Patent ID: 8689546

Claim:
An exhaust purification system of an internal combustion engine in which, inside an engine exhaust passage, an exhaust purification catalyst for causing a reaction between NO x which is contained in exhaust gas and modified hydrocarbons is arranged, precious metal catalysts are carried on an exhaust gas flow surface of the exhaust purification catalyst, and a basic exhaust gas flow surface part is formed around the precious metal catalysts, wherein the exhaust purification catalyst has a property of reducing NO x which is contained in exhaust gas if making a concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within a predetermined range of amplitude and within a predetermined range of period and has a property of a storage amount of NO x which is contained in the exhaust gas increasing if making a vibration period of the concentration of hydrocarbons longer than a predetermined range, the system is provided with a post treatment device which is arranged in the engine exhaust passage downstream from the exhaust purification catalyst and which is raised in temperature when reaching a predetermined state and is formed to use heat of oxidation of hydrocarbons which is generated in the exhaust purification catalyst to raise temperature of the exhaust gas and raise the temperature of the post treatment device as temperature elevation control, in a control for making the concentration of hydrocarbons which flow into the exhaust purification catalyst vibrate by within the predetermined range of amplitude and within the predetermined range of period, when feeding a predetermined total feed amount of hydrocarbons during a predetermined period, the exhaust purification catalyst has an ascending range where a NO x purification rate rises if making a feed period of hydrocarbons change to become longer and a high purification rate range where the NO x purification rate becomes higher than a predetermined rate, and, in the temperature elevation control, the total feed amount of hydrocarbons required for raising the temperature of the post treatment device is set, the feed period of hydrocarbons and a feed amount of hydrocarbons per feed are set in the high purification rate range in a region at an end at short side of feed period of hydrocarbons, and hydrocarbons are fed by a set feed period of hydrocarbons and feed amount of hydrocarbons per feed.