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.

A system for controlling emissions of a motor-vehicle spark-ignition internal combustion engine includes first and second exhaust gas treatment devices and a secondary air feeding system for feeding secondary air into an exhaust gas conduit, between the first and second exhaust gas treatment devices. The secondary air feeding system is activated only when engine load is greater than a predetermined load value and/or when engine rotational speed is greater than a predetermined speed value. In this condition, an air/fuel ratio of the engine is kept at a value lower than the stoichiometric value, so as to feed the engine with a rich mixture. In one example, an electronic controller is configured for controlling activation of the secondary air feeding system on the basis of a map, as a function of values of the engine load and rotational speed. The map is predetermined depending upon specific characteristics of the engine.

A method of controlling oxygen purge of a three-way catalyst may include: performing a fuel cut-off; determining whether a fuel cut-in condition is satisfied after the fuel cut-off; calculating an optimum valve overlap according to an intake amount, an engine rotation speed, and an ignition timing if the fuel cut-in condition is satisfied after the fuel cut-off; controlling a CVVD apparatus to be at the optimum valve overlap; and performing the oxygen purge at the optimum valve overlap.

Various embodiments include a method for operating an internal combustion engine with a three-way catalytic converter with lambda control, comprising: monitoring a NO. sensor for a lambda value downstream of the converter; setting a threshold value determining a lambda setpoint value upstream of the converter using the difference between the setpoint value of the electrical signal and the measured electrical signal if the signal is below the threshold; if above the threshold value, determining the lambda setpoint value upstream of the converter using the difference between a NH.sub.3 setpoint value of the NO. sensor and the measured NH.sub.3 signal of the NO. sensor; and if the measured NH.sub.3 concentration is higher than the NH.sub.3 setpoint value, increasing the lambda setpoint value upstream of the converter and, if the measured NH.sub.3 concentration is lower than the NH.sub.3 setpoint value, reducing the lambda setpoint value upstream of the converter.

An exhaust treatment system and method for the treatment of an exhaust stream from a combustion engine are provided. A first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust stream is carried out by a first oxidation catalyst. Further, a value (NO2_1/NOx_1)det for a ratio between a first amount of nitrogen dioxide and a first amount of nitrogen oxides leaving said first oxidation catalyst is determined. Active control of at least one parameter related to the combustion engine is carried out, based on the determined value, so that the ratio is impacted. A first additive is supplied into the exhaust stream, following which a first reduction of the first amount of nitrogen oxides is carried out through a catalytic reaction in a catalytic filter, which consists of a particulate filter with an at least partly catalytic coating with reduction characteristics. The catalytic filter is arranged for catching and oxidizing of soot particles, and to carry out the first reduction of the first amount of nitrogen oxides using the first additive.

The invention relates to a method for operating an internal combustion engine during any driving operation and in particular during a defined testing cycle which determines compliance with regulations. The internal combustion engine has at least one exhaust gas aftertreatment device with an adjustable degree of efficiency (for example by changing the reduction agent) or an exhaust gas recirculation device or alternative variables for changing the raw engine emissions. At least one monitoring window is assigned to the active profile. The aim of the invention is to allow strict exhaust gas regulations to be met in particular during real driving operations while simultaneously allowing a low fuel consumption. This is achieved in that at least one main monitoring window of the driving profile and a sub-monitoring window (F2) with a starting point and an end point are defined within a driving profile or test cycle. During the sub-monitoring window (F2), a predictive and quantitative estimation of at least one observed emission (E) for the main monitoring window F3 is carried out before reaching the end point of another main monitoring window F3, and the estimated emission quantity is compared with a defined maximum emission quantity. In the event of a large deviation of the maximum emission quantity, at least one control parameter of the internal combustion engine or the exhaust gas aftertreatment process is adaptively modified such that the quantity of the monitored emission (E) approximates the specified target value as much as possible and the consumption of operating resources is optimized.

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.

A control configuration for a combustion engine includes a control unit which has a function that determines a reference variable by taking into account an operating state information, an upper limit and a cumulative actual variable. The reference variable influences an operating state of the combustion engine such that a plurality of actual variables are adjusted so that, in an operating time period with a combination of arbitrary different operating states of the combustion engine that are set in a random order, cumulative actual variables do not exceed upper limits in this operating time period, wherein a target function is minimized by selecting the reference variable from Pareto-optimal alternatives through use of an indifference curve. A combustion engine and a vehicle are also provided.

A control device of a vehicle capable of improving acceleration responsiveness and suppressing increase in the NOx emission amount when a required torque is increased during a steady lean operation. A target air-fuel ratio (AFCMD) is set according to an accelerator pedal operation of a driver. When the driver depresses an accelerator pedal to make an acceleration request during the lean operation, in which the AFCMD is set to a predetermined lean air-fuel ratio (AFLN), air-fuel ratio reduction control is executed to reduce the AFCMD according to the acceleration request. In the air-fuel ratio reduction control, when the AFCMD calculated according to a required torque (TRQCMD) is smaller than a limit air-fuel ratio (AFLMT), the AFCMD is set to the AFLMT, and the AFLMT is set to a value smaller than the AFLN set in a steady state of the lean operation and larger than a theoretical air-fuel ratio (AFST).

In a method for controlling an engine, based on a control map of an engine speed N and a fuel injection amount Q of a common-rail fuel injection unit, a controller calculating the fuel injection amount Q depending on the engine speed N, calculating an injection amount deviation Qn as a fuel injection amount increase, and determining that an engine is in a transient state if the injection amount deviation Qn exceeds a reference transient injection amount deviation A2 or if a transient injection amount deviation count Xq is larger than or equal to a reference transient injection amount deviation count X2. If it is determined that the engine is in the transient state, the controller controls an EGR unit and a boost controller according to an excess air ratio that is an indicator indicating the state of the engine.