A urea injection system comprises a fluid conveying apparatus used for extracting a urea solution from a urea tank, several nozzles indirectly connected to the fluid conveying apparatus, and a controller used for controlling the urea injection system. The urea injection system is adapted to process exhaust gas of a plurality of engines at the same time. The nozzles comprise a first nozzle used for injecting a urea solution to a first exhaust pipe of a first engine and a second nozzle used for injecting the urea solution to a second exhaust pipe of a second engine. A plurality of nozzles respectively corresponding to a plurality of engines is arranged in the urea injection system, so as to process exhaust gas of the plurality of engines at the same time by using only one urea injection system.

A system for determining a performance status of an exhaust aftertreatment system may include determining an ammonia-to-nitrogen ratio using a sample ammonia input value and a sample NO.sub.x input value. An actual NO.sub.x input value and an actual ammonia input value can be received. An emission value from may be received from a first sensor. A NO.sub.x emission estimate, an ammonia slip estimate, and an optimal ammonia storage value for a selective catalytic reduction may be determined using an iterative inefficiency calculation based, at least in part, on the actual NO.sub.x input value, the actual ammonia input value, and the ammonia-to-nitrogen ratio; and the NO.sub.x emission estimate, the ammonia slip estimate, and the optimal ammonia storage value may be outputted to a diagnostic system.

An exhaust purification device for an engine facilitates thawing of a urea aqueous solution, which is frozen in a reducing agent tank of an exhaust purification device, more rapidly. When a urea aqueous solution in a reducing agent tank is frozen at a time of starting an engine, at least a part of the urea aqueous solution to be supplied to an injection nozzle is flown into a reducing agent circulation flow path, a part of which is adjacent to a heat source, and the urea aqueous solution thus heated is returned to the reducing agent tank.

An exhaust gas control apparatus has an exhaust gas control element other than an SCR catalyst. A temperature increase treatment unit executes temperature increase treatment that increases temperature of exhaust gas flowing into the exhaust gas control apparatus so as to increase the temperature of the exhaust gas control element to a specified target temperature. In this case, when operation of the internal combustion engine is stopped while the temperature increase treatment unit is not executing the temperature increase treatment, addition of an additive to the SCR catalyst from an addition valve is executed after operation stop of the internal combustion engine. When operation of the internal combustion engine is stopped while the temperature increase treatment unit is executing the temperature increase treatment, addition of the additive to the SCR catalyst from the addition valve is not executed after operation stop of the internal combustion engine.

A method is provided for controlling nitrogen oxide emissions in the exhaust gas of an internal combustion engine by means of successive actuation of catalytic converters in the exhaust tract and of the internal combustion engine, wherein the catalytic converters or the internal combustion engine are actuated in succession if the actuation of a first device is not sufficient for reducing the nitrogen oxide emissions. An arrangement for carrying out the method is also provided.

A method of calculating a nitrogen oxide (NOx) mass reduced from a lean NOx trap (LNT) during regeneration includes calculating a C3H6 mass flow used to reduce the NOx among a C3H6 mass flow flowing into the LNT of an exhaust purification device, calculating a NH3 mass flow used to reduce the NOx among a NH3 mass flow generated in the LNT, calculating a reduced NOx mass flow based on the C3H6 mass flow used to reduce the NOx and the NH3 mass flow used to reduce the NOx, and calculating the reduced NOx mass by integrating the reduced NOx mass flow over a regeneration period.

A safety device intended to detect a leakage in a dry area of an automotive liquid used in a fluid circuit onboard a vehicle, the automotive liquid containing at least one dangerous substance other than water, such as urea, the device including a detection cell sensitive, on the one hand, to the presence of a liquid in the dry area and, on the other hand, to the possible dangerous substance content of the liquid, the device also including a selective analysis unit, capable of distinguishing on the one hand whether the detection cell is in the presence of a liquid or not, and on the other hand, in the presence of liquid, whether the present liquid corresponds to the automotive liquid containing the dangerous substance or to another liquid, called neutral liquid, such as a water condensate.

A work vehicle includes an engine, a battery, an exhaust gas purification system or device, and a notification device. The exhaust gas purification system or device is capable of performing a purification process purifying exhaust gas of the engine, and operates with electric power from the battery and performs an end process. The notification device provides notification that the exhaust gas purification system or device is performing the end process or that the end process is completed.

An exhaust aftertreatment system for an internal combustion engine includes an outer casing defining an exhaust flow path for exhaust gases from the internal combustion engine, a selective catalytic reduction unit provided in the exhaust flow path for reducing nitrogen oxides, a urea dosing device for adding urea to the exhaust flow upstream of the selective catalytic reduction unit, and a rotatable mixer device for mixing the urea with exhaust gases upstream of the selective catalytic reduction unit. The exhaust aftertreatment system further comprises an air inlet valve provided upstream of the mixer device for introducing air into the exhaust flow path, and an electric motor arranged for rotating the mixer device to create a suction of air into the exhaust flow path via the air inlet valve.

An exhaust system according to an exemplary embodiment of the present invention includes a nitrogen oxide storing catalytic collector connected to an exhaust line and collecting a nitrogen oxide included an exhaust gas in a first temperature or less; a first selective catalytic reducer disposed at a rear portion of the nitrogen oxide storing catalytic collector and reducing a nitrogen oxide included in the exhaust gas; and a first urea injector disposed at the front side of the nitrogen oxide storing catalytic collector and supplying a urea solution when a temperature of the nitrogen oxide exceeds the first temperature.