Abstract: An exhaust purification system of an internal combustion engine comprises an air-fuel ratio control device controlling an air-fuel ratio of the inflowing exhaust gas to a target air-fuel ratio. If a first judged condition wherein an estimated amount of change of an oxygen storage amount of the catalyst when the target air-fuel ratio is maintained at the first set air-fuel ratio is equal to or greater than a first reference amount, and a second judged condition wherein a difference of an air-fuel ratio detected by the upstream side air-fuel ratio sensor and a stoichiometric air-fuel ratio is equal to or greater than a difference of a second judged air-fuel ratio and a stoichiometric air-fuel ratio are satisfied, the air-fuel ratio control device switches the target air-fuel ratio from the first set air-fuel ratio to the second set air-fuel ratio when the first judged condition and second judged condition are satisfied.

Abstract: An exhaust purification system comprises an air-fuel ratio control device. If the air-fuel ratio detected by the downstream side air-fuel ratio sensor 41 reaches a second judged air-fuel ratio, the air-fuel ratio control device sets the target air-fuel ratio to a third set air-fuel ratio when the air-fuel ratio reaches the second judged air-fuel ratio, and switch the target air-fuel ratio from the third set air-fuel ratio to the second set air-fuel ratio when the air-fuel ratio becomes a value at the stoichiometric air-fuel ratio side from the second judged air-fuel ratio. The first set air-fuel ratio, the first judged air-fuel ratio and the second judged air-fuel ratio are an air-fuel ratio in the first region. The second set air-fuel ratio and the third set air-fuel ratio are an air-fuel ratio in a second region at an opposite side from the first region.

Abstract: An exhaust purification system comprises a catalyst 20, an upstream side air-fuel ratio sensor 40, a downstream side air-fuel ratio sensor 41, and an air-fuel ratio control device. The air-fuel ratio control device alternately switches a target air-fuel ratio between a rich set air-fuel ratio and a lean set air-fuel ratio, calculates an oxygen storage amount and an oxygen discharge amount, updates a learning value, and corrects an air-fuel ratio-related parameter based on the learning value. The air-fuel ratio control device changes a condition for switching the target air-fuel, stores the learning value at the time when the operating state of the internal combustion engine changes from the first state to the second state as a first state value, and updates the learning value to the first state value when the operating state of the internal combustion engine returns from the second state to the first state.

Abstract: In a control system for an internal combustion engine, the internal combustion engine includes a first exhaust catalyst that is a three-way catalyst disposed in an exhaust path of the internal combustion engine, a second exhaust catalyst that is a three-way catalyst disposed in the exhaust path on a downstream side of the first exhaust catalyst, and a motor configured to drive the internal combustion engine. The control system includes an electronic control unit configured to, when operation of the internal combustion engine is stopped, stop fuel injection in the internal combustion engine and then, execute motoring in which the internal combustion engine is rotationally driven using drive power of the motor, and execute the motoring in a range in which an oxygen occlusion amount of the first exhaust catalyst becomes an oxygen occlusion amount smaller than an upper limit oxygen occlusion amount of the first exhaust catalyst.

Abstract: A control system of an internal combustion engine which can suppress a drop in the purification performance of an exhaust purification catalyst is provided. The control system of an internal combustion engine is provided with an exhaust purification catalyst and downstream side air-fuel ratio sensor, performs feedback control so that an air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst becomes a target air-fuel ratio, and performs target air-fuel ratio setting control which alternately switches the target air-fuel ratio to a lean set air-fuel ratio which is leaner than a stoichiometric air-fuel ratio and a rich set air-fuel ratio which is richer than the stoichiometric air-fuel ratio. In the control system, when an engine operating state is a steady operating state, compared with when it is not a steady operating state, at least one of a rich degree of the rich set air-fuel ratio or a lean degree of the lean set air-fuel ratio is made to increase.

