Clean pump

摘要

In a clean pump of the present invention, a magnetic coupling is formed by a permanent magnet attached to a rotor and a permanent magnet attached to an impeller, with a combined electromagnet arranged to be opposed to a soft iron member of the impeller at the side opposite to the rotor. The combined electromagnet is provided with a permanent magnet arranged at one side of its core and two coils wound around the permanent magnet. These coils are zero-power controlled by a control circuit based on outputs of position sensors such that the impeller is supported approximately at the center of a casing by an attracting force of the permanent magnets and an attracting force of the permanent magnet of the combined electromagnet.