Marine exhaust manifold

Abstract

A marine exhaust manifold comprises a collector for receiving exhaust gases from an engine, at least two exhaust runners for conducting exhaust gas from said engine to the collector, and a cooling jacket to cool said collector and exhaust runners. In one aspect at least one exhaust runner is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is forced across the gas outlet end of at least one other exhaust runner, thereby creating a pressure drop within said at least one other exhaust runner. In another aspect there are at least three exhaust runners and the gas outlet ends of the exhaust runners are provided in the collector in a substantially single plane, which is substantially parallel to the direction of expulsion of the exhaust gas into the collector. In another aspect the manifold is provided with a sacrificially corroding element, such as a sacrificial anode.

1 . A marine exhaust manifold comprising:
 a collector for receiving exhaust gases from an engine;   at least three exhaust runners for conducting exhaust gas from said engine to said collector; and   a cooling jacket which at least partially encloses said collector and exhaust runners so that a fluid within the cooling jacket can act to cool said collector and exhaust runners;   wherein each of said at least three exhaust runners has a gas outlet in the collector and wherein the gas outlets ends of the at least three exhaust runners are provided in a substantially single plane, said plane being substantially parallel to the direction of expulsion of the exhaust gas into the collector.   
     
     
         2 . A marine exhaust manifold as claimed in  claim 1  wherein the gas outlet ends of the at least three exhaust runners are provided substantially in a line. 
     
     
         3 . A marine exhaust manifold as claimed in  claim 1  wherein at least one exhaust runner is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet and of at least one other exhaust runner in order to thereby create a pressure drop within said at least one other exhaust runner. 
     
     
         4 . A marine exhaust manifold as claimed in  claim 3 , comprising four exhaust runners, which comprise two sets of the exhaust runners and wherein each exhaust runner of a set is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet end of the other exhaust runner of said set in order to thereby create a pressure drop within said other exhaust runner of said set. 
     
     
         5 . A marine exhaust manifold as claimed in  claim 3  wherein the marine exhaust manifold comprises three and only three exhaust runners and wherein each of the exhaust runners is adapted to expel exhaust gas into the collector so that the expelled exhaust has is, in use, forced across the gas outlet ends of the other exhaust runners in order to thereby create a pressure drop within said other exhaust runners. 
     
     
         6 . A marine exhaust manifold as claimed in  claim 3  wherein at least one exhaust runner gas outlet end is shaped other than as a radical section of the exhaust runner. 
     
     
         7 . A marine exhaust manifold as claimed in  claim 6  wherein at least one exhaust runner gas outlet end is shaped as a first part which corresponds to a radical sectional surface of the exhaust runner and a second part comprising a non-radical section of the exhaust runner. 
     
     
         8 . A marine exhaust manifold as claimed in  claim 3  wherein the cooling jacket is a water jacket having at least one inlet and at least one outlet in fluid connection with the inlet, in order to allow water to flow through the jacket. 
     
     
         9 . A marine exhaust manifold as claimed in  claim 3  wherein the marine exhaust manifold comprises at least one connection member, at or adjacent an exhaust gas inlet end of one or more exhaust runners, for connection to an engine head. 
     
     
         10 . A marine exhaust manifold as claimed in  claim 3  wherein a wall portion of the collector is welded to an external wall portion of each of the exhaust runners. 
     
     
         11 . A marine exhaust manifold as claimed in  claim 3  wherein the marine exhaust manifold is made substantially from stainless steel. 
     
     
         12 . A marine exhaust manifold as claimed in  claim 3  wherein the marine exhaust manifold is provided in electrically conducting contact with an element which sacrificially corrodes, thereby protecting the marine exhaust manifold from corrosion. 
     
     
         13 . A marine exhaust manifold as claimed in  claim 3  which has four, and only four exhaust runners, the gas outlet ends of the exhaust runners being provided substantially in a line. 
     
