Method for operating a diesel engine system

Abstract

A method is provided for operating a Diesel engine system. The diesel engine system includes, but is not limited to a Diesel engine, an intake line for feeding fresh induction air into the Diesel engine, an exhaust line for discharging exhaust gas from the Diesel engine, a Diesel Particulate Filter DPF located in the exhaust line, and an Exhaust Gas Recirculation EGR system for routing back exhaust gas into the Diesel engine. The EGR system includes, but is not limited to a long EGR route LRE that gets exhaust gas from the exhaust line downstream the DPF. The method includes, but is not limited to setting a soot threshold (Sth) for the amount of soot flowing into the LRE, determining the actual amount of soot (Saa) flowing into the LRE, and activating a LRE protection routine, if the actual amount of soot (Saa) exceeds the soot threshold (Sth).

1 . A method for operating a Diesel engine system, the Diesel engine system comprising:
 a Diesel engine;   an intake line adapted to feed fresh induction air into the Diesel engine;   an exhaust line adapted to discharge exhaust gas from the Diesel engine;   a Diesel Particulate Filter DPF located in the exhaust line; and   an Exhaust Gas Recirculation EGR system adapted to route back the exhaust gas into the Diesel engine, said EGR system comprising a long EGR route LRE adapted to receive the exhaust gas from the exhaust line downstream the DPF,   the method comprising:   setting a soot threshold (Sth) for an amount of soot flowing into the LRE;   determining an actual amount of soot (Saa) flowing into the LRE; and   activating a LRE protection routine if said actual amount of soot (Saa) exceeds said soot threshold (Sth).   
     
     
         2 . The method according to  claim 1 , wherein the determining of the actual amount of soot (Saa) flowing into the LRE comprises:
 determining an amount of soot (DPFin) entering the DPF;   determining a DPF filtration efficiency (DPFeff);   calculating the actual amount of soot (Saa) flowing into the LRE as a function of said amount of soot entering the DPF and said DPF filtration efficiency (DPFeff).   
     
     
         3 . The method according to  claim 2 , wherein the amount of soot (DPFin) entering the DPF is estimated with an engine-out soot model. 
     
     
         4 . The method according to  claim 2 , wherein the DPF filtration efficiency (DPFeff) is determined as the function of the amount of soot entering the DPF. 
     
     
         5 . The method according to  claim 4 , wherein the determining of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot trapped by the DPF; and   calculating the DPF filtration efficiency (DPFeff) as a second function of said amount of soot trapped by the DPF and the amount of soot (DPFin) entering the DPF.   
     
     
         6 . The method according to  claim 5 , wherein the amount of soot trapped by the DPF is estimated with a DPF soot loading model. 
     
     
         7 . The method according to  claim 4 , wherein the determining of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot exiting the DPF; and   calculating the DPF filtration efficiency (DPFeff) as a second function of said amount of soot exiting the DPF and the amount of soot (DPFin) entering the DPF.   
     
     
         8 . The method according to  claim 7 , wherein the amount of soot exiting the DPF is measured with a soot sensor. 
     
     
         9 . The method according to  claim 1 , wherein the LRE protection routine regulates at least one combustion managing parameter that affects soot production within the Diesel engine thereby decreasing said soot production. 
     
     
         10 . The method according to  claim 9 , wherein the LRE protection routine determine a correction index (Cegr, Clre) to be applied to a set point (EGRsp, LREsp) of said at least one combustion managing parameter. 
     
     
         11 . The method according to  claim 9 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by the EGR system. 
     
     
         12 . The method according to  claim 9 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by an amount of the exhaust gas that is routed back by a long EGR route. 
     
     
         13 . A computer readable medium embodying a computer program product, said computer program product comprising:
 a program for operating a Diesel engine system, the Diesel engine system comprising:   a Diesel engine;   an intake line adapted to feed fresh induction air into the Diesel engine;   an exhaust line adapted to discharge exhaust gas from the Diesel engine;   a Diesel Particulate Filter DPF located in the exhaust line; and   an Exhaust Gas Recirculation EGR system adapted to route back the exhaust gas into the Diesel engine, said EGR system comprising a long EGR route LRE adapted to receive the exhaust gas from the exhaust line downstream the DPF,   the program configured to:   set a soot threshold (Sth) for an amount of soot flowing into the LRE;   determine an actual amount of soot (Saa) flowing into the LRE; and   activate a LRE protection routine if said actual amount of soot (Saa) exceeds said soot threshold (Sth).   
     
     
         14 . The computer readable medium embodying the computer program product according to  claim 12 , wherein determination of the actual amount of soot (Saa) flowing into the LRE comprises:
 determining an amount of soot (DPFin) entering the DPF;   determining a DPF filtration efficiency (DPFeff);   calculating the actual amount of soot (Saa) flowing into the LRE as a function of said amount of soot (DPFin) entering the DPF and said DPF filtration efficiency (DPFeff).   
     
