An oxygen storage amount estimation device estimates an oxygen storage amount of a catalyst disposed in an exhaust passage of an internal combustion engine. The oxygen storage amount estimation device includes a storage device and processing circuitry. The storage device stores mapping data, which is data specifying a mapping that uses multiple variables including at least an excess-deficient amount variable and a previous value of a storage amount variable as an input to output a value of the storage amount variable. The processing circuitry executes a storage amount variable calculation process that repeatedly calculates a value of the storage amount variable based on an output of the mapping using the multiple variables and an operation process that operates predetermined hardware based on a calculation result of the storage amount variable calculation process. The mapping data includes data learned by machine learning.

The invention relates to a method for adjusting a fuel/air ratio of an internal combustion engine (10), comprising a catalyst volume (26) with a first catalyst partial volume (26.1) and a second catalyst partial volume (26.2). The second catalyst partial volume (26.2) is arranged downstream from the first catalyst partial volume (26.1). An actual filling level of an exhaust gas constituent in the catalyst volume (26) is calculated from operating parameters of the internal combustion engine (10) and the exhaust system (14) using a computing model, and is adjusted to a nominal value by modifying the fuel/air ratio. The adjustment is carried out first for the second catalyst partial volume (26.2) and only later for the first catalyst partial volume (26.1).

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. When a change in the amount of intake air occurs so that it increases, the lean degree is set lower than before, in at least part of the time period during which the target air-fuel ratio is set to the lean air-fuel ratio, and the rich degree is set lower than before, in at least part of the timer period during which the target air-fuel ratio is set to the rich air-fuel ratio.

When stopping combustion in a cylinder under a situation in which the crankshaft of an internal combustion engine having an ignition device is rotating, a controller executes a fuel introduction process of injecting fuel from a fuel injection valve and introducing the fuel from inside the cylinder to the exhaust passage without burning the fuel. Also, the controller executes a storing process before starting the fuel introduction process. In the storing process, the controller stores oxygen in a three-way catalyst by executing a fuel cutoff process of stopping fuel injection of the fuel injection valve under a situation in which the crankshaft is rotating.

The present invention provides a catalyst diagnosis device that enables precisely grasping a variation of AFR and diagnosing a deteriorated condition of the catalyst based on the variation. A timer counts elapsed time Tosc until downstream AFU (AFRd) meets a predetermined threshold condition when the fuel injection quantity is corrected by increasing or decreasing it so that as to the AFRu, the transition from either of leanness or richness to the other is repeated with the stoichiometric area between the leanness and the richness. An OSA calculating section calculates an Oxygen Storage Amount (OSA) as a function of the AFR, Mfuel, Ne and Tosa. An OPA calculating section calculates an Oxygen Purge Amount (OPA) as a function of the AFR, Mfuel, Ne and Topa. A deterioration diagnosing section diagnoses a deteriorated condition of the catalyst C on the basis of at least one of the OSA and OPA.

A method for operating an engine system that includes an internal combustion engine and an exhaust aftertreatment device. The method includes: carrying out a filling control in order to regulate a filling level of the exhaust aftertreatment device as a function of a predefined filling level setpoint value, a lambda setpoint value for a lambda regulation being predefined as a manipulated variable, adapting the filling control with the aid of an adaptation variable that indicates a correction value for the lambda setpoint value, and storing an adaptation value as a function of an operating range of the engine system, the adaptation value in question being updated with the value of the adaptation variable for the instantaneous operating range.

An exhaust gas purification system for vehicle includes: a housing disposed on an exhaust pipe to receive a exhaust gas discharged from an engine and to exhaust the exhaust gas passed rearward; a front end catalyst disposed in the housing to purify the exhaust gas flowing into the housing through a front end of the housing; a rear end catalyst disposed in the housing to purify the exhaust gas passing through the front end catalyst before the exhaust gas flows out to a rear end of the housing; and a controller connected to the exhaust pipe at a front end of the housing to control a concentration of unburned fuel contained in the exhaust gas flowing into the housing.

Methods and systems are provided for an exhaust aftertreatment arrangement. In one example, a system includes a LNT upstream of an SCR with an oxygen storage component arranged therebetween, and where a rich operation of an engine is limited based on an oxygen load of the oxygen storage component when an exhaust gas temperature is higher than a limit temperature.

An engine includes: an NOx catalyst and an SCR catalyst in an exhaust passage; an excess air ratio change device that changes an excess air ratio of an exhaust gas; and a reducing agent supply device that supplies a reducing agent for SCR including a material for NH.sub.3 or NH.sub.3 to a portion between the NOx catalyst and the SCR catalyst in the exhaust passages. The engine controls the reducing agent supply device in such a manner that a quantity of the reducing agent for SCR to be supplied from the reducing agent supply device to the exhaust passage 40 becomes small when the excess air ratio of the exhaust gas during regeneration control to regenerate the NOx catalyst is small, as compared to when the excess air ratio of the exhaust gas during regeneration control to regenerate the NOx catalyst is large.

Various methods and systems are provided for skip-firing an engine. As one embodiment, a method for an engine includes firing all cylinders of the engine and not altering the closing timing of the intake valves when fueling demands are greater than a threshold. The method further includes skip-firing the engine when fueling demands are less than a threshold, and holding open the intake valves of skipped cylinders for a greater duration than intake valves of firing cylinders.