Exhaust passage structure for an outboard motor

Abstract

An exhaust passage structure for an outboard motor is provided to prevent exhaust emission interference from occurring while employing a simple construction and without increasing the engine size. In an outboard motor 1 equipped with an engine 5 having a cylinder block 16 comprising a plurality of cylinders arranged in parallel to each other with an exhaust port 32 for each cylinder being formed in a cylinder head 15 that is joined with the cylinder block 16, exhaust passages 39 are formed in an exhaust manifold 25 for connecting each of the exhaust ports 32 and an exhaust discharge path 38 formed on the outboard motor 1 side, while all the exhaust passages 39 are joined after joining the exhaust passages 39-1 and 39-4 from the cylinders where combustion takes place in odd-numbered cycles and the exhaust passages 39-2 and 39-3 from the cylinders where combustion takes place in even-numbered cycles separately, with the exhaust passages 39 that are joined separately being disposed in parallel to each other in the longitudinal direction of the outboard motor 1.

Dependencies are inferred from the claim text.