US Patent 7805792 Pool cleaning robot

The subject of the invention is a pool cleaning robot having a structure for suctioning debris from the bottom of the pool and a propulsion nozzle (5) adapted for directing a propulsive jet of water in a direction opposite to a direction (D1,D2) of movement of the robot, characterized in that the nozzle (5) is rotatably mounted on an axis (z,z′) perpendicular to a plane of movement of the robot, in that the robot has a structure (12,13) for stopping the rotation of the nozzle in at least two essentially opposite directions and structure for controlling (7,71,72) the structure for stopping, equipped so as to be operated by a hydrodynamic force crated by the movement of the robot.