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: 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 flow meter which detects an amount of intake air. The control system of the internal combustion engine controls the exhaust air-fuel ratio to a target air-fuel ratio by feedback control, sets the target air-fuel ratio at a lean air-fuel ratio when the output air-fuel ratio of the downstream side air-fuel ratio sensor becomes a rich air-fuel ratio, and sets the target air-fuel ratio at a rich air-fuel ratio when the output air-fuel ratio of the downstream side air-fuel ratio sensor becomes a lean air-fuel ratio.

Abstract: An exhaust gas control apparatus for an internal combustion engine, controls an exhaust operation of the internal combustion engine (200) provided with an exhaust gas purification catalyst (216) in an exhaust passage (215). The exhaust gas control apparatus for the internal combustion engine is provided with; a warming-up device configured to warm up the exhaust gas purification catalyst; and an oxygen supplying device (220, 221) configured to supply oxygen to the exhaust gas purification catalyst after the end of the warm-up. This makes it possible to preferably desorb sulfur adsorbed to the exhaust gas purification catalyst during warm-up. It is therefore possible to suppress a reduction in purification ability of the exhaust gas purification catalyst due to sulfur coating.

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: The internal combustion engine comprises an exhaust purification catalyst and a downstream side air-fuel ratio sensor which is arranged at a downstream side of the exhaust purification catalyst. The control system 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 and performs learning control which corrects the control center air-fuel ratio based on the output air-fuel ratio of the downstream side air-fuel ratio sensor. The target air-fuel ratio is switched between the lean air-fuel ratio and the rich air-fuel ratio.

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 applied to an internal combustion engine in which when an opening degree of a valve body of a waste gate valve is less than the predetermined opening degree, the extension line intersects a wall surface of an exhaust passage located upstream of the upstream side end face of the exhaust gas purification catalyst, the control apparatus controls the waste gate valve so that at the time of execution of fuel cut off processing, when the temperature of the exhaust gas purification catalyst is less than a predetermined temperature, the valve body is fully closed, whereas when the temperature of the exhaust gas purification catalyst is not less than the predetermined temperature, the opening degree of the valve body is made to a deterioration suppression opening degree which is larger than when the valve body is fully closed and which is smaller than the predetermined opening degree.

Abstract: An internal combustion engine comprises an exhaust purification catalyst and a downstream side air-fuel ratio sensor which is arranged at the downstream side of the exhaust purification catalyst. The control system performs feedback control so that the air-fuel ratio of the exhaust gas becomes the target air-fuel ratio, and performs learning control to correct the control center air-fuel ratio based on the output air-fuel ratio of the downstream side sensor. The target air-fuel ratio is switched to the lean air-fuel ratio when the output air-fuel ratio of the downstream side sensor becomes the rich judged air-fuel ratio and is switched to the rich air-fuel ratio when the output air-fuel ratio becomes the lean judged air-fuel ratio.

Abstract: A control device of an internal combustion engine which is provided with an exhaust purification catalyst is provided with a downstream side air-fuel ratio sensor, a feed control means for controlling the fuel feed amount so that the air-fuel ratio of the exhaust gas becomes a target air-fuel ratio, and an excess/deficiency estimating means which estimates an oxygen excess/deficiency in the exhaust gas. The target air-fuel ratio is switched to a lean air-fuel ratio when the output air-fuel ratio of the downstream side air-fuel ratio sensor becomes a rich air-fuel ratio and is switched to the rich air-fuel ratio when the stored amount of oxygen of the exhaust purification catalyst after this becomes a switching reference amount or more.

Abstract: An internal combustion engine comprises an exhaust purification catalyst. A control system of the engine comprises a downstream side air-fuel ratio sensor at a downstream side 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 an 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 an 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 device for an internal combustion engine, equipped with: an exhaust purification catalyst capable of storing oxygen; a downstream-side air-fuel ratio sensor arranged downstream in the direction of flow of exhaust from the exhaust purification catalyst; and an air-fuel ratio control device that controls the air-fuel ratio such that air-fuel ratio of the exhaust flowing into the exhaust purification catalyst reaches a target air-fuel ratio.

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 comprising: a catalyst arranged in an exhaust passage and able to store oxygen, a variable valve timing mechanism able to change a valve overlap amount between an intake valve and an exhaust valve, and a fuel supplying means for feeding fuel to the exhaust passage. The fuel supplying means feeds fuel to the exhaust passage only in an initial cycle after scavenging where valve overlap causes air to be expelled from an intake passage through a cylinder to the exhaust passage if such scavenging occurs.

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: 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: 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: 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 of an internal combustion engine which is provided with an exhaust purification catalyst is provided with a downstream side air-fuel ratio sensor, a feed control means for controlling the fuel feed amount so that the air-fuel ratio of the exhaust gas becomes a target air-fuel ratio, and an excess/deficiency estimating means which estimates an oxygen excess/deficiency in the exhaust gas. The target air-fuel ratio is switched to a lean air-fuel ratio when the output air-fuel ratio of the downstream side air-fuel ratio sensor becomes a rich air-fuel ratio and is switched to the rich air-fuel ratio when the stored amount of oxygen of the exhaust purification catalyst after this becomes a switching reference amount or more.