Internal combustion engine exhaust line

Abstract

The invention relates to an exhaust line of an internal combustion engine comprising: a pipe receiving exhaust gases, and a particulate filter impregnated with a first catalytic coating forming a reduction catalyst for nitrogen oxides (NO x ), and with a second catalytic coating forming a first oxidation catalyst for carbon monoxide (CO) and hydrocarbons (HC). The line comprises an additional filter housed in the pipe downstream of the particulate filter and impregnated with a catalytic coating forming a second reduction catalyst for nitrogen oxides (NO x ). And, the additional filter has an internal structure such that the additional filter creates a pressure drop which is less than the pressure drop created by the same volume of particulate filter impregnated with the same quantity of the same catalytic coating.

1 .- 10 . (canceled) 
     
     
         11 . An exhaust line for an internal combustion engine, said exhaust line comprising:
 a pipe structured and operable for receiving exhaust gases;   a particulate filter, housed inside the pipe and impregnated with:
 a first catalytic coating forming a first reduction catalyst of nitrogen oxides (NOx), and 
 a second catalytic coating forming an oxidation catalyst for carbon monoxides (CO) and hydrocarbons (HC); and 
   an additional filter, housed in the pipe upstream of the particulate filter, and impregnated with a catalytic coating forming a second reduction catalyst for nitrogen oxides (NOx), the additional filter comprising an internal structure such that the additional filter creates a pressure drop lower than the pressure drop created by the same volume of the particulate filter impregnated with the same amount of the same catalytic coating.   
     
     
         12 . The exhaust line according to  claim 11 , wherein:
 the particulate filter includes:
 intake ducts only leading to an inlet face for the exhaust gases, 
 exhaust ducts only leading to an outlet face for the exhaust gases, and 
 porous walls for fluidly connecting the intake ducts and the exhaust ducts, and 
   the additional filter further comprises ducts leading to an inlet face and to an outlet face, wherein the diameter of the ducts is greater than the pore diameter of the porous walls of the particulate filter.   
     
     
         13 . The exhaust line according to  claim 11 , wherein the specific heat capacity of the material of which the additional filter is made is lower than the specific heat capacity of the material of which the particulate filter is made. 
     
     
         14 . The exhaust line according to  claim 13  further comprises a reducing agent which decomposes when heated to produce a reagent which intervenes in the reduction of nitrogen oxides by the first catalytic coating, and an injector for injecting the reducing agent into the pipe upstream of the additional filter. 
     
     
         15 . The exhaust line according to  claim 11 , wherein the catalytic coating with which the additional filter is impregnated comprises zeolites so as to accelerate the decomposition of the reducing agent. 
     
     
         16 . The exhaust line according to  claim 11 , wherein at least one of:
 the additional filter is made of cordierite, and   the particulate filter is made of silicon carbide.   
     
     
         17 . The exhaust line according to  claim 12 , wherein the intake ducts of the particulate filter are impregnated with only the first catalytic coating, and the exhaust ducts are impregnated with only the second catalytic coating. 
     
     
         18 . A vehicle drive assembly, said assembly comprising:
 an internal combustion engine; and   an exhaust line, the exhaust line comprising:
 a pipe structured and operable for receiving exhaust gases; 
 a particulate filter, housed inside the pipe and impregnated with:
 a first catalytic coating forming a first reduction catalyst of nitrogen oxides (NOx), and 
 a second catalytic coating forming an oxidation catalyst for carbon monoxides (CO) and hydrocarbons (HC); and 
 
 an additional filter, housed in the pipe upstream of the particulate filter, and impregnated with a catalytic coating forming a second reduction catalyst for nitrogen oxides (NOx), the additional filter comprising an internal structure such that the additional filter creates a pressure drop lower than the pressure drop created by the same volume of the particulate filter impregnated with the same amount of the same catalytic coating. 
   
     
     
         19 . The assembly according to  claim 18 , wherein the engine is a diesel type engine. 
     
     
         20 . A vehicle comprising:
 a vehicle drive assembly, said assembly comprising:
 an internal combustion engine; and 
 an exhaust line, the exhaust line comprising:
 a pipe structured and operable for receiving exhaust gases; 
 a particulate filter, housed inside the pipe and impregnated with:
 a first catalytic coating forming a first reduction catalyst of nitrogen oxides (NOx), and 
 a second catalytic coating forming an oxidation catalyst for carbon monoxides (CO) and hydrocarbons (HC); and 
 
 an additional filter, housed in the pipe upstream of the particulate filter, and impregnated with a catalytic coating forming a second reduction catalyst for nitrogen oxides (NOx), the additional filter comprising an internal structure such that the additional filter creates a pressure drop lower than the pressure drop created by the same volume of the particulate filter impregnated with the same amount of the same catalytic coating.