초록 ▼

The marine propulsion device includes a lower unit normally submerged in water, a propeller carried by the lower unit, and an annular shroud surrounding the propeller blades and defining a passageway through which water flows. The shroud, which can be in the form of a Kort-type nozzle for augmenting

The marine propulsion device includes a lower unit normally submerged in water, a propeller carried by the lower unit, and an annular shroud surrounding the propeller blades and defining a passageway through which water flows. The shroud, which can be in the form of a Kort-type nozzle for augmenting propeller thrust, has a trailing edge located rearwardly of the travel path of the propeller blade tips. The trailing edge of the shroud includes an annular recess through which either engine exhaust gases or atmospheric air is delivered to ventilate the low pressure area created behind the trailing edge of the shroud during forward movement of the lower unit through water.

대표청구항 ▼

A marine propulsion device including an engine, a lower unit having a lower portion normally submerged in water and including an exhaust gas passageway communicating with said engine, a rotatable propeller carried by said lower unit, driven by said engine, and having at least one radially extending

A marine propulsion device including an engine, a lower unit having a lower portion normally submerged in water and including an exhaust gas passageway communicating with said engine, a rotatable propeller carried by said lower unit, driven by said engine, and having at least one radially extending blade terminating in an outer tip, an annular Kort-type nozzle surrounding said propeller and defining a venturi-like passageway through which water flows to augment propeller thrust, said nozzle having a trailing end portion terminating in a blunt trailing surface which is located rearwardly of the propeller blade tip travel path and extends transversely of the direction of travel of said lower unit, means for delivering gas from said gas passageway to the area behind said nozzle trailing surface including an annular recess in said nozzle trailing end portion opening rearwardly into the area behind said nozzle, extending forwardly from said nozzle trailing surface, and communicating with said gas passageway, and an anti-cavitation plate on said lower portion located above said nozzle and extending rearwardly beyond said nozzle trailing surfaces for minimizing upward migration of gas from said annular recess.