in an appropriate manner.

Abstract: The air-fuel-ratio control apparatus for an internal combustion engine obtains a composite air-fuel ratio abyfs from a downstream-side correction value Vafsfb(k) based upon an output value Voxs from a downstream air-fuel-ratio sensor 67 and an output value Vabyfs from an upstream air-fuel-ratio sensor 66, and obtains an upstream-side feedback correction value DFi on the basis of the composite air-fuel ratio abyfs. A fuel injection quantity Fi is determined to a value obtained by adding the upstream-side correction value DFi to a control-use base fuel injection quantity Fbasec (=base fuel injection quantity Fbase·coefficient Ksub).

Abstract: An air-fuel ratio control system of a multi-cylinder internal combustion engine provided with a throttle valve and opening characteristic control means, which system performs feedback control of an air-fuel ratio based on an output of a sensor detecting an air-fuel ratio of exhaust gas and is capable of performing more accurate air-fuel ratio control, is provided. In the feedback control, the relationship of the output of the sensor and a feedback value is corrected based on a feedback learning correction value learned and determined based on the output of the sensor during the feedback control, and, when newly learning the feedback learning correction value, the intake air amount is controlled by only the throttle valve.