Exhaust gas purifying apparatus for internal combustion engine

Abstract

An exhaust gas purifying apparatus for an internal combustion engine, having a filter for trapping particulates in exhaust gases from the engine, is disclosed. A first particulate amount indicates an amount of particulates to be trapped by the filter and is calculated according to an operating condition of the engine. A second particulate amount indicates an amount of particulates trapped by the filter and is calculated according to a temperature of the filter when a filter regeneration of burning the particulates trapped by the filter is performed. The first particulate amount is compared with the second particulate amount, and a failure determination of the filter is performed according to a result of the comparison.

1 . An exhaust gas purifying apparatus for an internal combustion engine having filtering means for trapping particulates in exhaust gases from said engine, the exhaust gas purifying apparatus comprising: 
 first trapping amount calculating means for calculating a first particulate amount indicative of an amount of particulates to be trapped by said filtering means, according to an operating condition of said engine;    second trapping amount calculating means for calculating a second particulate amount indicative of an amount of particulates trapped by said filtering means, according to a temperature of said filtering means when a filter regeneration of burning the particulates trapped by said filtering means is performed; and    failure determining means for comparing the first particulate amount with the second particulate amount, and performing a failure determination of said filtering means according to a result of the comparison.    
   
   
       2 . The exhaust gas purifying apparatus according to  claim 1 , wherein said failure determining means calculates a particulate trapping rate of said filtering means according to a ratio of the first and second particulate amounts, and determines that said filtering means fails when the particulate trapping rate is less than or equal to a predetermined threshold value.  
   
   
       3 . The exhaust gas purifying apparatus according to  claim 1 , wherein said first trapping amount calculating means calculates the first particulate amount by calculating an amount of particulates emitted from said engine at constant time intervals according to the operating condition of said engine, and accumulating the emitted amount.  
   
   
       4 . The exhaust gas purifying apparatus according to  claim 1 , wherein the filter regeneration is performed by a post-injection for increasing an amount of fuel supplied to said engine, or naturally performed in a high load operating condition of said engine.  
   
   
       5 . An exhaust gas purifying method for an internal combustion engine having a filter for trapping particulates in exhaust gases from said engine, said exhaust gas purifying method comprising the steps: 
 a) calculating a first particulate amount indicative of an amount of particulates to be trapped by said filter, according to an operating condition of said engine;    b) calculating a second particulate amount indicative of an amount of particulates trapped by said filter, according to a temperature of said filter when a filter regeneration of burning the particulates trapped by said filter is performed;    c) comparing the first particulate amount with the second particulate amount; and    d) performing a failure determination of said filter according to a result of the comparison.    
   
   
       6 . The exhaust gas purifying method according to  claim 5 , wherein a particulate trapping rate of said filter is calculated according to a ratio of the first and second particulate amounts, and a determination is made that said filter fails when the particulate trapping rate is less than or equal to a predetermined threshold value.  
   
   
       7 . The exhaust gas purifying method according to  claim 5 , wherein the first particulate amount is calculated by calculating an amount of particulates emitted from said engine at constant time intervals according to the operating condition of said engine, and accumulating the emitted amount.  
   
   
       8 . The exhaust gas purifying method according to  claim 5 , wherein the filter regeneration is performed by a post-injection for increasing an amount of fuel supplied to said engine, or naturally performed in a high load operating condition of said engine.  
   
   
       9 . A computer program embodied on a computer-readable medium, for causing a computer to implement an exhaust gas purifying method for an internal combustion engine having a filter for trapping particulates in exhaust gases from said engine, said exhaust gas purifying method comprising the steps: 
 a) calculating a first particulate amount indicative of an amount of particulates to be trapped by said filter, according to an operating condition of said engine;    b) calculating a second particulate amount indicative of an amount of particulates trapped by said filter, according to a temperature of said filter when a filter regeneration of burning the particulates trapped by said filter is performed;    c) comparing the first particulate amount with the second particulate amount; and    d) performing a failure determination of said filter according to a result of the comparison.    
   
   
       10 . The computer program according to  claim 9 , wherein a particulate trapping rate of said filter is calculated according to a ratio of the first and second particulate amounts, and a determination is made that said filter fails when the particulate trapping rate is less than or equal to a predetermined threshold value.  
   
   
       11 . The computer program according to  claim 9 , wherein the first particulate amount is calculated by calculating an amount of particulates emitted from said engine at constant time intervals according to the operating condition of said engine, and accumulating the emitted amount.  
   
   
       12 . The computer program according to  claim 9 , wherein the filter regeneration is performed by a post-injection for increasing an amount of fuel supplied to said engine, or naturally performed in a high load operating condition of said engine.