A fluid pump with rotary impeller is disclosed which comprises an electromagnetically driven rotary impeller levitated by localized opposed fluid forces. Levitation by localized opposed fluid forces of an impeller driven by electromagnetic forces eliminates the need for bearings and seals in the driving...http://www.google.com.hk/patents/US5055005?utm_source=gb-gplus-share專利 US5055005 - Fluid pump with levitated impeller
