| 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. At the time of engine operation, the amplitude of change of the concentration of hydrocarbons which flow into the exhaust purification catalyst (13) is made to become within a predetermined range of amplitude by control of the injection amount of hydrocarbons from the hydrocarbon feed valve (15), the concentration of hydrocarbons flowing into the exhaust purification catalyst (13) is made to vibrate by a predetermined range of period by control of the injection period of hydrocarbons from the hydrocarbon feed valve (15), and thereby the NOx contained in the exhaust gas and the NOx stored in the exhaust purification catalyst (13) are reduced. |
| 主权项 |
1. An exhaust purification system of an internal combustion engine, the exhaust purification system comprising:
a hydrocarbon feed valve for feeding hydrocarbons-is arranged inside of an engine exhaust passage, an exhaust purification catalyst for reacting NOx contained in exhaust gas and reformed hydrocarbons arranged inside of the engine exhaust passage and downstream of the hydrocarbon feed valve, a precious metal catalyst carried on an exhaust gas flow surface of the exhaust purification catalyst, a basic exhaust gas flow surface part formed around the precious metal catalyst, and an electronic control unit, wherein the electronic control unit is configured to control a vibration of a concentration of hydrocarbons flowing into the exhaust purification catalyst within a predetermined range of amplitude and within a predetermined range of period, and is configured to control the vibration period of the hydrocarbon concentration longer than the predetermined range of period, wherein
when the electronic control unit controls the vibration of the concentration of hydrocarbons flowing into the exhaust purification catalyst within the predetermined range of amplitude and within the predetermined range of period, the exhaust purification catalyst has a property of chemically reducing the NOx that is contained in exhaust gas without storing, or storing a fine amount of nitrates in the exhaust purification catalyst, and when the electronic control unit controls the vibration period of the hydrocarbon concentration longer than the predetermined range, the exhaust purification catalyst has a property of being increased in a storage amount of NOx, and at the time of engine operation, when NOx is stored in the exhaust purification catalyst, the electronic control unit is further configured to optionally control an injection amount and an injection period of hydrocarbons from the hydrocarbon feed valve so that the amplitude of the change of concentration of hydrocarbons flowing into the exhaust purification catalyst comes within the predetermined range of amplitude, and vibrates within the predetermined range of period, thereby the NOx that is contained in the exhaust gas and the NOx that is stored in the exhaust purification catalyst are chemically reduced. |
