EXHAUST GAS PURIFICATION DEVICE

摘要

This exhaust gas purification device (1) is provided with: a DPF (6) for capturing PM included in exhaust gas; a fuel addition valve (7) for supplying fuel to the DPF; a differential pressure sensor (8) for detecting the pressure differential (DPF pressure differential) between pressure on the upstream side of the DPF and pressure on the downstream side of the DPF; a reproduction control unit (15) for controlling the fuel addition valve so as to burn the PM deposited on the DPF with fuel when the DPF differential pressure is equal to or greater than a differential pressure determination threshold value; a differential pressure change rate calculation unit (12) for calculating the change rate of the DPF differential pressure; an ash deposit amount estimation unit (13) for estimating the amount of ash deposited on the DPF on the basis of the rate of change of the DPF differential pressure; and a differential pressure determination threshold value setting unit (14) for setting a differential pressure determination threshold value according to the amount of ash deposited. The greater the amount of ash deposited, the greater the differential pressure determination threshold value setting unit makes the differential pressure determination threshold value.