Patent ID: 6250982
Filing Date: 2001-06-26
Classification: B63H,F01N,F01P,F02B

Abstract:
An outboard motor comprised of a power head and a drive shaft housing and lower unit depending from said power head, said power head containing a powering internal combustion engine and a surrounding protective cowling, a propulsion device contained within said lower unit for propelling an associated watercraft through a body of water in which it is operating, a transmission system for transmitting drive from said engine to said propulsion device, an expansion chamber formed in said drive shaft housing, said expansion chamber being defined by a peripheral wall, an exhaust pipe depending from said engine into said expansion chamber for delivery of exhaust gases to said expansion chamber, a cooling jacket provided along a side of said exhaust pipe and formed integrally with said exhaust pipe, said cooling jacket receiving liquid coolant for cooling said exhaust pipe, and a discharge passage from said cooling jacket is directed toward the peripheral wall of the expansion chamber and away from the exhaust pipe for returning liquid coolant from said cooling jacket to the body of water in which the watercraft is operating.