To provide a diesel particulate filter (DPF) clogging detection method using relatively less sensors and computation for precisely detecting the clogged condition of the DPF to determine a regeneration starting time for the DPF, and to provide an exhaust emission control system.
The exhaust emission control system 1 has the DPF 40. A pressure loss coefficient ζc of the DPF and a Reynolds number Re of exhaust gas passing through the DPF 40 are calculated from a measured differential pressure ΔPm between the front and rear of the DPF, an exhaust temperature Tim in the DPF, exhaust pressure Pi at the inlet of the DPF and an exhaust flow rate Mexh detected by an exhaust flow rate detecting means. By comparing the calculated pressure loss coefficient ζc of the DPF with determined values ζsc, ζec calculated from data of pressure loss coefficients ζs, ζe for determination value previously created on the basis of the exhaust temperature Ti in the DPF and the Reynolds number Re, the clogged condition of the DPF 40 is detected.
Takashi Noguchi
Kazuhiko Saishita
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