Patent ID: 8074446
Filing Date: 2011-12-13
Classification: F01N,F02B,F02D,Y02T

Abstract:
1. An exhaust gas purification system for an internal combustion engine, comprising: a NOx storage reduction catalyst that is provided in an exhaust passage of said internal combustion engine; a reducing agent adding valve that is provided in said exhaust passage on an upstream side of said NOx storage reduction catalyst and that adds a reducing agent to exhaust gas; and a controller that is programmed to: wherein when the total amount of the reducing agent that is added by said reducing agent adding valve while the rich spike control is being performed does not reach the total amount of the reducing agent that is added when the rich spike control is performed in the state in which the clogging of said reducing agent adding valve has not occurred, the number of times the air-fuel ratio in the exhaust gas is lowered while the rich spike control is being performed is increased, even if the period during which the reducing agent is added by said reducing agent adding valve in each time when the air-fuel ratio in the exhaust gas is lowered while the rich spike control is being performed is lengthened to an upper limit value by said controller.