Exhaust manifold having improved NVH characteristics

Abstract

An exhaust manifold and method of manufacturing the same is provided that includes at least one tube within shells of an exhaust manifold. The tube limits fluid communication from the tube into the shells of the exhaust manifold. An inlet flange is connectable to the exhaust manifold and is attachable to a cylinder head of a combustion engine. Exhaust gases expelled from the cylinder head are transmitted into the exhaust manifold. At least a portion of the exhaust gases pass through the tube. The exhaust manifold reduces NVH and cures emission control issues.

1 . An exhaust manifold comprising:
 an upper half shell;   a lower half shell secured to the upper half shell to define a housing; and   a tube positioned within an interior of the housing, the tube having a wall structure to substantially limit fluid communication between an interior of the tube and the interior of the housing.   
     
     
         2 . The exhaust manifold of  claim 1  further comprising:
 an inlet flange attached to one of the lower half shell or the upper half shell, the inlet flange attachable to a cylinder head of a combustion engine.   
     
     
         3 . The exhaust manifold of  claim 2  wherein the tube is attached to the inlet flange. 
     
     
         4 . The exhaust manifold of  claim 3  further comprising:
 an opening formed in the inlet flange, the openings providing fluid communication between an exterior of the housing and the interior of the housing.   
     
     
         5 . The exhaust manifold of  claim 3  further comprising:
 an outlet flange attached to one of the lower half shell or the upper half shell, the outlet flange attached at an opposite side of the housing from the inlet flange.   
     
     
         6 . The exhaust manifold of  claim 5  wherein the tube extends from the inlet flange and terminates prior to the outlet flange. 
     
     
         7 . The exhaust manifold of  claim 6  wherein the tube is connected to the inlet flange at the opening of the inlet flange. 
     
     
         8 . The exhaust manifold of  claim 5  wherein the tube is connected to the inlet flange and the outlet flange. 
     
     
         9 . The exhaust manifold of  claim 5  wherein the tube extends from the outlet flange and terminates within the housing without connection to the inlet flange. 
     
     
         10 . The exhaust manifold of  claim 5  wherein the tube extends within the housing and terminates a first distance from the inlet flange and a second distance from the outlet flange. 
     
     
         11 . An exhaust manifold comprising:
 a housing including an upper half shell and a lower half shell, the housing attachable to a cylinder head of an internal combustion engine; and   a plurality of tubes positioned at least partially within the housing, the tubes having a wall structure to limit fluid communication between an interior of the tubes and the housing.   
     
     
         12 . The exhaust manifold of  claim 11  further comprising:
 an inlet flange connected to the housing and securable to combustion chambers of an internal combustion engine.   
     
     
         13 . The exhaust manifold of  claim 12  wherein the inlet flange has a plurality of openings, and further wherein the tubes are equal in number to the openings in the flange. 
     
     
         14 . The exhaust manifold of  claim 12  wherein at least one of the plurality of tubes is connected to the inlet flange and extends within the housing. 
     
     
         15 . The exhaust manifold of  claim 12  wherein the plurality of tubes are within the housing without attachment to the inlet flange. 
     
     
         16 . The exhaust manifold of  claim 12  further comprising:
 an outlet flange connected to the housing, the outlet flange connected at an opposite end of the housing from the inlet flange.   
     
     
         17 . The exhaust manifold of  claim 16  wherein at least one of the plurality of tubes extends from the inlet flange and terminates a distance from the outlet flange without attachment to the outlet flange. 
     
     
         18 . A method for manufacturing an exhaust manifold assembly comprising:
 forming a first half shell;   positioning a plurality of tubes within the first half shell;   connecting the first half shell to a second half shell to form a housing having an interior defined between the first half shell and the second half shell, the plurality of tubes positioned within the interior of the housing, wherein the plurality of tubes have a wall structure to limit fluid communication from the plurality of tubes into the housing along the length of each of the plurality of tubes;   connecting at least one of the shells to an inlet flange securable to a cylinder head of an engine; and   securing at least one of the tubes of the plurality of tubes to the inlet flange.   
     
     
         19 . The method of  claim 18  wherein the first half shell and the second half shell are molded over the plurality of tubes. 
     
     
         20 . The method of  claim 18  further comprising:
 connecting an outlet flange to one of the shells opposite the inlet flange, wherein at least one of the tubes terminates without attachment to the outlet flange.   
     
     
         21 . The exhaust manifold of  claim 1  wherein the tube has one or more apertures providing fluid communication between the interior of the housing and the interior of the tube.