Abstract: An internal combustion engine 100 comprises an air-fuel ratio control device. The air-fuel ratio control device controls the amount of fuel fed to the combustion chamber by feedback control so that the air-fuel ratio detected by the upstream side air-fuel ratio sensor matches the target air-fuel ratio when a blow-through amount of air blown from the intake passage through a cylinder to the exhaust passage due to an occurrence of valve overlap is a reference blow-through amount or less. The air-fuel ratio control device sets the target air-fuel ratio of the inflowing exhaust gas based on the air-fuel ratio detected by the downstream side air-fuel ratio sensor and, without performing the feedback control, feeds the amount of fuel calculated from the target air-fuel ratio to the combustion chamber when the blow-through amount is greater than the reference blow-through amount.

Abstract: An internal combustion engine comprises an exhaust purification catalyst. The control system comprises a temperature detecting means for detecting or estimating a temperature of the exhaust purification catalyst, performs feedback control so that an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst becomes a target air-fuel ratio, and performs target air-fuel ratio setting control which alternately sets the target air-fuel ratio to a rich set air-fuel ratio and a lean set air-fuel ratio. In addition, the control system increases a variation difference, obtained by subtracting a rich degree of the rich set air-fuel ratio from a lean degree of a lean set air-fuel ratio, when a temperature of the exhaust purification catalyst detected or estimated by the temperature detecting means is a predetermined upper limit temperature or less compared with when it is higher than the upper limit temperature.

Abstract: An internal combustion engine includes an exhaust purification catalyst. A control system includes an air-fuel ratio sensor downstream of the exhaust purification catalyst, and an air-fuel ratio control device which controls the air-fuel ratio of the exhaust gas. The target air-fuel ratio is set to a lean air-fuel ratio when output air-fuel ratio of the sensor becomes a rich judged air-fuel ratio or less and is set to a rich air-fuel ratio when output air-fuel ratio becomes a lean judged air-fuel ratio or more. When the engine operating state is a steady operation state and is a low load operation state, at least one of an average lean degree of the target air-fuel ratio while the target air-fuel ratio is set to a lean air-fuel ratio and an average rich degree of the target air-fuel ratio while the target air-fuel ratio is set to a rich air-fuel ratio is increased.

Abstract: A control apparatus for an internal combustion engine is provided. The control apparatus includes an electronic control unit. The electronic control unit is configured to: set a target air-fuel ratio at a lean air-fuel ratio that is leaner than a theoretical air-fuel ratio from time at which an output air-fuel ratio of a downstream-side air-fuel ratio sensor becomes equal to or lower than a rich determination air-fuel ratio; and set the target air-fuel ratio at a rich air-fuel ratio that is richer than the theoretical air-fuel ratio after an oxygen storage amount of the exhaust gas control catalyst becomes equal to or larger than the specified switching reference storage amount and the output air-fuel ratio of the downstream-side air-fuel ratio sensor becomes higher than the rich determination air-fuel ratio.

Abstract: In a control apparatus for use an internal combustion engine in which warming-up time air fuel ratio control is executed, the air fuel ratio of the exhaust gas flowing into the three-way catalyst is changed to an air fuel ratio higher by the predetermined amount, by using as a trigger the timing at which a measured value of an air fuel ratio sensor indicates a rich air fuel ratio. In addition, when the timing at which the measured value of the air fuel ratio sensor indicates the rich air fuel ratio is earlier than a reference timing, the starting-time-rich-air-fuel-ratio in the next and following warming-up time air fuel ratio control is corrected to an air fuel ratio which is higher than that in the current warming-up time air fuel ratio control.

Abstract: An internal combustion engine includes an upstream side exhaust purification catalyst and a downstream side exhaust purification catalyst. The control device includes a storage amount estimating device which estimates the oxygen storage amount of the downstream side exhaust purification catalyst, and can execute fuel cut control which cuts the feed of fuel to the combustion chamber during operation of the internal combustion engine when the engine speed is the lowest reference speed or more. The control device lowers the lowest reference speed when the storage amount estimated by the storage amount estimating device has become a given limit storage amount or less, compared with when it is larger than the limit storage amount. As a result, a control device can effectively keep the oxygen storage amount of the downstream side exhaust purification catalyst from decreasing to zero.

