Methods and systems are provided for a resonator of an exhaust system. In one example, the resonator is a quarter wave resonator with a diaphragm configured to provide pulsations during low-end engine torque conditions.

The present invention relates to a method for cleaning exhaust gas, and a correspondingly designed exhaust gas system. The present method, or the corresponding system, serves to avoid the formation of nitrous oxide as a secondary exhaust gas, which may primarily be created during the loading of specific catalyst types with NH.sub.3.

An overall exhaust gas purification function based on an NOx reduction function and an HC oxidation function in an NSR catalyst arranged in an exhaust passage of an internal combustion engine is improved. In the NSR catalyst, a portion of an NOx storage catalyst layer supported by a carrier, which extends from its upstream end to an X % (0<X≦75) of an overall length thereof along the flow of exhaust gas, forms an upstream side catalyst layer, and a portion of the NOx storage catalyst layer at the downward side of the upstream side catalyst layer along the flow of exhaust gas forms a downstream side catalyst layer. The upstream side catalyst layer does not contain potassium (K) as an NOx storage material, but the downstream side catalyst layer contains potassium (K) as an NOx storage material.

The invention relates to a catalyst system for reducing nitrogen oxides, which comprises a nitrogen oxide storage catalyst and an SCR catalyst, wherein the nitrogen oxide storage catalyst consists of at least two catalytically active washcoat layers on a supporting body, wherein a lower washcoat layer A contains cerium oxide, an alkaline earth compound and/or alkali compound, as well as platinum and palladium, and an upper washcoat layer B, which is arranged over the washcoat layer A, contains cerium oxide, platinum and palladium, and no alkali compound and no alkaline earth compound. The invention also relates to a method for converting NOx in exhaust gases of motor vehicles that are operated by means of engines that are operated in a lean manner.

An exhaust system including: an exhaust pipe including a straight portion, and a bent portion that is bent and extends from a downstream end of the straight portion; a muffler provided on a downstream side of the exhaust pipe; and a reinforcing member, wherein: the straight portion of the exhaust pipe is connected with an upstream end of the muffler through the bent portion; and the reinforcing member is provided so as to extend across a downstream end portion of the straight portion, and an upstream end portion of the muffler.

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.

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.

The present invention relates to the use of different regeneration strategies for nitrogen oxide storage catalysts (NOx storage catalyst, LNT or NSC), depending on the exhaust gas temperatures, to reduce in the total exhaust gas the greenhouse gas N.sub.2O (nitrous oxide) that is produced as a secondary emission during the regeneration of the storage catalyst. If the exhaust gas temperature is below 275° C.-290° C., regeneration takes place using a strategy with short pulses of around 2 seconds and λ Lambda 0.95 rich.

A regeneration system includes a first module, a mode selection module and an adsorber regeneration control (ARC) module. The first module monitors at least one of (i) a temperature of a first catalyst of a catalyst assembly in an exhaust system of an engine and (ii) an active catalyst volume of the first catalyst. The mode selection module is configured to select an adsorber regeneration mode and generates a mode signal based on the at least one of the temperature and the active catalyst volume. The ARC module at least one of activates an air pump and cranks the engine to regenerate an adsorber of the catalyst assembly while the engine is deactivated based on the mode signal.

In a control apparatus for an internal combustion engine in which processing of regenerating the NOx storage capacity of an NSR catalyst is carried out in accompany with processing of diagnosing an abnormality in an exhaust gas purification device including the NSR catalyst, the present invention is intended to suppress the fluctuation of torque at the time of regenerating the NOx storage capacity of the NSR catalyst, and to terminate abnormality diagnostic processing quickly. According to the invention, by setting an engine air fuel ratio, which has been set to a lean air fuel ratio before the processing of regenerating the NOx storage capacity of the NSR catalyst is started, to a weak lean air fuel ratio which is lower than a basic lean air fuel ratio and higher than a stoichiometric air fuel ratio, it becomes possible to suppress the fluctuation of torque at the time of regeneration processing being started, and to terminate abnormality diagnostic processing at an early period of time.