Patent ID: 7467930
Filing Date: 2008-12-23
Classification: A61M,F04D

Abstract:
1. A magnetically levitated pump, comprising: a pump unit including a disk-shaped impeller for feeding liquid; a magnetic bearing unit provided opposite to one of end faces along an axial direction of said impeller; and a casing unit provided opposite to the other of said end faces; wherein said magnetic bearing unit includes: said pump unit includes: said casing unit includes a casing-side ferromagnetic body provided opposite to said impeller-side ferromagnetic body and attracting said impeller toward said casing unit; said electro-magnet for the magnetic bearing has a magnetizing current flowing therethrough controlled to balance an attractive force between said electro-magnet for the magnetic bearing and said soft magnetic member opposite to the electro-magnet, an attractive force between said impeller-side ferromagnetic body and said casing-side ferromagnetic body, a force acting on said impeller generated by said rotary driving means, and other disturbance influencing said impeller; and opposite surfaces of said impeller-side ferromagnetic body and said casing-side ferromagnetic body are adapted to have mutually different shapes from each other, so that a maximum required attractive force is suppressed between said electro-magnet for the magnetic bearing and said soft magnetic member opposite to the electro-magnet.