Patent ID: 8171918

Claim:
An exhaust gas recirculation device of an internal combustion engine, comprising: an EGR passage linking an exhaust passage of the internal combustion engine and an intake passage of the internal combustion engine; an EGR valve provided in the EGR passage and blocking the EGR passage when closed; an EGR catalyst that is provided between a connection portion with the exhaust passage in the EGR passage and an installation position of the EGR valve, purifies an exhaust gas flowing in the EGR passage, and is arranged in the vicinity of the connection portion in the EGR passage; an EGR cooling device that is provided between the installation position of the EGR valve and an installation position of the EGR catalyst in the EGR passage and cools the exhaust gas flowing in the EGR passage; and a control unit that performs exhaust gas recirculation control by which the EGR valve is opened and the exhaust gas flowing in the exhaust passage is recirculated to the intake passage via the EGR passage, wherein the EGR catalyst is provided in a position that can be reached by the exhaust gas flowing from the exhaust passage into the EGR passage due to pressure fluctuations in the exhaust gas caused by operation of the internal combustion engine in a state in which the EGR valve is closed, wherein the position that can be reached by the inflowing exhaust gas is a position such that a volume of a portion between the connection portion and the EGR catalyst in the EGR passage, in the state in which the EGR valve is closed, is less than a minimum value of a volume of the exhaust gas flowing from the exhaust passage into the EGR passage due to pressure fluctuations in the exhaust gas caused by the operation of the internal combustion engine, and wherein the EGR cooling device is provided in a position such that the exhaust gas, which flows out of the EGR cooling device due to pressure fluctuations in the exhaust gas caused by the operation of the internal combustion engine in a state in which the EGR valve is closed, is prevented from reaching the EGR catalyst.