Abstract: A degradation diagnosis device includes a downstream air-fuel ratio sensor and a control device. The control device is configured to perform a rich process and a lean process alternately and repeatedly in a degradation diagnosis process for diagnosing degradation of the exhaust gas control catalyst. The control device is configured to, in the degradation diagnosis process, determine that the exhaust gas control catalyst has been degraded when the lean process is executed and the frequency with which an output air-fuel ratio of the downstream air-fuel ratio sensor is equal to the lean air-fuel ratio is equal to or more than a predetermined frequency.

Abstract: A degradation diagnosis device includes a downstream air-fuel ratio sensor and a control device. The control device is configured to perform a rich process and a lean process alternately and repeatedly in a degradation diagnosis process for diagnosing degradation of the exhaust gas control catalyst. The control device is configured to, in the degradation diagnosis process, determine that the exhaust gas control catalyst has been degraded when the lean process is executed and the frequency with which an output air-fuel ratio of the downstream air-fuel ratio sensor is equal to the lean air-fuel ratio is equal to or more than a predetermined frequency.

Abstract: An exhaust purification system of the internal combustion engine, is provided with: an exhaust purification catalyst having a catalytic function; a particulate filter arranged at a downstream side from the exhaust purification catalyst; an oxygen feed device feeding gas containing oxygen into exhaust gas flowing into the particulate filter; a detection device detecting a concentration of ammonia in exhaust gas flowing out from the particulate filter; and a control device. The control device controls the oxygen feed device so as to feed oxygen from the oxygen feed device to the particulate filter if a temperature of the exhaust purification catalyst is equal to or greater than an activation temperature and an air-fuel ratio of exhaust gas is a rich air-fuel ratio, and estimates the amount of deposition of particulate matter on the particulate filter based on the output of the detection device when feeding oxygen.

Abstract: An internal combustion engine comprises a filter and is configured to enable attachment of a secondary air feed system feeding air into exhaust gas flowing into the filter. A control device of the engine is configured, in the PM removal control for removing particulate matter deposited on the filter, to perform temperature raising processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body 1 is a rich air-fuel ratio and for feeding air from the secondary air feed system, and to perform regeneration processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body is a stoichiometric air-fuel ratio and for feeding air from the secondary air feed system so that the air-fuel ratio of the exhaust gas flowing into the filter is a lean air-fuel ratio.

Abstract: An exhaust gas control apparatus includes an exhaust gas control catalyst disposed in an exhaust passage, a filter disposed downstream of the catalyst, a secondary air supply device configured to supply secondary air into exhaust gas flowing into the filter at a location downstream of the catalyst in an exhaust gas flow direction, and an electronic control unit. The electronic control unit is configured to, when a temperature of the catalyst is higher than or equal to an activation temperature and an air-fuel ratio of exhaust gas emitted from an engine body is a rich air-fuel ratio, cause the supply device to supply secondary air into exhaust gas while periodically increasing or reducing the air such that the air-fuel ratio of exhaust gas flowing into the filter alternately varies between rich and lean air-fuel ratios.

Abstract: The controller includes a fuel amount control unit adjusting amount of fuel supplied to a cylinder through feedback control with an air-fuel ratio deviation as input, a target air-fuel ratio adjustment unit alternately repeating a lean period process and a rich period process, and a learning value correction unit updating a learning value to compensate for a steady deviation in an air-fuel ratio. If an absolute value of an oxygen amount deviation is less than a determination value, the learning value update unit updates a learning value only when one of the lean period process and the rich period process is switched to the other one. If the absolute value of the oxygen amount deviation is greater than or equal to the determination value, the learning value is updated both when one of the processes is switched to the other one and when the switching is reversed.

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: 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: The controller includes a fuel amount control unit adjusting amount of fuel supplied to a cylinder through feedback control with an air-fuel ratio deviation as input, a target air-fuel ratio adjustment unit alternately repeating a lean period process and a rich period process, and a learning value correction unit updating a learning value to compensate for a steady deviation in an air-fuel ratio. If an absolute value of an oxygen amount deviation is less than a determination value, the learning value update unit updates a learning value only when one of the lean period process and the rich period process is switched to the other one. If the absolute value of the oxygen amount deviation is greater than or equal to the determination value, the learning value is updated both when one of the processes is switched to the other one and when the switching is reversed.

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: 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: 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: 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: 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: The internal combustion engine comprises an exhaust purification catalyst and downstream side air-fuel ratio sensor. 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. In the learning control, when the target air-fuel ratio is set to the rich air-fuel ratio and the output air-fuel ratio of the downstream side air-fuel ratio sensor is maintained in an air-fuel ratio region in proximity to the stoichiometric air-fuel ratio for the stoichiometric air-fuel ratio judgment time or more, stoichiometric air-fuel ratio stuck learning is performed, changing air-fuel ratio of the exhaust gas to the rich side.

Abstract: An internal combustion engine comprises a filter and is configured to enable attachment of a secondary air feed system feeding air into exhaust gas flowing into the filter. A control device of the engine is configured, in the PM removal control for removing particulate matter deposited on the filter, to perform temperature raising processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body 1 is a rich air-fuel ratio and for feeding air from the secondary air feed system, and to perform regeneration processing for controlling the engine so that the air-fuel ratio of the exhaust gas discharged from the engine body is a stoichiometric air-fuel ratio and for feeding air from the secondary air feed system so that the air-fuel ratio of the exhaust gas flowing into the filter is a lean air-fuel ratio.

Abstract: An exhaust purification system of the internal combustion engine, is provided with: an exhaust purification catalyst having a catalytic function; a particulate filter arranged at a downstream side from the exhaust purification catalyst; an oxygen feed device feeding gas containing oxygen into exhaust gas flowing into the particulate filter; a detection device detecting a concentration of ammonia in exhaust gas flowing out from the particulate filter; and a control device. The control device controls the oxygen feed device so as to feed oxygen from the oxygen feed device to the particulate filter if a temperature of the exhaust purification catalyst is equal to or greater than an activation temperature and an air-fuel ratio of exhaust gas is a rich air-fuel ratio, and estimates the amount of deposition of particulate matter on the particulate filter based on the output of the detection device when feeding oxygen.

Abstract: An exhaust gas control apparatus includes an exhaust gas control catalyst disposed in an exhaust passage, a filter disposed downstream of the catalyst, a secondary air supply device configured to supply secondary air into exhaust gas flowing into the filter at a location downstream of the catalyst in an exhaust gas flow direction, and an electronic control unit. The electronic control unit is configured to, when a temperature of the catalyst is higher than or equal to an activation temperature and an air-fuel ratio of exhaust gas emitted from an engine body is a rich air-fuel ratio, cause the supply device to supply secondary air into exhaust gas while periodically increasing or reducing the air such that the air-fuel ratio of exhaust gas flowing into the filter alternately varies between rich and lean air-fuel ratios.

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: 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.