A vacuum cleaner has a housing that includes a separation chamber and collection chamber, a floor unit with a suction opening, and a passage between the suction opening and separation chamber. A suction source establishes a stream of air from the suction opening to the separation chamber for separation...http://www.google.es/patents/US7293324?utm_source=gb-gplus-sharePatente US7293324 - Vacuum cleaner with level control
