Method for controlling turbine outlet temperatures in a diesel engine at idle and light load conditions

Abstract

A method and system for controlling an exhaust temperature for an internal combustion engine at idle and light load conditions is disclosed. The method and system comprise determining a desired range of fuel consumption within the internal combustion engine to meet a desired exhaust temperature. The method and system further comprise controlling the fuel consumption to fall within the range. Control strategies to elevate exhaust temperature at idle or light load conditions are disclosed. These strategies allow for exhaust temperatures for aftertreatment regeneration to be reached.

1 . A method for controlling an exhaust temperature for an internal combustion engine comprising: 
 determining a desired range of fuel consumption at idle and light load conditions within the internal combustion engine to meet a desired exhaust temperature; and    controlling the fuel consumption to fall within the range.    
   
   
       2 . The method of  claim 1  wherein the range of fuel consumption is determined by the equation (1):  
     
       
         
           
             
               
                 T 
                 out 
               
               = 
               
                 
                   T 
                   
                     i 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     n 
                   
                 
                 × 
                 
                   ( 
                   
                     1 
                     - 
                     
                       
                         η 
                         t 
                       
                       × 
                       
                         ( 
                         
                           1 
                           - 
                           
                             1 
                             
                               P 
                               r 
                               0.252 
                             
                           
                         
                         ) 
                       
                     
                   
                   ) 
                 
                 × 
                 
                   F 
                   c 
                 
               
             
             , 
           
         
       
     
     , where T out =Turbine outlet temperature, T in =Turbine inlet temperature, η t =turbine operating efficiency, P r =Turbo inlet pressure/Turbo outlet pressure, and F c =a correction factor to correct the slope of the final output to ensure that the desired exhaust temperature is maintained.  
   
   
       3 . The method of  claim 1  wherein controlling the fuel consumption comprises changing the charge to fuel ratio.  
   
   
       4 . The method of  claim 1  wherein the combustion efficiency of the engine is changed to increase the exhaust temperature.  
   
   
       5 . The method of  claim 4  wherein the combustion efficiency is changed by changing any combination of the fuel rail pressure, timing, charge fuel ratio and the exhaust gas recirculation fraction.  
   
   
       6 . The method of  claim 4  wherein variable valve actuation (VVA) is utilized to alter the combustion efficiency.  
   
   
       7 . The method of  claim 1  wherein the pumping work is changed to increase fuel consumption.  
   
   
       8 . The method of  claim 7  wherein a variable gate turbine actuator is overdosed and an exhaust throttling method is used to increase the pumping work.  
   
   
       9 . The method of  claim 1  wherein the engine speed is changed to increase fuel consumption.  
   
   
       10 . The method of  claim 1  wherein accessory loading is utilized to increase fuel consumption.  
   
   
       11 . The method of  claim 1  wherein the accessory loading comprises any of alternator and transmission loading.  
   
   
       12 . The method of  claim 1  wherein the pumping work is on a cylinder by cylinder basis by reducing the number of cylinders that are firing in the engine and engaging compression braking on the non-firing cylinders.  
   
   
       13 . An internal combustion engine system comprising: 
 an internal combustion engine; and aftertreatment system coupled to the turbocharger; and a mechanism for controlling an exhaust temperature for the internal combustion engine further comprising determining a range of desired fuel consumption at idle and light load conditions within the internal combustion engine to meet a desired exhaust temperature; and controlling the fuel consumption to fall within the range.    
   
   
       14 . The internal combustion engine of  claim 13  wherein the range of fuel consumption is determined by the equation (1):  
     
       
         
           
             
               
                 T 
                 out 
               
               = 
               
                 
                   T 
                   
                     i 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     n 
                   
                 
                 × 
                 
                   ( 
                   
                     1 
                     - 
                     
                       
                         η 
                         t 
                       
                       × 
                       
                         ( 
                         
                           1 
                           - 
                           
                             1 
                             
                               P 
                               r 
                               0.252 
                             
                           
                         
                         ) 
                       
                     
                   
                   ) 
                 
                 × 
                 
                   F 
                   c 
                 
               
             
             , 
           
         
       
     
     , where T out =Turbine outlet temperature, T in =Turbine inlet temperature, η t =turbine operating efficiency, P r =Turbo inlet pressure/Turbo outlet pressure, and F c =a correction factor to correct the slope of the final output to ensure that the desired exhaust temperature is maintained.  
   
   
       15 . The internal combustion engine of  claim 13  wherein controlling the fuel consumption comprises changing the charge to fuel ratio.  
   
   
       16 . The internal combustion engine of  claim 13  wherein the combustion efficiency of the engine is changed to increase the exhaust temperature.  
   
   
       17 . The internal combustion engine of  claim 16  wherein the combustion efficiency is changed by changing any combination of the fuel rail pressure, timing, charge fuel ratio and the exhaust gas recirculation fraction.  
   
   
       18 . The internal combustion engine of  claim 16  wherein variable valve actuation (VVA) is utilized to alter the combustion efficiency.  
   
   
       19 . The internal combustion engine of  claim 13  wherein the pumping work is changed to increase fuel consumption.  
   
   
       20 . The internal combustion engine of  claim 19  wherein a variable gate turbine actuator is overdosed and an exhaust throttling method is used to increase the pumping work.  
   
   
       21 . The internal combustion engine of  claim 13  wherein the engine speed is changed to increase fuel consumption.  
   
   
       22 . The internal combustion engine of  claim 13  wherein accessory loading is increased to increase the fuel consumption.  
   
   
       23 . The internal combustion engine of  claim 13  wherein the accessory loading comprises any of alternator and transmission loading.  
   
   
       24 . The internal combustion engine of  claim 13  wherein the pumping work is on a cylinder by cylinder basis by reducing the number of cylinders that are firing in the engine and engaging compression braking on the non-firing cylinders.  
   
   
       25 . A computer readable medium containing program instructions for controlling an exhaust temperature for an internal combustion engine comprising: 
 determining a range of fuel consumption at idle or light load conditions within the internal combustion engine to meet a desired exhaust temperature; and    controlling the fuel consumption to fall within the range.    
   
   
       26 . The computer readable medium of  claim 25  wherein the range of acceptable charge flows are determined by the equation (1):  
     
       
         
           
             
               
                 T 
                 out 
               
               = 
               
                 
                   T 
                   
                     i 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     n 
                   
                 
                 × 
                 
                   ( 
                   
                     1 
                     - 
                     
                       
                         η 
                         t 
                       
                       × 
                       
                         ( 
                         
                           1 
                           - 
                           
                             1 
                             
                               P 
                               r 
                               0.252 
                             
                           
                         
                         ) 
                       
                     
                   
                   ) 
                 
                 × 
                 
                   F 
                   c 
                 
               
             
             , 
           
         
       
     
     where T out =Turbine outlet temperature, T in =Turbine inlet temperature, η t =turbine operating efficiency, P r =Turbo inlet pressure/Turbo outlet pressure, and F c =a correction factor to correct the slope of the final output to ensure that the desired exhaust temperature is maintained.