Patent ID: 7607290
Filing Date: 2009-10-27
Classification: F01N,F02B,F02M,Y02T

Abstract:
1. A method for purifying exhaust gas of an internal combustion engine, comprising: trapping particulate matter in exhaust gas by an exhaust purifying mechanism located in an exhaust passage of the internal combustion engine; adding fuel to exhaust gas that passes through the exhaust purifying mechanism, to increase the temperature of the exhaust purifying mechanism so as to burn particulate matter; detecting a pressure difference between a section upstream and a section downstream of the exhaust purifying mechanism; comparing an estimated accumulation amount of particular matter in the exhaust purifying mechanism with a threshold value when continuous fuel addition is being executed; comparing the pressure difference with a pressure difference reference value when the continuous fuel addition is being executed; and switching the manner of adding fuel from the continuous fuel addition to intermittent fuel addition such that the temperature distribution of the exhaust purifying mechanism is suppressed from being uneven when it is determined that the estimated accumulation amount of particular matter becomes equal to or less than the threshold value and the pressure difference exceeds the pressure difference reference value, wherein the threshold value is a value for determining that the intermittent fuel addition does not cause abrupt burning of particulate matter, and the pressure difference reference value is a value for determining that the continuous fuel addition does not cause sufficient burning of particulate matter.