Abstract: 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.

Abstract: 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.

Abstract: Invention suppresses deterioration of emission if there is air-fuel ratio imbalance among cylinders.

Abstract: The internal combustion engine comprises a supercharger, a variable valve timing mechanism able to change a valve overlap amount, a catalyst arranged in an exhaust passage and able to store oxygen, a downstream side air-fuel ratio sensor arranged at a downstream side of the catalyst in an exhaust flow direction and able to detect an air-fuel ratio of outflowing exhaust gas flowing out from the catalyst, and a scavenging control device able to control a scavenging amount by controlling the valve overlap amount by the variable valve timing mechanism. The scavenging control device reduces the valve overlap amount when an air-fuel ratio detected by the downstream side air-fuel ratio sensor changes from less than a lean judged air-fuel ratio leaner than a stoichiometric air-fuel ratio to the lean judged air-fuel ratio or more during scavenging.

Abstract: This control device for an internal combustion engine equipped with an exhaust purification catalyst, which is disposed in an exhaust passage of the internal combustion engine and capable of storing oxygen, includes: a downstream air-fuel ratio detection means that is disposed downstream of the exhaust purification catalyst in the exhaust flow direction; and an inflow air-fuel ratio control means that controls the air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst. If the outflow air-fuel ratio detected by the downstream air-fuel ratio detection means is equal to or less than a rich-determination air-fuel ratio, which is richer than the stoichiometric air-fuel ratio, the inflow air-fuel ratio control means sets the target air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst continuously or intermittently leaner than the stoichiometric air-fuel ratio until the oxygen storage amount of the exhaust purification catalyst reaches a prescribed storage amount.

Abstract: A control apparatus for a gasoline engine having a fuel injection means including an in-cylinder injection valve. The control apparatus comprises a controller configured to, when warming up an exhaust gas purification catalyst provided in an exhaust passage provided of the gasoline engine, control the fuel injection means to conduct one or more main injections, control the in-cylinder injection valve to conduct a post injection, perform a retard correction of an ignition timing at which fuel injected by the one or more main injections is ignited, determine an injection quantity by the one or more main injections and an injection quantity by the post injection such that an air-fuel mixture formed in the cylinder by gasoline fuel injected by the one or more main injections has a predetermined lean air-fuel ratio at which a difference between an actual output torque and a required torque is within a predetermined allowable range.

Abstract: The control system of an internal combustion engine performs normal operation control including lean control for making the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst a lean air-fuel ratio, and rich control for making the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst a rich air-fuel ratio. The normal operation control includes judgment reference decreasing control decreasing the judgment reference storage amount in the lean control when during the time period of performing the lean control, the air-fuel ratio of the exhaust gas flowing out from the exhaust purification catalyst becomes the lean judged air-fuel ratio or more. The control system judges that the exhaust purification catalyst is abnormal when the judgment reference storage amount becomes less than a deterioration judgment value.

Abstract: A control device for an internal combustion engine includes: an upstream catalyst; a downstream catalyst that is provided further downstream than the upstream catalyst in the exhaust flow direction; a downstream air-fuel ratio detection device that is provided between these catalysts; a storage amount estimation device that estimates the oxygen storage amount of the downstream catalyst; and an inflow air-fuel ratio control device that controls the air-fuel ratio of the exhaust gas flowing into the upstream catalyst such that the air-fuel ratio of the exhaust gas reaches a target air-fuel ratio.

Abstract: A control device for an internal combustion engine, said control device implementing a lean control, whereby the air-fuel ratio of the exhaust gas flowing into an exhaust purification catalyst is set to a lean air-fuel ratio setting, and a rich control, whereby the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst is set to a rich air-fuel ratio setting. When the amount of oxygen absorbed by the exhaust purification catalyst during lean control reaches or exceeds a criterion storage amount, a control is executed to switch to rich control. In addition, a control is executed to set the lean air-fuel ratio setting for a first intake air amount so as to be richer than the lean air-fuel ratio setting for a second intake air amount that is less than the first intake air amount.