Method and device pertaining to cooling of dosing units of scr systems

Abstract

A method for cooling a dosing unit ( 250 ) pertaining to an SCR system for exhaust cleaning: after cessation of exhaust flow, cooling a reducing agent dosing unit ( 250 ) by reducing agent supplied to the unit. Intermittently running a feed device ( 230 ) to supply reducing agent, and running the feed device ( 230 ) at reduced power compared with its ordinary operation. Also a computer programme product containing programme code (P) for a computer ( 200; 210 ) for implementing the method. Also an SCR system and a motor vehicle ( 100; 110 ) which is equipped with the SCR system are disclosed

1 . A method for cooling a dosing unit pertaining to an SCR system for exhaust cleaning for a combustion engine having an exhaust flow when the engine is operating, a reducing agent dosing unit located generally at the exhaust flow;
 the method comprising the steps of:   operating the engine having the exhaust flow; then halting operation of the engine having the exhaust flow and thereby ceasing the exhaust flow;   after cessation of exhaust flow, cooling the reducing agent dosing unit by supplying a reducing agent to the dosing unit;   intermittently running a feed device to supply said coolant reducing agent, and   running said feed device at reduced power compared with power at which said feed device is run during ordinary operation of said feed device.   
     
     
         2 . A method according to  claim 1 , further comprising running said feed device intermittently with a predetermined interval configuration. 
     
     
         3 . A method according to  claim 2 , wherein said predetermined interval configuration is selected for catering for rewarming effects of said dosing unit. 
     
     
         4 . A method according to  claim 1 , further comprising intermittently activating operation of said feed device based on a measured temperature of at least one portion of said SCR system. 
     
     
         5 . A method according to  claim 1 , wherein said feed device is operated to cool said dosing unit to a temperature below a predetermined limit value. 
     
     
         6 . A method according to  claim 1 , wherein said reducing agent is a fluid solution which contains urea. 
     
     
         7 . An SCR system for a combustion engine having an exhaust flow when said engine is operating for exhaust cleaning, the system comprises:
 a coolable reducing agent dosing unit located generally at the exhaust flow;   a cooling device operable after cessation of exhaust flow from the engine for cooling said reducing agent dosing unit by supplying reducing agent to said dosing unit; and   a control device for intermittently running said feed device to supply said coolant reducing agent, and said feed device is configured and operable to run at reduced power during intermittent running as compared with power at which said feed device is run during ordinary operation of said feed device.   
     
     
         8 . An SCR system according to  claim 7 , wherein said feed device is run intermittently with a predetermined interval configuration. 
     
     
         9 . An SCR system according to  claim 8 , wherein said predetermined interval configuration is selected for catering for rewarming effects of said dosing unit. 
     
     
         10 . An SCR system according to  claim 7 , wherein said feed device is configured to be activated based on a measured temperature of at least one portion of said SCR system. 
     
     
         11 . An SCR system according to  claim 7 , wherein said feed device, when operating, is configured and operable to cool said dosing unit to a temperature below a predetermined limit value. 
     
     
         12 . An SCR system according to  claim 7 , wherein said reducing agent is a fluid solution which contains urea. 
     
     
         13 . A motor vehicle comprising an SCR system according to  claim 7 . 
     
     
         14 . A motor vehicle according to  claim 13 , comprising a truck, bus or passenger car. 
     
     
         15 . A computer programme pertaining to an SCR reducing agent system for exhaust cleaning of an engine which generates exhaust during operation, wherein said dosing system comprises a dosing unit for reducing agent, and wherein said programme product comprises non-transitory programme code with non-transitory programme instructions for causing a computer system to perform steps on an electronic control unit or causing another computer connected to the electronic control unit to perform steps according to  claim 1  when instructions in said code are run on said computer system. 
     
     
         16 . A computer programme product according to  claim 15 , wherein the product contains a programme code stored on a non-transitory computer-readable medium which can be read by said computer system for performing method steps, wherein said computer programme is run on an electronic control unit or another computer connected to electronic control unit