Patent ID: 8631691

Claim:
An abnormality detection device for an EGR device that adjusts the amount of gas recirculated from an exhaust path to an intake path of an internal combustion engine with a supercharger by controlling the degree of opening of an EGR valve disposed in an EGR path that connects the intake path to the exhaust path, the abnormality detection device comprising: a first sensor that is installed in the EGR path and disposed on the exhaust path side relative to the EGR valve, and outputs a signal capable of identifying whether the air-fuel ratio of a gas passing therethrough is lean or rich; a second sensor that is installed in the exhaust path and disposed downstream of a connecting portion between the exhaust path and the EGR path, and outputs a signal capable of identifying whether the air-fuel ratio of a gas passing therethrough is lean or rich; and an abnormality judgment device that uses the signal output from the first sensor and the signal output from the second sensor to judge whether the EGR device is abnormal; wherein, when the signal output from the first sensor indicates leanness while the internal combustion engine is conducting a stoichiometric or rich operation and when the signal output from the second sensor subsequently indicates leanness within a predetermined time range according to the operating status of the internal combustion engine, the abnormality judgment device concludes that the EGR valve is unable to close.