Method and device pertaining to limiting the temperature of a hc dosing unit in an exhaust system

Abstract

A method pertaining to an HC dosing system for cleaning of exhaust gases from an engine ( 150 ), including a dosing unit in thermal contact with the engine's exhaust system ( 250 ) and supplying a fuel to an exhaust duct ( 240 ) of the exhaust system, the step of determining (s 340 ) whether there is an undesired temperature level of the dosing unit ( 250 ), and if so, limiting (s 360 ) the temperature of the exhaust duct ( 240 ) by control of operation of the engine. Also a computer programme product containing programme code (P) for a computer ( 200; 210; 400 ) for implementing the method, and also to a device and a motor vehicle ( 100 ) which is equipped with the device.

1 . A method pertaining to an HC dosing system for cleaning of exhaust gases from an engine that produces exhaust gases when the engine is operating, and the engine comprising a dosing unit situated in thermal contact with an exhaust system of the engine;
 the method comprising:   supplying fuel by said dosing unit to an exhaust duct of the exhaust system,   determining whether an undesired temperature level of said dosing unit exists and if said undesired temperature level is determined, limiting the temperature of said exhaust duct by controlling at least one operation of said engine.   
     
     
         2 . A method according to  claim 1 , wherein said limitation of said temperature comprises reducing a maximum available torque of an output shaft of the engine. 
     
     
         3 . A method according to  claim 1 , wherein said limitation of said temperature comprises influencing an EGR content of said engine. 
     
     
         4 . A method according to  claim 1 , wherein said limitation of said temperature comprises influencing injection times for fuel of at least one cylinder of said engine or influencing ignition times of at least one cylinder of said engine. 
     
     
         5 . A method according to  claim 1 , further comprising setting said undesired temperature level on the basis of characteristics of said fuel. 
     
     
         6 . A method according to  claim 1 , in which said determining whether there is an undesired temperature level of said dosing unit is based on at least one of:
 directly measuring a temperature of said dosing unit;   measuring a temperature of an exhaust flow in said exhaust duct; and   calculating a temperature of said dosing unit by a calculation model.   
     
     
         7 . A method according to  claim 1 , wherein said fuel is diesel fuel or another hydrocarbon-based fuel. 
     
     
         8 . A device of an HC dosing system for cleaning of exhaust gases from an engine having an exhaust system that produces exhaust gases when the engine is operating;
 the engine comprising a dosing unit situated in thermal contact with the exhaust system of the engine, and the exhaust system including an exhaust duct, and the dosing unit being configured and operable to supply a fuel to the exhaust duct of the exhaust system;   a determining device for determining whether there exists an undesired temperature level of said dosing unit; and   if said undesired temperature level is determined, a control device is configured and operable for limiting the temperature of said exhaust duct by control of operation of said engine.   
     
     
         9 . A device according to  claim 8 , wherein said engine has an output shaft, and said control device is configured and operable for reducing a maximum available torque of said output shaft of the engine to limit said temperature. 
     
     
         10 . A device according to  claim 8 , further comprising said control device being configured and operable for influencing an EGR content of said engine to limit said temperature. 
     
     
         11 . A device according to  claim 8 , further comprising said control device is configured and operable for limiting said temperature by influencing injection times for fuel of at least one cylinder of the engine or by influencing ignition times of at least one cylinder of the engine. 
     
     
         12 . A device according to  claim 8 , wherein said control device is settable for an undesired temperature level based on characteristics of said fuel. 
     
     
         13 . A device according to  claim 8 , further comprising at least one of the following:
 a measurement device for directly measuring a temperature of the dosing unit;   a measurement device for measuring a temperature of an exhaust flow in said exhaust duct; and   a calculating device for calculating a temperature of said dosing unit by a calculation model.   
     
     
         14 . A device according to  claim 8 , wherein said fuel is diesel fuel or another hydrocarbon-based fuel. 
     
     
         15 . A motor vehicle comprising a device according to  claim 8 . 
     
     
         16 . A motor vehicle according to  claim 15 , comprising a truck, bus or passenger car. 
     
     
         17 . A computer programme pertaining to an HC dosing system for cleaning of exhaust gases from an engine, comprising a dosing unit to supply a fuel to an exhaust duct, which programme contains programme code for causing an electronic control unit or another computer connected to the electronic control unit to perform steps according to  claim 1 . 
     
     
         18 . A computer programme product according to  claim 17 , wherein the product contains a programme code stored on a non-transitory programme computer-readable medium which can be read by said computer system for performing method steps, when said computer programme is run on an electronic control unit or another computer connected to said electronic control unit .