     
         14 . A marine exhaust manifold comprising:
 a collector for receiving exhaust gases from an engine;   at least two exhaust runners for conducting exhaust gas from said engine to the collector; and   a cooling jacket which at least partially encloses said collector and exhaust runners so that a fluid within the cooling jacket can act to cool said collector and exhaust runners;   wherein at least one exhaust runner is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet end of at least one other exhaust runner in order to thereby create a pressure drop within said at least one other exhaust runner.   
     
     
         15 . A marine exhaust manifold as claimed in  claim 14  wherein there are provided at least three exhaust runners, and wherein the gas outlet ends of the at least three exhaust runners are provided substantially in a substantially single plane, said plane being substantially parallel to the direction of expulsion of the exhaust gas into the collector. 
     
     
         16 . A marine exhaust manifold as claimed in  claim 14  wherein there are provided at least three exhaust runners, and wherein the gas outlet ends of the at least three exhaust runners are provided substantially in a line. 
     
     
         17 . A marine exhaust manifold as claimed in  claim 14 , comprising four exhaust runners, which comprise two sets of exhaust runners and wherein each exhaust runner of a set is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet end of the other exhaust runner of said set in order to thereby create a pressure drop within said other exhaust runner of said set. 
     
     
         18 . A marine exhaust manifold as claimed in  claim 14 , wherein the marine exhaust manifold comprises three and only three exhaust runners and wherein each of the exhaust runners is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet ends of the other exhaust runners in order to thereby create a pressure drop within said other exhaust runners. 
     
     
         19 . A marine exhaust manifold as claimed in  claim 14  wherein at least one exhaust runner gas outlet is shaped other than as a radical section of the exhaust runner. 
     
     
         20 . A marine exhaust manifold as claimed in  claim 19  wherein at least one exhaust runner gas outlet end is shaped as a first part which corresponds to a radical sectional surface of the exhaust runner and a second part comprising a non-radical section of the exhaust runner. 
     
     
         21 - 22 . (canceled) 
     
     
         23 . A marine exhaust manifold as claimed in  claim 14  wherein a wall portion of the collector is welded to a external wall portion of each of the exhaust runners. 
     
     
         24 . A marine exhaust manifold as claimed in  claim 14  wherein the marine exhaust manifold is made substantially from stainless steel. 
     
     
         25 . A marine exhaust manifold as claimed in  claim 14  wherein the marine exhaust manifold is provided in electrically conducting contact with an element which sacrificially corrodes, thereby protecting the marine exhaust manifold from corrosion. 
     
     
         26 . (canceled) 
     
     
         27 . A marine exhaust manifold comprising:
 a collector for receiving exhaust gases from an engine;   at least two exhaust runners for conducting exhaust gas from said engine to the collector; and   a cooling jacket which at least partially encloses said collector and exhaust runners so that a fluid within the cooling jacket can act to cool said collector and exhaust runners; and   wherein the marine exhaust manifold is provided in electrically conducting contact with an element which sacrificially corrodes, thereby protecting the marine exhaust manifold from corrosion.   
     
     
         28 . A marine exhaust manifold as claimed in  claim 27  wherein the element which sacrificially corrodes is replaceably retained in a fitting provided on the marine exhaust manifold. 
     
     
         29 . A marine exhaust manifold as claimed in  claim 27  wherein the element which sacrificially corrodes is metallic. 
     
     
         30 . A marine exhaust manifold as claimed in  claim 27  wherein the element which sacrificially corrodes is a sacrificial anode. 
     
     
         31 . A marine exhaust manifold as claimed in  claim 27  wherein the marine exhaust manifold is formed substantially from stainless steel. 
     
     
         32 . A marine exhaust manifold as claimed in  claim 27  wherein at least one exhaust runner is adapted to expel exhaust gas into the collector so that the expelled exhaust gas is, in use, forced across the gas outlet end of at least one other exhaust runner in order to thereby create a pressure drop within said at least one other exhaust runner.