Exhaust system for outboard motors

An outboard motor having a power head comprised of an internal combustion engine having an exhaust port and a surrounding protective cowling, a drive shaft housing and lower unit depending from said power head and containing a propulsion device driven by said engine for propelling associated watercraft, means for affixing said outboard motor to a hull of an associated watercraft, an expansion chamber formed in said drive shaft housing and lower unit and positioned to be at least partially submerged beneath the body of water in which the watercraft is operating at least when the watercraft is stationary, an exhaust pipe extending from said exhaust port into said expansion chamber below the upper end thereof for delivering exhaust gases from said engine to said expansion chamber, an underwater exhaust gas discharge positioned to extend beneath the water level in substantially all running conditions of the watercraft, and exhaust conduit means extending from said expansion chamber to said underwater exhaust gas discharge for delivering exhaust gases from said engine to the atmosphere through the body of water in which said watercraft is operating, said exhaust conduit means including a trap portion for precluding the entry of water into said expansion chamber from said underwater exhaust gas discharge comprised of, a first upwardly extending section extending upwardly from an inlet end in said expansion chamber, a horizontally extending section disposed above the water level and receiving gases from the upwardly extending section at one end thereof, and a downwardly extending section extending from the other end of said horizontally extending section to said underwater exhaust gas discharge, said trap portion being disposed at the level of said engine and in a rear portion of said power head behind said engine.

An outboard motor having a power head comprised of an internal combustion engine having an exhaust port and a surrounding protective cowling, a drive shaft housing and lower unit depending from said power head and containing a propulsion device for propelling an associated watercraft which propulsion device is driven by said engine, means for affixing said outboard motor to a transom of the associated watercraft for pivotal movement about a horizontally disposed tilt axis, an expansion chamber formed in said drive shaft housing and lower unit and positioned to be at least partially submerged beneath the body of water in which the water craft is operating at least when the watercraft is stationary, an exhaust pipe extending from said exhaust port into said expansion chamber below the upper end thereof for delivering exhaust gases from said engine to said expansion chamber, an underwater exhaust gas discharge positioned to extend beneath the water level in substantially all running conditions of the watercraft, and exhaust conduit means extending from said expansion chamber to said underwater exhaust gas discharge for discharging exhaust gases from said engine to the atmosphere through the body of water in which the watercraft is operating, said exhaust conduit means including a trap portion for precluding the entry of water into said expansion chamber from said underwater exhaust gas discharge comprising an upwardly extending section extending upwardly from an inlet end in said expansion chamber, a horizontally extending section disposed entirely on the opposite side of said exhaust pipe from said tilt axis and extending transversely from the upper end of said upwardly extending section and parallel to said tilt pivot axis and a downwardly extending section extending from the other end of said horizontally extending section to said underwater exhaust gas discharge.

An outboard motor having a power head comprised of, a "V" type internal combustion engine having a pair of angularly disposed cylinder banks each having an exhaust port and a surrounding protective cowling, a drive shaft housing and lower unit depending from said power head and containing a propulsion device driven by said engine for propelling associated watercraft, means for affixing said outboard motor to a hull of an associated watercraft, an expansion chamber formed in said drive shaft housing and lower unit in position to be at least partially submerged below the body of water in which the watercraft is operating at least when the watercraft is stationary, an exhaust pipe extending from said exhaust ports into said expansion chamber below the upper end thereof for delivering exhaust gases from said engine to said expansion chamber, an underwater exhaust gas discharge positioned to extend below the water level in substantially all running conditions of the watercraft, and exhaust conduit means extending from said expansion chamber to said underwater exhaust gas discharge to discharge the exhaust gases from said engine to the atmosphere to the body of water in which said watercraft is operating, said exhaust conduit means including a trap portion disposed at least in part in a valley formed between said cylinder banks for precluding the entry of water into said expansion chamber from said underwater exhaust gas discharge comprising, an upwardly extending section extending from an inlet end in said expansion chamber, a horizontally extending section connected at one end to said upwardly extending section and a downwardly extending section extending from the other end of said horizontally extending section to said underwater exhaust gas discharge.

An outboard motor having a power head comprised of an internal combustion engine having a plurality of in line horizontally extending cylinders each having at least one exhaust port and a surrounding protective cowling, a drive shaft housing and lower unit depending from said power head and containing a propulsion device driven by said engine for propelling an associated watercraft to which said outboard motor is attached, said cylinders being inclined to a longitudinally extending vertical plane extending parallel to the direction of the propulsion force and at an acute angle to said longitudinally extending vertical plane, an expansion chamber formed in said drive shaft housing and lower unit, exhaust pipe means for conveying exhaust gases from said exhaust ports to said expansion chamber, an underwater exhaust gas discharge for discharging exhaust gases to the atmosphere through the body of water in which said watercraft is operating and conduit means for conveying exhaust gases to said underwater exhaust gas discharge from said expansion chamber, said conduit means including a trap portion for precluding the entry of water into said expansion chamber from said underwater exhaust gas discharge, said trap portion being contained within said power head apart from said engine and disposed at least in part on the side of said cylinders adjacent said longitudinally extending vertical plane and in part between said cylinders and said plane.

An outboard motor having a power head comprised of an internal combustion engine having an exhaust port and a surrounding protective housing, a drive shaft housing and lower unit depending from said power head and containing a propulsion device driven by said engine for propelling associated watercraft, means for affixing said outboard motor to a hull of an associated watercraft, an expansion chamber formed in said drive shaft housing and lower unit and positioned to be at least partially submerged beneath the body of water in which the watercraft is operating at least when the watercraft is stationary, an exhaust pipe extending from said exhaust port into said expansion chamber below the upper end thereof for delivering exhaust gases from said engine to said expansion chamber, an underwater exhaust gas discharge positioned to extend beneath the water level in substantially all running conditions of the watercraft, and exhaust conduit means extending from said expansion chamber to said underwater exhaust gas discharge for delivering exhaust gases from said engine to the atmosphere through the body of water in which said watercraft is operating, said exhaust conduit means including a trap portion for precluding the entry of water into said expansion chamber from said underwater exhaust gas discharge comprised of, a pair of upwardly extending sections extending upwardly from an inlet end in said expansion chamber, a horizontally extending section disposed above the water level and receiving gases from the upwardly extending section at one end thereof, and a downwardly extending section extending from the other end of said horizontally extending section to said underwater exhaust gas discharge, and a pair of separate catalyst beds each positioned in a respective one of said pair of upwardly extending sections and separated from each other.