Cleaning device, in particular for robotic vacuum cleaners

A device for cleaning a horizontal surface, the device comprising:

• (a) a fan having an inlet side and an outlet side;
• (b) a rotary brush comprising a plurality of rotating blades, the rotary brush positioned within a rotary brush chamber which is connected to the inlet side of the fan to create a negative air pressure therein;
• (c) an overpressure subsystem for receiving positive pressure air from the outlet side of the fan and for delivering a high velocity overpressure flow through a flat nozzle onto the horizontal surface in a forward direction toward the rotary brush blades;
• wherein the flat nozzle is elevated above the horizontal surface when the device is disposed on the horizontal surface;
• and
• wherein the flat nozzle has an outlet comprising a convex transfer surface having a convex curvature that, as viewed from the flat nozzle, first curves toward the horizontal surface to a transfer point that is a point of the convex transfer surface that is closest to the horizontal surface and then curves away from the horizontal surface to a raised trailing edge adjacent the rotary brush chamber, the convex transfer surface being disposed and arranged within the device such that as the high velocity overpressure flow leaves the flat nozzle it passes along the convex curvature between the convex transfer surface and the horizontal surface until the high velocity overpressure flow reaches the transfer point on the convex transfer surface whereupon the flow of air is tangential to the horizontal surface and a change in static pressure acting on the high velocity overpressure flow by virtue of the convex curvature of the convex transfer surface causes the flow of air to pass along the horizontal surface in the forward direction toward the rotary brush blades.