Exhaust aftertreatment device

Abstract

When an estimated value (A value) of an accumulation amount in a filter for trapping particulate matter reaches a prescribed value A 1 corresponding to a prescribed accumulation amount Qm of the particulate matter and ash (S 12 ), the forced regeneration of the filter is performed (S 20 ); and when the estimated value (A value) reaches the prescribed value A 1 again before the elapsed time since the completion of the forced regeneration of the filter reaches a prescribed time period T 1 (S 12, S 14 ), it is judged that the amount of the ash accumulated in the filter is equal to or larger than a regulation amount (cleaning is required).

1 . An exhaust aftertreatment device comprising: a filter that is interposed in an exhaust path of an internal combustion engine and traps particulate matter and ash in exhaust gas;
 differential-pressure detecting means for detecting differential pressure between exhaust pressure on an exhaust-gas upstream side of the filter and exhaust pressure on an exhaust-gas downstream side of the filter in the exhaust path;   accumulation-amount estimating means for estimating an accumulation amount of the particulate matter and ash trapped in the filter at least on the basis of differential pressure information transmitted from the differential-pressure detecting means;   forced regeneration means for forcibly regenerating the filter by burning and removing the particulate matter trapped in the filter when an estimated value obtained by the accumulation-amount estimating means reaches a prescribed value corresponding to a prescribed accumulation amount of the particulate matter and the ash;   timing means for measuring an elapsed time since the completion of the forced regeneration of the filter by the forced regeneration means; and   ash-judging means for judging that an amount of ash accumulated in the filter is equal to or larger than a regulation amount when the estimated value obtained by the accumulation-amount estimating means reaches the prescribed value again before the elapsed time measured by the timing means reaches a prescribed time period.   
     
     
         2 . The exhaust aftertreatment device according to  claim 1 , wherein the ash-judging means judges that the amount of the ash accumulated in the filter is equal to or larger than the regulation amount when the forced regeneration of the filter by the forced regeneration means is repeated, and the estimated value reaches the prescribed value a predetermined number of times or more before the elapsed time measured by the timing means reaches a regulation time period. 
     
     
         3 . The exhaust aftertreatment device according to either one of  claims 1  and  2 , further having warning means for giving a warning to urge the cleaning of the filter when the ash-judging means judges that the amount of the ash is equal to or larger than the regulation amount.