A control device of an internal combustion engine calculates on the basis of the air-fuel ratio difference a correction for the estimated fuel supply amount correction for correcting the estimated fuel supply amount to make the estimated and detected air-fuel ratios correspond to each other and calculates correction values for the fuel supply difference compensation and the air amount detection difference compensation by dividing the correction value for the estimated fuel supply amount correction, using the fuel supply and air amount detection difference proportions, and performing the air-fuel ratio control, using the corrected estimated fuel supply and detected air amounts. The correction value for the estimated fuel supply amount correction is divided to the correction values for the fuel supply difference compensation and the air amount detection difference compensation such that a value equivalent to the air-fuel ratio difference becomes equal to the air-fuel ratio difference, using these correction values.

A fuel injection controller includes an oxygen sensor that responds to an oxygen concentration inside an exhaust passage, and an injection amount control unit programmed to control a fuel injection amount based on the output of the oxygen sensor. The injection amount control unit includes an injection amount correction value computing unit that determines an injection amount correction value based on the output of the oxygen sensor, a short-time learning value computing unit that determines a short-time learning value based on the injection amount correction value, a long-time learning value computing unit that determines a long-time learning value based on the short-time learning value; a feedback correction amount computing unit that computes a feedback correction amount, an injection amount control value computing unit that computes a control value of the fuel injection amount, and a long-time learning value holding unit that holds the long-time learning value.

A control device of an internal combustion engine including an electronic control unit configured to execute: a base injection amount calculation process of calculating a base value; an injection valve operation process of operative the fuel injection valve; a feedback process of correcting an injection amount in the injection valve operation process; and a determination process of determining whether or not the amount of fuel flowing into the cylinders other than fuel injected from the fuel injection valve is equal to or larger than a threshold value. When it is determined as a result of the determination that the amount of fuel flowing into the cylinders other than the fuel injected from the fuel injection valve is equal to or larger than the threshold value, the electronic control unit (does not execute the process of injecting fuel from the fuel injection valve with the feedback process stopped.

The internal combustion engine comprises an exhaust purification catalyst able to store oxygen, and a downstream side air-fuel ratio sensor arranged at a downstream side of the exhaust purification catalyst in a direction of exhaust flow. The control system performs feedback control of an amount of fuel fed to a combustion chamber of the internal combustion engine so that an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst becomes a target air-fuel ratio and performs learning control to correct a parameter relating to the feedback control based on an air-fuel ratio of exhaust gas detected by the downstream side air-fuel ratio sensor. The target air-fuel ratio is alternately switched between a rich set air-fuel ratio and a lean set air-fuel ratio leaner. When a condition for learning acceleration, which is satisfied when it is necessary to accelerate correction of the parameter by the learning control, is satisfied, a rich degree of the rich set air-fuel ratio is increased. Therefore, there is provided an internal combustion engine able to suitably change the speed of updating the learning value.

An internal combustion engine comprises: an exhaust purification catalyst; a downstream side air-fuel ratio sensor which is arranged at a downstream side of the exhaust purification catalyst; and an air-fuel ratio control system which performs feedback control so that the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst becomes a target air-fuel ratio. The air-fuel ratio control system switches the target air-fuel ratio to a lean set air-fuel ratio when the air-fuel ratio detected by the downstream side air-fuel ratio sensor becomes a rich judged air-fuel ratio or less; changes the target air-fuel ratio to a slight lean set air-fuel ratio after switching the target air-fuel ratio to the lean set air-fuel ratio and before an estimated value of the oxygen storage amount of the exhaust purification catalyst becomes a switching reference storage amount or more; and switches the target air-fuel ratio to a rich air-fuel ratio when the estimated value of the oxygen storage amount of the exhaust purification catalyst becomes the switching reference storage amount or more.

An exhaust purification system includes: an NOx reduction type catalyst, which is provided in an exhaust system; and a regeneration treatment unit, which recovers an NOx purification capacity of the NOx reduction type catalyst, wherein the regeneration treatment unit includes: a target setting unit, which sets a target injection amount of at least one of a post injection and an exhaust pipe injection that is required for setting an excess-air-ratio of the exhaust gas to the target excess-air-ratio, based on a suction air amount of the internal combustion engine, the target excess-air-ratio, and a fuel injection amount of the internal combustion engine; and an injection controller, which controls an injection amount of at least one of the post injection and the exhaust pipe injection, based on the target injection amount input from the target setting unit.

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.

In a control apparatus for an internal combustion engine, a vapor concentration learned value learned as a concentration of fuel in purge gas is reflected in an injection amount command value used for fuel injection amount control. An electronic control unit changes a reflection mode of reflecting the vapor concentration learned value in the injection amount command value depending on a pattern of switching an inlet through which the purge gas flows into an intake passage, between a first inlet and a second inlet upstream of the first inlet, and executes the reflection in the changed reflection mode during a period from a start of an intake of intermediate gas into a cylinder to completion of the intake of the intermediate gas. The intermediate gas is present in a portion of the intake passage between the first inlet and the second inlet when switching of the inlet is performed.

An injection control device includes: a fuel injection quantity command value output unit that outputs a command value for a fuel injection quantity of a fuel injection valve; a fuel injection quantity correction unit that calculates an air-fuel correction amount and corrects the command value for the fuel injection quantity; and a controller that executes current control on the fuel injection valve. The controller executes current area correction by calculating an area correction amount for an energization time. The injection control device further includes a learning controller that stops the air-fuel learning.