| 摘要 |
In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged. The exhaust purification catalyst (13) is comprised of an upstream-side catalyst (14a) and a downstream-side catalyst (14b) arranged in series. The upstream-side catalyst (14a) is a three-way catalyst which has an oxygen storage ability. On the exhaust gas flow surface of the downstream side catalyst (14b), precious metal catalysts (55, 56) are carried. Further, around the precious metal catalysts (55, 56), a basic exhaust gas flow surface part (58) is formed. The concentration of hydrocarbons which flow into the upstream-side catalyst (14a) is made to vibrate by within a predetermined range of amplitude of a 200 ppm or more and within a predetermined range of period of 5 seconds or less, whereby the NO x which is contained in exhaust gas is reduced at the exhaust purification catalyst (13). |
