A method for operating a petrol engine, in which air is introduced into an exhaust tract through which exhaust gas from the petrol engine can flow, bypassing the petrol engine, includes introducing the air into the exhaust tract at a point arranged downstream of a first three-way catalytic converter arranged in the exhaust tract and upstream of a second three-way catalytic converter arranged in the exhaust tract downstream of the first three-way catalytic converter, while the petrol engine is operated with a sub-stoichiometric combustion air ratio, where a desulphurization of the second three-way catalytic converter is effected.

A secondary air introduction device is configured to supply air into an exhaust passage of an engine to combust unburned gas contained in exhaust gas. The secondary air introduction device includes: an air introduction passage configured to introduce air into the exhaust passage; and a secondary air valve configured to be attached to an outer surface of a cylinder head of the engine and to control opening and closing of the air introduction passage. The secondary air valve is configured to be attached to an outer lateral surface of the cylinder head on one side in an axial direction of a crankshaft, and the secondary air valve includes an air introduction inlet formed in a position opposite to the outer lateral surface of the cylinder head in the axial direction of the crankshaft.

The invention relates to an exhaust gas aftertreatment system for an internal combustion engine (10), in particular for an internal combustion engine (10) which is charged by means of a turbocharger (30) and spark-ignited by means of spark plugs (16). A particulate filter (24) and an electrically heatable three-way catalytic converter (26) downstream of the particulate filter (24) are arranged in a position close to the engine in an exhaust gas system (20) connected to an outlet (12) of the internal combustion engine (10). A further three-way catalytic converter (28) is arranged in the underbody position of the motor vehicle downstream of the electrically heatable catalytic converter (26). According to the invention, the electrically heatable three-way catalytic converter (26) is heated electrically after engine start, and the particulate filter (24), the electrically heatable three-way catalytic converter (26) and the further three-way catalytic converter are additionally heated by the exhaust gas flow from the internal combustion engine (10). The electric heating of the electrically heatable three-way catalytic converter (26) is switched off when the electrically heatable three-way catalytic converter (26) has reached its light-off temperature.

A secondary air introduction device is configured to supply air into an exhaust passage of an engine to combust unburned gas contained in exhaust gas. The secondary air introduction device includes: an air introduction passage configured to introduce air into the exhaust passage; and a secondary air valve configured to be attached to an outer surface of a cylinder head of the engine and to control opening and closing of the air introduction passage. The secondary air valve is configured to be attached to an outer lateral surface of the cylinder head on one side in an axial direction of a crankshaft, and the secondary air valve includes an air introduction inlet formed in a position opposite to the outer lateral surface of the cylinder head in the axial direction of the crankshaft.

A heating device for an exhaust system of an internal combustion engine; the heating device has: a first tubular body wherein a combustion chamber is obtained; a fuel injector to inject fuel into the combustion chamber; an inlet opening, which is obtained through the first tubular body and can be connected to a fan to receive an air flow, which is directed into the combustion chamber; a hot air outlet opening to let hot air out of the combustion chamber; an outlet duct, which originates from the outlet opening; a spark plug which is mounted through a side wall of the first tubular body to trigger the combustion of a mixture of air and fuel; and a labyrinth, which surrounds a side wall of the tubular body, starts from the inlet opening, ends in the combustion chamber, and the air must necessarily flow out of the inlet opening until reaching the combustion chamber.

The invention relates to a regeneration air system for an exhaust aftertreatment system of an internal combustion engine and to such an exhaust aftertreatment system. The regeneration air system comprises a regeneration air delivery element, a regeneration air duct, and a regeneration air valve. A sensor system is provided in the regeneration air duct with which a regeneration air mass flow {dot over (m)}.sub.SL can be determined exactly. The exhaust aftertreatment system comprises an exhaust system with an exhaust duct in which, in the direction of flow of an exhaust gas through the exhaust duct, a three-way catalytic converter is arranged underhood and a four-way catalytic converter is arranged downstream. A provision is made that an intake point for the regeneration air from the regeneration air system is formed on the exhaust duct downstream from the underhood three-way catalytic converter and upstream from the four-way catalytic converter.

An exhaust pipe for the exhaust tract of a combustion machine, which has an inlet opening for an air connection, is characterized by an inner pipe section which is surrounded by an outer pipe section in order to form an annular channel that is closed at one end and at the other end is open toward the inner volume of the exhaust pipe, wherein the inlet opening for the air connection opens into the outer pipe section. By means of such an exhaust pipe, advantageous mixing of air supplied via the air connection into the exhaust gas flowing within the exhaust pipe can be achieved with a simple design, which can be attributed in particular to the complete introduction of the air in combination with the flow direction that is present along the longitudinal axis of the annular channel and the exhaust pipe.

An exhaust system for a vehicle having an internal combustion engine includes an exhaust pipe having a central axis and configured to receive an exhaust gas flow from the engine, a catalytic converter disposed within the exhaust pipe, and an exhaust gas burner assembly having a burner unit configured to generate and supply a heated burner flow to a supply pipe. An outlet end of the supply pipe is disposed within the exhaust pipe and extends substantially parallel to the exhaust pipe central axis such that the exhaust gas flows around the supply pipe outlet end. A plurality of mixing apertures are formed in the supply pipe outlet end and configured to promote mixing of the heated burner flow and the exhaust gas flow to disperse heat over the catalytic converter for rapid heating thereof.

An exhaust purification system includes a filter, an oxygen supply device, and a controller. The filter is configured to trap particulate matters contained in exhaust gas of an engine. The oxygen supply device is configured to supply oxygen contained in intake air of the engine to the filter. The controller is configured to execute filter regeneration processing to oxidize and remove the particulate matters deposited on the filter. The filter regeneration processing includes regeneration processing during an engine stop that is executed during a shut-down of the engine. In the regeneration processing during the engine stop, a future temperature of the filter is calculated. Then, an operation amount of the oxygen supply device is variably set based on a result of comparing the future temperature with an upper limit temperature of the filter.

The invention relates to an exhaust gas aftertreatment system for an internal combustion engine (10), in particular for an internal combustion engine (10) which is charged by means of a turbocharger (30) and spark-ignited by means of spark plugs (16). A particulate filter (24) and an electrically heatable three-way catalytic converter (26) downstream of the particulate filter (24) are arranged in a position close to the engine in an exhaust gas system (20) connected to an outlet (12) of the internal combustion engine (10). A further three-way catalytic converter (28) is arranged in the underbody position of the motor vehicle downstream of the electrically heatable catalytic converter (26). According to the invention, the electrically heatable three-way catalytic converter (26) is heated electrically after engine start, and the particulate filter (24), the electrically heatable three-way catalytic converter (26) and the further three-way catalytic converter are additionally heated by the exhaust gas flow from the internal combustion engine (10). The electric heating of the electrically heatable three-way catalytic converter (26) is switched off when the electrically heatable three-way catalytic converter (26) has reached its light-off temperature.