Engine exhaust treatment system

Abstract

An engine exhaust treatment system is provided. The system may include a catalyst-based device including a catalyst configured to reduce an amount of NO x in exhaust gases produced by an engine, by using ammonia stored in the catalyst-based device. The system may also include a controller configured to control one or more operating parameters of the engine to, under predetermined operating conditions of the engine or catalyst-based device, increase an amount of NO x produced by the engine to prevent at least some of the ammonia stored in the catalyst-based device from being released from the catalyst-based device into the exhaust.

1 . An engine exhaust treatment system, comprising:
 a catalyst-based device including a catalyst configured to reduce an amount of NOx in exhaust gases produced by an engine, by using reductant stored in the catalyst-based device; and   a controller configured to control one or more operating parameters of the engine to, in response to a rate of increase of a temperature associated with the catalyst-based device, increase an amount of NOx produced by the engine to prevent at least some of the reductant stored in the catalyst-based device from being released from the catalyst-based device into the exhaust.   
   
   
       2 . The exhaust treatment system of  claim 1 , wherein the controller is configured to control one or more operating parameters of the engine in response to the rate of increase of the temperature associated with the catalyst-based device being faster than a threshold rate of temperature increase. 
   
   
       3 . The exhaust treatment system of  claim 2 , wherein, in response to the rate of increase of the temperature associated with the catalyst-based device being faster than a threshold rate of temperature increase, the controller is further configured to reduce an amount of urea injected into the catalyst-based device. 
   
   
       4 . The exhaust treatment system of  claim 1 , wherein the controller is configured to increase the amount of NOx produced by the engine by advancing injection timing. 
   
   
       5 . The exhaust treatment system of  claim 1 , wherein the controller is configured to increase the amount of NOx produced by the engine by reducing exhaust gas recirculation flowrate. 
   
   
       6 . The exhaust treatment system of  claim 1 , wherein the controller is configured to increase the amount of NOx produced by the engine by increasing injection pressure. 
   
   
       7 . The exhaust treatment system of  claim 1 , wherein the controller is configured to increase the amount of NOx produced by the engine by changing valve actuation strategy. 
   
   
       8 . A method of exhaust treatment, comprising:
 storing reductant in a catalyst-based device, wherein the catalyst-based device includes a catalyst configured to reduce an amount of NOx in exhaust gases produced by an engine by using the reductant stored in the catalyst-based device; and   controlling one or more operating parameters of the engine to, in response to a rate of increase of a temperature associated with the catalyst-based device, increase an amount of NOx produced by the engine to prevent at least some of the reductant stored in the catalyst-based device from being released from the catalyst-based device into the exhaust.   
   
   
       9 . The method of  claim 8 , wherein controlling one or more operating parameters of the engine occurs in response to the rate of increase of the temperature associated with the catalyst-based device being faster than a threshold rate of temperature increase. 
   
   
       10 . The method of  claim 8 , further including reducing an amount of urea injected into the catalyst-based device, in response to the rate of increase of the temperature associated with the catalyst-based device being faster than a threshold rate of temperature increase. 
   
   
       11 . The method of  claim 8 , wherein increasing the amount of NOx produced by the engine is accomplished at least in part by advancing injection timing. 
   
   
       12 . The method of  claim 8 , wherein the increasing the amount of NOx produced by the engine is accomplished at least in part by reducing exhaust gas recirculation flowrate. 
   
   
       13 . The method of  claim 8 , wherein the increasing the amount of NOx produced by the engine is accomplished at least in part by increasing injection pressure. 
   
   
       14 . The method of  claim 8 , wherein the increasing the amount of NOx produced by the engine is accomplished at least in part by changing valve actuation strategy. 
   
   
       15 . A power system, comprising:
 an exhaust producing engine; and   an engine exhaust treatment system configured to reduce an amount of one or more constituents of the exhaust produced by the engine, the engine exhaust treatment system including:
 a catalyst-based device including a catalyst configured to reduce an amount of NOx in exhaust gases produced by the engine, by using reductant stored in the catalyst-based device; and 
 a controller configured to control one or more operating parameters of the engine to, in response to a rate of increase of a temperature associated with the catalyst-based device being faster than a threshold rate of temperature increase, increase an amount of NOx produced by the engine to prevent at least some of the reductant stored in the catalyst-based device from being released from the catalyst-based device into the exhaust; 
   
   
   
       16 . The power system of  claim 15 , wherein, in response to the rate of increase of the temperature associated with the catalyst-based device being faster than the threshold rate of temperature increase, the controller is further configured to reduce an amount of urea injected into the catalyst-based device. 
   
   
       17 . The power system of  claim 15 , wherein the controller is configured to increase the amount of NOx produced by the engine by advancing injection timing. 
   
   
       18 . The power system of  claim 15 , wherein the controller is configured to increase the amount of NOx produced by the engine by reducing exhaust gas recirculation flowrate. 
   
   
       19 . The power system of  claim 15 , wherein the controller is configured to increase the amount of NOx produced by the engine by increasing injection pressure. 
   
   
       20 . The power system of  claim 15 , wherein the controller is configured to increase the amount of NOx produced by the engine by changing valve actuation strategy.