DEFECT DETECTING DEVICE OF EXHAUST PURIFYING FILTER

PROBLEM TO BE SOLVED: To provide a defect detecting device capable of accurately detecting a local defect in an exhaust purifying filter.SOLUTION: A DPF (Diesel Particulate Filter) as the exhaust purifying filter is divided into three areas mutually defined in parallel to a flow of exhaust gas, and flow rate sensors are arranged for respectively detecting an exhaust flow rate of passing through the three areas. Just after regenerating the DPF (S1), when under an operation condition of being steady and exceeding a threshold value in the exhaust flow rate (S2), a deviation in the exhaust flow rate among the three areas is arithmetically operated (S3 and S4), and a maximum value MAX among an absolute value of the deviation is compared with a defect determining level SL (S5). When the maximum value MAX is the defect determining level SL or more, the occurrence of a detect (melting damage) is determined, and a warning lamp is turned on (S6).