     
         15 . The computer readable medium embodying the computer program product according to  claim 14 , wherein the amount of soot (DPFin) entering the DPF is estimated with an engine-out soot model. 
     
     
         16 . The computer readable medium embodying the computer program product according to  claim 14 , wherein the DPF filtration efficiency (DPFeff) is determined as a second function of the amount of soot entering the DPF. 
     
     
         17 . The computer readable medium embodying the computer program product to  claim 16 , wherein the determination of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot trapped by the DPF; and   calculating the DPF filtration efficiency (DPFeff) as the second function of said amount of trapped of soot and the amount of soot (DPFin) entering the DPF.   
     
     
         18 . The computer readable medium embodying the computer program product according to  claim 17 , wherein the amount of soot trapped by the DPF is estimated with a DPF soot loading model. 
     
     
         19 . The computer readable medium embodying the computer program product according to  claim 16 , wherein the determination of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot exiting the DPF; and   calculating the DPF filtration efficiency (DPFeff) as the function of said amount of soot exiting the DPF and the amount of soot entering the DPF.   
     
     
         20 . The computer readable medium embodying the computer program product according to  claim 19 , wherein the amount of soot exiting the DPF is measured with a soot sensor. 
     
     
         21 . The computer readable medium embodying the computer program product according to  claim 13 , wherein the LRE protection routine regulates at least one combustion managing parameter that affects soot production within the Diesel engine thereby decreasing said soot production. 
     
     
         22 . The computer readable medium embodying the computer program product according to  claim 21 , wherein the LRE protection routine determine a correction index (Cegr, Clre) to be applied to a set point (EGRsp, LREsp) of said at least one combustion managing parameter. 
     
     
         23 . The computer readable medium embodying the computer program product according to  claim 21 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by the EGR system. 
     
     
         24 . The computer readable medium embodying the computer program product according to  claim 21 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by an amount of the exhaust gas that is routed back by a long EGR route 
     
     
         25 . A Diesel engine system, comprising:
 a Diesel engine;   an intake line adapted to feed fresh induction air into the Diesel engine;   an exhaust line adapted to discharge exhaust gas from the Diesel engine;   a Diesel Particulate Filter DPF located in the exhaust line;   an Exhaust Gas Recirculation EGR system adapted to route back the exhaust gas into the Diesel engine, said EGR system comprising a long EGR route LRE adapted to receive the exhaust gas from the exhaust line downstream the DPF; and   a control unit configured to:   sett a soot threshold (Sth) for an amount of soot flowing into the LRE;   determine an actual amount of soot (Saa) flowing into the LRE; and   activate a LRE protection routine if said actual amount of soot (Saa) exceeds said soot threshold (Sth).   
     
     
         26 . The Diesel engine according to  claim 25 , wherein determination of the actual amount of soot (Saa) flowing into the LRE by the control unit comprises:
 determining an amount of soot (DPFin) entering the DPF;   determining a DPF filtration efficiency (DPFeff);   calculating the actual amount of soot (Saa) flowing into the LRE as a function of said amount of soot entering the DPF and said DPF filtration efficiency (DPFeff).   
     
     
         27 . The Diesel engine according to  claim 26 , wherein the amount of soot (DPFin) entering the DPF is estimated with an engine-out soot model. 
     
     
         28 . The Diesel engine according to  claim 27 , wherein the DPF filtration efficiency (DPFeff) is determined as the function of the amount of soot entering the DPF. 
     
     
         29 . The Diesel engine according to  claim 28 , wherein the determination of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot trapped by the DPF; and   calculating the DPF filtration efficiency (DPFeff) as a second function of said amount of soot trapped and the amount of soot (DPFin) entering the DPF.   
     
     
         30 . The Diesel engine according to  claim 29 , wherein the amount of soot trapped by the DPF is estimated with a DPF soot loading model. 
     
     
         31 . The Diesel engine according to  claim 28 , wherein the determination of the DPF filtration efficiency (DPFeff) comprises:
 determining the amount of soot exiting the DPF; and   calculating the DPF filtration efficiency (DPFeff) as the function of said amount of soot exiting the DPF and the amount of soot entering the DPF.   
     
     
         32 . The Diesel engine according to  claim 31 , wherein the amount of soot exiting the DPF is measured with a soot sensor. 
     
     
         33 . The Diesel engine according to  claim 25 , wherein the LRE protection routine regulates at least one combustion managing parameter that affects soot production within the Diesel engine thereby decreasing said soot production. 
     
     
         34 . The Diesel engine according to  claim 33 , wherein the LRE protection routine determine a correction index (Cegr, Clre) to be applied to a set point (EGRsp, LREsp) of said at least one combustion managing parameter. 
     
     
         35 . The Diesel engine according to  claim 33 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by the EGR system. 
     
     
         36 . The Diesel engine according to  claim 33 , wherein said at least one combustion managing parameter is a total amount of exhaust gas which is routed back by an amount of the exhaust gas that is routed back by a long EGR route