Cold-start engine loading for accelerated warming of exhaust aftertreatment system

Abstract

The methods of the present invention are adapted to adjust engine loading during catalyst warm up to accelerate heating of the exhaust aftertreatment system and thereby decrease catalyst light-off times. According to a preferred embodiment of the present invention, the method includes: monitoring the current catalyst temperature; determining if the current catalyst temperature is less than a predetermined minimum catalyst temperature; and, if the current catalyst temperature is less than the predetermined minimum catalyst temperature, increasing the current engine load. The current engine load is increased by activating a reducing agent tank heating device and/or a reducing agent line heating device.

1 . A method for warming an exhaust aftertreatment system to improve performance of a catalyst, comprising:
 monitoring a current catalyst temperature;   determining whether the current catalyst temperature is less than a predetermined minimum catalyst temperature; and   increasing a current engine load if the current catalyst temperature is less than the predetermined minimum catalyst temperature;   wherein increasing the current engine load includes activating at least one of a reducing agent tank heating device and a reducing agent line heating device.   
     
     
         2 . The method of  claim 1 , wherein increasing the current engine load includes calculating a minimum engine load required to increase the current catalyst temperature to the predetermined minimum catalyst temperature, and increasing the current engine load to equal the minimum engine load. 
     
     
         3 . The method of  claim 2 , wherein increasing the current engine load further includes calculating a minimum alternator load required to induce the minimum engine load, and commanding the at least one reducing agent tank heating device and reducing agent line heating device to generate the minimum alternator load. 
     
     
         4 . The method of  claim 3 , wherein increasing the current engine load further includes calculating a minimum electric draw of the at least one reducing agent tank heating device and reducing agent line heating device required to generate the minimum alternator load. 
     
     
         5 . The method of  claim 2 , wherein increasing the current engine load further includes determining whether the current engine load is less than the minimum engine load, and increasing the current engine load if the current catalyst temperature is less than the predetermined minimum catalyst temperature and the current engine load is less than the minimum engine load. 
     
     
         6 . The method of  claim 2 , wherein the minimum engine load is based at least in part upon the current engine load and a current engine speed. 
     
     
         7 . The method of  claim 1 , wherein the predetermined minimum catalyst temperature is based at least in part upon the current engine load and a current engine speed. 
     
     
         8 . The method of  claim 1 , wherein increasing the current engine load further includes adjusting activation of the at least one reducing agent tank heating device and reducing agent line heating device in response to variations in vehicle operating conditions. 
     
     
         9 . The method of  claim 1 , further comprising:
 adjusting a fuel command to compensate for the increase in engine load.   
     
     
         10 . The method of  claim 1 , further comprising:
 monitoring a current exhaust temperature;   determining whether the current exhaust temperature is less than a predetermined minimum exhaust temperature; and   increasing the current engine load if the current catalyst temperature is less than the predetermined minimum catalyst temperature and the current exhaust temperature is less than the predetermined minimum exhaust temperature.   
     
     
         11 . A method for accelerated warming of an exhaust aftertreatment system having a catalytic converter device with a catalyst for the reduction and oxidation of emissions generated by an internal combustion engine in a motorized vehicle, the method comprising:
 establishing a target minimum catalyst temperature;   monitoring a current catalyst temperature;   determining whether the current catalyst temperature is less than the target minimum catalyst temperature;   calculating a minimum engine load required to increase the current catalyst temperature to the target minimum catalyst temperature;   calculating a minimum alternator load required to induce the minimum engine load;   increasing a current engine load to equal the minimum engine load if the current catalyst temperature is less than the target minimum catalyst temperature;   wherein increasing the current engine load includes activating a reducing agent tank heating device and a reducing agent line heating device, and commanding the reducing agent tank heating device and reducing agent line heating device to generate the minimum alternator load.   
     
     
         12 . The method of  claim 11 , further comprising:
 monitoring the current engine load and a current engine speed;   wherein establishing the target minimum catalyst temperature is based at least in part upon the current engine load and the current engine speed.   
     
     
         13 . The method of  claim 11 , wherein increasing the current engine load further includes calculating a minimum electric draw of the reducing agent tank heating device and reducing agent line heating device required to generate the minimum alternator load. 
     
     
         13 . The method of  claim 11 , wherein increasing the current engine load further includes adjusting activation of the reducing agent tank heating device and reducing agent line heating device in response to variations in vehicle operating conditions. 
     
     
         14 . The method of  claim 11 , further comprising:
 increasing a fuel command to the engine to offset the increase in engine load generated by activating the reducing agent tank and reducing agent heating device.