In an exhaust gas purification apparatus provided in an exhaust as path of an engine, it is an object of the present invention to shorten a pipe length of a bypass path bypassing a purification catalyst as short as possible, thereby reducing initial costs. The exhaust gas purification apparatus includes a purification casing in which at least the purification catalyst is accommodated. The purification catalyst purifies exhaust gas from the engine. The purification casing is integrally provided with the bypass path separately from the purification path in which the purification catalyst exists. The bypass path makes the exhaust gas bypasses the purification catalyst without passing through the purification catalyst.

In a method for operating a urea dosing system in an exhaust aftertreatment system (EATS) of an engine, an ambient temperature is measured in an environment in which the EATS is disposed, one or more temperatures associated with the EATS to which there is a relationship to a temperature of area in the urea dosing system are monitored. After turning off the engine, whether urea in the urea dosing system is subject to freezing is determined based on the measured ambient temperature and the one or more monitored temperatures. A reversion operation is performed after turning off the engine with a delay until one or more events occur, the one or more events including determining that urea in the urea dosing system is subject to freezing. An engine system is also provided.

An exhaust system assembly including a catalyst housing, a catalyst core, and a swirler tube positioned inside the catalyst housing. The swirler tube has a plurality of openings that permit radial exhaust flow into an inner volume of the swirler tube from the catalyst housing. One end of the swirler tube has blades that extend inward and include oblique surfaces arranged at oblique angles relative to a centerline axis of the swirler tube. These blades induce a vortex in the exhaust gases exiting the first swirler tube end. The swirler tube is arranged inside the catalyst housing such that a sequential flow path is created where the exhaust gases flowing through the catalyst housing must first pass through the openings in the swirler tube and then by the blades at the first swirler tube end.

An exhaust system for a combustion engine includes first and second catalytic converters arranged downstream of the combustion engine in a flow direction of exhaust gas. First and second exhaust pipes extend from the combustion engine to the first and second catalytic converters, respectively, with a first valve disposed in the first exhaust pipe, and a second valve disposed in the second exhaust pipe. The first and second valves operate such that in the presence of an exhaust temperature which is equal to or less than a limit value, at least the first valve opens to allow exhaust gas from the combustion engine to flow through the first catalytic converter, and that the first valve closes and the second valve opens, when the exhaust temperature is greater than the limit value to thereby allow exhaust gas from the combustion engine to flow through the second catalytic converter.

A method for determining a mass flow of ammonia between two SCR catalytic converters disposed one after the other in an SCR catalytic converter system in an exhaust system, which comprises only one reduction agent dosing unit upstream of the first SCR catalytic converter, characterized in that the determination is carried out from the signal of a NOx sensor disposed between the two SCR catalytic converters and the signal of a NOx sensor disposed downstream of the second SCR catalytic converter.

Emissions control assemblies including substrates defining a plurality of channels that are configured to receive engine exhaust passing through the substrates, and heating elements configured to heat the substrates.

An aftertreatment system for treating an exhaust gas comprises an exhaust conduit, a preheating oxidation catalyst, a primary oxidation catalyst disposed downstream of the preheating oxidation catalyst, and a selective catalytic reduction system disposed in the exhaust conduit downstream of the primary oxidation catalyst. A controller is configured to determine a temperature of an exhaust gas at an inlet of the selective catalytic reduction system. In response to the temperature being below a threshold temperature, the controller generates a hydrocarbon insertion signal configured to cause hydrocarbons to be inserted into or upstream of the preheating oxidation catalyst so as to increase a temperature of the exhaust gas to above the threshold temperature.

A method and system for mitigating a urea deposit within an SCR system that includes determining a mass of an accumulated urea deposit present within the SCR catalyst and SCR piping, comparing the mass of the accumulated urea deposit with a deposit upper threshold limit, and initiating an SCR regeneration event when the mass of the accumulated urea deposit is greater than the deposit upper threshold limit. The method further includes determining an amount of NH.sub.3 passing through the SCR catalyst downstream of the urea deposit, comparing the amount of NH.sub.3 passing through the SCR catalyst with an NH.sub.3 regeneration threshold limit, and terminating the SCR regeneration event when the level of NH.sub.3 passing through the SCR catalyst is less than the SCR NH.sub.3 regeneration threshold.

Reductant delivery systems are disclosed that include a dry reductant source and a liquid reductant source which are operable to selectively provide gaseous reductant and liquid reductant to an exhaust aftertreatment system for treatment and reduction of NOx emissions. The gaseous reductant is provided to the exhaust aftertreatment system for treatment of NOx emissions under a first temperature condition associated with the exhaust system and the liquid reductant for treatment of NOx emissions under a second temperature condition associated with the exhaust system.

A method of calculating an ammonia (NH3) mass generated in a lean NOx trap (LNT) of an exhaust purification device includes sequentially calculating a NH3 mass flow at a downstream of each slice from a first slice to an n-th slice, and integrating the NH3 mass flow at the downstream of the n-th slice over a predetermined time, wherein the calculation of the NH3 mass flow at the downstream of the i-th slice comprises calculating a NH3 mass flow flowing into the i-th slice, calculating a NH3 mass flow generated at the i-th slice, and adding the NH3 mass flow generated at the i-th slice to a value obtained by subtracting the NH3 mass flow used to reduce the NOx and the O2 at the i-th slice from the NH3 mass flow flowing into the i-th slice.