Exhaust Manifold With Thin Flanges

Abstract

An exhaust manifold for an engine has at least one collecting pipe for conveying exhaust gases. Several exhaust gas inlets are in fluid communication with the collecting pipe. Several flanges each define one of the exhaust gas inlets. Each flange has an external face adapted to be pressed against a receiving surface of the engine. Several back flanges are each associated to one of the flanges and are adapted to press the corresponding flange against the receiving surface. The flanges are areas of a single plate, which has a thickness between 0.2 and 2 mm. The areas are continuously connected to one another by other areas of the plate. The collecting pipe is not integral with the plate. The manifold has leak tight connections connecting the collecting pipe to each of the flanges.

1 . An exhaust manifold for an engine, the exhaust manifold comprising:
 at least one collecting pipe for conveying exhaust gases;   several exhaust gas inlets in fluid communication with the at least one collecting pipe;   several flanges each defining one of the exhaust gas inlets, each flange having an external face adapted to be pressed against a receiving surface of the engine;   several back flanges, each back flange being associated to one of the flanges and being adapted to press the corresponding flange against the receiving surface; and   wherein the flanges are areas of a single plate, the plate having a thickness between 0.2 and 2 mm, said areas being continuously connected to one another by other areas of the plate, and wherein the collecting pipe is not integral with the plate, the exhaust manifold having leak tight connections connecting the at least one collecting pipe to each of the flanges.   
     
     
         2 . The exhaust manifold of  claim 1 , wherein the flanges are integral with one another. 
     
     
         3 . The exhaust manifold of  claim 1 , wherein the at least one collecting pipe has a wall thickness between 0.2 and 2 mm. 
     
     
         4 . The exhaust manifold of  claim 1 , wherein the exhaust manifold has an outer casing inside which the at least one collecting pipe is located, and has a layer of a thermal insulation material between the at least one collecting pipe and the outer casing, the outer casing being connected to the plate so that the plate and the outer casing together define a closed box for containment of the thermal insulation material. 
     
     
         5 . The exhaust manifold of  claim 4 , wherein the back flanges are located inside said closed box. 
     
     
         6 . The exhaust manifold of  claim 4 , wherein the plate has two outer raised edges opposite to one another, raised toward a direction opposite to the engine, the outer casing being connected to the two outer raised edges of the plate. 
     
     
         7 . The exhaust manifold of  claim 1 , wherein each back flange has an aperture, the corresponding flange having around the exhaust gas inlet a flanged edge extending into said aperture of the back flange and connected to the at least one collecting pipe by the corresponding connection. 
     
     
         8 . The exhaust manifold of  claim 1 , wherein the plate comprises slots. 
     
     
         9 . The exhaust manifold of  claim 1 , wherein the at least one collecting pipe has at least two tubular sections for conveying the exhaust gases, and at least one thermal compensation device integral with the two tubular sections. 
     
     
         10 . The exhaust manifold of  claim 9 , wherein the thermal compensation device connects respective ends of the two tubular sections to one another and defines internally a passage for conveying the exhaust gases from one tubular section to the other tubular section. 
     
     
         11 . The exhaust manifold of  claim 9 , wherein at least one of the tubular sections has a peripheral wall with a hole connected to one of the flanges by one of the connections and being in fluid communication with the corresponding exhaust gas inlet, said peripheral wall having a substantially flat area, the hole having at least a zone extending across the flat area. 
     
     
         12 . The exhaust manifold of  claim 11 , wherein said exhaust gas inlet has a given surface area, said zone having a surface area between 30% and 50% of the given surface area. 
     
     
         13 . The exhaust manifold of  claim 11 , wherein said zone is separated from an edge of the hole by a gap. 
     
     
         14 . The exhaust manifold of  claim 9 , wherein the thermal compensation device is a bellow. 
     
     
         15 . The exhaust manifold of  claim 1 , wherein each of the leak tight connections is a tube which is either integral with the corresponding flange and welded, brazed, or soldered to the at least one collecting pipe, or integral with the collecting pipe and welded, brazed, or soldered to the corresponding flange, or welded, soldered, or brazed to both the corresponding flange and the at least one collecting pipe. 
     
     
         16 . The exhaust manifold of  claim 1 , wherein the back flanges each have a thickness between 1.5 and 2.5 mm. 
     
     
         17 . The exhaust manifold of  claim 1 , including tie rods adapted to secure the exhaust manifold to the engine, spacer sleeves through which the tie rods pass, and screws fitted on threaded ends of the tie rods, said screws pressing the back flanges toward the engine, the spacer sleeves being obtained by stamping a metal tube or by folding a sheet of metal.