The device of propulsion of ships have of the helices are concentric and against - rotating and ships teams of such a device.

摘要

Marine propulsive device (1) comprising two concentric and contra-rotating propellers (5, 6), rotating at the same speed but in opposite directions, with reversed pitches, said propellers (5, 6) being driven by two primary shafts (3, 4) from either two thermal engines (21, 22) rotating in opposite directions and, each driving a primary shaft, or from a cam engine (2) comprising two concentric primary shafts (3, 4) rotating at the same speed but in opposite directions, such drive means preventing any reaction torque of the ship (1) about the propeller axis (5, 6), the torques of the propellers (5, 6) and of the or both engines. The device is characterized in that the concentric and contra-rotating propellers (5, 6) are placed within a cylindrical shroud, thereby avoiding cavitation and the formation of vortexes generated by each propeller, the shroud (7) being arranged such that its water outlet walls (7) constitute a thrust reverser by closing the water outlet and opening either in two parts or in corolla shape in order to reverse the direction of water flow and provide reverse thrust.