| 摘要 |
<p>In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged. On the exhaust purification catalyst (13), platinum Pt (51) is carried and a basic layer (53) is formed. At the time of engine operation, a main concentration changing action in which the concentration of hydrocarbons which flow into the exhaust purification catalyst (13) is made to change by a predetermined amplitude (”HA) and predetermined period (”TA) is performed. Furthermore, before each main concentration changing action, an auxiliary concentration changing action in which the concentration of hydrocarbons is made to change by an amplitude (”HB) smaller than the amplitude (”HA) at the time of each main concentration changing action is performed.</p> |
