Exhaust purification control device and exhaust purification system of internal combustion engine

Abstract

If it is determined that accumulation quantity of deposit on an inner wall of an exhaust passage is equal to or larger than a predetermined value, addition quantity of urea solution from a urea solution addition valve is decreased. Thereafter, exhaust gas temperature is increased rapidly when request torque of a diesel engine increases. Thus, the deposit having accumulated on the inner wall of the exhaust passage is decomposed at once and is supplied to a urea SCR as ammonia.

1 . An exhaust purification control device of an internal combustion engine that is applied to an exhaust purification device having a purification device provided in an exhaust passage of the internal combustion engine for purifying nitrogen oxides in exhaust gas and an addition device for adding a reducing agent into the exhaust gas upstream of the purification device and that performs purification control of the nitrogen oxides with the purification device while adjusting addition quantity of the reducing agent based on operation of the addition device, the exhaust purification control device comprising:
 an estimating means for estimating accumulation quantity of deposit on an inner wall of the exhaust passage resulting from the addition of the reducing agent; and   a decreasing means for compulsorily decreasing the addition quantity of the reducing agent when at least one of a condition that the estimated accumulation quantity is equal to or larger than a specified value and a condition that increase speed of the accumulation quantity is equal to or higher than specified speed is established.   
   
   
       2 . The exhaust purification control device as in  claim 1 , further comprising:
 an exhaust gas temperature increasing means for increasing exhaust gas temperature of the internal combustion engine to temperature capable of removing the deposit when the estimated accumulation quantity is equal to or larger than a predetermined value.   
   
   
       3 . The exhaust purification control device as in  claim 2 , wherein
 the increase processing of the exhaust gas temperature is stopped when it is determined that the accumulation quantity has become equal to or smaller than a predetermined value.   
   
   
       4 . The exhaust purification control device as in  claim 1 , further comprising:
 a torque increase timing temperature increasing means for increasing the exhaust gas temperature of the internal combustion engine to temperature capable of removing the deposit at higher speed than speed of exhaust gas temperature increase accompanying increase of torque of the internal combustion engine when request torque of the internal combustion engine increases.   
   
   
       5 . The exhaust purification control device as in  claim 2 , wherein
 the addition quantity of the reducing agent added by the addition device is decreased when the exhaust gas temperature increasing means performs the increase processing of the exhaust gas temperature.   
   
   
       6 . The exhaust purification control device as in  claim 2 , wherein
 the exhaust gas temperature increasing means performs at least one of delaying processing of fuel injection timing of the internal combustion engine, fuel supplying processing to the exhaust passage of the internal combustion engine and increasing processing of exhaust gas recirculation quantity of the internal combustion engine.   
   
   
       7 . The exhaust purification control device as in  claim 2 , wherein
 the internal combustion engine is an in-vehicle internal combustion engine, an output shaft of which is connected to a drive wheel through a transmission, and   the exhaust gas temperature increasing means operates a change gear ratio of the transmission to decrease rotation speed of the output shaft of the internal combustion engine, while inhibiting fall of running speed of a vehicle.   
   
   
       8 . The exhaust purification control device as in  claim 1 , wherein
 the estimating means estimates the accumulation quantity based on a parameter correlated with temperature of an exhaust system of the internal combustion engine and the addition quantity.   
   
   
       9 . The exhaust purification control device as in  claim 1 , wherein
 the estimating means estimates the accumulation quantity based on a time, in which idling of the internal combustion engine is performed, during the idling.   
   
   
       10 . The exhaust purification control device as in  claim 1 , wherein
 the reducing agent is urea solution.   
   
   
       11 . An exhaust purification system of the internal combustion engine comprising:
 the exhaust purification control device as in  claim 1 ; and   the purification device.