Outboard engine assembly having an idle relief system

Abstract

An outboard engine assembly has an engine unit including an engine unit housing, an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber, a gearcase connected to the engine unit housing, and an exhaust system, the exhaust system including an idle relief passage fluidly communicating with an exhaust passage, the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the outboard engine assembly is mounted to a watercraft and the watercraft is at rest, and a propulsion device operatively connected to the engine.

What is claimed is: 
     
         1 . An outboard engine assembly for a watercraft, comprising:
 an engine unit including:
 an engine unit housing; 
 an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber; 
 a gearcase connected to the engine unit housing; and 
 an exhaust system including:
 an exhaust passage fluidly communicating with the at least one combustion chamber, 
 the exhaust passage having an exhaust outlet, the exhaust passage extending through the gearcase, the exhaust passage being configured for supplying exhaust gases from the at least one combustion chamber to an exterior of the gearcase via the exhaust outlet; and 
 an idle relief passage fluidly communicating with the exhaust passage, 
 the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, 
 the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the outboard engine assembly is mounted to a watercraft and the watercraft is at rest; and 
 
   a propulsion device operatively connected to the engine.   
     
     
         2 . The outboard engine assembly of  claim 1 , wherein the idle relief outlet is disposed vertically higher than the gearcase. 
     
     
         3 . The outboard engine assembly of  claim 1 , further comprising an anti-ventilation plate connected to the gearcase; and
 wherein the idle relief outlet is vertically higher than the anti-ventilation plate.   
     
     
         4 . The outboard engine assembly of  claim 1 , wherein the idle relief outlet is disposed on a front side of the engine unit housing. 
     
     
         5 . The outboard engine assembly of  claim 1 , wherein:
 the engine unit further includes:
 a driveshaft operatively connected to and driven by the internal combustion engine; and 
   the propulsion device includes:
 a propeller shaft disposed at least in part in the gearcase, the propeller shaft being operatively connected to and driven by the driveshaft; and 
 a propeller operatively connected to and driven by the propeller shaft. 
   
     
     
         6 . The outboard engine assembly of  claim 5 , wherein:
 the internal combustion engine further comprises a crankshaft operatively connected to the driveshaft for driving the driveshaft, the crankshaft defining a crankshaft axis; and   the idle relief outlet is disposed between the crankshaft axis and an axis of the propeller shaft.   
     
     
         7 . The outboard engine assembly of  claim 1 , further comprising a lower motor mount; and
 wherein the idle relief outlet is aligned with the lower motor mount.   
     
     
         8 . The outboard engine assembly  claim 1 , wherein:
 the internal combustion engine comprises an engine block; and   the idle relief outlet is disposed between an upper side and a lower side of the engine block.   
     
     
         9 . The outboard engine of  claim 1 , wherein the idle relief outlet is disposed between 6 inches to 8 inches below the waterline. 
     
     
         10 . The outboard engine assembly of  claim 1 , wherein:
 the idle relief passage includes an inlet;   the exhaust passage is a high-rise exhaust passage having an apex; and   the inlet of the idle relief passage is positioned downstream from the apex of the high-rise exhaust passage.   
     
     
         11 . The outboard engine assembly of  claim 1 , wherein:
 the idle relief passage further comprises a tube disposed outside the engine housing; and   the tube defines the idle relief outlet and is sized such that the idle relief outlet is below the waterline.   
     
     
         12 . The outboard engine assembly of  claim 1 , further comprising:
 a transom bracket;   wherein the propulsion device further comprises a driveshaft operatively connected to and driven by the internal combustion engine; and   the idle relief outlet is disposed below the transom bracket when an axis of the driveshaft is vertical.   
     
     
         13 . A watercraft comprising:
 a watercraft body; and   an outboard engine assembly pivotably connected to the watercraft body, the outboard engine comprising:
 an engine unit including:
 an engine unit housing; 
 an internal combustion engine disposed in the engine unit housing, 
 
 the engine defining at least one combustion chamber;
 a gearcase connected to the engine unit housing; and 
 an exhaust system including:
 an exhaust passage fluidly communicating with at least one combustion chamber, 
 the exhaust passage having an exhaust outlet, the exhaust passage extending through the gearcase, the exhaust passage being configured for supplying exhaust gases from the at least one combustion chamber to an exterior of the gearcase via the exhaust outlet; and 
 an idle relief passage fluidly communicating with the exhaust passage, 
 the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, 
 the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the watercraft is at rest; and 
 
 
 a propulsion device operably connected to the engine. 
   
     
     
         14 . The watercraft of  claim 13 , wherein:
 the watercraft body comprises a rear platform; and   the outboard engine assembly is connected below the rear platform.   
     
     
         15 . The watercraft of  claim 14 , wherein the idle relief outlet is disposed below the platform. 
     
     
         16 . The watercraft of  claim 13 , wherein the outboard engine assembly further comprises:
 a transom bracket having a watercraft portion connected to the watercraft body; and   the idle relief outlet is disposed longitudinally between the watercraft portion of the transom bracket and the watercraft body.   
     
     
         17 . The watercraft of  claim 13 , wherein:
 the idle relief passage further comprises a tube disposed outside the engine housing; and   the tube defines the idle relief outlet and is sized such that the idle relief outlet is below the waterline.   
     
     
         18 . The watercraft of  claim 13 , wherein:
 the internal combustion engine includes a crankshaft;   the engine unit includes a driveshaft operatively connected to and driven by the crankshaft;   the propulsion device includes:
 a propeller shaft disposed at least in part in the gearcase, the propeller shaft being operatively connected to and driven by the driveshaft; and 
 a propeller operatively connected to and driven by the propeller shaft; and 
   the idle relief outlet is disposed between an axis of the crankshaft and an axis of the propeller shaft.   
     
     
         19 . The watercraft of  claim 13 , wherein:
 the internal combustion engine comprises an engine block; and   the idle relief outlet is disposed between an upper side and a lower side of the engine block.   
     
     
         20 . The watercraft of  claim 13 , wherein:
 the outboard engine assembly further comprises an anti-ventilation plate connected to the gearcase; and   the idle relief outlet is vertically higher than the anti-ventilation plate.