Method For The Regeneration Of A Particle Filter Installed In The Exhaust Gas Train Of A Vehicular Diesel Engine

Abstract

A method for regenerating a soot-laden particle filter in the exhaust gas train of a diesel engine in a vehicle, wherein the engine is equipped with a fuel injection system having an injection valve for each cylinder and an exhaust braking device including a butterfly valve in the exhaust gas train upstream of the particle filter. An exhaust braking phase is initiated by closing the butterfly valve, thereby causing hot exhaust gas to be compressed upstream of the butterfly valve. Regeneration of the particle filter is then initiated by injecting diesel fuel into the cylinders substantially after the respective pistons pass top dead center, and allowing the hot exhaust gas mixture containing unburned fuel and air to flow past the butterfly valve so that the mixture ignites the soot and then supports combustion of the soot, thereby regenerating the particle filter.

1 . A method for regenerating a particle filter installed in an exhaust gas train of a diesel engine in a vehicle and partially loaded with separated soot particles, wherein the engine is equipped with a fuel injection system comprising an injection valve for each cylinder and an exhaust braking device comprising a butterfly valve in the exhaust gas train upstream of the particle filter, the method comprising:
 initiating an exhaust braking phase by closing the butterfly valve, thereby causing hot exhaust gas to be compressed upstream of the butterfly valve;   initiating regeneration of the particle filter during an exhaust braking phase by injecting diesel fuel into the cylinders substantially after the respective pistons pass top dead center, thereby creating a hot gas mixture containing unburned fuel and air; and   allowing the hot gas mixture to flow past the butterfly valve so that the mixture ignites the soot and then supports combustion of the soot, thereby regenerating the particle filter.   
   
   
       2 . The method of  claim 1  wherein regeneration is initiated when the diesel engine is in an RPM range which is significantly lower than a nominal RPM value of the diesel engine. 
   
   
       3 . The method of  claim 1  further comprising:
 detecting actual pressure values in the exhaust gas train at a time before or immediately after initiating an exhaust braking phase; and   determining the degree of soot loading of the particle filter based on the actual pressure values.   
   
   
       4 . The method of  claim 3  comprising:
 predefining a nominal pressure value range,   determining the degree of soot loading of the particle filter by comparing the actual pressure values to the nominal pressure value range; and   determining when the particle filter should be regenerated based on the location of the actual pressure values in the nominal pressure value range.   
   
   
       5 . The method of  claim 1  comprising:
 detecting the temperature value of the particle filter during regeneration;   injecting the diesel fuel during regeneration with a timing that is set within a range between a minimum and a maximum after top dead center; and   injecting the diesel fuel during regeneration in a quantity which is set as a function of the detected temperature values of the particle filter, wherein the quantity of fuel injected is inversely proportional to the temperature.   
   
   
       6 . The method of  claim 5  wherein the injection timing is between a minimum of 5 crankshaft degrees after TDC and a maximum of 120 crankshaft degrees after TDC. 
   
   
       7 . The method of  claim 1  further comprising:
 detecting operating values relevant to regeneration during regeneration, the operating values comprising exhaust gas backpressure between the butterfly valve and the particle filter; and   terminating the regeneration when the detected operating values indicate a satisfactory degree of regeneration.   
   
   
       8 . The method of  claim 1  wherein the regeneration is controlled by a computer-based electronic control unit, the method comprising:
 storing nominal value data in the electronic control unit;   transmitting actual operating values to the electronic control unit;   evaluating the actual operating values based on the stored nominal value data; and   based on the evaluation, generating control commands for elements including the butterfly valve, the injection valves, and an exhaust bypass around the butterfly valve.