Patent ID: 8312711

Claim:
An exhaust purification device of an internal combustion engine comprising: an NOx selective reducing catalyst arranged to be able to reduce NOx in the presence of ammonia in an engine exhaust passage; a urea aqueous solution feed valve for feeding a urea aqueous solution in the engine exhaust passage upstream of the NOx selective reducing catalyst; wherein the NOx contained in the exhaust gas is reduced by the urea aqueous solution fed from the urea aqueous solution feed valve in the NOx selective reducing catalyst, wherein an HC adsorption catalyst having the function of adsorbing HC in the exhaust gas is arranged in the engine exhaust passage between said urea aqueous solution feed valve and the NOx selective reducing catalyst, wherein the urea aqueous solution fed from the urea aqueous solution feed valve and the NOx contained in the exhaust gas are reacted with the HC adsorbed on the HC adsorption catalyst to form intermediate products having cyano groups, oximes, and amino groups, and the intermediate products are sent to the NOx selective reducing catalyst to promote the action of reduction of NOx contained in the exhaust gas, and wherein a routine executed by the exhaust purification device calculates: an amount M1 of ammonia formed from the intermediate products at the NOx selective reducing catalyst, an amount M2 of the ammonia formed from the urea passing through the HC adsorption catalyst and adsorbed at the NOx selective reducing catalyst and the ammonia exhausted at the NOx selective reducing catalyst, and an amount M3 of ammonia consumed for purifying NOx exhausted from the HC adsorption catalyst at the NOx selective reducing catalyst.