Filter controller system

Abstract

In order to calculate an estimation of the amount of deposited particulates in a first filter ( 61 ) or a second filter ( 62 ), a first estimation calculating section ( 100 ) for outputting first estimation data (XA) based on pressure differential across the filter and a second estimation calculating section ( 110 ) for outputting second estimation data (XB) based on engine operating state are provided, the data between the first estimation data (XA) and the second estimation data (XB) that is the more reliable estimation data in light of engine ( 2 ) rotation is selected and whether or not filter regeneration should be conducted is decided. In addition, the difference between the first and second estimation data (XA, XB) is considered and when the difference is larger than a prescribed value, then even if the engine ( 2 ) rpm is high, selection of the first estimation data XA, which is apt to be an estimated value of low reliability owing to cracking of the deposited particulates, is avoided.

1 . A filter control system that controls regeneration of a filter for collecting particulates contained in engine exhaust gas based on estimated amount of particulates deposited in the filter, the filter control system comprising
 detection means for detecting engine operating state;   first estimation means for estimating amount of particulates deposited in the filter based on exhaust gas pressure differential across the filter;   second estimation means for estimating amount of particulates deposited in the filter based on engine operating state;   difference calculating means for calculating the difference between the estimated values of the deposited amount of particulates obtained by the first and second estimation means; and   selection means responsive to the difference calculating means and the detection means for selecting one estimation between those of the first and second estimation means,   the time for starting regeneration of the filter being decided in accordance with the estimation selected by the selection means.   
     
     
         2 . A filter control system as claimed in  claim 1 , wherein the detection means is means for detecting engine exhaust flow rate. 
     
     
         3 . A filter control system as claimed in  claim 1 , wherein the second estimation means conducts calculation for estimating the amount of deposited particulates based on at least one among fuel quantity injected into the engine, engine rpm, exhaust gas recirculation rate in the engine and filter pre-entry temperature. 
     
     
         4 . A filter control system as claimed in  claim 1 , wherein the second estimation means conducts calculation for estimating the amount of deposited particulates utilizing map calculation using measured data obtained by measuring increase in amount of deposited particulates per unit time using an actual engine. 
     
     
         5 . A filter control system as claimed in  claim 4 , wherein the second estimation means is configured to obtain the estimated value of the amount of deposited particulates in the filter by integrating data obtained by the map calculation. 
     
     
         6 . A filter control system as claimed in  claim 5 , wherein the estimated value of the amount of deposited particulates being used for filter regeneration control at each time the engine is stopped is stored in memory and the stored value of the deposited amount of particulates is used as the initial value for the integration in the second estimation means. 
     
     
         7 . A filter control system as claimed in  claim 1 , wherein when one estimation between those of the first and second estimation means is selected, the discrepancy between the estimations is calculated, the discrepancy is stored in memory as a learned value, and the calculated value in the second estimation means is corrected in accordance with the learned value. 
     
     
         8 . A filter control system as claimed in  claim 7 , wherein a coefficient dependent on the discrepancy is calculated and the calculated value in the second estimation means is corrected by the coefficient. 
     
     
         9 . A filter control system as claimed in  claim 7 , wherein when one of the values exceeds a prescribed value, such fact is displayed to the operator. 
     
     
         10 . A filter control system as claimed in  claim 1 , wherein when the difference is equal to or greater than a prescribed value at engine start, the estimation of the second estimation means is selected irrespective of the detection result of the detection means. 
     
     
         11 . A filter control system as claimed in  claim 1 , wherein when the difference is equal to or greater than a prescribed value at engine start, the estimation of the second estimation means is selected during a prescribed period irrespective of the detection result of the detection means. 
     
     
         12 . A filter control system as claimed in  claim 11 , wherein the prescribed period is a period that the estimated value of the amount of deposited particulates started by the second estimation means from engine start takes to reach a prescribed value. 
     
     
         13 . A filter control system as claimed in  claim 11 , wherein when the difference becomes smaller than a prescribed value, the estimation by the first estimation means is selected instead of the estimation by the second estimation means. 
     
     
         14 . A filter control system that estimates amount of particulates deposited in a filter for collecting particulates contained in engine exhaust gas and conducting filter regeneration based on the estimation, the filter control system comprising:
 first estimation means for estimating amount of particulates deposited in the filter based on exhaust gas pressure differential across the filter; and   second estimation means for estimating amount of particulates deposited in the filter based on deposited amount data indicating amount of deposited particulates in the filter per unit time,   one estimation between those of the first and second estimation means being selected in accordance with the engine operating state and the time for regenerating the filter being decided in accordance with the selected estimation.   
     
     
         15 . A filter control system as claimed in  claim 14 , wherein the estimation is selected in accordance with engine exhaust flow rate. 
     
     
         16 . A filter control system as claimed in  claim 14 , wherein the second estimation means calculates the deposited amount data based on at least one among fuel quantity injected to the engine, engine rpm, exhaust gas recirculation rate in the engine and filter pre-entry temperature. 
     
     
         17 . A filter control system as claimed in  claim 14 , wherein the second estimation means calculates the deposited amount data by map calculation in which increase in amount of deposited particulates per unit time measured by the use of an actual engine. 
     
     
         18 . A filter control system as claimed in  claim 14 , wherein the second estimation means is configured to obtain the estimated value of the amount of deposited particulates in the filter by integrating the deposited amount data. 
     
     
         19 . A filter control system as claimed in  claim 14 , wherein when estimation switching is conducted, discrepancy between the two estimations is calculated, the discrepancy is stored in memory as a learned value, and the value calculated in the second estimation means is corrected in accordance with the learned value. 
     
     
         20 . A filter control system as claimed in  claim 19 , wherein a coefficient dependent on the discrepancy is calculated and the calculated value in the second estimation means is corrected by the coefficient. 
     
     
         21 . A filter control system as claimed in  claim 19 , wherein when the discrepancy exceeds a prescribed value, such fact is displayed to the operator.