Exhaust gas cleaning device for outboard motor

摘要

Several embodiments of water cooled outboard motors embodying an exhaust system that includes at least one expansion chamber contained within the drive shaft housing and that is provided with a coolant jacket. A catalyst is positioned in the exhaust system within the expansion chamber for treating the exhaust gases delivered from the engine to the expansion chamber. The coolant from the cooling jacket is delivered back to the body of water in which the watercraft is operating without flowing into the expansion chamber so as to protect the catalyst from water damage. In some embodiments, plural expansion chambers are incorporaed. In these other embodiments, the expansion chambers are arranged so as to preclude the likelihood of water impinging on the catalyst if it enters through an underwater exhaust gas discharge opening and also the arrangement is such that water will not contact the catalyst when the outboard motor is tilted up to an out of the water condition.