Patent ID: 7641527

Claim:
A marine outboard engine comprising: an upper motor cover; a lower cover disposed vertically below the upper motor cover; an engine disposed at least in part in the upper motor cover; a driveshaft disposed generally vertically in the lower cover, the driveshaft having a first end and a second end, the first end of the driveshaft being operatively connected to the engine; a gear case connected to the lower cover; a rotor shaft disposed at least in part in the gear case generally perpendicular to the driveshaft, the rotor shaft being operatively connected to the second end of the driveshaft; a bladed rotor connected to the rotor shaft; a first exhaust housing disposed in the lower cover below the engine, the first exhaust housing having a left side, a right side, a front side, and a rear side; a second exhaust housing disposed in the lower cover below the engine, the second exhaust housing at least partially surrounding the first exhaust housing; a first exhaust chamber formed by the first exhaust housing, the first exhaust chamber fluidly communicating with the engine; a second exhaust chamber formed between the second exhaust housing and at least a portion of at least two of the left, right, front, and rear sides of the first exhaust housing, the second exhaust chamber fluidly communicating with the first exhaust chamber; and a third exhaust chamber formed between the second exhaust housing and at least a portion of at least two of the left, right, front, and rear sides of the first exhaust housing below the second exhaust chamber, the third exhaust chamber fluidly communicating with the second exhaust chamber and an exterior of the marine outboard engine; wherein exhaust gases from the engine flow to the first exhaust chamber, from the first exhaust chamber to the second exhaust chamber, from the second exhaust chamber to the third exhaust chamber, and from the third exhaust chamber to the exterior of the marine outboard engine.