Patent ID: 7908844

Claim:
An exhaust purification device of an internal combustion engine provided with a first exhaust passage and a second exhaust passage branched from a common exhaust passage and providing an NOx absorbent storing NOx in an exhaust gas when the air-fuel ratio of inflowing exhaust gas is a lean air-fuel ratio and releasing stored NOx when the air-fuel ratio of inflowing exhaust gas is a rich air-fuel ratio in each of the first exhaust passage and second exhaust passage, wherein a fuel addition valve is arranged in said common exhaust passage upstream of the first exhaust passage and second exhaust passage and, when NOx should be released from the NOx absorbent arranged in the first exhaust passage, fuel added from the fuel addition valve is guided into the first exhaust passage and, after the fuel is guided into the first exhaust passage, the first exhaust passage is closed so as to maintain the air-fuel ratio of the exhaust gas in the first exhaust passage rich by using this fuel and, when NOx should be released from the NOx absorbent arranged in the second exhaust passage, fuel added from the fuel additional valve is guided into the second exhaust passage and, after the fuel is guided into the second exhaust passage, the second exhaust passage is closed so as to maintain the air-fuel ratio of the exhaust gas in the second exhaust passage rich by using this fuel, wherein, when the first exhaust passage is closed, the exhaust gas circulating through the common exhaust passage flows into only the second exhaust passage, and wherein, when the second exhaust passage is closed, the exhaust gas circulating through the common exhaust passage flows into only the first exhaust passage.