Exhaust Gas Aftertreatment System For Engines Equipped With Exhaust Gas Recirculation

Abstract

A system for treating exhaust of an internal combustion engine having an exhaust recirculation system and a turbocharger includes an exhaust passageway adapted to receive exhaust from the engine. A heat exchanger is adapted to be positioned within the exhaust gas recirculation system. A pressurized air supply system includes a conduit containing pressurized air and extending within the heat exchanger. A regeneration unit for combusting a fuel and heating the exhaust flowing through the exhaust passageway is supplied air from the air supply system that has been heated by the heat exchanger. An exhaust treatment device is positioned downstream from the regeneration unit in receipt of the heated exhaust.

1 . A system for treating the exhaust of an internal combustion engine, the exhaust treatment system comprising:
 an exhaust passageway adapted to receive the exhaust from the engine;   a heat exchanger adapted to be positioned within the exhaust passageway;   a side branch in communication with the exhaust passageway;   a regeneration unit positioned within the side branch for combusting a fuel and heating the exhaust flowing through the exhaust passageway, the regeneration unit being supplied a source of oxygen heated by the heat exchanger; and   an exhaust treatment device positioned downstream of the regeneration unit in receipt of heated exhaust.   
     
     
         2 . The system of  claim 1 , wherein the source of oxygen includes a secondary air supply system including an air compressor. 
     
     
         3 . The system of  claim 2 , wherein the secondary air supply system includes a conduit for transferring air that passes through the heat exchanger. 
     
     
         4 . The system of  claim 3 , wherein the vehicle includes a turbocharger and the heat exchanger is adapted to be positioned upstream of the turbocharger. 
     
     
         5 . The system of  claim 4 , wherein the exhaust treatment device includes a particulate filter selectively regenerated by the regeneration unit. 
     
     
         6 . The system of  claim 1 , wherein the regeneration unit includes a hydrocarbon injector having a heated oxygen inlet and a fuel inlet, the injector atomizing the fuel and heated oxygen for combustion within the regeneration unit. 
     
     
         7 . The system of  claim 1 , further including a controller for selectively operating the regeneration unit to increase the exhaust temperature, the controller being operable to control a supply of fuel and heated oxygen to the regeneration unit. 
     
     
         8 . The system of  claim 1 , wherein the heat exchanger is positioned downstream of the exhaust treatment device. 
     
     
         9 . The system of  claim 8 , further including a diesel oxidation catalyst positioned immediately upstream of the diesel particulate filter. 
     
     
         10 . The system of  claim 1 , wherein the vehicle includes an exhaust gas recirculation system having a branch communicating exhaust to an intake of the engine, the heat exchanger being adapted to be positioned within the exhaust gas recirculation system. 
     
     
         11 . A system for treating the exhaust of an internal combustion engine having an exhaust gas recirculation system and a turbocharger, the exhaust treatment system comprising:
 an exhaust passageway adapted to receive the exhaust from the engine;   a heat exchanger adapted to be positioned within the exhaust gas recirculation system;   a pressurized air supply system including a conduit containing pressurized air, a portion of the conduit extending with the heat exchanger;   a regeneration unit for combusting a fuel and heating the exhaust flowing through the exhaust passageway, the regeneration unit being supplied air from the air supply system that has been heated by the heat exchanger; and   an exhaust treatment device positioned downstream of the regeneration unit in receipt of heated exhaust.   
     
     
         12 . The system of  claim 11 , wherein the oxygen supply system includes a compressor separate from the turbocharger. 
     
     
         13 . The system of  claim 12 , wherein the heat exchanger is adapted to be positioned upstream of the turbocharger. 
     
     
         14 . The system of  claim 13 , wherein the exhaust treatment device includes a particulate filter selectively regenerated by the regeneration unit. 
     
     
         15 . The system of  claim 14 , wherein the regeneration unit includes a hydrocarbon injector having a heated air inlet and a fuel inlet, the injector atomizing the fuel and heated air for combustion within the regeneration unit. 
     
     
         16 . The system of  claim 11 , further including a controller for selectively operating the regeneration unit to increase the exhaust temperature, the controller being operable to control a supply of fuel and heated air to the regeneration unit. 
     
     
         17 . The system of  claim 11 , wherein the heat exchanger is positioned downstream of the exhaust treatment device. 
     
     
         18 . The system of  claim 17 , further including a diesel oxidation catalyst positioned immediately upstream of the diesel particulate filter.