Exhaust gas system and method for operating such a system

Abstract

The invention relative to an exhaust gas system ( 10 ) for a spark-ignition internal combustion engine ( 12 ), comprising an HC adsorber ( 22 ) as well as, downstream from it, a catalytic converter ( 20 ) designed at least to convert hydrocarbons (HC), and it also relates to a method for operating an exhaust gas system ( 10 ). It is provided that a burner device ( 30 ) which is operated or can be operated with air and fuel is installed downstream from the HC adsorber ( 22 ) and upstream from the catalytic converter ( 20 ).

1 . An exhaust gas system for a spark-ignition internal combustion engine, comprising
 an HC adsorber as well as, downstream from it, a catalytic converter designed at least to convert hydrocarbons (HC),   wherein a burner device which is operated or can be operated with air and fuel is installed downstream from the HC adsorber and upstream from the catalytic converter.   
     
     
         2 . The exhaust gas system according to  claim 1 , wherein the HC adsorber is configured as a full-flow adsorber. 
     
     
         3 . The exhaust gas system according to  claim 1 , wherein a preconverter that is located near the engine is arranged upstream from the HC adsorber. 
     
     
         4 . The exhaust gas system according to  claim 1 , wherein the catalytic converter or the preconverter, or both, are configured as a three-way catalytic converter. 
     
     
         5 . The exhaust gas system according to  claim 4 , wherein the catalytic converter and the preconverter, or both, are configured as a three-way catalytic converter with a particulate-filter function. 
     
     
         6 . The exhaust gas system according to  claim 1 , wherein the catalytic converter and the burner device are arranged at a position underneath the exhaust gas system. 
     
     
         7 . The exhaust gas system according to  claim 1 , further comprising a control unit for controlling the operation of the burner device. 
     
     
         8 . A method for operating an exhaust gas system according to  claim 1 , whereby, at the time of or after the start of the internal combustion engine, the burner device is started and kept in operation until at least 90% of the hydrocarbons adsorbed by the HC adsorber has desorbed, and/or until the catalytic converter has reached a prescribed temperature threshold. 
     
     
         9 . The method according to  claim 8 , wherein the burner device continues to operate for a certain period of time after desorption of at least 90% of the hydrocarbons adsorbed by the HC adsorber, and/or after a prescribed temperature threshold (TS K ) of the catalytic converter has been reached. 
     
     
         10 . The method according to  claim 8 , wherein the heating output of the burner device is regulated via the amount of fuel fed to the burner device, whereby the amount of fuel is pre-regulated as a function of the volume of air fed into the burner device.