A selective catalytic reduction (SCR) system is provided for treating exhaust gas in an exhaust passage. The system comprises a hydrolysis catalyst located in the exhaust passage, and a diesel exhaust fluid (DEF) dosing unit configured to inject DEF onto the hydrolysis catalyst. A SCR catalyst is located in the passage downstream of the hydrolysis catalyst, and a controller controls DEF dosing by the dosing unit. The controller is configured to control the DEF dosing unit such that the DEF is injected at a modulated frequency of less than or equal to 1 Hertz. A method of treating exhaust gas in an exhaust passage using an SCR system is also provided.

A controller for removing deposits in a vehicle is disclosed. The controller includes at least one processor and a memory storing instructions therein that, when executed by the at least one processor, cause the at least one processor to: determine an amount of deposits accumulated in the vehicle based on an amount of time; determine a combustion target for the vehicle in response to determining that the amount of deposits exceeds a deposit threshold; and modulate a fluid flow of the vehicle based on the determined combustion target.

A mixer assembly for mixing an injected reductant with an exhaust gas comprises a tubular housing including a reductant inlet, an exhaust gas inlet and an exhaust gas outlet. The reductant inlet is positioned on a first side of the tubular housing and oriented to direct injected reductant along an injection access that extends transversely to a longitudinal axis. A first flow guide element is shaped as a sheet including a first aperture extending therethrough as well as a surface facing upstream. Exhaust gas flowing through the first aperture is impinged by the injected redundant. A second flow guide element is shaped as a sheet, positioned downstream from the first flow guide element and fixed to the first flow guide element to define a mixing chamber between the first flow guide element and the second flow guide element in which the injected redundant and the exhaust gas mix.

A spray bar injector including a spray bar defining a longitudinal axis and including a fluid inlet and a plurality of spray outlet orifices spaced apart longitudinally in a direction along the longitudinal axis. A check or spray valve is operatively connected to each spray outlet orifice. A master valve is in fluid communication with the fluid inlet, operatively connected to divert flow from the fluid inlet into a first passage and block flow into a second passage in a first position to open the check valves and issue a spray from the spray outlet orifices, and to divert flow from the fluid inlet into the second passage and block flow into the first passage in a second position to close the check valves and block issue of spray from the spray outlet orifices.

The present disclosure relates to a method of compacting an ash deposited in a particulate filter for a vehicle exhaust gas system, the method includes the steps of: a) providing a low-temperature melting salt to the particulate filter, thereby forming a mixture of the ash and the low-temperature melting salt: and b) heating the particulate filter to a compaction temperature, thereby compacting the mixture of the ash and the low-temperature melting salt. The disclosure further relates to engine oils, dosage products, engine systems and vehicles for implementing such a method.

Various embodiments include methods for determining the efficiency of an SCR catalytic converter in a system including a nitrogen oxide sensor, and a metering device for a reducing agent arranged in an exhaust-gas duct, and an exhaust recirculation line with a recirculation valve disposed downstream of the SCR catalytic converter and feeding an intake region of the engine. The methods comprise: setting or identifying a quasi-steady-state operating state and an associated recirculation rate; adding a first quantity of reducing agent using the metering device; measuring a resulting first nitrogen oxide value using the sensor; adding a further predefined quantity, different from the first quantity; measuring the resulting nitrogen oxide values using the sensor; and determining the efficiency of the SCR catalytic converter based at least in part on the associated exhaust-gas recirculation rate and the measured nitrogen oxide values.

An after-treatment exhaust gas mixer for mixing the exhaust gas with a reducing agent, such as a diesel exhaust fluid for selective catalyst reduction, comprises a mixing chamber through which the exhaust gas circulates, from an inlet to an outlet, and a reducing agent sprayer, able to spray a reducing agent into the mixing chamber. The mixing chamber comprises a pipe that is rectilinear along an axis and the sprayer is positioned in the upstream part of the rectilinear pipe and oriented so as to spray in the downstream direction substantially parallel to the axis.

The present disclosure relates to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus and, more particularly, to a system and a method for removing noxious gas from cleaning liquid discharged from an exhaust gas treatment apparatus, which are capable of adjusting the discharge rate of the cleaning liquid in a noxious gas removal unit, which removes noxious gas remaining in a gaseous state in the cleaning liquid discharged from the exhaust gas treatment apparatus and discharges the cleaning liquid from which the noxious gas in the gaseous state has been removed, on the basis of a result of measurement of the level of the cleaning liquid in the noxious gas removal unit.

Selective catalytic reduction (SCR) systems are known and are generally included in the exhaust systems of diesel engines in order to treat the exhaust gases of such engines. Such systems typically involve the introduction of a diesel exhaust fluid (DEF) into exhaust gas flowing in an exhaust passage of an engine. DEF dosing systems are limited by the amounts of DEF that can be delivered without deposits forming on surfaces of the aftertreatment system. An impaction device is dosed with DEF at a first rate based on a set of characteristics of the SCR system. A second set of characteristics, such as an available storage capacity for DEF, is determined based on a set of criteria, such as a decomposition rate of DEF. Based on the second set of characteristics, the DEF dosing rate is changed to a second rate. The dosing rate is reverted to the first rate after a second set of criteria, e.g. a lower threshold of available storage for DEF, are fulfilled.

A mixer assembly comprises a tubular housing including a reductant inlet, an exhaust gas inlet and an exhaust gas outlet. The tubular housing defines a longitudinal axis along which exhaust enters the housing. The reductant inlet is positioned on a first side of the tubular housing. An upstream element covers approximately one-half of the cross sectional area of the enhaust gas inlet and is positioned upstream of the reductant inlet. An upstream surface of the upstream mixing element directs exhaust gas flow transversly toward the reductant inlet. A downstream mixing element along with the upstream mixing element at least partially defines a reductant receiving duct in which injected reductant and exhaust gas mix.