An exhaust gas aftertreatment system for an internal combustion engine, which comprises an exhaust system which can be connected to the outlet of an internal combustion engine. A catalytic converter close to the engine and a second catalytic converter arranged downstream of the catalytic converter in an underbody of a motor vehicle are provided in the flow direction of an exhaust gas from the internal combustion engine flowing through an exhaust gas duct of the exhaust system. An inlet point for secondary air, an exhaust gas burner, and a fuel injector for introducing fuel into the exhaust gas duct are arranged downstream of the catalytic converter close to the engine and upstream of the second catalytic converter. According to the invention, the exhaust gas burner is activated immediately after the internal combustion engine is started in order to heat the second catalytic converter to its light-off temperature. Once the second catalytic converter has reached its light-off temperature, secondary air and fuel are additionally introduced into the exhaust gas duct and are exothermically reacted on the second catalytic converter in order to support the heating of the second catalytic converter.

A method for heating a catalytic converter in an exhaust system of an internal combustion engine, in which an exhaust gas burner for heating the catalytic converter is arranged, upstream of the catalytic converter. A lambda probe for controlling the combustion air ratio of the exhaust gas burner is arranged immediately downstream of the exhaust gas burner and upstream of the catalytic converter. The method includes operating the internal combustion engine with a stoichiometric combustion air ratio (λ.sub.E=1), activating the exhaust gas burner, which is operated alternately with a substoichiometric combustion air ratio (λ.sub.B<1) and a superstoichiometric combustion air ratio (λ.sub.B>1), wherein from the substoichiometric combustion air ratio (λ.sub.B<1) to the superstoichiometric combustion air ratio (λ.sub.B>1) as soon as a rich breakthrough is detected by the second lambda probe (34), and wherein a switchover from the superstoichiometric combustion air ratio (λ.sub.B>1) to the substoichiometric combustion air ratio (λ.sub.B<1) takes place as soon as a lean breakthrough is detected by the second lambda probe.

An exhaust gas system for a motor vehicle includes an exhaust gas burner and a pressure sensor for sensing flame formation in the exhaust gas burner.

A system for injecting fuel into an exhaust pipe and preventing fuel leakage. An exhaust pipe is connected to an engine via an exhaust adaptor and the fuel is injected directly into the exhaust pipe through a fuel injection valve provided in the exhaust adaptor. A lower end of the exhaust adaptor is provided with a lower flange part to which a front end flange part of the exhaust pipe is connected, and a tubular shielding part for preventing the fuel from falling onto flange surfaces and of the front end flange part and the lower flange part protrudes into the exhaust pipe.

The risk of a particulate filter from being damaged is reduced while an increase in pressure loss of the particulate filter due to ash is suppressed. Micropore zones are defined at upstream sides of partition walls of a particulate filter and macropore zones are defined at downstream sides of partition walls. The pore size of the partition walls at the micropore zones is set so that the particulate matter and the ash can be trapped by the partition walls at the micropore zones, while the pore size of the partition walls at the macropore zones is set so that the ash can pass through the partition walls at the macropore zones. When the difference dQPM between the quantity of the particulate matter which is trapped at the micropore zones and the quantity of particulate matter which is trapped at the macropore zones exceeds a predetermined threshold value, PM removal control is executed.

An exhaust gas purification system for an internal combustion engine is provided with a filter including a selective catalytic reduction NOx catalyst carried thereon. Further, a post-catalyst is provided for an exhaust gas passage disposed on a downstream side from the filter. The post-catalyst has an oxidizing function, and the post-catalyst has such a function that the production of N.sub.2 based on the oxidation of ammonia is facilitated in a predetermined first temperature area. A filter regeneration process execution unit is programmed to control the temperature of the post-catalyst to be in the first temperature area while adjusting the temperature of the filter to be in a predetermined second temperature area lower than a filter regeneration temperature during a certain period of time.

A device for exhaust gas aftertreatment in an internal combustion engine can be connected to an outlet of the internal combustion engine. The device comprises an exhaust gas system with an exhaust gas channel in which a three-way catalytic converter is arranged, and an exhaust gas burner with which hot burner exhaust gases can be fed into the exhaust gas channel at a feed point upstream from the three-way catalytic converter. The three-way catalytic converter is configured as a lambda probe catalytic converter and comprises a first catalyst volume and a second catalyst volume, whereby a lambda probe is arranged downstream from the first catalyst volume and upstream from the second catalyst volume, whereby the first catalyst volume has a lower oxygen storage capacity than the second catalyst volume. A method for exhaust gas aftertreatment in an internal combustion engine has such an exhaust gas aftertreatment device.

A device for exhaust gas aftertreatment in an internal combustion engine can be connected to an outlet of the internal combustion engine. The device comprises an exhaust gas system with an exhaust gas channel in which a three-way catalytic converter is arranged, and an exhaust gas burner with which hot burner exhaust gases can be fed into the exhaust gas channel at a feed point upstream from the three-way catalytic converter. The three-way catalytic converter is configured as a lambda probe catalytic converter and comprises a first catalyst volume and a second catalyst volume, whereby a lambda probe is arranged downstream from the first catalyst volume and upstream from the second catalyst volume, whereby the first catalyst volume has a lower oxygen storage capacity than the second catalyst volume. A method for exhaust gas aftertreatment in an internal combustion engine has such an exhaust gas aftertreatment device.

An exhaust gas purification apparatus for an internal combustion engine, capable of carrying out oxidation removal of PM deposited in a filter as a whole in an efficient manner, includes a filter arranged in an exhaust passage of the internal combustion engine and having an oxidation catalyst supported in at least an upstream side portion thereof, and a heating device arranged so as to be able to heat the upstream side portion of the filter irrespective of oxidation reaction heat of the oxidation catalyst, wherein when filter upstream regeneration processing to oxidize and remove deposition PM in the upstream side portion of the filter is carried out by controlling a heating device, an amount of decrease of the upstream side deposition PM by the filter upstream regeneration processing is reflected on an amount of filter PM deposition in the ordinary filter regeneration processing which oxidizes and removes the deposition PM in the entire filter by means of oxidation reaction heat of unburnt fuel generated by the oxidation catalyst supported in the filter, and the filter upstream regeneration processing is ended, even if the thus reflected amount of filter PM deposition is in a state of being larger than a reference amount of deposition which is a threshold value for ending the ordinary filter regeneration processing.

An exhaust gas purification apparatus for an internal combustion engine, capable of carrying out oxidation removal of PM deposited in a filter as a whole in an efficient manner, includes a filter arranged in an exhaust passage of the internal combustion engine and having an oxidation catalyst supported in at least an upstream side portion thereof, and a heating device arranged so as to be able to heat the upstream side portion of the filter irrespective of oxidation reaction heat of the oxidation catalyst, wherein when filter upstream regeneration processing to oxidize and remove deposition PM in the upstream side portion of the filter is carried out by controlling a heating device, an amount of decrease of the upstream side deposition PM by the filter upstream regeneration processing is reflected on an amount of filter PM deposition in the ordinary filter regeneration processing which oxidizes and removes the deposition PM in the entire filter by means of oxidation reaction heat of unburnt fuel generated by the oxidation catalyst supported in the filter, and the filter upstream regeneration processing is ended, even if the thus reflected amount of filter PM deposition is in a state of being larger than a reference amount of deposition which is a threshold value for ending the ordinary filter regeneration processing.