| 摘要 |
The invention relates to an exhaust gas purification device of an internal combustion engine that can improve NOx purification capability. The exhaust gas purification device includes a DPF (16) for capturing PM in an exhaust gas, a urea water spraying unit (21) for spraying urea water into the exhaust gas, an SCR (22) for reducing and purifying NOx in the exhaust gas, electrostatic capacity detecting units (17a, 17b, 41) for detecting the electrostatic capacity of the DPF (16), a DPF temperature estimating unit (43) for estimating the inside temperature of the DPF (16) based on the electrostatic capacity, and a regeneration controlling unit (44) for executing forced DPF (16) regeneration. A target lower limit temperature is defined as temperature to trigger PM combustion, and a target upper limit temperature is defined as temperature to avoid filter erosion. The regeneration controlling unit (44) executes the forced regeneration with an amount of fuel supplied for causing the inside temperature to reach the target lower limit temperature when the inside temperature is at or above the SCR activation temperature, and executes the forced regeneration with another amount of fuel supplied for causing the inside temperature to reach the target upper limit temperature when the inside temperature is below the SCR activation temperature. |
