A magnet pump in which an impeller having a permanent magnet embedded therein is rotatably driven by a magnetic force from the outside of the impeller is disclosed. The pump comprises a pump casing including a suction port,Magnetic pumps a discharge port and a pumping chamber in which the impeller is contained. The impeller is rotatably contained in the pumping chamber of the casing and has the permanent magnet embedded therein. A pair of bearings, one being fixed to the casing and the other being fixed to the impeller is provided. A magnetic force driving mechanism constitutes a means for affording the magnetic force on the permanent magnet within the impeller to rotatably drive the latter. The magnetic force driving mechanism is mounted on a non-liquid-contacting portion of the casing at a position facing the impeller in respect to the direction of the rotary shaft axis of the impeller.Vacuum pumps A fluid inlet passage for communicating between the suction port and the pumping chamber is formed to pass through the center portion of the magnetic force driving mechanism. In a magnetically levitated pump, an impeller-side ferromagnetic body (second ferromagnetic body) provided on a circumferential surface of an impeller facing a casing unit on the side of a position sensor and a casing-side ferromagnetic body (third ferromagnetic body) opposite to the impeller-side ferromagnetic body (second ferromagnetic body) to attract the impeller toward the casing unit on the side of the position sensor are adapted to have opposite portions of mutually different shapes, so that the maximum required attractive force of an electro-magnet for magnetic bearing is suppressed and length of the electro-magnet for magnetic bearing is made shorter.

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2011-12-23

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