Patent ID: 8397700

Claim:
An abnormality diagnosis device for an exhaust gas recirculation device in an internal combustion engine, the exhaust gas recirculation device having an exhaust gas recirculation valve that adjusts the amount of recirculation exhausts gas returned from an exhaust passage to an intake passage of the engine, the abnormality diagnosis device comprising a control section that changes the exhaust gas recirculation valve to diagnose an abnormality in the exhaust gas recirculation device, wherein, when an abnormality diagnosis execution condition is met, the control section executes a valve closing operation to reduce the opening degree of the valve to a first target opening degree and monitors a degree of change of a state quantity of intake that changes under the influence of a change in exhaust gas recirculation amount caused by the execution of the valve closing operation, and when the degree of change is less than a determination value, the control section determines that there is an abnormality in the exhaust gas recirculation device, and wherein, when the abnormality diagnosis execution condition is met, the control section, prior to the execution of the valve closing operation, executes a valve opening process to increase the opening degree of the valve from the opening degree at the time to a second target opening degree greater than the first target opening degree, wherein the first target opening degree and the second target opening degree are predetermined values regardless of the opening degree of the valve at the time when the execution condition is met.