US Patent 7360275 Dirt separation system for a vacuum cleaner

A vacuum cleaner includes a dirt separation system that has a dirt cup retaining a filter assembly having a screen element, an exit, and a filter element disposed between the screen element and the exit. A nozzle disposed in the dirt cup directs an airstream generally parallel to the surface of the screen element so that particles in the airstream are primarily separated by the screen element and, as the airstream ultimately travels towards the exit in the dirt cup, are secondarily separated by the filter element.