Detection of exhaust particulate filter substrate failure

Abstract

A method of detecting failure of a substrate in a particulate filter includes comparing an absolute value of a difference between a theoretical temperature difference and an actual temperature difference between an upstream end and a downstream end of the particulate filter to a temperature differential threshold, and comparing an absolute value of a difference between a theoretical pressure difference and an actual pressure difference between the upstream end and the downstream end of the particulate filter to a pressure differential threshold. Failure of the substrate is indicated by one or both of the temperature difference and the pressure difference being greater than the temperature differential threshold and the pressure differential threshold respectively.

1 . A method of detecting a failure in a substrate of a particulate filter in an exhaust system of a vehicle, the method comprising:
 calculating an absolute value of a difference between a theoretical temperature difference between an upstream end and a downstream end of the particulate filter and an actual temperature difference between the upstream end and the downstream end of the particulate filter;   comparing the absolute value of the difference between the theoretical temperature difference and the actual temperature difference to a temperature differential threshold to determine if the absolute value of the difference between the theoretical temperature difference and the actual temperature difference is greater than the temperature differential threshold;   calculating an absolute value of a difference between a theoretical pressure difference between the upstream end and the downstream end of the particulate filter and an actual pressure difference between the upstream end and the downstream end of the particulate filter;   comparing the absolute value of the difference between the theoretical pressure difference and the actual pressure difference to a pressure differential threshold to determine if the absolute value of the difference between the theoretical pressure difference and the actual pressure difference is greater than the pressure differential threshold; and   indicating a substrate failure if the absolute value of the difference between the theoretical temperature difference and the actual temperature difference is greater than the temperature differential threshold or if the absolute value of the difference between the theoretical pressure difference and the actual pressure difference is greater than the pressure differential threshold.   
     
     
         2 . A method as set forth in  claim 1  further comprising defining a particulate matter threshold. 
     
     
         3 . A method as set forth in  claim 2  further comprising detecting a particulate matter level of particulate matter trapped in the particulate filter. 
     
     
         4 . A method as set forth in  claim 3  further comprising comparing the particulate matter level to the particulate matter threshold to determine if the particulate matter level is greater than the particulate matter threshold. 
     
     
         5 . A method as set forth in  claim 4  wherein comparing the particulate matter level to the particulate matter threshold is further defined as comparing the particulate matter level to the particulate matter threshold after comparing the absolute value of the difference between the theoretical temperature difference and the actual temperature difference to the temperature differential threshold. 
     
     
         6 . A method as set forth in  claim 5  wherein comparing the particulate matter level to the particulate matter threshold is further defined as comparing the particulate matter level to the particulate matter threshold before comparing the absolute value of the difference between the theoretical pressure difference and the actual pressure difference to the pressure differential threshold. 
     
     
         7 . A method as set forth in  claim 6  further comprising stopping analysis of the substrate without indicating a substrate failure prior to comparing the absolute value of the difference between the theoretical pressure difference and the actual pressure difference to the pressure differential threshold when the particulate matter level is greater than the particulate matter threshold. 
     
     
         8 . A method as set forth in  claim 1  further comprising defining the theoretical temperature difference between the upstream end and the downstream end of the particulate filter. 
     
     
         9 . A method as set forth in  claim 8  wherein defining the theoretical temperature difference includes calculating a theoretical upstream temperature and a theoretical downstream temperature of the exhaust gas for the current operating conditions of the exhaust system. 
     
     
         10 . A method as set forth in  claim 8  wherein defining the theoretical temperature difference includes referencing stored temperature values from a table for the current operating conditions of the exhaust system to determine a theoretical upstream temperature and a theoretical downstream temperature of the exhaust gas. 
     
     
         11 . A method as set forth in  claim 1  further comprising defining the theoretical pressure difference between the upstream end and the downstream end of the particulate filter. 
     
     
         12 . A method as set forth in  claim 11  wherein defining the theoretical pressure difference includes calculating a theoretical upstream pressure and a theoretical downstream pressure of the exhaust gas for the current operating conditions of the exhaust system. 
     
     
         13 . A method as set forth in  claim 11  wherein defining the theoretical pressure difference includes referencing stored pressure values from a table for the current operating conditions of the exhaust system to determine a theoretical upstream pressure and a theoretical downstream pressure of the exhaust gas. 
     
     
         14 . A method as set forth in  claim 1  further comprising measuring the actual temperature difference between the upstream end and the downstream end of the particulate filter. 
     
     
         15 . A method as set forth in  claim 1  further comprising measuring the actual pressure difference between the upstream end and the downstream end of the particulate filter. 
     
     
         16 . A method as set forth in  claim 1  further comprising defining the temperature differential threshold. 
     
     
         17 . A method as set forth in  claim 1  further comprising defining the pressure differential threshold. 
     
     
         18 . A method as set forth in  claim 1  further comprising stopping analysis of the substrate without indicating a substrate failure if the absolute value of the difference between the theoretical temperature difference and the actual temperature difference is less than the temperature differential threshold and if the absolute value of the difference between the theoretical pressure difference and the actual pressure difference is less than the pressure differential threshold. 
     
     
         19 . A method of detecting a failure in a substrate of a particulate filter in an exhaust system of a vehicle, the method comprising:
 measuring the actual temperature difference between an upstream end and a downstream end of the particulate filter;   calculating an absolute value of a difference between a theoretical temperature difference between the upstream end and the downstream end of the particulate filter and the actual temperature difference between the upstream end and the downstream end of the particulate filter;   comparing the absolute value of the difference between the theoretical temperature difference and the actual temperature difference to a temperature differential threshold to determine if the absolute value of the difference between the theoretical temperature difference and the actual temperature difference is greater than the temperature differential threshold;   comparing a measured particulate matter level of particulate matter trapped in the particulate filter to a particulate matter threshold to determine if the particulate matter level is greater than the particulate matter threshold;   measuring the actual pressure difference between the upstream end and the downstream end of the particulate filter;   calculating an absolute value of a difference between a theoretical pressure difference between the upstream end and the downstream end of the particulate filter and an actual pressure difference between the upstream end and the downstream end of the particulate filter;   comparing the absolute value of the difference between the theoretical pressure difference and the actual pressure difference to a pressure differential threshold to determine if the absolute value of the difference between the theoretical pressure difference and the actual pressure difference is greater than the pressure differential threshold when the particulate matter level is less than the particulate matter threshold; and   indicating a substrate failure if the absolute value of the difference between the theoretical temperature difference and the actual temperature difference is greater than the temperature differential threshold, or if the absolute value of the difference between the theoretical pressure difference and the actual pressure difference is greater than the pressure differential threshold.   
     
     
         20 . A method as set forth in  claim 19  wherein comparing a particulate matter level of particulate matter trapped in the particulate filter to a particulate matter threshold is further defined as comparing the particulate matter level to the particulate matter threshold after comparing the absolute value of the difference between the theoretical temperature difference and the actual temperature difference to the temperature differential threshold.