Patent ID: 8336293
Filing Date: 2012-12-25
Classification: F01N,F02D,Y02T

Abstract:
1. An exhaust gas purification system of an internal combustion engine comprising: a first exhaust gas purification device that is arranged in an exhaust passage of an internal combustion engine and has an oxygen occlusion ability; a second exhaust gas purification device that is arranged in said exhaust passage at the downstream side of said first exhaust gas purification device and has an oxygen occlusion ability; an upstream air fuel ratio acquisition unit that acquires the air fuel ratio of an exhaust gas at the upstream side of said first exhaust gas purification device in said exhaust passage; a downstream air fuel ratio detection unit which is arranged in said exhaust passage at the downstream side of said second exhaust gas purification device, and detects the air fuel ratio of an exhaust gas from said second exhaust gas purification device; a first air fuel ratio estimation unit that estimates the air fuel ratio of an exhaust gas between said first exhaust gas purification device and said second exhaust gas purification device based on the air fuel ratio of the exhaust gas at the upstream side of said first exhaust gas purification device acquired by said upstream air fuel ratio acquisition unit, and the oxygen occlusion ability of said first exhaust gas purification device in its normal operation; a second air fuel ratio estimation unit that estimates the air fuel ratio of an exhaust gas at the downstream side of said second exhaust gas purification device based on the air fuel ratio estimated by said first air fuel ratio estimation unit and the oxygen occlusion ability of said second exhaust gas purification device in its normal operation; and a determination unit that determines the degradation of said first exhaust gas purification device and the degradation of said second exhaust gas purification device in a distinguished manner based on the air fuel ratio estimated by said first air fuel ratio estimation unit, the air fuel ratio estimated by said second air fuel ratio estimation unit, and the air fuel ratio detected by said downstream air fuel ratio detection unit.