Exhaust purification device of internal combustion engine, and control method thereof

Abstract

An exhaust purification device includes a particulate filter ( 10 ), an air flow meter ( 7 ) that detects the amount of fresh air flowing in an intake passageway ( 3 ), and an EGR device ( 30 ) that supplies gas to a site in the intake passageway ( 3 ) between the air flow meter ( 7 ) and the particulate filter ( 10 ). The exhaust purification device detects the amount of flow of exhaust passing through the particulate filter on the basis of the amount of gas supplied by the EGR device ( 30 ), and the intake air amount detected by the air flow meter (S 108 ), and detects the differential pressure between the upstream side and the downstream side of the particulate filter, and determines whether the particulate filter is clogged on the basis of the amount of flow and the differential pressure of exhaust (S 110 ).

1 .- 9 . (canceled) 
   
   
       10 . An exhaust purification device of an internal combustion engine, comprising:
 a particulate filter that is provided in an exhaust passageway and that traps a particulate matter in exhaust;   an intake air amount detection portion that detects an amount of fresh air flowing in an intake passageway;   a gas supply portion that supplies a gas to the intake passageway that is on a downstream side of the intake air amount detection portion and on an upstream side of the particulate filter;   an exhaust flow calculation portion that calculates an amount of flow of exhaust passing through the particulate filter based on the amount of the gas supplied and the amount of fresh air detected;   a differential pressure detection portion that detects a differential pressure between the upstream side and the downstream side of the particulate filter in the exhaust passageway; and   a clogging determination portion that determines whether the particulate filter is clogged based on the amount of flow of exhaust calculated and the differential pressure detected;   a turbocharger that has a turbine in the exhaust passageway, and a compressor in the intake passageway,   a high-pressure EGR passageway that connects the exhaust passageway upstream of the particulate filter and the intake passageway downstream of the intake air amount detection portion; and   a high-pressure EGR valve that changes the passageway cross-sectional area of the high-pressure EGR passageway;   wherein the gas supply portion is an EGR device that has an EGR passageway that connects the exhaust passageway downstream of the particulate filter and the intake passageway downstream of the intake air amount detection portion, and an EGR valve that is provided in the EGR passageway and that changes a passageway cross-sectional area of the EGR passageway;   wherein the amount of the gas supplied by the gas supply portion is the amount of an EGR gas detected by EGR gas amount detection portion for detecting the amount of the EGR gas flowing in the EGR passageway;   wherein the EGR passageway is a low-pressure EGR passageway that connects the exhaust passageway downstream of the turbine and the intake passageway upstream of the compressor;   wherein when it is determined by the clogging determination portion whether the particulate filter is clogged, the degree of opening of the EGR valve is made smaller than when it is not determined whether the particulate filter is clogged, and the EGR gas amount flowing in the high-pressure EGR passageway is changed by the high-pressure EGR valve so that the EGR gas amount supplied into a cylinder of the internal combustion engine is constant.   
   
   
       11 . The exhaust purification device of the internal combustion engine according to  claim 10 , wherein the clogging determination portion estimates an amount of the particulate matter trapped on the particulate filter. 
   
   
       12 . The exhaust purification device of the internal combustion engine according to  claim 10 , wherein the EGR gas amount detection portion detects the amount of flow of gas in the low-pressure EGR passageway from at least the differential pressure between the passageway on the upstream side of the EGR valve and the passageway on the downstream side of the EGR valve, and a degree of opening of the EGR valve. 
   
   
       13 . The exhaust purification device of the internal combustion engine according to  claim 10 , wherein when the clogging determination portion determines whether the particulate filter is clogged, the degree of opening of the EGR valve is fixed. 
   
   
       14 . The exhaust purification device of the internal combustion engine according to  claim 13 , wherein the degree of opening of the EGR valve is fixed to a fully closed state when it is determined by the clogging determination portion whether the particulate filter is clogged. 
   
   
       15 . The exhaust purification device of the internal combustion engine according to  claim 10 , wherein when it is determined by the clogging determination portion whether the particulate filter is clogged, the degree of opening of the EGR valve is set to a degree of opening that is not the fully closed state, and the exhaust flow calculation portion estimates the amount of flow of exhaust passing through the particulate filter based on the amount of fresh air detected by the intake air amount detection portion and the amount of the EGR gas detected by the EGR gas amount detection portion, and the clogging determination portion determines whether the particulate filter is clogged based on the amount of flow of exhaust estimated by the exhaust flow calculation portion and the differential pressure detected by the differential pressure detection portion. 
   
   
       16 . The exhaust purification device of the internal combustion engine according to  claim 10 , wherein determination by the clogging determination portion as to whether the particulate filter is clogged is performed when at least one of (i) a condition that the internal combustion engine is in a steady state, (ii) a condition that temperature of the particulate filter is within a predetermined range, and (iii) a condition that the vehicle has traveled a predetermined distance, is met. 
   
   
       17 . A control method of an exhaust purification device of an internal combustion engine which includes:
 a particulate filter that is provided in an exhaust passageway and that traps a particulate matter in exhaust;   an intake air amount detection portion that detects an amount of fresh air flowing in an intake passageway;   a gas supply portion that supplies a gas to the intake passageway that is on a downstream side of the intake air amount detection portion and on an upstream side of the particulate filter;   a differential pressure detection portion that detects a differential pressure between the upstream side and the downstream side of the particulate filter in the exhaust passageway;   a turbocharger that has a turbine in the exhaust passageway, and a compressor in the intake passageway;   a high-pressure EGR passageway that connects the exhaust passageway upstream of the particulate filter and the intake passageway downstream of the intake air amount detection portion; and   a high-pressure EGR valve that changes the passageway cross-sectional area of the high-pressure EGR passageway;   wherein the EGR passageway is a low-pressure EGR passageway that connects the exhaust passageway downstream of the turbine and the intake passageway upstream of the compressor;   the control method comprising:   calculating an amount of flow of exhaust passing through the particulate filter based on the amount of the gas supplied and the amount of fresh air detected; and   determining whether the particulate filter is clogged based on the amount of flow of exhaust calculated and the differential pressure detected; wherein:   the gas supply portion is an EGR device that has an EGR passageway that connects the exhaust passageway downstream of the particulate filter and the intake passageway downstream of the intake air amount detection portion, an EGR valve that is provided in the EGR passageway and that changes a passageway cross-sectional area of the EGR passageway;   the amount of the gas supplied by the gas supply portion is the amount of an EGR gas detected by EGR gas amount detection portion that detects the amount of the EGR gas flowing in the EGR passageway; and when it is determined by the clogging determination portion whether the particulate filter is clogged, the degree of opening of the EGR valve is made smaller than when it is not determined whether the particulate filter is clogged, and the EGR gas amount flowing in the high-pressure EGR passageway is changed by the high-pressure EGR valve so that the EGR gas amount supplied into a cylinder of the internal combustion engine is constant.