Non-methane hydrocarbon conversion efficiency diagnostic for a diesel after-treatment system

摘要

A method of assessing non-methane hydrocarbon (NMHC) conversion efficiency in a diesel after-treatment (AT) system having a diesel oxidation catalyst (DOC) arranged upstream of a diesel particulate filter (DPF) includes regenerating the AT system. Additionally, the method monitors DOC inlet and outlet temperatures during the regeneration. The method also assesses whether the DOC is operating at or above threshold efficiency by determining a DOC inlet/outlet temperature difference and comparing the determined inlet/outlet temperature difference with a threshold inlet/outlet temperature difference. The method also monitors DPF outlet temperature if the DOC is operating at or above the threshold efficiency and determines a DOC temperature/DPF outlet temperature difference. The method additionally assesses whether NMHC conversion efficiency of the DPF is at or above a threshold value by comparing the determined DOC temperature/DPF outlet temperature difference with a threshold DOC temperature/DPF outlet temperature difference. A system and a vehicle are also disclosed.

主权项

1. A method of assessing non-methane hydrocarbon (NMHC) conversion efficiency in a diesel engine after-treatment (AT) system, the method comprising:
regenerating the AT system, wherein the AT system includes a diesel oxidation catalyst (DOC) arranged upstream of a diesel particulate filter (DPF); monitoring DOC inlet and outlet temperatures during the regeneration; assessing whether the DOC is operating at or above a threshold DOC efficiency by determining the difference between the DOC inlet and outlet temperatures and comparing the determined DOC inlet/outlet temperature difference with a threshold DOC inlet/outlet temperature difference; monitoring DPF outlet temperature if the DOC is determined to be operating at or above the threshold DOC efficiency; determining the difference between a DOC temperature and the monitored DPF outlet temperature, wherein the DOC temperature is one of the DOC inlet and outlet temperature; assessing whether the NMHC conversion efficiency of the DPF is at or above a threshold NMHC conversion efficiency by comparing the determined DOC temperature/DPF outlet temperature difference with a threshold DOC inlet/DPF outlet temperature difference; determining via a controller that the DOC has failed if the determined DOC temperature/DPF outlet temperature difference is less than the threshold DOC temperature/outlet temperature difference; and generating via the controller a signal indicative of the DOC having failed, if the determined DOC temperature/outlet temperature difference is less than the threshold DOC temperature/outlet temperature difference.