Exhaust manifold

Abstract

An exhaust manifold has a first upstream pipe connected to an exhaust ports of a group of cylinders of within an engine; a second upstream pipe connected to exhaust ports of cylinders other than the group of cylinders; and a merging pipe that merges the downstream ends of the first and second upstream pipe. The first upstream pipe is formed by a plurality of pipes and each pipe of the plurality of pipes forms a separate exhaust path that extends from the exhaust ports to the inside the merging pipe, and the second upstream pipe encloses the plurality of pipes and forms, between an inner surface of the second upstream pipe and an outer surface of the plurality of pipes, a plurality of exhaust paths that extend from the exhaust ports other than the exhaust ports of the group of cylinders to the inside of the merging pipe.

1 . An exhaust manifold comprising:
 a first upstream pipe connected to exhaust ports of a group of cylinders within an engine;   a second upstream pipe connected to exhaust ports of cylinders other than the group of cylinders; and   a merging pipe that merges the downstream ends of the first upstream pipe and the second upstream pipe, wherein the first upstream pipe is formed by a plurality of pipes and each pipe of the plurality of pipes forms a separate exhaust path that extends from the exhaust port of the group of cylinders to the inside the merging pipe, and the second upstream pipe encloses the plurality of pipes and forms, between an inner surface of the second upstream pipe and an outer surface of the plurality of pipes, a plurality of exhaust paths that extend from the exhaust port other than the exhaust port of the group of cylinders to the inside of the merging pipe.   
   
   
       2 . The exhaust manifold according to  claim 1 , wherein each pipe of the plurality of pipes that forms the first upstream pipe is connected to the exhaust port of the group of cylinders having exhaust strokes that are mutually distanced. 
   
   
       3 . The exhaust manifold according to  claim 1 , wherein each pipe of the plurality of pipes is respectively connected to an exhaust port of the cylinders positioned at the ends of a cylinder block. 
   
   
       4 . The exhaust manifold according to  claim 3 , wherein the engine is an in-line 4-cylinder engine, and wherein each pipe of the plurality of pipes is respectively connected to the exhaust port of the first cylinder and the fourth cylinder of the in-line 4-cylinder engine. 
   
   
       5 . The exhaust manifold according to  claim 2 , wherein the engine is an in-line 4-cylinder engine, and wherein each pipe of the plurality of pipes is respectively connected to the exhaust port of a second cylinder and a third cylinder of the in-line 4-cylinder engine. 
   
   
       6 . The exhaust manifold according to  claim 1 , wherein each pipe of the plurality of pipes forms a fan-shaped aperture plane adjacently in the merging pipe, and wherein semicircular or fan-shaped aperture plane corresponding to a downstream end of the exhaust path of the second upstream pipe is formed in the merging pipe. 
   
   
       7 . The exhaust manifold according to  claim 1 , wherein a gap is formed between the plurality of pipes and the second upstream pipe, and a heat-insulating spacer is provided within the gap. 
   
   
       8 . The exhaust manifold according to  claim 1 , wherein the second upstream pipe is formed by a pair of sheet metal members that sandwich the first upstream pipe and that are hermetically joined each other. 
   
   
       9 . The exhaust manifold according to  claim 8 , wherein the merging pipe is formed by the pair of sheet metal members integrated with the second upstream pipe. 
   
   
       10 . An exhaust manifold comprising:
 a first upstream pipe connected to at least one exhaust port of a plurality of cylinders of an engine;   a second upstream pipe connected to the exhaust port of a cylinder other than the cylinders connected to the first upstream pipe; and   a merging pipe that merges the downstream ends of the first upstream pipe and the second upstream pipe, wherein the first upstream pipe forms a separate exhaust path that extends from the exhaust port of the cylinders to inside the merging pipe, and the second upstream pipe encloses the first upstream pipe and forms, between an inner surface of the second upstream pipe and an outer surface of the first upstream pipe, an exhaust path that extends from the exhaust port of the cylinder that is not connected to the first upstream pipe to the inside of the merging pipe.   
   
   
       11 . The exhaust manifold according to  claim 10 , wherein the engine is an in-line 6-cylinder engine, and the second upstream pipe has a first part connected to the first cylinder to the third cylinder of the in-line 6-cylinder engine and a second part connected to the fourth cylinder to the sixth cylinder in the in-line 6-cylinder engine. 
   
   
       12 . The exhaust manifold according to  claim 11 , wherein the first upstream pipe connects to at least one of the second cylinder and the fifth cylinder of the in-line 6-cylinder engine. 
   
   
       13 . The exhaust manifold according to  claim 11 , wherein the first upstream pipe is formed by a plurality of pipes, and each pipe of the plurality of pipes is respectively connected to at least one of an exhaust port of the first cylinder and the third cylinder of the in-line 6-cylinder engine and the fourth cylinder and the sixth cylinder of the in-line 6-cylinder engine. 
   
   
       14 . The exhaust manifold according to  claim 10 , wherein the first upstream pipe forms a fan-shaped aperture plane in the merging pipe, and wherein semicircular or fan-shaped aperture plane corresponding to a downstream end of the exhaust path of the second upstream pipe is formed in the merging pipe. 
   
   
       15 . The exhaust manifold according to  claim 10 , wherein a gap is formed between the first upstream pipe and the second upstream pipe, a heat-insulating spacer is provided within the gap. 
   
   
       16 . The exhaust manifold according to  claim 10 , wherein the second upstream pipe is formed by a pair of sheet metal members that sandwich the first upstream pipe and that are hermetically joined each other. 
   
   
       17 . The exhaust manifold according to  claim 16 , wherein the merging pipe is formed by the pair of sheet metal members integrated with the second upstream pipe.