An exhaust baffle apparatus includes an enclosure having longitudinal, lateral, and anterior dimensions. The apparatus defines an internal volume defining an airflow path proceeding from an intake opening to an exhaust opening. There are a multiplicity of mixers within the enclosure. Each mixer includes a length spanning the lateral dimension of the enclosure. Each mixer further comprises a hollow airfoil substantially open at lateral ends of the mixer and at least one vent oriented toward the exhaust opening. A different feature involves a method of dampening noise and heat form engine exhaust.

An exhaust gas aftertreatment system is disclosed. The system may include an inlet to receive an exhaust gas produced by an engine and a first section to receive the exhaust gas from the inlet. The system may include a mixing tube to receive the exhaust gas from the first section and a reductant injector to inject a reductant into the mixing tube. The system may include a second section to receive the exhaust gas from the mixing tube and to facilitate mixing of the reductant and the exhaust gas after the exhaust gas exits the mixing tube and a diffuser to receive the exhaust gas from the second section. The system may include a plurality of catalysts to receive the exhaust gas from the diffuser and at least one outlet to receive the exhaust gas from the plurality of catalysts.

An exhaust gas aftertreatment system is disclosed. The system may include an inlet to receive an exhaust gas produced by an engine and a first section to receive the exhaust gas from the inlet. The system may include a mixing tube to receive the exhaust gas from the first section and a reductant injector to inject a reductant into the mixing tube. The system may include a second section to receive the exhaust gas from the mixing tube and to facilitate mixing of the reductant and the exhaust gas after the exhaust gas exits the mixing tube and a diffuser to receive the exhaust gas from the second section. The system may include a plurality of catalysts to receive the exhaust gas from the diffuser and at least one outlet to receive the exhaust gas from the plurality of catalysts.

The temperature of exhaust gas discharged from a compact air-cooled engine used as a power source for an engine-driven working machine is reduced. An engine has a muffler mounted directly to the exhaust opening of the cylinder, and a resin muffler cover covering the muffler. An exhaust gas restriction member is provided to a wall surface of the muffler, and two exhaust passages serving as outlets for exhaust gas are formed in the exhaust gas restriction member. The exhaust passages are arranged independent of each other, and the streams of discharged exhaust gas are discharged to be slightly separated from each other as the streams flow away from the exhaust openings. The separated streams of discharged exhaust gas form a negative pressure space between the streams promoting the introduction of a cooling air stream into the negative pressure portion. Thus, the temperature of the exhaust gas can be reduced.

The temperature of exhaust gas discharged from a compact air-cooled engine used as a power source for an engine-driven working machine is reduced. An engine has a muffler mounted directly to the exhaust opening of the cylinder, and a resin muffler cover covering the muffler. An exhaust gas restriction member is provided to a wall surface of the muffler, and two exhaust passages serving as outlets for exhaust gas are formed in the exhaust gas restriction member. The exhaust passages are arranged independent of each other, and the streams of discharged exhaust gas are discharged to be slightly separated from each other as the streams flow away from the exhaust openings. The separated streams of discharged exhaust gas form a negative pressure space between the streams promoting the introduction of a cooling air stream into the negative pressure portion. Thus, the temperature of the exhaust gas can be reduced.

The invention relates to an exhaust gas aftertreatment system for a spark ignition internal combustion engine based on the Otto principle. The internal combustion engine is connected on the outlet side to an exhaust gas system, wherein an electrically heatable three-way catalytic converter, a four-way catalytic converter downstream from the electrically heatable three-way catalytic converter, and a further three-way catalytic converter downstream from the four-way catalytic converter are situated in the exhaust gas system in the flow direction of an exhaust gas through the exhaust gas system. Before the internal combustion engine is started, the electrically heatable three-way catalytic converter and preferably also the four-way catalytic converter are heated to allow efficient exhaust gas aftertreatment of the untreated emissions of the internal combustion engine upon starting the internal combustion engine. The exhaust gas aftertreatment system is also configured to allow efficient conversion of the pollutants also during a regeneration of the four-way catalytic converter, and thus, to ensure particularly low emissions in all operating states of the motor vehicle.

A method (200) for ascertaining an air volume provided by means of an electric air pump (134) in an exhaust system (120) of an internal combustion engine (110), including detecting at least one activation parameter (5) of the air pump and ascertaining (220) a provided air mass flow rate (8) on the basis of a calculation specification from the at least one activation parameter (5) by utilizing an inertia of the air pump (134) and/or an inertia of the air upstream and/or downstream from the air pump (134) and/or a differential pressure from upstream from the air pump to downstream from the air pump. In addition, a processing unit and a computer program for carrying out a method (200) of this type is provided.

A method (200) for ascertaining an air volume provided by means of an electric air pump (134) in an exhaust system (120) of an internal combustion engine (110), including detecting at least one activation parameter (5) of the air pump and ascertaining (220) a provided air mass flow rate (8) on the basis of a calculation specification from the at least one activation parameter (5) by utilizing an inertia of the air pump (134) and/or an inertia of the air upstream and/or downstream from the air pump (134) and/or a differential pressure from upstream from the air pump to downstream from the air pump. In addition, a processing unit and a computer program for carrying out a method (200) of this type is provided.

An exhaust purification system of an internal combustion engine comprises an HC adsorbent 20 arranged adsorbing HC in exhaust gas, an NOx adsorbent 20 adsorbing NOx in exhaust gas, a catalyst 24 removing HC and NOx at a predetermined air-fuel ratio, an air-fuel ratio control part 31 configured to control an air-fuel ratio of exhaust gas, and an HC concentration calculating part 32 configured to calculate a concentration of HC desorbed from the HC adsorbent. A peak of a desorption temperature of HC at the HC adsorbent and a peak of a desorption temperature of NOx at the NOx adsorbent are substantially the same. The air-fuel ratio control part is configured to control an air-fuel ratio of inflowing exhaust gas flowing into the catalyst to the predetermined air-fuel ratio based on the concentration of HC calculated by the HC concentration calculating part when HC is desorbed from the HC adsorbent.

A method for operating an exhaust burner with a secondary air system downstream of a combustion engine of a motor vehicle. The method includes: activating an ignition device as a function of a release condition, the ignition device being heated up to a specifiable target temperature; metering fuel at a first time point into a combustion chamber of the exhaust burner at a first injection frequency using an injection valve, and the combustion chamber not being actively supplied with air; setting a first target air-mass flow using a secondary air system at a further, second time point, wherein the air-mass flow is increased strictly monotonically; controlling the air-fuel ratio to a first target air-fuel ratio as a function of a lambda sensor starting from the second time point, and metering fuel at a second injection frequency; setting a second target air-mass flow at a further, third time point.