Exhaust treatment control system for an internal combustion engine

Abstract

The present invention relates to an engine exhaust treatment system ( 20 ) including a first exhaust gas path ( 24 ) having a diesel particulate filter ( 32 ) and a second exhaust gas path ( 26 ) having a catalytic converter ( 34 ). The system also includes a valve arrangement ( 36, 38 ), for controlling exhaust gas flow between the first and second paths ( 24, 26 ). The system ( 20 ) further includes a controller ( 40 ) for sensing/monitoring operating conditions of the engine ( 22 ) and the condition of the diesel particulate filter ( 32 ). The controller ( 40 ) shifts exhaust gas flow between the first and second paths ( 24, 26 ) based on the operating condition of the engine ( 22 ) and/or the condition of the diesel particulate filter ( 32 ) to optimize filtration efficiency while preventing unacceptable levels of backpressure and detrimental regeneration of the filter ( 32 ).

1 . An exhaust treatment system for treating exhaust gas, the system comprising: 
 a first flow path including a particulate filter;    a second flow path including a catalytic converter;    a valve arrangement for controlling flow to the first and second flow paths; and    a controller that interfaces with the valve arrangement to modify flow between the first and second flow paths in response to changes in the operating conditions of the system.    
   
   
       2 . The system of  claim 1 , wherein the controller proportions flow between the first and second flow paths.  
   
   
       3 . The system of  claim 1 , wherein the controller opens and closes flow to the first and second flow paths.  
   
   
       4 . The system of  claim 1 , wherein the controller directs flow to the second flow path when a backpressure of the system exceeds a predetermined value.  
   
   
       5 . The system of  claim 1 , wherein the particulate filter has a particulate mass reduction efficiency greater than 80 percent.  
   
   
       6 . The system of  claim 5 , wherein the catalytic converter has a particulate mass reduction efficiency less than 50 percent.  
   
   
       7 . The system of  claim 1 , wherein the catalytic converter and the particulate filter are mounted in a single housing.  
   
   
       8 . The system of  claim 7 , wherein the single housing comprises a muffler shell.  
   
   
       9 . The system of  claim 1 , further comprising a structure positioned along at least one of the first and second flow paths for reducing nitrogen oxide emissions.  
   
   
       10 . The system of  claim 1 , further comprising a temperature sensor for measuring exhaust temperature that interfaces with the controller, wherein the controller directs flow to the second flow path when the temperature of the exhaust gas is less than a predetermined temperature, and wherein the controller directs flow to the first flow path when the temperature of the exhaust gas exceeds the predetermined temperature.  
   
   
       11 . The system of  claim 10 , wherein the exhaust gas is generated by a diesel engine, wherein the controller monitors an operating condition of the engine to detect a condition indicative of high soot production, and wherein the controller directs flow to the first flow path when a condition indicative of high soot production is detected even if the temperature is less than the predetermined temperature.  
   
   
       12 . The system of  claim 1 , wherein the exhaust gas is generated by a diesel engine, wherein the controller monitors an operating condition of the engine to detect a condition indicative of high soot production, and wherein the controller directs flow to the first flow path when a condition indicative of high soot production is detected.  
   
   
       13 . The system of  claim 3 , further comprising a heating device for regenerating the particulate filter.  
   
   
       14 . The system of  claim 13 , wherein the heating device includes an electric heating element.  
   
   
       15 . The system of  claim 13 , wherein the heating device includes a diesel fuel burner.  
   
   
       16 . The system of  claim 1 , wherein the controller directs flow to the first flow path when a temperature of the exhaust gas exceeds a predetermined level to promote passive regeneration of the particulate filter.  
   
   
       17 . The system of  claim 16 , wherein the controller suppresses regeneration of the particulate filter if a condition indicative of a detrimental regeneration is detected.  
   
   
       18 . The system of  claim 17 , wherein the controller suppresses detrimental regeneration of the particulate filter by closing flow to the first flow path.  
   
   
       19 . An exhaust treatment system for treating exhaust gas, the system comprising: 
 a first flow path including a particulate filter; and    a second flow path including a catalytic converter, the second flow path and the first flow path being arranged in parallel relative to one another.    
   
   
       20 . The exhaust treatment system of  claim 19 , further comprising a muffler shell in which both the catalytic converter and the particulate filter are mounted.  
   
   
       21 . A method for treating exhaust gas using a system including a catalytic converter and a particulate filter, the method comprising; 
 modifying flow provided to the catalytic converter and the particulate filter in response to operating conditions of the system.    
   
   
       22 . The system of  claim 13 , wherein the controller suppresses regeneration of the particulate filter if a condition indicative of a detrimental regeneration is detected.  
   
   
       23 . The system of  claim 22 , wherein the controller suppresses detrimental regeneration of the particulate filter by closing flow to the first flow path.