Air Shielded Water Cooled Exhaust Manifold With Exhaust Tube Support

Abstract

An internal combustion engine includes a cylinder block defining at least one cylinder, and a cylinder head coupled to the cylinder block. An exhaust manifold is coupled to the cylinder head and configured to receive exhaust gas from the cylinder head. The exhaust manifold includes a water jacket tube defining a plurality of liquid coolant passages and an exhaust tube received within the water jacket tube. The exhaust manifold also includes an air gap between the exhaust tube and the water jacket tube. A support mat is positioned in the air gap and compressed between an outer surface of the exhaust tube and an inner surface of the water jacket tube.

What is claimed is: 
     
         1 . An internal combustion engine, comprising:
 a cylinder block defining at least one cylinder;   a cylinder head coupled to the cylinder block;   an exhaust manifold coupled to the cylinder head and configured to receive exhaust gas from the cylinder head, wherein the exhaust manifold includes a water jacket tube defining a plurality of liquid coolant passages and an exhaust tube received within the water jacket tube, wherein the exhaust manifold includes an air gap between the exhaust tube and the water jacket tube; and   a support mat positioned in the air gap, wherein the support mat is compressed between an outer surface of the exhaust tube and an inner surface of the water jacket tube.   
     
     
         2 . The internal combustion engine of  claim 1 , wherein the support mat includes a high temperature insulation material. 
     
     
         3 . The internal combustion engine of  claim 2 , wherein the support mat defines a continuous annular band. 
     
     
         4 . The internal combustion engine of  claim 2 , wherein the high temperature insulation material is intumescent. 
     
     
         5 . The internal combustion engine of  claim 2 , wherein the support mat has a compressed radial thickness of between about 3 millimeters and about 20 millimeters. 
     
     
         6 . The internal combustion engine of  claim 5 , wherein the support mat has an axial length of between about 75 millimeters and about 125 millimeters. 
     
     
         7 . The internal combustion engine of  claim 1 , wherein the exhaust manifold is a modular exhaust manifold including a plurality of exhaust manifold segments coupled together along a common axis, wherein each of the exhaust manifold segments includes a segment of the water jacket tube and a segment of the exhaust tube received within the water jacket tube segment. 
     
     
         8 . The internal combustion engine of  claim 7 , wherein each exhaust manifold segment includes at least one support mat compressed between the exhaust tube segment and the water jacket tube segment. 
     
     
         9 . The internal combustion engine of  claim 8 , wherein the at least one support mat is positioned at a first end of each exhaust manifold segment, and at a second end of each exhaust manifold segment the exhaust tube segment has a flared end for receiving the exhaust tube segment of an adjacent exhaust manifold segment. 
     
     
         10 . The internal combustion engine of  claim 7 , wherein the exhaust tube is configured to direct exhaust gas in a first direction relative to the common axis and the liquid coolant passages are configured to direct liquid coolant in a second direction relative to the common axis that is opposite the first direction. 
     
     
         11 . A modular exhaust manifold for an internal combustion engine, comprising:
 a first exhaust manifold segment including a first segment of a water jacket tube defining a first plurality of liquid coolant passages and a first segment of an exhaust tube received within the first water jacket tube segment;   wherein the first exhaust manifold segment includes a first air gap between the first exhaust tube segment and the first water jacket tube segment; and   a first support mat positioned in the first air gap, wherein the first support mat is compressed between an outer surface of the first exhaust tube segment and an inner surface of the first water jacket tube segment.   
     
     
         12 . The modular exhaust manifold of  claim 11 , wherein the first support mat includes a high temperature insulation material. 
     
     
         13 . The modular exhaust manifold of  claim 12 , wherein the first support mat defines a continuous annular band. 
     
     
         14 . The modular exhaust manifold of  claim 12 , wherein the high temperature insulation material is intumescent. 
     
     
         15 . The modular exhaust manifold of  claim 12 , wherein the support mat has a compressed radial thickness of between about 3 millimeters and about 20 millimeters. 
     
     
         16 . The modular exhaust manifold of  claim 15 , wherein the support mat has an axial length of between about 75 millimeters and about 125 millimeters. 
     
     
         17 . The modular exhaust manifold of  claim 11 , further including:
 a second exhaust manifold segment including a second segment of the water jacket tube defining a second plurality of liquid coolant passages and a second segment of the exhaust tube received within the second water jacket tube segment;   wherein the second exhaust manifold segment includes a second air gap between the second exhaust tube segment and the second water jacket tube segment; and   a second support mat positioned in the second air gap, wherein the second support mat is compressed between an outer surface of the second exhaust tube segment and an inner surface of the second water jacket tube segment.   
     
     
         18 . The modular exhaust manifold of  claim 17 , wherein the first support mat is positioned at a first end of the first exhaust manifold segment and the second support mat is positioned at a first end of the second exhaust manifold segment, wherein at a second end of the first exhaust manifold segment the first exhaust tube segment has a flared end for receiving the second exhaust tube segment. 
     
     
         19 . A method of assembling a modular exhaust manifold for an internal combustion engine, comprising steps of:
 assembling a first exhaust manifold segment by:
 positioning a first support mat around a first segment of an exhaust tube; 
 receiving the first exhaust tube segment within a first segment of a water jacket tube defining a first plurality of liquid coolant passages; 
 wherein the receiving step includes compressing the first support mat between an outer surface of the first exhaust tube segment and an inner surface of the first water jacket tube segment; and 
 maintaining an air gap between the first exhaust tube segment and the first water jacket tube segment with the first support mat. 
   
     
     
         20 . The method of  claim 19 , further including:
 attaching a second exhaust manifold segment to the first exhaust manifold segment;   wherein the attaching step includes receiving the first exhaust tube segment of the first exhaust manifold segment within a flared end of the second exhaust tube segment.