Exhaust arrangements for marine propulsion devices

摘要

An internal combustion engine and a method of forming an internal combustion engine are for a marine propulsion device. A first engine casting defines a first flow passage configured to receive the exhaust gases from a piston-cylinder. A die cast second engine casting defines a second flow passage that is configured to receive the exhaust gases from the first flow passage and convey the exhaust gases to a catalyst. The second flow passage has an upstream first leg that is parallel to the first flow passage and a downstream second leg that is transversely oriented to the first leg. An inside corner is between the first and second legs. The second flow passage has an inlet end that is configured to receive exhaust gases from the first flow passage. The first flow passage has an outlet end that is configured to convey exhaust gases to the inlet end of the second flow passage. The outlet end of the first flow passage is sized smaller than the inlet end of the second flow passage so that exhaust gases are directed away from the inside corner as the exhaust gases travel from the outlet end of the first flow passage to the inlet end of the second flow passage.

主权项

1. An internal combustion engine for a marine propulsion device, the internal combustion engine comprising:
a piston-cylinder that discharges exhaust gases, a first engine casting that defines a first flow passage configured to receive the exhaust gases from the piston-cylinder, and a second engine casting that defines a second flow passage configured to receive the exhaust gases from the first flow passage and convey the exhaust gases to a catalyst; wherein the second flow passage has an upstream first leg that is parallel to the first flow passage, and a downstream second leg that is transversely oriented to the first leg; wherein the first and second flow passages face each other at a planar mounting face between the first and second engine castings; an inside corner between the first and second legs; wherein the second flow passage has an inlet end that is configured to receive the exhaust gases from the first flow passage; wherein the first flow passage has an outlet end that is configured to convey the exhaust gases to the inlet end of the second flow passage; wherein the outlet end of the first flow passage is sized smaller than the inlet end of the second flow passage so that the exhaust gases are directed away from the inside corner as the exhaust gases travel from the outlet end of the first flow passage to the inlet end of the second flow passage; and wherein the first and second flow passages together form a smooth outside radius along which the exhaust gases travel, away from the inside corner.