Patent ID: 8122708

Claim:
An exhaust gas purification device disposed in an exhaust system of an internal combustion engine, comprising: a diesel particular filter (DPF); a sound pressure measurement means for measuring an exhaust sound pressure that is an actual sound pressure of exhaust gas on at least one of upstream and downstream sides of the DPF; a storage means for storing sound pressure maps for converting a sound pressure of exhaust gas passed through the DPF into a particulate matter (PM) accumulating amount in the DPF, wherein the sound pressure maps are prepared so as to correspond to various driving states of the internal combustion engine defined by different temperatures of exhaust gas; and a calculation means for calculating a PM accumulation amount from the exhaust sound pressure measured by the sound pressure measurement means and from the sound pressure maps, wherein the calculation means selects an optimal sound pressure map among the stored sound pressure maps so as to correspond to an actual driving state of the internal combustion engine.