Marine engine with thermally insulated catalyst structures

Abstract

A catalyst system for a marine engine supports a catalyst device within a catalyst housing structure in such a way that a space is defined around the device in order to thermally insulate the device from the catalyst housing structure. A rim of the catalyst device cooperates with the housing structure to provide a seal at a bottom portion of the catalyst device to trap water within a reservoir to prevent the water from flowing toward exhaust ports of the engine. The space between the catalyst device and the housing structure provides a thermal insulation which allows the catalyst device to operate at an elevated temperature.

1 . (canceled) 
     
     
         2 . An exhaust system for a marine engine, comprising:
 a first catalyst device comprising a first catalyst material disposed within a first generally tubular member;   a catalyst housing structure having a first generally tubular cavity formed therein, said first tubular cavity being shaped to receive said first tubular member therein, said first tubular cavity and said first tubular member being sized to define a first space disposed between an outer surface of said first generally tubular member and an inner surface of said first generally tubular cavity; and   a first rim attached to an end of said first generally tubular member and mounting said generally tubular member as a cantilever in said first space.   
     
     
         3 . The exhaust system of  claim 2 , wherein:
 said first rim is configured to form a first seal to inhibit a liquid from flowing out of said first space in a downward direction.   
     
     
         4 . The exhaust system of  claim 2 , further comprising:
 a second catalyst device comprising a second catalyst material disposed within a second generally tubular member and a second rim attached to an end of said second generally tubular member, said catalyst housing structure having a second generally tubular cavity formed therein, said second tubular cavity being shaped to receive said second tubular member therein, said second tubular cavity and said second tubular member being sized to define a second space disposed between an outer surface of said second generally tubular member and an inner surface of said second generally tubular cavity, said second rim being configured to form a second seal in cooperation with said catalyst housing structure at a lower portion of said second catalyst device to inhibit said liquid from flowing out of said second space in a downward direction.   
     
     
         5 . The exhaust system of  claim 4 , wherein:
 said first and second catalyst devices are disposed in a common plane.   
     
     
         6 . The exhaust system of  claim 4 , wherein:
 said first and second catalyst devices are disposed in serial fluid communication with a plurality of exhaust ports which are configured to direct a flow of exhaust gas from a plurality of cylinders of said marine engine.   
     
     
         7 . The exhaust system of  claim 4 , wherein:
 said first and second catalyst devices are disposed in parallel fluid communication with each other.   
     
     
         8 . An exhaust system for a marine engine, comprising:
 a first catalyst device comprising a first catalyst material disposed within a first generally impermeable tubular member;   a first rim attached to an end of said first generally impermeable tubular member, said first rim being configured to form a first seal to inhibit a liquid from flowing out of said first space in a downward direction;   a catalyst housing structure having a first generally tubular cavity formed therein, said first tubular cavity being shaped to receive said first generally impermeable tubular member therein, said first tubular cavity and said first generally impermeable tubular member being sized to define a first space disposed between an outer surface of said first generally tubular member and an inner surface of said first generally tubular cavity;   a second catalyst device comprising a second catalyst material disposed within a second generally impermeable tubular member and a second rim attached to an end of said second generally impermeable tubular member, said catalyst housing structure having a second generally tubular cavity formed therein, said second tubular cavity being shaped to receive said second generally impermeable tubular member therein, said second tubular cavity and said second generally impermeable tubular member being sized to define a second space disposed between an outer surface of said second generally impermeable tubular member and an inner surface of said second generally tubular cavity, said second rim being configured to form a second seal in cooperation with said catalyst housing structure at a lower portion of said second catalyst device to inhibit said liquid from flowing out of said second space in a downward direction;   said first rim mounting said first generally impermeable tubular member as a first cantilever in said first space; and   said second rim mounting said second generally impermeable tubular member as a second cantilever in said second space.   
     
     
         9 . The exhaust system of  claim 8 , wherein:
 said first and second catalyst devices are disposed in a common plane.   
     
     
         10 . The exhaust system of  claim 9 , wherein:
 said first and second catalyst devices are disposed in serial fluid communication with a plurality of exhaust ports which are configured to direct a flow of exhaust gas from a plurality of cylinders of said marine engine.   
     
     
         11 . The exhaust system of  claim 10 , wherein:
 said first and second catalyst devices are disposed in parallel fluid communication with each other.   
     
     
         12 . (canceled) 
     
     
         13 . An exhaust system for a marine engine, comprising:
 a first catalyst device comprising a first catalyst material disposed within a first generally cylindrical member;   a catalyst housing structure having a first generally cylindrical cavity formed therein, said first generally cylindrical cavity being shaped to receive said first generally cylindrical member therein, said first generally cylindrical cavity and said first generally cylindrical member being sized to define a first space disposed between an outer surface of said first generally cylindrical member and an inner surface of said first generally cylindrical cavity; and   a first rim attached to an end of said first generally cylindrical member and mounting said first generally cylindrical member as a cantilever in said first space.   
     
     
         14 . The exhaust system of  claim 13 , wherein:
 said first rim is configured to form a first seal to inhibit a liquid from flowing out of said first space in a downward direction.   
     
     
         15 . The exhaust system of  claim 14 , further comprising:
 a second catalyst device comprising a second catalyst material disposed within a second generally cylindrical member and a second rim attached to an end of said second generally cylindrical member, said catalyst housing structure having a second generally cylindrical cavity formed therein, said second generally cylindrical cavity being shaped to receive said second generally cylindrical member therein, said second generally cylindrical cavity and said second generally cylindrical member being sized to define a second space disposed between an outer surface of said second generally cylindrical member and an inner surface of said second generally cylindrical cavity, said second rim being configured to form a second seal in cooperation with said catalyst housing structure at a lower portion of said second catalyst device to inhibit said liquid from flowing out of said second space in a downward direction.   
     
     
         16 . The exhaust system of  claim 15 , wherein:
 said first and second catalyst devices are disposed in a common plane.   
     
     
         17 . The exhaust system of  claim 16 , wherein:
 said first and second catalyst devices are disposed in serial fluid communication with a plurality of exhaust ports which are configured to direct a flow of exhaust gas from a plurality of cylinders of said marine engine.   
     
     
         18 . The exhaust system of  claim 17 , wherein:
 said first and second catalyst devices are disposed in parallel fluid communication with each other.