Fiber reinforced ceramic matrix composite marine engine riser elbow

Abstract

A corrosion-resistant, thermally insulative riser elbow for a marine engine. The riser elbow has an exhaust gas conduit made of fiber reinforced ceramic matrix composite (FRCMC) material formed from a polymer-derived ceramic resin in its ceramic state and fibers. Employing a FRCMC material results in a low-cost, light-weight, corrosion-resistant exhaust gas conduit not available with existing riser elbows. In addition, a FRCMC exhaust gas conduit is thermally insulative and so more of the heat of the exhaust is retained rather than being transferred to the conduit. This allows the cooling requirements for the riser elbow to be lowered, while still maintaining a touch temperature below prescribed levels. FRCMC can also be formed into practically any shape and size desired and can be very ductile thereby making the exhaust gas conduit fracture resistant and capable of withstanding thermally-induced strains typical of the environment of a marine engine's exhaust system. The riser elbow also includes a water jacket sleeve formed integrally with and surrounding the exhaust gas conduit so as to define a cooling water channel between the outer wall of the exhaust gas conduit and the inner wall of the water jacket sleeve. Preferably, a plastic material capable of withstanding long-term exposure to at least 250 degree Fahrenheit cooling water, which can be salt water, without structural degradation is employed to form the water jacket sleeve. In addition, the plastic material should have a sufficient ductility to withstand handling and thermally-induced strains associated with the riser elbow of a marine engine.

Dependencies are inferred from the claim text.