Optimizing the On Board Diagnostic System (OBD) to Monitor for Reduction of the SCR Catalyst Conversion Efficiency using the NOx Sensor IAV do Brasil

Format:

Conference/Event

Author/Creator:

de Oliveira Costa, de Oliveira Costa, author.

Contributor:

Rossin, Fernando Martins

Conference Name:

SAE Brasil 2010 Congress and Exhibit (2010-10-05 : Sao Paulo, Brazil)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2010

Summary:

Due to the independent operation of the aftertreatment systemfrom the engine, the aim of the OBD system (On Board Diagnostic) isto guarantee the powertrain emissions stay within the emissionsstandards during all the vehicle useful life. In the case ofheavy-duty diesel vehicles, that uses the SCR system (SelectiveCatalytic Reduction) as the aftertreatment technology to meet thestringent emissions levels, the use of a NOx sensor in the exhaustpipe will be indispensable for a reliable monitoring of theemissions.Analyzing the European directives that are legislating the OBDsystem, the NOx sensor must be monitored by the emissions controlsystem, guaranteeing faults detection in the aftertreatment systemthat could increase the emissions. According to the annex 4 of thedirective 2005/78/EC item 3.3.2.1 (requirements for the OBD systemStage 2), it is needed to monitor the catalyst efficiency as anisolated component of the system.In case of efficiency reduction of the aftertreatment system,due to the low quality of the SCR reagent liquid, physical damageor catalyst aged, the current softwares are ready to detect thefaults, but providing a generic and inaccurate diagnostic.The SCR catalyst aging, due to the high level of sulfur in thediesel, to the lubricant oil burning or to the high exhaust gastemperature, will be verified in real applications when the SCRsystem is implemented. When it is aged, the main feature of thecatalyst (the ammonia storage capacity) is reduced, which can causeammonia emissions (slip) in the ambient. The treatment of thisparticular feature can also be found in sophisticated softwarestrategies, but applying a theoric factor to the catalyst agingbased on the system operating conditions to be applied as acorrection factor in the closed-loop dosing control strategy.This work consists in the development of a software algorithm tobe integrated to the OBD system that allows diagnosing, through adynamic functional test, a NOx conversion efficiency reduction inthe SCR catalyst as an isolated component of the complete system.With this diagnostic, applied within the strategies for catalystaging detection, the dosing controller can correct the reagentliquid injection, preventing ammonia emissions in the ambient, andgetting a faster and easier fault resolution

Notes:

Vendor supplied data

Publisher Number:

2010-36-0198

Access Restriction:

Restricted for use by site license