Method and device for operating an exhaust-gas after-treatment system

Abstract

The invention relates to a method for operating a motor vehicle exhaust-gas aftertreatment system ( 1 ), in which oxygen is fed to and removed from the oxygen tank ( 8 ) of an exhaust-gas aftertreatment component ( 7 ). According to the invention, the oxygen quantity in the oxygen tank ( 8 ) is determined and a rich-lean cycle is influenced in accordance with the determined oxygen quantity. The invention also relates to a motor vehicle exhaust-gas aftertreatment system ( 1 ), which permits a temperature regulation of the oxygen tank ( 8 ) and/or an uninterrupted desulphation during the transition between a rich operation and a lean operation.

1 . A method for operating a motor-vehicle exhaust-gas after-treatment system in which oxygen is fed to or removed from an oxygen accumulator of an exhaust-gas after-treatment component, wherein at least one changing parameter defined by the oxygen accumulator and its oxygen content is determined and is used in the operation of the motor-vehicle exhaust-gas after-treatment system. 
     
     
         2 . The method according to  claim 1 , wherein an oxygen quantity in the oxygen accumulator is defined. 
     
     
         3 . The method according to  claim 1 , wherein the oxygen quantity in the oxygen accumulator is incorporated as a parameter for setting a rich-lean cycle. 
     
     
         4 . The method according to  claim 1 , wherein a cyclical change of a stored oxygen quantity is used for the defined influence of a temperature of the exhaust gas or the oxygen accumulator. 
     
     
         5 . The method according to  claim 1 , wherein an additional oxygen supply in the motor-vehicle exhaust-gas after-treatment system is performed as a function of the determined oxygen quantity. 
     
     
         6 . The method according to  claim 1 , wherein the oxygen quantity is calculated by means of an oxygen balancing across the oxygen accumulator. 
     
     
         7 . The method according to  claim 6 , wherein a first probe determines a continuous measurement of an oxygen content before the oxygen accumulator, while a second probe determines whether an exhaust gas is a rich mix or lean mix. 
     
     
         8 . The method according to  claim 1 , wherein for a regeneration of a particulate filter and/or an NOx-accumulating catalytic converter, the determined oxygen quantity is included as a parameter. 
     
     
         9 . The method according to  claim 1 , wherein for desulfurization of an oxide accumulator, the determined oxygen quantity is included as a parameter. 
     
     
         10 . The method according to  claim 8 , wherein for determining a beginning of the desulfurization and/or the regeneration, the determined oxygen quantity is included as a parameter. 
     
     
         11 . The method according to  claim 8 , wherein for determining a time period of the desulfurization and/or the regeneration, the determined oxygen quantity is included as a parameter. 
     
     
         12 . The method according to  claim 1 , wherein a cyclical use of the oxygen accumulator is used for increasing the temperature before a diesel particulate filter regeneration. 
     
     
         13 . The method according to  claim 1 , wherein at least one threshold is set with respect to the determined stored oxygen quantity, and when this threshold is exceeded, a cycle change between lean operation and rich operation is triggered. 
     
     
         14 - 15 . (canceled) 
     
     
         16 . The method according to  claim 1 , wherein an internal combustion engine is operated in a rich-lean cycle, wherein a temperature of the oxygen accumulator is determined and an operating parameter influencing the stored oxygen quantity is changed as a function of the determined temperature. 
     
     
         17 . The method according to  claim 1 , wherein a temperature regulation or temperature control system, with respect to the exhaust-gas after-treatment component having the oxygen accumulator changes an oxygen quantity discharged from or absorbed in the oxygen accumulator per unit time for adjusting the temperature of the exhaust-gas after-treatment component. 
     
     
         18 . The method according to  claim 1 , wherein during desulfurization of an oxide-accumulating catalytic converter, a rich-lean cycle is at least partially performed and an air ratio is detected before and after the oxide-accumulating catalytic converter, wherein the oxygen quantity is determined and the oxygen accumulator is used to avoid substoichiometry and/or hyperstoichiometry of the air ratio after the oxide-accumulating catalytic converter. 
     
     
         19 . An exhaust-gas after-treatment system with a connected internal combustion engine, wherein the internal combustion engine has a motor control system, and the exhaust-gas after-treatment system has at least one regulated catalytic converter and an oxygen accumulator, wherein a first probe is arranged before the oxygen accumulator and a second probe is arranged after the oxygen accumulator, wherein at least the first probe determines a first parameter characterizing the oxygen content, and a signal transmission of the parameter recorded by the first and the second probes to an evaluation unit is provided, and the evaluation unit is coupled with a motor control system with a regulation or control unit that takes into account a rich-lean cycle based on the determined parameter. 
     
     
         20 . The exhaust-gas after-treatment system according to  claim 19 , wherein the second probe is a temperature probe whose parameter is included in a control or regulation system of a lambda value of the motor control system. 
     
     
         21 . The exhaust-gas after-treatment system according to  claim 20 , wherein a rich-lean cycle is included as a desired value in a lambda regulation of the internal combustion engine. 
     
     
         22 . The exhaust-gas after-treatment system according to  claim 19 , wherein the first and the second probes each determine a first parameter characterizing an oxygen content, and a signal transmission of the first parameter from the first and the second probes to an evaluation unit is provided, and the evaluation unit determines, from the first parameters, a second parameter characterizing the oxygen content of the oxygen accumulator, and the motor control system is coupled with a device for setting an air ratio in the exhaust-gas after-treatment system, wherein an adaptation of the air ratio is provided as a function of the second parameter by means of the device. 
     
     
         23 . The exhaust-gas after-treatment system according to  claim 19 , wherein the first probe is a broadband lambda probe and the second probe is a transition probe. 
     
     
         24 . The exhaust-gas after-treatment system according to  claim 19 , wherein the oxygen accumulator has a first part and a second part that are arranged in one or at least two different exhaust-gas after-treatment components. 
     
     
         25 . The exhaust-gas after-treatment system according to  claim 19 , wherein the oxygen accumulator is a component of an NOx catalytic converter or a particulate filter. 
     
     
         26 . (canceled) 
     
     
         27 . The exhaust-gas after-treatment system according to  claim 19 , wherein a measurement probe is provided for determining a temperature of the oxygen accumulator. 
     
     
         28 . The exhaust-gas after-treatment system according to  claim 22 , wherein at least one of a control system or a regulation system is included and is geared toward the second parameter, in order to trigger a change between rich and lean operation. 
     
     
         29 - 32 . (canceled)