Patent ID: 11859527
Assignee: MARELLI EUROPE S.P.A.
Field: Environmental technology (Chemistry)
Classification: CPC F  Y | IPC F

Claim 10:
11. A method to control an internal combustion engine (1) provided with an exhaust system (2) for the exhaust gases of a motor vehicle having an exhaust duct (10) and an exhaust gas after-treatment system (14), the method comprises the steps of:
providing at least one catalytic converter (15, 17) arranged along the exhaust duct (10);
providing an oxygen sensor (18, 18*, 18**), that detects an air/fuel ratio of the exhaust gases, said oxygen sensor having an output that indicates a content of oxygen in the exhaust gases;
providing a burner (21), that introduces exhaust gases into the exhaust duct (10) so as to speed up a heating of said at least one catalytic converter (15, 17), wherein inside the burner (21) there is defined a combustion chamber (22), which receives fresh air through an air feeding device (23), which is provided with a pumping device (24) feeding air, and fuel from an injector (27), which is designed to inject fuel into the combustion chamber (22);
providing a spark plug (28) coupled to the burner (21) so as to ignite the mixture present inside the combustion chamber (22);
calculating a thermal power (POBJ) needed to reach a nominal operating temperature of said at least one catalytic converter (15, 17) obtained with an objective value (λOBJ) of the air/fuel ratio;
determining both an objective fuel flow rate ({dot over (m)}F_OBJ) and an objective air flow rate ({dot over (m)}A_OBJ) to be fed to the burner (21) in order to obtain the thermal power (POBJ) needed to reach the nominal operating temperature of said at least one catalytic converter (15, 17);
determining a nominal fuel flow rate using the following formula:, m
    
     .
    
   
   
    FUEL
    -
    N
   
  
  =
  
   
    
     m
     
      .
     
    
    A
   
   
    (
    
     
      
       A
       F
      
      STEC
     
     *
     
      λ
      OBJ
     
    
    ), {dot over (m)}FUEL_N nominal fuel flow rate;, λA estimated air flow rate;, A/FSTEC stoichiometric air and fuel ratio;, ΛOBJ objective value of the air/fuel ratio;
determining a closed-loop contribution ({dot over (m)}F_CL) of the fuel flow rate by means of a PID controller, which zeroes a difference between the objective value (λOBJ) of the air/fuel ratio and an actual value (λ) of the air/fuel ratio measured by the oxygen sensor (18, 18*, 18**);
determining a further contribution ({dot over (m)}F_ADAT) of the fuel flow rate depending on an integral action of the PID controller under stationary conditions; and
determining an objective fuel flow rate ({dot over (m)}F_OBJ) by means of the sum of the nominal fuel flow rate ({dot over (m)}FUEL_N), the closed-loop contribution ({dot over (m)}F_CL) of the fuel flow rate and the further contribution ({dot over (m)}F_ADAT) of the fuel flow rate; and
signaling a fault when the sum of the closed-loop contribution ({dot over (m)}F_CL) and the further contribution ({dot over (m)}F_ADAT) of the fuel flow rate exceeds a predetermined threshold value.