Exhaust arrangements for marine propulsion devices

摘要

A marine propulsion device and a method of making a marine propulsion device including an internal combustion engine that discharges exhaust gases. The internal combustion engine has first and second castings. A first exhaust flow passage is in the first casting and a second exhaust flow passage is in the second casting. The second exhaust flow passage has a first and second leg that are transversely oriented to each other. A catalyst is disposed in the second exhaust flow passage and configured to treat the exhaust gases. A flow control element is between the first and second flow passages. The flow control element forms a smooth transition that is devoid of edges such that the exhaust gases flow across and are dispersed by the flow control element before being treated by the catalyst.

主权项

1. A marine propulsion device comprising:
an internal combustion engine that discharges exhaust gases, the internal combustion engine comprising first and second engine castings; a first exhaust flow passage in the first casting and a second exhaust flow passage in the second casting; 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; a catalyst disposed in the second exhaust flow passage and configured to treat the exhaust gases; and a flow control element between the upstream first leg and downstream second leg, the flow control element forming a smooth transition that is devoid of edges such that the exhaust gases flow across and are dispersed by the flow control element before being treated by the catalyst; wherein the engine comprises a crankcase, a cylinder block, and a cylinder head; a driveshaft housing that is located vertically below the engine; wherein the cylinder block has at least one piston-cylinder and wherein the cylinder head has at least one exhaust outlet that is configured to discharge the exhaust gases from the piston-cylinder; wherein the first exhaust flow passage is formed in the cylinder head and wherein the second exhaust flow passage is formed by the crankcase and the driveshaft housing; and wherein the flow control element comprises an extension having a first planar surface that abuts the second casting, a second planar surface that is parallel to the first planar surface and that faces the first exhaust flow passage, and a curved outer transition surface that connects the first and second planar surfaces, the curved outer transition surface being devoid of edges.