Sulphur oxide (sox) removal method and system and stop module for said system

Abstract

The invention relates to a system for the removal of SOx (sulphur oxide) stored in a nitrogen oxide (NOx) trap associated with an oxidation catalyst and disposed in an exhaust line of an engine, said system including a stop module ( 54 ) capable of controlling the stopping a NOx trap purge task as a function of the SOx removal speed estimated by an estimator ( 60 ).

1 . System for removing SOx (Sulfur Oxide) stored in a NOx (Nitrogen Oxide) trap associated with an oxidation catalyst and arranged in an exhaust line of a motor vehicle engine, this system including:
 a fuel supply controller adapted to execute at least one purge cycle of the NOx trap, this cycle comprising commanding a fuel supply device to supply the engine with a lean mixture that makes it possible to raise and maintain the temperature of the trap within a range that enables SOx removal, alternating with a rich mixture that allows the SOx stored in the NOx trap to be removed,   an estimator adapted to estimate the removal rate of the SOx stored in the NOx trap while running the purge cycle, and   a shut-off module for the purge cycle,   wherein the shut-off module is adapted to control the shut-off of the purge cycle as a function of the rate estimated by the estimator.   
   
   
       2 . System according to  claim 1 , for a motor vehicle that also has a particulate filter and a supervisor for the particulate filter adapted to send a request to regenerate the particulate filter so that the fuel supply controller executes a particulate filter regeneration cycle, and in which the shut-off module is also adapted to command the purge cycle to shut off as a function of the particulate filter regeneration request sent by the particulate filter supervisor. 
   
   
       3 . System according to  claim 1 , wherein the shut-off module is adapted to compare the quantity of SOx removed, obtained by integrating the estimated rate as a function of the time elapsed from the beginning of the purge cycle run, to a minimum threshold that increases as a function of the time elapsed from the beginning of the purge cycle run, and to command the purge cycle to shut off according to the result of this comparison. 
   
   
       4 . System according to  claim 1 , wherein the shut-off module is also adapted to immediately command the purge cycle to shut off as soon as the estimated quantity of SOx removed is greater than a preset threshold. 
   
   
       5 . Shut-off module that can be implemented in a SOx removal system according to  claim 1 , wherein said shut-off module is adapted to command the purge cycle to shut off as a function of the rate estimated by the estimator. 
   
   
       6 . Method for removing SOx stored in a NOx trap using a removal system according to  claim 1 , wherein the shut-off module commands the purge cycle to shut off as a function of the rate estimated by the estimator. 
   
   
       7 . Information recording medium, which has instructions for executing a SOx removal method according to  claim 6 , when these instructions are executed by an electronic computer.