Patent ID: 7367182

Claim:
An exhaust emission control method for an internal combustion engine, for capturing particulate matter contained in exhaust gases in a particulate filter interposed in an exhaust passage of an internal combustion engine and forcibly combusting the particulate matter captured in said particulate filter with a forced regeneration device to regenerate said particulate filter, said forced regeneration device including oxidation catalysts located upstream from said particulate filter or in said particulate filter and a burner provided upstream from said oxidation catalysts, wherein said burner has an intake air port for introducing fresh air to assist combustion in the burner, the method comprising the steps of: (a) operating said burner in a combustion mode for a first predetermined period to combust a fuel spray injected from said burner by inflammation to raise temperature of exhaust gases in the exhaust passage; (b) after the step (a), suspending the burner operation for a second predetermined period by stopping fuel supply to the burner for the second predetermined period; (c) after the step (b), operating said burner in a fuel supply mode for a third predetermined period to supply only a fuel spray to the exhaust passage without inflammation for the third predetermined period; and (d) after the step (c), suspending the burner operation for a fourth predetermined period by stopping fuel supply to the burner for the fourth predetermined period; and (e) repeating the steps (a) and (d) for a fifth predetermined period.