| 摘要 |
PROBLEM TO BE SOLVED: To produce NHwhile reducing the amount of generated NO.SOLUTION: An exhaust gas purifier of an internal combustion engine includes: a selective reduction type NOx catalyst for reducing NOx by using NHas a reducer; an exhaust gas purification catalyst provided upstream the NOx catalyst in an exhaust gas passage, and producing NHwhen the air-fuel ratio of an exhaust gas is equal to or lower than a stoichiometric air-fuel ratio; and air-fuel ratio adjustment means for adjusting the air-fuel ratio of the exhaust gas. When the air-fuel ratio of the exhaust gas of the internal combustion engine is switched from the stoichiometric air-fuel ratio to a lean air-fuel ratio, the air-fuel ratio adjustment means first changes the air-fuel ratio to a rich air-fuel ratio lower than the stoichiometric air-fuel ratio and lower than an air-fuel ratio at which the amount of generated NO becomes maximum, and then switches the air-fuel ratio to the lean air-fuel ratio. |
