Patent ID: 7827783

Claim:
An exhaust gas purifying apparatus for an internal combustion engine having a NOx removing device provided in an exhaust system of the engine and fuel injection means for injecting fuel into a combustion chamber of said engine, the exhaust gas purifying apparatus comprising: temperature detecting means for detecting a temperature of said NOx removing device; and regeneration means for performing a regeneration process which removes sulfur oxide accumulated in said NOx removing device, wherein said regeneration means includes: post injection control means for performing at least one post injection after performing a main injection by said fuel injection means to raise a temperature of said NOx removing device and control exhaust gases flowing into said NOx removing device in a reducing state; main injection control means for increasing a main injection amount of fuel to raise the temperature of said NOx removing device, without performing the post injection, and control the exhaust gases flowing into said NOx removing device in the reducing state; and determining means for determining whether the temperature of said NOx removing device is equal to or higher than a temperature threshold value at which the sulfur oxide accumulated in said NOx removing device is removable, wherein when said post injection control means is being operated and the temperature of said NOx removing device is higher than a high-temperature determination temperature under the condition where the temperature of said NOx removing device is determined to be equal to or higher than the temperature threshold value, the operation of said post injection control means is stopped and said main injection control means is made to operate.