Filter regeneration using filter temperature modulation

Abstract

According to one embodiment, an apparatus for controlling the regeneration of a particulate filter of an internal combustion engine system includes an operating conditions module that is configured to monitor at least one engine system condition. The apparatus also includes a regeneration module that is configured to trigger a regeneration event if the at least one engine system condition meets a threshold. Further, the apparatus includes a thermal management module that is configured to operate the internal combustion engine system in a thermal management mode for a first time period while a regeneration event is triggered by the regeneration module. Also, the apparatus includes a high NO x module configured to operate the internal combustion engine system in a high NO x mode for a second time period following the first time period while the regeneration event is triggered by the regeneration module.

What is claimed is: 
     
         1 . An apparatus for controlling the regeneration of a particulate filter of an exhaust aftertreatment system of an internal combustion engine system; comprising:
 an operating conditions module configured to monitor at least one condition of the internal combustion engine system;   a regeneration module configured to trigger a regeneration event if the at least one condition of the internal combustion engine system meets a threshold;   a thermal management module configured to operate the internal combustion engine system in a thermal management mode for a first time period while a regeneration event is triggered by the regeneration module; and   a high NO x  module configured to operate the internal combustion engine system in a high NO x  mode for a second time period following the first time period while the regeneration event is triggered by the regeneration module.   
     
     
         2 . The apparatus of  claim 1 , wherein operation of the engine system in the thermal management mode results in oxidation regeneration of the particulate filter, and operation of the engine system in the high NO x  mode results in noxidation regeneration of the particulate filter. 
     
     
         3 . The apparatus of  claim 1 , wherein the length of the first time period is dependent on a temperature of the exhaust gas exiting an oxidation catalyst upstream of the particulate filter. 
     
     
         4 . The apparatus of  claim 1 , wherein the first time period ends when a temperature of the exhaust gas exiting an oxidation catalyst upstream of the particulate filter exceeds an oxidation catalyst outlet temperature threshold for a predetermined amount of time. 
     
     
         5 . The apparatus of  claim 4 , wherein the oxidation catalyst outlet temperature threshold comprises the difference between an oxidation catalyst outlet target temperature and an allowable temperature variation. 
     
     
         6 . The apparatus of  claim 1 , wherein the first time period ends when a temperature of the exhaust gas exiting the particulate filter exceeds a particulate filter outlet temperature threshold. 
     
     
         7 . The apparatus of  claim 4 , wherein the predetermined amount of time is less than 50% of the amount of time necessary to substantially completely regenerate the particulate filter via noxidation regeneration. 
     
     
         8 . The apparatus of  claim 1 , wherein the second time period is between approximately 90% and 98% longer than the first time period. 
     
     
         9 . The apparatus of  claim 1 , wherein the at least one condition of the internal combustion engine system comprises an amount of particulate matter accumulated on the particulate filter and the threshold comprises a maximum allowable amount of particulate matter accumulated on the particulate filter. 
     
     
         10 . The apparatus of  claim 1 , wherein the second time period begins after the first time period ends, when a temperature of exhaust gas exiting an oxidation catalyst upstream of the particulate filter is greater than a minimum temperature associated with a NO 2 -to-NO x  ratio of at least a threshold ratio, and when a NO x  reduction efficiency of a selective catalytic reduction (SCR) catalyst is greater than a minimum efficiency threshold. 
     
     
         11 . The apparatus of  claim 1 , wherein the second time period begins after the first time period ends, when an estimate of the NO 2  flux exiting an oxidation catalyst upstream of the particulate filter exceeds an oxidation catalyst outlet NO 2  flux threshold, and when a NO x  reduction efficiency of a selective catalytic reduction (SCR) catalyst is greater than a minimum efficiency threshold. 
     
     
         12 . The apparatus of  claim 1 , wherein the second time period ends when a temperature of a bed of an oxidation catalyst upstream of the particulate filter drops below a minimum oxidation catalyst bed temperature. 
     
     
         13 . The apparatus of  claim 12 , wherein the minimum oxidation catalyst bed temperature is the bed temperature at which a predetermined minimum particulate matter burn rate from the particulate matter filter is achievable. 
     
     
         14 . The apparatus of  claim 1 , wherein the second time period ends when a temperature of the exhaust gas entering an oxidation catalyst upstream of the particulate filter is within a predetermined oxidation catalyst inlet exhaust temperature range, a flow rate of exhaust gas through the particulate filter is within a predetermined exhaust flow rate range, and a temperature of a bed of the particulate filter is within a predetermined particulate filter bed temperature range. 
     
     
         15 . The apparatus of  claim 1 , wherein the thermal management module is configured to operate the internal combustion engine system in the thermal management mode for a third time period following the second time period while the regeneration event is triggered by the regeneration module, wherein the triggered regeneration event is untriggered when an amount of particulate matter accumulated on the particulate filter is less than a minimum particulate matter accumulation threshold. 
     
     
         16 . The apparatus of  claim 1 , wherein the thermal management module is configured to operate the internal combustion engine system in the thermal management mode for a third time period following the second time period while the regeneration event is triggered by the regeneration module, wherein the triggered regeneration event is untriggered when the regeneration event has been triggered for more than a predetermined time threshold. 
     
     
         17 . The apparatus of  claim 1 , wherein the high NO x  module is further configured to operate the internal combustion engine system in the high NO x  mode for a third time period separate from the first and second time periods while a regeneration event is not triggered by the regeneration module. 
     
     
         18 . A method for controlling the regeneration of a particulate filter of an internal combustion engine system, comprising:
 triggering a regeneration of the particulate filter;   operating the internal combustion engine system in a thermal management mode if a regeneration of the particulate filter has been triggered and while an at least one first operating condition has not met an at least one first threshold;   switching operation of the internal combustion engine system from the thermal management mode to a high NO x  mode if the regeneration of the particulate filter remains triggered and when the at least one first operating condition meets the at least one first threshold;   operating the internal combustion engine system in the high NO x  mode while an at least one second operating condition has not met an at least one second threshold; and   ceasing operation of the internal combustion engine system in the high NO x  mode when the at least one second operating condition meets the at least one second threshold.   
     
     
         19 . The method of  claim 18 , further comprising switching operation of the internal combustion engine system from the high NO x  mode back to the thermal management mode after ceasing operation of the internal combustion system in the high NO x  mode and when at least one third operation condition has met a third threshold. 
     
     
         20 . An internal combustion engine system having an internal combustion engine, comprising:
 an oxidation catalyst in exhaust receiving communication with the internal combustion engine;   a particulate filter downstream from the oxidation catalyst, the particulate filter being in exhaust receiving communication with the oxidation catalyst; and   a controller comprising:
 a regeneration module configured to initiate a regeneration event on a particulate filter; 
 a thermal management module configured to control the regeneration event according to a thermal management mode; 
 a high NO x  module configured to control the regeneration event according to a high NO x  mode; and 
 a switch module configured to monitor operating conditions of the internal combustion engine system during the regeneration event and to selectively switch between first and second regeneration states during the regeneration event, the first regeneration state comprising enablement of the thermal management module and disablement of the high NO x  module, and the second regeneration state comprising disablement of the thermal management module and enablement of the high NO x  module. 
   
     
     
         21 . The internal combustion engine system of  claim 19 , wherein the switch module switches from the first regeneration state to the second regeneration state when excess oxidation catalyst out NO 2  will not result in excess tailpipe out NO x .