| 摘要 |
A PM sensor (32) is disposed on the downstream side of a partially stopped filter (31) for collecting particulate matter (PM) in the exhaust gas of an engine (11), and first and second sensor abnormality diagnoses are performed on the basis of the output of the PM sensor (32). In the first sensor abnormality diagnosis, a filter outflow PM amount (the PM amount flowing out from the partially stopped filter (31)) is estimated on the basis of the operating condition of the engine (11) and the PM collection efficiency of the partially stopped filter (31), and whether or not there is an abnormality in the output of the PM sensor (32) is determined by comparing the sensor detection PM amount (the PM amount detected on the basis of the output of the PM sensor (32)) and the filter outflow PM amount. In the second sensor abnormality diagnosis, an engine discharge PM amount (the PM amount discharged from the engine (11)) is estimated on the basis of the operating condition of the engine (11), and whether or not there is an abnormality in the output of the PM sensor (32) is determined by comparing the increase rate of the output of the PM sensor (32) and the increase rate of the engine discharge PM amount. |
