Control of passive soot oxidation

Abstract

A system and method for controlling passive soot oxidation in a diesel particulate filter that includes sensing the temperature of exhaust gases upstream and downstream of the diesel particulate filter. The sensed temperatures are used by a control unit to predict whether the temperature of the exhaust gas within the diesel particulate is within a predetermined temperature range for passive oxidation of soot in the diesel particulate filter. If the temperatures are below passive oxidation temperatures, an auxiliary component is activated that increases the temperature of exhaust gas delivered to the diesel particulate filter. When the exhaust gas temperature within the DPF is predicted to be within passive oxidation levels but below active regeneration temperatures, the auxiliary component is deactivated.

What is claimed is: 
     
         1 . A method for controlling passive soot oxidation in a diesel particulate filter comprising:
 sensing a temperature of an exhaust gas delivered to the diesel particulate filter;   sensing a temperature of the exhaust gas released out of the diesel particulate filter;   predicting, by an electronic control module, a temperature of the exhaust gas within the diesel particulate filter using the sensed temperatures of the exhaust gas delivered to and released out of the diesel particulate filter;   determining, by the electronic control module, whether the predicted exhaust gas temperature is within a predetermined temperature range for passive soot oxidation within the diesel particulate filter; and   activating an auxiliary component to increase the temperature of the exhaust gas delivered to the diesel particulate filter to a passive soot oxidation temperature when the predicted exhaust gas temperature within the diesel particulate filter is determined to be below the predetermined temperature range.   
     
     
         2 . The method of  claim 1 , further including the step of predicting, by the electronic control module, a second temperature of the exhaust gas within the diesel particulate filter while the auxiliary component is activated, and deactivating the auxiliary component when the second temperature of the exhaust gas reaches a predetermined limit, the predetermined limit being below active regeneration temperatures. 
     
     
         3 . The method of  claim 2 , wherein the method further includes monitoring the temperature of the exhaust gas downstream of the diesel particulate filter after the auxiliary component has been deactivated. 
     
     
         4 . The method of  claim 3 , further including initiating a timer after the auxiliary component has been deactivated. 
     
     
         5 . The method of  claim 4 , further including predicting the level of soot accumulation in the diesel particulate filter using a soot accumulation model. 
     
     
         6 . The method of  claim 4 , further including detecting the difference in pressure between the exhaust gas delivered to, and removed from within, the diesel particulate filter, and predicting a soot level within the diesel particulate filter using the detected pressure difference. 
     
     
         7 . The method of  claim 1 , wherein the predetermined temperature range is around 280° C. to around 320° C. 
     
     
         8 . A system for monitoring and heating exhaust gas to control passive soot oxidation comprising:
 a diesel particulate filter;   a first temperature sensor positioned upstream of the diesel particulate filter, the first temperature sensor configured to detect the temperature of the exhaust gas delivered to the diesel particulate filter;   a second temperature sensor positioned downstream of the diesel particulate filter, the second temperature sensor configured to detect the temperature of the exhaust gas flowing out of the diesel particulate filter;   an auxiliary component configured to elevate the temperature of exhaust gas delivered to the diesel particulate filter when the auxiliary component is activated;   a control module configured to predict a first temperature of the exhaust gas within the diesel particulate filter based on the temperature sensed by the first and second temperature sensors before the auxiliary component is activated and predict a second temperature of the exhaust gas within the diesel particulate filter based on the temperature sensed by the first and second temperature sensors before an activated auxiliary component is de-activated, the control module also being configured to activate the auxiliary component when the first temperature is below a predetermined passive soot oxidation temperature range, and deactivate the auxiliary component when the second temperature is within the predetermined passive soot oxidation temperature range.   
     
     
         9 . The system of  claim 8 , wherein the auxiliary component is a burner unit. 
     
     
         10 . The system of  claim 8 , wherein the auxiliary component is an external reformer unit. 
     
     
         11 . The system of  claim 8 , wherein the auxiliary component is a fuel dosing unit and a reformer. 
     
     
         12 . The system of  claim 8 , further including a first pressure sensor upstream of the diesel particulate filter and a second pressure sensor downstream of the diesel particulate filter, the control module being configured to predict a soot level in the diesel particulate filter using the difference in pressures between the first and second pressure sensors. 
     
     
         13 . The system of  claim 8 , wherein the diesel particulate filter has a large thermal inertia. 
     
     
         14 . The system of  claim 8 , wherein the first temperature is below the balance point temperature. 
     
     
         15 . The system of  claim 8 , wherein the first and second temperature sensors are resistance temperature detectors.