Exhaust system and heating-up method

Abstract

The present invention relates to an exhaust system for a combustion engine, particularly of a vehicle, with an oxidation catalytic converter (oxicat), with an electrically heatable catalytic converter (E-cat) arranged upstream of the oxicat and with a fuel injector arranged upstream of the E-cat. An energetically favourable mode of operation is achieved when a particle filter is arranged downstream of the oxicat, when a bypass path bypassing the E-cat commences downstream of the fuel injector and ends upstream of the oxicat and when the E-cat is designed for a smaller exhaust gas flow rate than the oxicat.

1 . An exhaust system for a combustion engine, particularly of a vehicle, comprising:
 an oxidation catalytic converter (oxicat);   with an electrically heatable catalytic converter (E-cat) arranged upstream of the oxicat;   a fuel injector arranged upstream of the E-cat;   a particle filter arranged upstream of the oxicat;   a bypass path bypassing the E-cat and commencing upstream of the fuel injector and ending downstream of the oxicat; and   wherein the E-cat is configured for a smaller exhaust gas flow rate than the oxicat.   
     
     
         2 . The exhaust system according to  claim 1 , wherein the E-cat and oxicat are arranged in one of a common exhaust pipe or common housing in which the bypass path is also formed. 
     
     
         3 . The exhaust system according to  claim 1 , including at least one of a configuration wherein the bypass path is throttled, and a configuration between E-cat and oxicat a flow mixing device is arranged. 
     
     
         4 . The exhaust system according to  claim 1 , wherein between the E-cat and oxicat at least one additional oxidation catalytic converter (additional oxicat) is arranged so that the bypass path bypasses the E-cat and the at least one additional oxicat, and at least one additional bypass path that bypasses the E-cat is provided, which commences upstream of the E-cat and ends upstream of the additional oxicat, and wherein the at least one additional oxicat is configured for a smaller exhaust gas flow rate than the main oxicat, and the E-cat is designed for a smaller exhaust gas flow rate than the additional oxicat. 
     
     
         5 . The exhaust system according to  claim 4 , wherein the E-cat, main oxicat and the at least one additional oxicat are arranged in one of a common exhaust pipe or housing in which the main bypass path and the at least one additional bypass path are also formed. 
     
     
         6 . The exhaust system according to  claim 4 , wherein at least one separating wall is provided, which separates the main bypass path from the at least one additional bypass path and comprising a configuration wherein at least one of: the main bypass path is throttled, the additional bypass path is throttled, between the E-cat and the at least one additional oxicat a flow mixing device is arranged, and/or between the at least one additional oxicat and main oxicat a flow mixing device is arranged. 
     
     
         7 . A method for heating-up a particle filter in an exhaust system of a combustion engine, particularly of a vehicle, comprising:
 injecting fuel into a flow of engine exhaust gas transported in the exhaust system in order to form an engine exhaust gas-fuel mixture;   wherein a part flow of the engine exhaust gas-fuel mixture is converted in an electrically heatable catalytic converter (E-cat) in order to form a catalytic converter waste gas;   wherein the catalytic converter waste gas is admixed to a residual flow of the engine exhaust gas-fuel mixture in order to form a catalytic converter waste gas-engine exhaust gas-fuel mixture; and   wherein the catalytic converter waste gas-engine exhaust gas-fuel mixture is converted in an oxidation catalytic converter in order to form a catalytic converter waste gas for heating-up the particle filter.   
     
     
         8 . The exhaust system according to  claim 7 , wherein the residual flow of the engine exhaust gas-fuel mixture is conducted past the E-cat, and wherein the residual flow of the engine exhaust gas-fuel mixture is conducted past the E-cat so that heat from the E-cat is transferred to the residual flow of the engine exhaust gas-fuel mixture. 
     
     
         9 . A method for heating-up a particle filter in an exhaust system of a combustion engine, particularly of a vehicle, comprising:
 injecting fuel into a flow of engine exhaust gas transported in the exhaust system in order to form an engine exhaust gas-fuel mixture;   wherein a part flow of the engine exhaust gas-fuel mixture is converted in an electrically heatable catalytic converter (E-cat) in order to form a catalytic converter waste gas;   wherein the catalytic converter waste gas is supplied to a further part flow of the engine exhaust gas-fuel mixture in order to form a catalytic converter waste gas-engine exhaust gas-fuel mixture;   wherein this catalytic converter waste gas-engine exhaust gas-fuel mixture is converted in an additional oxidation catalytic converter in order to form a further catalytic converter waste gas;   wherein the further catalytic converter waste gas is admixed to a residual flow of the engine exhaust gas-fuel mixture in order to form a catalytic converter waste gas-engine exhaust gas-fuel mixture;   wherein the catalytic converter waste gas-engine exhaust gas-fuel mixture is converted in a main oxidation catalytic converter in order to from a catalytic converter waste gas for heating-up the particle filter.   
     
     
         10 . The method according to  claim 9 , wherein the further part flow of the engine exhaust gas-fuel mixture is conducted past the E-cat so that heat from the E-cat is transferred to the further part flow of the engine exhaust gas-fuel mixture. 
     
     
         11 . The method according to  claim 9 , wherein the residual flow of the engine exhaust gas-fuel mixture is conducted past at least one of the E-cat and the additional oxidation catalytic converter in a heat-transferring manner so that heat from the E-cat and/or from the additional oxidation catalytic converter is transferred to the residual flow of the engine exhaust gas-fuel mixture. 
     
     
         12 . The method according to  claim 9 , wherein the residual flow of the engine exhaust gas-fuel mixture flows onto a porous evaporation wall arranged upstream of one of the oxidation catalytic converter or of the main oxidation catalytic converter, while one of the catalytic converter waste gas coming from the E-cat or from the additional oxidation catalytic converter flows through the evaporation wall.