Method and device for controlling the temperature of exhaust gas from an internal-combustion engine flowing through a means of treating the pollutants contained in this gas

Abstract

The present invention relates to a method for controlling the temperature of exhaust gas circulating in an exhaust line ( 20 ) of an internal-combustion engine ( 10 ), said line comprising means ( 30 ) of treating the pollutants contained in this gas and heat exchange means ( 32 ) for cooling or heating said exhaust gas flowing through these pollutant treatment means. According to the invention, the method consists in using evaporator ( 38 ) of a fluid circulation closed circuit ( 34 ) as heat exchange means ( 32 ).

1 ) A method for controlling the temperature of exhaust gas circulating in an exhaust line of an internal-combustion engine, said line comprising means of treating pollutants contained in this gas and heat exchange means for cooling or heating said exhaust gas flowing through these pollutant treatment means, characterized in that it consists in using evaporator of a fluid circulation closed circuit as heat exchange means. 
     
     
         2 ) A method as claimed in  claim 1 , characterized in that it consists in feeding a hot fluid into the evaporator so that it heats the exhaust gas. 
     
     
         3 ) A method as claimed in  claim 2 , characterized in that it consists in using a hot fluid contained in a fluid storage means connected to the circuit. 
     
     
         4 ) A method as claimed in  claim 1 , characterized in that it consists in connecting storage means to evaporator by means of a bypass line. 
     
     
         5 ) A device for controlling the temperature of exhaust gas circulating in an exhaust line of an internal-combustion engine, said line comprising means of treating pollutants contained in this gas and reversible heat exchange means for cooling or heating said exhaust gas flowing through these pollutant treatment means, characterized in that the reversible heat exchange means are an evaporator of a fluid circulation closed circuit. 
     
     
         6 ) A device as claimed in  claim 5 , characterized in that circuit comprises a storage tank for a hot fluid. 
     
     
         7 ) A device as claimed in  claim 6 , characterized in that the tank is a thermally insulated tank. 
     
     
         8 ) A device as claimed in  claim 6 , characterized in that the tank comprises fluid heating means. 
     
     
         9 ) A device as claimed in  claim 5 , characterized in that circuit comprises a bypass line for allowing the fluid from the tank into evaporator. 
     
     
         10 ) A device as claimed in  claim 9 , characterized in that bypass line carries a throttling means. 
     
     
         11 ) A device as claimed in  claim 5 , characterized in that the pollutant treatment means comprise a selective catalytic reduction catalyst.